Stresses of Cucurbits: Current Status and Management [1st ed.] 9789811578908, 9789811578915

Table of contents :
Front Matter ....Pages i-xvi
An Introduction to Cucurbits (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 1-46
Insect Pests and Non-insect Pests of Cucurbits (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 47-113
Deaseas of Cucurbits and Their Management (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 115-222
Weed and Its Management in Cucurbitaceous Vegetables (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 223-237
Abiotic Stresses: Nutritional and Physiological Disorders (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 239-256
Breeding of Cucurbits for Resistance Against Biotic Stresses (Bholanath Mondal, Chandan Kumar Mondal, Palash Mondal)....Pages 257-260
Back Matter ....Pages 261-297

Citation preview

Bholanath Mondal Chandan Kumar Mondal Palash Mondal

Stresses of Cucurbits: Current Status and Management

Stresses of Cucurbits: Current Status and Management

Bholanath Mondal • Chandan Kumar Mondal • Palash Mondal

Stresses of Cucurbits: Current Status and Management

Bholanath Mondal Department of Plant Pathology Palli-Siksha Bhavana (Institute of Agriculture), Visva-Bharati Bolpur, West Bengal, India

Chandan Kumar Mondal Department of Horticulture Ramkrishna Ashram Krishi Vigyan Kendra Nimpith, West Bengal, India

Palash Mondal Department of Agricultural Entomology Palli-Siksha Bhavana (Institute of Agriculture), Visva-Bharati Bolpur, West Bengal, India

ISBN 978-981-15-7890-8 ISBN 978-981-15-7891-5 https://doi.org/10.1007/978-981-15-7891-5

(eBook)

# Springer Nature Singapore Pte Ltd. 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Foreword

Agricultural land is shrinking day by day due to the modernization of our society. This has resulted in a drastic reduction of per capita cultivable land holding capacity in the world. Though vegetables still now have not come under staple food for the vast population of the world, it potentially plays a major role in global food security. Cucurbits are a vast group of vegetables grown almost throughout the world. Part of the daily diet of the majority of people around the world is comprised of cucurbitaceous vegetables. The vegetables are a very good source of nutrients and can be a remedy for those people who are suffering from undernourishment. It gives me a full satisfaction that the book entitled “STRESSES OF CUCURBITS: CURRENT STATUS AND MANAGEMENT” is an excellent combined effort by the authors to enlighten every aspect for successful production of these vegetables. It also gives me an immense pleasure that in the book special attention has been paid by the authors for the students so that they can use it as a textbook for their academic syllabus. There are numerous books and articles available on cucurbits but comprehensive and up-to-date information regarding cucurbit cultivation is lacking in them. However, the aspects of cucurbits cultivation and management of different abiotic and biotic stresses have efficiently and effectively been addressed in this unique book. Definitely, Dr. Bholanath Mondal, Dr. Chandan Kumar Mondal and Dr. Palash Mondal deserve credit for such joint contribution. I am sure that this book will provide to be a useful guide for the researchers, scientists, teachers, students, extension workers, vegetable growers and policymakers as well. I wish all success of this publication. Retired Professor, Palli-Siksha Bhavana (Institute of Agriculture), Visva-Bharati Santiniketan, West Bengal, India

Debabrata Das Gupta

Former Vice-Chancellor, Bidhan Chandra Krishi Viswavidyalaya Mohapur, West Bengal, India

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Preface

Available land for cultivation is shrinking day by day due to rapid urbanization and industrialization. Conversely, the human population in the world is increasing at a sharp rate which urgently needs the demand for higher production of food. Vegetables are the miraculous example that can meet up the growing demand of this planet. The vegetables are not only rich in different kinds of nutrients but also fetch good remuneration globally. With the advent of improved cultivation techniques and more efforts on crop production research, vegetables are now cultivated all the year round and thus meeting the demand for the daily dietary requirement of ever-increasing population of the world. However, this intensification of vegetable production makes the crops more prone to abiotic and biotic stresses which severely reduce the yield and quality of vegetables. Like other vegetables, cucurbits are also highly prone to attack by different pests due to its tenderness and softness of the crops. To mitigate these biotic stresses, a concomitant expansion in the use of synthetic pesticides has already been witnessed by us. So, concerns over potential health and environmental dangers, increased pest resistance to pesticides and continued prevalence of pest-induced crop losses have stimulated the search for better understanding of this diverse group of vegetables. This book is meant to give the reader a holistic appreciation of the importance of cucurbitaceous vegetables and also deals comprehensively on these issues for better cultivation of cucurbits in a sustainable way. We hope that the book will be useful to all the users including farmers, farm advisors, students, scientists, agriculture researchers, agriculture practitioners as well as plant protection specialists. Many photographs have been incorporated in this book for better and easy understanding of different topics. We sincerely acknowledge the contribution of those resource persons who have uploaded the photos, figures, documents in the public domain as many of their helpful information have been incorporated during the writing of this book. Suggestions to improve the contents of the book are most welcome.

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About the Book

In global vegetable production, India ranks second only after China. Vegetables are important in the daily diet not only for the diversity in the menu but it is also the only natural means of boosting the human immune system. It ensures health and nutritional security by supplying vitamins and minerals, which, in other ways, are not so easily available, as well as acceptable to the human body system. Conversely, vegetable cultivation nowadays has become an entrepreneurial activity for small farmers, providing employment opportunity to a vast number of rural youths. Among different vegetables, cucurbit is the big group of almost indigenous vegetables, grown all over the country (or subcontinent) since time immemorial. The members of this big family are tropical in nature and fetch several biotic and abiotic stresses. These stresses cause severe losses in both yield and quality. Intensive farming practices, climatic vulnerability and rapid shift in vegetable ecosystem ultimately increase these stresses day by day. Stresses like insects, mites, nematodes, bacteria, fungi, weeds, rodents, etc. are the most significant biotic stresses, which are responsible in limiting potential productivity as well as quality deterioration of produces. Application of hazardous toxic chemicals to combat these pests of cucurbits not only results in a continuous increase in residual toxicity in the produce as well as in nature but also paralyzing agro-ecosystem. Again, changes in climatic condition and increased use of modern agro-technology towards intensive farming make these problems more and more complex. Besides, abiotic stresses such as drought (water stress), excessive watering (waterlogging), extreme temperatures (cold, frost and heat), salinity and mineral toxicity, nutrient deficiency, etc. play negatively on the growth and development of the crops. In this backdrop, updated and alternative information with regard to holistic management of crops as well as its problems is of urgent need for successful and profitable production of cucurbit vegetables. The book contains complete information on all the issues regarding the problems and panacea for the successful production of these particular vegetables. The book will cover all the issues related with these aspects, i.e. about cucurbits, holistic crop management including abiotic stresses, management of insect pests, diseases, mites, nematodes, weeds, rodents and other vertebrates with latest information, findings and approaches. It will be helpful for agricultural students (both UG and PG level including PhD), amateur gardeners, corporate farming personnel, horti-enthusiasts extension ix

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About the Book

workers, policymakers, etc. in India and abroad. The book is divided into 13 sections. Each of these sections is further divided into one or more subsections for better understanding. Numerous figures and tables are included to facilitate the comprehension of the presented material. Related colour photographs have also been incorporated. It will be a treasure of knowledge with regard to the management of cucurbitaceous vegetables for better productivity and remunerative cultivation. The authors are from Visva-Bharati, Santiniketan, West Bengal and Ramkrishna Ashram Krishi Vigyan Kendra (ICAR), Nimpith, West Bengal having vast knowledge and experience in teaching, research and extension in this sector.

Contents

An Introduction to Cucurbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Importance of Cucurbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Commonly Grown Cucurbits in India . . . . . . . . . . . . . . . . . . . . . . . . 4 Botany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Crop-Wise Important Varieties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Soil and Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Package of Practices for Cultivation of Different Cucurbits . . . . . . . . 7.1 Agronomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Nutrient Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Intercultural Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 1 2 2 7 9 9 40 40 40 42 45

Insect Pests and Non-insect Pests of Cucurbits . . . . . . . . . . . . . . . . . . . 1 Insect Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Fruit Fly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Pumpkin Beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Hadda Beetle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Pumpkin Caterpillar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Snake Gourd Semilooper . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Bottle Gourd Plume Moth . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 Stem Gall Fly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 Serpentine Leaf Miner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 Stem Borer or Clear Winged Moth . . . . . . . . . . . . . . . . . . . . . 1.10 Flea Beetle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11 Aphids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.12 Blister Beetle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.13 Leaf Footed Plant Bug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.14 Stink Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.15 Stem Boring Beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.16 Melon Thrips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . .

47 47 47 55 59 64 68 69 71 73 76 80 82 85 88 91 94 97

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Contents

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101 101 106 106 110

Deaseas of Cucurbits and Their Management . . . . . . . . . . . . . . . . . . . . 1 Fungal Diseases of Cucurbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Root Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Leaf Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Stem Rot, Vine Rot or Collar Rot Diseases . . . . . . . . . . . . . . . . 1.4 Fruit Rot Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Bacterial Diseases of Cucurbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Angular Leaf Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Bacterial Leaf Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Bacterial Wilt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Bacterial Soft Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Bacterial Rind Necrosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 Bacterial Fruit Blotch of Watermelon . . . . . . . . . . . . . . . . . . . . 3 Diseases Caused by Phytoplasmas . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Phyllody . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Witches’ Broom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Little Leaf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Post-Harvest Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Cottony Rot Caused by Fusarium spp. . . . . . . . . . . . . . . . . . . . 4.2 Cottony Leak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Soft Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Stem End Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Brown Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Calyx End Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Grey White Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 Green Mould Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 Dirty Grey Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10 Waxy Rot or Sour Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.11 Anthracnose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12 Charcoal Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.13 Black Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.14 Physiological Ripening/Yellowing . . . . . . . . . . . . . . . . . . . . . . 4.15 Management of Post-Harvest Diseases . . . . . . . . . . . . . . . . . . . 5 Viral Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Mosaic Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Cucumber Mosaic Virus (Cucumovirus) . . . . . . . . . . . . . . . . . . 5.3 Cucumber Green Mottle Mosaic Virus (Tobamovirus) . . . . . . . . 5.4 Watermelon Mosaic Virus (WMV) (Potyviruses) . . . . . . . . . . . 5.5 Pumpkin Yellow Vein Mosaic Virus (Geminiviruses) . . . . . . . .

115 115 118 133 154 160 171 171 173 174 176 177 178 180 180 181 181 182 183 186 187 188 189 190 190 190 191 191 192 193 193 193 195 197 200 201 203 206 208

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Mite Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Red Spider Mite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vertbrate Pest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Rats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Other Vertebrate Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents

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209 210 210 211 217 217 219 220

Weed and Its Management in Cucurbitaceous Vegetables . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Some Important Weeds Infesting Cucurbits . . . . . . . . . . . . . . . . . . . . . 2.1 Broad Leaf Weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Sedges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Weed Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

223 223 224 224 227 227 228

Abiotic Stresses: Nutritional and Physiological Disorders . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Nitrogen Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Phosphorus Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Potassium Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Iron Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Manganese Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Molybdenum Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Zinc Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Boron Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Calcium Deficiency (Blossom End Rot) . . . . . . . . . . . . . . . . . . . . . . . 11 Magnesium Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Fertilizer Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Pesticide Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Salt Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Chilling Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Solar Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Excess Soil Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Air Pollution Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Premature Senescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Vein Tract Browning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Misshapen Fruits or Bottle Neck of Fruit . . . . . . . . . . . . . . . . . . . . . .

239 239 242 243 243 245 246 247 248 249 250 251 251 252 253 253 254 254 255 255 255 256

6 7

5.6 Tobacco Ring Spot Virus (Nepovirus) . . . . . . . . . . . . . . . . . . 5.7 Cucumber Latent Virus (CLV) . . . . . . . . . . . . . . . . . . . . . . . . 5.8 Zucchini Yellow Mosaic Virus (ZYMV) . . . . . . . . . . . . . . . . 5.9 Management of Viral Diseases . . . . . . . . . . . . . . . . . . . . . . . . Angiospermic Parasite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Broomrape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diseases Caused by Nematodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Root-Knot of Cucurbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Breeding of Cucurbits for Resistance Against Biotic Stresses . . . . . . . . . 257 Some Important Plates Related to Cucurbit Cultivation . . . . . . . . . . . . . 261 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

About the Authors

Bholanath Mondal, Assistant Professor, Department of Plant Pathology, PalliSiksha Bhavana, Visva-Bharati, has over 12 years of teaching, research and extension experience. He has honoured with Fellow of SAS Society and received Outstanding Paper Award from Department of Science and Technology, GoWB. He is an editorial board member of different journals, acted as Chief Editor of the Journal Green Technology, organized numbers of national and international conferences and published over 55 research articles, 15 book chapters, three booklets, many popular articles, five practical manuals and eight books. He is associated with many research projects and has guided six PhD scholars and ten Master’s students for their dissertation works. He has conferred with Young Scientist Award, Best Young Scientist Award, Rashtriya Gaurav Award and Mahatma Gandhi Lifetime Achievement Award for his contribution in Agriculture. Chandan Kumar Mondal, Eminent Horticulture Scientist, gained vast experience during his 15 years of service at Ramkrishna Ashram Krishi Vigyan Kendra, Nimpith. He is associated with several research projects and has standardized different new technologies on vegetable, fruit and plantation crops cultivation. He is also attached as Guest Faculty at Department of Horticulture, Institute of Agricultural Science, University of Calcutta and has guided seven Master’s students for their dissertation works. He has published 27 research papers, developed several extension literature, four books, five booklets and three book chapters. He was conferred with the Best Young Scientist Award (Horticulture) and Best Krishi Vigyan Kendra Scientist Award (Horticulture) at National level during 2016 and 2020 respectively. Palash Mondal, Assistant Professor, Department of Agricultural Entomology, PalliSiksha Bhavana, Visva-Bharati, has over 18 years of experience in teaching, research and extension. He was the recipient of Merit Scholarship of ICAR and Senior Research Fellowship of CSIR. He is a member of various scientific societies and associated with the editorial board of some peer-reviewed journals. He was associated with an international project sponsored by DFID, London. Presently, a

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About the Authors

number of research projects are under his supervision. He has published 65 research papers, number of extension articles, ten book chapters, two books and a handful of laboratory manuals. He has guided nine PhD scholars and 16 Master’s students in the field of agricultural entomology.

An Introduction to Cucurbits

1

Introduction

Among the vegetables, cucurbits form one of the largest groups with their wide adaptation from arid climates to the humid tropics. The term ‘Cucurbits’ was coined by Liberty Hyde Bailey for cultivated species of the family Cucurbitaceae (Robinson and Decker-Walters 1997). The family Cucurbitaceae consists of about 825 species in around 118 genera (Jeffrey 1990). In Asia, nearly 23 edible major and minor cucurbits are grown and consumed. They are grown mainly in summer and rainy seasons in India and even in winter in some parts of southern and western India as both annual and perennial crops. Cucurbits are frost sensitive, mostly tendril-bearing vines and the members of this broad family are mostly of tropical and subtropical origin. A few numbers of species that are native to or cultivated in temperate climate are prolific seed producing annuals or perennials that live for one season until killed by frost. The Cucurbitaceae family is divided into two sub-families: Zanonioideae and Cucurbitoideae. Cucurbitoideae contains the plants of economic importance, which would be discussed here. Most important genera of this sub-family are as follows: Genera Lagenaria Momordica Luffa Cucurbita Cucumis Citrullus

Type Gourds Gourds (with spiny/warted, edible skinned fruit) Gourds (fibrous fruit) Pumpkin, Squashes Cucumber and some melons Watermelon and others

# Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_1

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An Introduction to Cucurbits

Importance of Cucurbits

• Gourds and pumpkins are consumed as vegetables after cooking; Melons (watermelon, muskmelon, etc.) are consumed mainly as desert fruits and cucumber is usually taken as salad. • Ash gourd and pointed gourd fruits are used in making ketchups, sweets and candies. • Leaves and shoots of many species are boiled and eaten as a vegetable in both Africa and Asia. • Some of the crops are well known for their unique medicinal properties. Fruits (including seeds) usually contain several bioactive compounds such as cucurbitacins, triterpenes, sterols and alkaloids. Cucurbitacins are a group of bitter triterpenes, confined mainly to the seeds of Cucurbitaceae (Bisognin 2002). • Cucurbits are actively used as traditional herbal remedies for various diseases such as anti-inflammatory, antitumor, hepatoprotective, cardiovascular and immunoregulatory activities (Rajasree et al. 2016). It is purported that pointed gourd possesses the medicinal property of lowering total cholesterol and blood sugar. • Cucurbitaceous vegetables are in general a good source of vitamin A and C and various other vital minerals (Table 1). These vegetables, as rich in vitamin A, help to promote healthy wound healing by activating collagen synthesis through stimulating the body’s natural inflammatory response (Priya 2017). • Due to their low carbohydrate content and the ability to supply of certain amount of minerals and vitamins (Table 1), it is highly recommended for diabetics. • Luffas are used as natural sponges, an indispensable part of bathing in most of the Asian and African countries. • Lagenaria siceraria, the bottle gourd, has been in use as vessels in African and Asian cultures by many societies in varied and attractive ways. It was, perhaps, first used as a water carrier, but quickly found diverse uses in making pipes, snuff boxes, musical instruments, salt keeping cages, cricket cages, interior decoration of light and even life jackets. Containers crafted from the fruit rind of the gourd were in constant use as bottles for carrying wine and water, making the name "bottle gourd" especially appropriate for the crop. A host of musical instruments were also fashioned from bottle gourds, which are in use in Eastern India including Bangladesh, even today.

3

Commonly Grown Cucurbits in India

The cucurbits are mostly of tropical and subtropical origin. The cultivated types as well as their wild relatives are distributed in Asia (specifically South-East Asia), Topical America and Africa. Details of different cucurbits commonly grown in India are given in Table 2.

Vegetables Bottle gourd Bitter gourd (small) Bitter gourd (large) Spine gourd Ridge gourd Sponge gourd Pumpkin (ripe) Winter squash Summer squash Wax gourd Snake gourd Pointed gourd Cucumber Muskmelon Snapmelon Watermelon Round melon/Indian squash

Carbohydrates (g) 2.5 10.6

4.2

7.7 3.4 2.9 4.6

6.6

3.5

1.9 3.3 2.2 2.5 3.5 3 3.3 3.4

Moisture (g) 69.1 83.2

92.4

84.1 95.2 93.2 86

86

94.8

96.5 94.6 92 96.1 95.2 95.7 95.8 93.5

0.4 0.5 2 0.4 0.3 0.3 0.2 1.4

1

1.1

3.1 0.5 0.5 1.4

1.6

Protien (g) 0.2 2.1

0.1 0.3 0.3 0.1 0.2 0.1 0.2 0.2

0.1

0.2

1 0.1 0.1 0.1

0.2

Fat (g) 0.1 1

0 160 255 0 3420 265 590 23

260

3300

2596 56 120 2180

210

Vit A (IU) 0 210

0.06 0.04 0.05 0.03 0.11 – 0.02 0.04

0.05

0.03

0.05 0.01 0.02 0.06

0.07

Vit B-1 (thiamine) (mg) 0.03 0.07

0.1 0.06 0.06 0.01 0.08 – 0.04 0.08

0.03

0.05

0.18 0.01 0.06 0.04

0.09

Vit B-2 (riboflavin) (mg) 0.01 0.06

Table 1 Nutritive value of cultivated cucurbits (Per 100 g edible portion on fresh weight basis)

1 0 29 7 26 10 1 18

18

6

0 5 0 2

88

Vit C (ascorbic acid) (mg) 6 96

30 26 30 10 32 – 11 25

10

14.2

33 18 36 10

20

Calcium (mg) 20 23

0.8 0.3 1.7 1.5 1.4 – 7.9 0.9

0.6

0.4

4.6 5 1.1 0.7

1.8

Iron (mg) 0.7 2

(continued)

20 20 40 25 14 – 12 24

30

20.9

42 26 19 30

70

Phosphorus (mg) 10 38

3 Commonly Grown Cucurbits in India 3

Vegetables Ivy gourd Mirliton squash/ chayote

Moisture (g) 93.5 92.5

Table 1 (continued)

Carbohydrates (g) 3.1 5.7

Protien (g) 1.2 0.7

Fat (g) 0.1 0.1

Vit A (IU) 249 50

Vit B-1 (thiamine) (mg) 0.07 0.06

Vit B-2 (riboflavin) (mg) 0.08 0.02

Vit C (ascorbic acid) (mg) 15 15 Calcium (mg) 40 50

Iron (mg) 1.4 0.4

Phosphorus (mg) 30 22

4 An Introduction to Cucurbits

Pumpkin

Winter squash Summer squash

Wax or ash gourd

Snake gourd

Pointed gourd Cucumber Muskmelon Snapmelon Long or serpent melon

7

8 9

10

11

12 13 14 15 16

6

Parwal Khira Kharbuza Phoot Kakri

Chinchinda

Sitaphal/ Kashiphal Kaddu Chappan kaddu Petha

Ghia tori

Kali tori

Trichosanthes cucumerina (syn. T. anguina L.) Trichosanthes dioica Roxb. Cucumis sativus L. Cucumis melo L. Cucumis melo var. momordica Cucumis melo var. utilissimus

Benincasa hispida (Thunb.) Cogn.

Luffa cylindrica (L.) Roem (syn. L. aegyptiaca) Cucurbita moschata (Duch. Ex. Lam.) Duch & Poir Cucurbita maxima Duch Cucurbita pepo L.

22 14 24 24 24

22

24

40 40

40

26

26

South East Asia, India, Burma Africa, Asia (India) Africa, Iran Iran, India India

South East Asia, India, China, Malaysia India

South America North and Central America

Central America

Tropical Asia, India

Tropical Asia, India

Ribbed or ridge gourd Sponge gourd

Momordica cochinchinensis (Lour.) Spreng Luffa acutangula (L.) Roxb.

(continued)

Dioecious Monoecious Monoecious Monoecious Monoecious

Monoecious

Monoecious

Monoecious Monoecious

Monoecious

Monoecious

Monoecious

Dioecious

5

Kheksa

28

Sweet gourd

Sex expression Monoecious Monoecious Dioecious

4

Centre of origin Central Africa, India China, Malaysia, India Asia (extensive distribution in India and Bangladesh) Southeast Asia

Common name Bottle gourd Bitter gourd Spine gourd

Sl. no. 1 2 3

2n number 22 22 28

Table 2 Important information of some cultivated cucurbits Botanical name Lagenaria siceraria (Mol.) Standl. Momordica charantia L. Momordica dioica Roxb.

Commonly Grown Cucurbits in India

Indian name Louki Karela Kakrol

3 5

Sparrow gourd

Mirliton squash/ chayote

20

21

Sechium edule (Jacq) Sw.

Coccinia grandis (L.) Voigt (syn. C. cordifolia) Cyclanthera pedata Schrad.

Kundru or Tondli Meetha Karela Chow chow

Tinda

Botanical name Citrullus lanatus (Thunb.) (syn. C. vulgaris Schrad) Praecitrullus fistulosus Pang.

Indian name Tarbuz

24

32

24

24

2n number 22

Central America

Andean South America

India

India

Centre of origin Kalahari Dessert, Africa

Monoecious

Monoecious

Dioecious

Monoecious

Sex expression Monoecious

a Coccinia indica Wight & Arn (syn. Cephalandra indica), a wild monoecious relative of Coccinia is used as edible vegetable in parts of Eastern and NorthEastern India and Bangladesh. It is believed to have good medicinal properties like lowering blood sugar and blood cholesterol level

19

Round melon/Indian squash Ivy gourda

Common name Watermelon

18

Sl. no. 17

Table 2 (continued)

6 An Introduction to Cucurbits

4

Botany

7

In addition to above, there are some underutilized cucurbitaceous vegetables viz. Cucumis hystrix, Cucumis trigonus, Luffa graveolens, Momordica macrophylla, Momordica subangulata, Trichosanthes khasiana, Trichosanthes ovata and Trichosanthes truncata, which are grown and consumed mostly by the local peoples of North-Eastern region of India.

4

Botany

1. Cucurbits are herbaceous annuals or perennials with a long tap root and lateral roots, usually confined to a depth of 60 cm; however, in Cucurbita sp., the root can go deep to 170 cm to 180 cm. For this reason, these crops are suitable for growing in river bed system to utilize the subterranean moisture. Some of the cucurbits also have xerophytic nature. 2. The plants grow either prostrate along the ground or climb using tendrils. The stems are branched; root may appear in nodes when it comes in contact with moist soil. Some cucurbits (like summer squash, some genotypes of muskmelon, watermelon) show erect or bush like growth habit due to its shorter internodes. 3. The tendrils are borne at the axils of leaves and can grow either simple (in Cucumis, Momordica and Benincasa) or branched. Bush types do not possess tendrils. 4. Leaves can range from simple (3–5 lobed), cordate, reniform to palmately compound. Deeply lobed or nearly pinnatifid leaves are found in Citrullus. Those leaves that develop later are more deeply lobed and extra-floral nectaries are often found. 5. Inflorescence is axillary and solitary or clustered or racemose. The flowers are usually large, attractive, mostly unisexual and monoecious. Other sex forms like andromonoecious (in muskmelon), gynomonoecious, gynoecious (in cucumber) and hermaphrodite (in ridge gourd) are also available. Gynoecious sex form is used for producing hybrids in cucumber. 6. Dioecy is present in some of the cucurbits like Spine gourd, Sweet gourd, Pointed gourd and Ivy gourd. 7. All female flowers of cucurbitaceae show prominent large inferior ovary. Exceptionally, in pumpkin, the staminate flowers converting into hermaphrodite have superior ovary—an unusual phenomenon in cucurbits (Singh 2013). 8. As the cucurbit species are mostly unisexual and male and female flowers are borne separately, the pollination and fruit setting are governed by insect pollinators. The typical pollinators are bees and moths. However, sometimes, rich supply of nectar and pollen within the flowers draw hummingbirds and bats. 9. Majority of cucurbits starts flowering in 30–45 days after sowing (Gopalakrishnan 2007). The first 4 to 6 flowering nodes bear male flower, and then female flowers appear in few nodes. Usually the ratio of male to female flower in monoecious cucurbits varies from 25–30:1 to 15:1 (Pessarakli 2016). The lower the male flower population, the higher would be the economic gain.

8

An Introduction to Cucurbits

High Nitrogen content, long days and high temperature accelerate male flower appearance. 10. For different cucurbit crops, the flowering/anthesis time are different, which are discussed hereunder (as per Singh 2013; Pessarakli 2016): a. The pumpkin group (Cucurbita sp.) usually flowers at early morning. Anthesis occurs between 04:30 h and 04:50 h. b. In Momordica, anthesis starts by 04:00 h and gets completed by 09:00 h, with anther dehiscence between 05:00 h to 07:30 h. Stigma is receptive 24 h before and after anthesis. c. In Spine gourd (M. dioica) both staminate and pistillate flowers are solitary, axillary and light yellow in colour. Anthesis of both flowers takes place in the evening/night in between 19:30 h. and 21:00 h. Closing of petals continues till 6:00 a.m. and beyond. Pollination is done by visit of colourful insect pollinators during night. d. In Sweet gourd (M. cochinchinensis), both staminate and pistillate flowers are solitary, axillary and creamy white in colour. The anthesis of both flowers takes place in the morning. In sweet gourd natural fruit set is very nominal. The interior of the opened flowers is marked by three big and black spots, posing scaring view of the flower, which may be a distracting factor for insect visit. e. Anthesis in Benincasa takes place between 04:30 h to 07:30 h with anther dehiscence at 03:00 to 05:00 h. Stigma is receptive from 8 h before to 18 h after anthesis. f. In Melons (Cucumis sp.), the time of anthesis and anther dehiscence are 05:30 hrs to 06:30 h and 05:00–06:00 h, respectively. g. In Cucumber, anthesis and anther dehiscence occurs by 05:30–07:00 h and 04:30–05:00 h, respectively. Here, stigma remains receptive 2 h before and after anthesis. h. Anthesis in Watermelon occurs between 06:30–08:00 h in autumn and by 05:30–07:00 h in spring. i. In Ivy gourd anthesis takes place in the morning in between 07:00 and 08:00 h. Parthenocarpic fruit set is common in ivy gourd. j. In Luffa, the male inflorescence is a raceme, whereas the female flowers are borne solitary in the axils. k. In sponge gourd (L. cylindrica) the anthesis and dehiscence occur early in the morning at around 4:45 a.m. and flower remains open the whole day. l. In Luffa acutangula anther dehiscence occurs at around 16:30 h and anthesis in both staminate and pistillate flowers takes place an hour later i.e. at around 17:30 h. m. In Lagenaria, anthesis and anther dehiscence take place by 16:30 h to 19:00 h, where stigma remains receptive 36 h before anthesis to 60 h after anthesis. n. Anthesis in Snake gourd (T. anguina) occurs between 17:15–21:30 h and anther dehiscence happens before anthesis (Bharathi et al. 2013; Hasanuzzaman et al. 2004). o. In pointed gourd (T. dioica) anthesis of both staminate and pistillate flowers takes place in the evening in between 19:30 h and 20:00 h. Staminate flowers open a few minutes earlier than pistillate flowers.

6

Soil and Climate

9

11. Fruits are essentially ‘berry’ (inferior), although called ‘pepo’ because of tough rind at maturity. 12. Fruits are of different colours and sizes, either consumed as immature (cucumber, Lagenaria, Luffa), mature (Trichosanthes, Momordica, Benincasa, Cucurbita) or in ripe form (Watermelon, pumpkin). The seeds are borne with parietal placentation. The edible portion is placenta in cucumber and watermelon. In Cucurbita, Trichosanthes and melons, the edible portion is pericarp with a little part of mesocarp. In Luffa and Benincasa the edible portion is endocarp.

5

Crop-Wise Important Varieties

A number of varieties are cultivated widely by the farmers in India. Some important varieties of commercially grown cucurbitaceous vegetables are described hereunder in Table 3.

6

Soil and Climate

1. Cucurbit vegetables are in general warm season crop. For commercial production, climate must be tropical or subtropical. A slight frost kills the young cucurbits very rapidly. 2. Seed does not germinate if the temperature is less than 11  C. At any point, the soil temperature should not be less than 15.5  C. For most effective seed germination, soil temperature should be from 18 to 24  C. Speed of germination increases with increase in temperature till 30  C (Wien 1997; Maynard and Hochmuth 2007). 3. The ideal soil temperature for maximum plant growth and yield is 18 to 29  C. Cucurbits grow well in the day temperature range of 25–35  C. It can thrive up to minimum temperature 20–25  C and maximum 40  C. 4. Melons prefer tropical climate with high temperature during fruit development. Day temperature of 35–40  C, cool nights and warm days give better quality fruits in melons. 5. Occurrence of prolonged period of cool and cloudy weather during the flowering period adversely affects production due to reduced bee activity, which results in poor pollination and fruit setting. 6. Long days with profuse sunlight generally increase number of male flowers. Whereas, shorter days with less light or less intense light tend to increase growth of female flowers. Short days and high night temperatures augment the production of fruit (Deyo and O’Malley 2008). 7. Presence of high level of humidity during the later part of crop growth increases chances of occurring fungal diseases. 8. Most of the cucurbits are deep rooted crop and the roots of some of the cucurbits can penetrate up to a depth of 200 cm (Weaver and Bruner 1927). So, a deep and

IARI, New Delhi

IARI, New Delhi

IARI, New Delhi

IARI, New Delhi

IARI, New Delhi

IARI, New Delhi

Variety 1. Bottle gourd Pusa summer Prolific long

Pusa summer Prolific round

Pusa Meghdoot (F1)

Pusa Manjari (F1)

Pusa Naveen

Pusa Sandesh

Release detail Centre of release

1994

1992

1971

1971

1975

1975

Year

Northern plains of India

MP and Maharashtra

–

–

–

All over India

Suitable for the area

Table 3 Important varieties of some commonly grown cucurbits

Its vines are vigorous in growth and bears long cylindrical fruits. It has very good yield potential This was developed through selection from local. It has vigorous growth round fruits of 15–18 cm girth. It is prolific bearer and heavy yielder This is an F1 hybrid between Pusa Summer Prolific Long and Sel. 2. Fruits are long, light green and attractive. It is relatively early and suitable for cultivation in spring-summer season. Considerably high yielder than Pusa Summer Prolific Long This is a round fruited F1 hybrid between Pusa Summer Prolific Round and Sel. 11. It has given 48% higher early yield and 106% total yield over Pusa Summer Prolific Round Fruits round, 15–18 cm in girth, green; prolific bearer; suitable for both summer and kharif seasons; first picking in 60–65 days Fruits attractive green, round, deep oblate, medium sized, weighing 600 g; first picking in 55–60 days in kharif and 60–65 days in summer. Suitable for commercial cultivation in springsummer and kharif seasons

Varietal characters

32 t/ha

30–32 t/ha

20–22 t/ha

20–22 t/ha

20–22 t/ha

25–30 t/ha

Yield

10 An Introduction to Cucurbits

IARI, New Delhi

IARI, New Delhi

IIHR, Hesaraghatta, Bengaluru

IIVR, Varanasi

ICAR-RCER, Patna

Pusa Samridhi

Pusa Santushti

Arka Bahar

Kashi Ganga

Swarna Sneha

2013

2006

2006

2008

2005

Jharkhand, Bihar and adjoining areas

UP, Punjab and Jharkhand

–

Delhi and Haryana

– Fruits are long without neck. In springsummer (308 q/ha) in kharif, an increase of 19% and 14%, respectively, over the check Pusa Naveen. Superior in nutritional qualities. Maturity in 50–55 days Fruits attractive green, smooth, pear shaped, fruit length 18.50 cm, fruit diameter 12.40 cm, sets fruit under low temperature (10–12  C) as well as high temperature (35–40  C), fruit weight 0.8–1.0 kg. Maturity in 55–60 days Pure line selection from IIHR-20A. Fruits medium long, straight without crookneck. Light green shining fruit skin when tender (1 kg). Tolerant to blossom end rot This is an early variety derived from the cross IC-92465  DVBG-151. Fruits are light green, length 30 cm, diameter 7 cm, fruit weight 800–900 g. It is tolerant to anthracnose. Suitable for rainy and summer season Swarna sneha was developed through pureline selection from IC284939 collected from NBPGR, New Delhi. Plant is vigorous with 4–5 m vine length early flowering and fruiting and suitable for summer and rainy season crop. It is tolerant to powdery mildew and downy mildew. • Fruits are long (30–35 cm length), light green and fruit weight 900–1000 g. Average yield is 40% higher over local check (Arka Bahar)

Soil and Climate (continued)

50–55 t/ha

48–55 t/ha

40–45 t/ha

Kharif: 28–29 t/ ha summer: 26.1 t/ha

27–28 t/ha

6 11

MPKV, Rahuri

CSAUAT, Kanpur CSAUAT, Kanpur

IARI, New Delhi

Samarat

Azad Nutan

Pusa hybrid 3

Kalyanpur long green

AAU, Anand, Gujarat

Anand bottle Gourd-1

Variety Punjab Komal

Release detail Centre of release PAU, Ludhiana

Table 3 (continued)

1998

1999

2006

2006

2012

Year 2006

Delhi, Haryana, UP and Punjab

Punjab, Tarai region of UP, Uttarakhand, Bihar and Jharkhand

Maharashtra

–

Suitable for the area –

The vines are vigorous and long, fruits are long with tapering and somewhat pointed blossom end. The crop duration is 120 days Fruits green, slightly club shaped without neck; suitable for easy packing and long distance transportation; first picking in 50–55 days

Varietal characters It is an early maturing, medium sized, oblong fruited variety. Marketable fruits are available in about 70 days after sowing. The fruits are light green with pubescence. There are 10–12 fruits/vine. The fruits are tender and borne on medium long, thin pedicels on 4–5th mode onwards. It is tolerant to cucumber mosaic virus The fruits are long, tender, attractive, light green colour, slightly rounded at stem end as well as blossom end with fine cluster. The fruit skin is smooth, non-hairy and has long shelf life Fruits are 30–40 cm long, green in colour, cylindrical in shape Good for box packing, suitable for kharif and summer seasons Long, green. High yielding cultivar

Kharif: 47 t/ha summer: 42– 43 t/ha

30 t/ha

35–40 t/ha

24 t/ha

Yield 40 t/ha

12 An Introduction to Cucurbits

GBPUA&T, Pantnagar

GBPUA&T, Pantnagar

Pant Sankar Lauki-2

Pant Lauki-3

IARI, New Delhi

GBPUA&T, Pantnagar

Pant Sankar Lauki-1

2. Bitter gourd Pusa Do Mausami

IIVR, Varanasi

Kashi Bahar (hybrid)

1975

2005

2006

1999

2006

Delhi, Punjab, Haryana, UP and Bihar

The plains and hills areas of North India

UP and Uttarakhand

UP and Uttarakhand

UP, Punjab, Bihar and Jharkhand

The fruits reach edible stage in about 55 days from sowing, fruits are dark green, long, medium thick, club shaped with 7–8 continuous ridges, 18 cm long at edible stage, 8–10 fruits weigh 1 kg

This is a long fruited hybrid with green vine and vigorous growth, fruit straight, light green, length 30–32 cm and average weight 780–850 g. It is suitable for rainy and summer season. It is tolerant to anthracnose, downy mildew and Cercospora leaf spot under field conditions The fruits are intermediate sized long and somewhat cylindrical (about 35 cm long). The fruits are green. Vine length is about 5.5 m. The first picking is possible in about 60 days. It is suitable for planting in the plains as well as in the hills The fruits are about 40 cm long, clubs shaped with smooth green colour. The first green fruit is harvested in 65 days. This is suitable for plains and hills. It can be sown from March to July in plains and April to May in the hills This is the medium duration and high yielding variety of bottle gourd. It has long fruits (40 cm) of light green colour with light strips having hairs

Soil and Climate (continued)

12–15 t/ha

30 t/ha

40 t/ha

40 t/ha

50–55 t/ha

6 13

IIVR, Varanasi

IIHR, Hesaraghatta, Bengaluru

ICAR-RCER, Patna

Kashi Urvasi

Arka Harit

Swarna Yamini

Variety Pusa Vishesh

Release detail Centre of release IARI, New Delhi

Table 3 (continued)

2013

1996

Year 1987

Jharkhand and Bihar and adjoining areas

–

UP, Punjab and Jharkhand

Suitable for the area Delhi and Haryana

Varietal characters Fruits thick, medium long, glossy green; suitable for spring-summer season; vines short, hence more number of plants can be accommodated per unit area; first picking in 55–60 days This variety has been derived from the cross IC-85650B  IC-44435A, having dark green and long fruits, mild projection, length 16–18 cm, fruit weight 90–110 g. This is suitable for cultivation under both rainy and summer seasons Pure line selection from IIHR-4, a local collection from Rajasthan. Fruits spindle shaped, glossy green skin colour without tubercles. Medium-sized fruits, thick flesh, moderate bitterness, with less seeds Swarna Yamini was developed through hybridization followed by pedigree selection. Plant is vigorous with 2.5–3.0 m vine length. Early flowering and fruiting. Suitable for summer and rainy season. Tolerant to powdery mildew and downy mildew. Fruits (65–70 g) are dark green with deep tubercles. Shows 49% increase in yield over local check (Arka Harit) 20 t/ha

9–12 t/ha

20–22 t/ha

Yield 15 t/ha

14 An Introduction to Cucurbits

GBPUA&T, Pantnagar

MPKV, Rahuri

MPKV, Rahuri

KKV, Dapoli

KAU, Vellanikkara

KAU, Vellanikkara

IARI, New Delhi

IARI, New Delhi

Pant Karela-1

Phule Green Gold

Hirkani

Konkan Tara

Preethi

Priya

Pusa hybrid 1

Pusa Hybrid 2

2002

1990

2001

1976

1987

1987

1998

1991

Punjab, Haryana, Gujarat, Rajasthan, Uttar Pradesh, Bihar, Jharkhand, Orissa, AP, Chhattisgarh and Delhi

–

–

–

–

–

Maharashtra

UP and Uttarakhand

The vine length is about 2 m. Fruits are thick, about 15 cm long with tapering ends. It takes about 55 days to first harvest. It is suitable for planting in the hills Fruits are dark green, 25–30 cm long with prickles, tolerant to downy mildew, suitable for kharif and summer seasons Developed by selection from local type. Fruits are dark green, 15–20 cm long with pickles. Crop duration is 160 days Fruits are green, prickly, medium long (15–16 cm) and spindle shaped. Fruits have good keeping quality, shelf-life is 7–8 days under ambient temperature Selection from local type. Fruits are white, medium, spiny, 30 cm long and average fruit weight is 310 g A selection from local type. Fruits are 39 cm long, green-spiny-fruits with white tinge at stylar end Fruits medium long, medium thick, glossy green; suitable for pickling and dehydration; yield higher than Pusa Vishesh and Pusa Do Mausami; first picking in 55–60 days; suitable for growing in spring-summer Fruits dark green, medium long and medium thick (fruit length 12.5 cm and breadth 4.5 cm) with irregular smooth ridges. The average fruit weight is 85–90 g. Maturity in 52 days

Soil and Climate (continued)

18 t/ha

20 t/ha

30 t/ha

15–34 t/ha

24 t/ha

14 t/ha

23 t/ha

15 t/ha 6 15

IARI, New Delhi

IIHR-CHES, Bhubaneswar

Arka Neelachal Gaurav

4. Ridge gourd Pusa Nasdar

IIHR-CHES, Bhubaneswar

IIHR-CHES, Bhubaneswar

Arka Neelachal Shanti (hybrid)

Variety 3. Spine gourd Arka Neelachal Shree

Release detail Centre of release

Table 3 (continued)

1964

2012

2012

2012

Year

–

–

Mid-season, flowering in 50 days, 15–20 fruits per vine, fruits ridged, light green. More suited for rainy season

Developed through clonal selection. This variety has good appearance, high yield (4–5 kg/plant) and high market preference. The vine of this variety is thin and spreading which grows very well on three line wire trellis system It is developed through hybridization between spine gourd (M. suboica) and teasel gourd (M. dioica), naturally pollinated, high yielding (15–16 kg/ vine) with medium-sized fruit (20 g), moderately tolerant to fruit borer, anthracnose and downy mildew. The variety exhibits plant and flower morphology more similar to teasel gourd while its fruit morphology is more close to spine gourd An improved variety of teasel gourd (M. dioica) developed through selection. It has excellent culinary properties. Good yield (10–12 kg/plant; fruit weight 30–35 g), round, soft seeded fruits, moderately tolerant to anthracnose and downy mildew

–

–

Varietal characters

Suitable for the area

18–20 t/ha

25–30 t/ha

10–12 t/ha

Yield

16 An Introduction to Cucurbits

IARI, New Delhi

IIHR, Hesaraghatta, Bengaluru

IIHR, Hesaraghatta, Bengaluru

IIHR, Hesaraghatta, Bengaluru

HAU, Hisar

Pusa Nutan

Arka Prasan

Arka Sujat

Arka Sumeet

Hisar Kalitori

–

–

1984

–

–

–

–

1985

–

– Fruits are long (25–30 cm), straight, attractive green, average fruit weight 105 g, flesh tender, suitable for springsummer and kharif seasons. Maturity in 45–50 days Open pollinated variety developed by inbred selection from the segregating germplasm, IIHR-53. Early variety (42–45 days for first picking), green, long, tender fruits, excellent cooking quality, nutritionally rich in antioxidant activity and minerals like phosphorus, calcium and zinc. Crop duration is 120–135 days Developed by pedigree method of breeding between IIHR-54 X IIHR-18 followed by selection. Lush green and tender, medium long (35–45 cm) fruits with prominent ridges and delicate aroma. Good transport and cooking qualities Developed by pedigree method of breeding between IIHR-54 X IIHR-18 followed by selection. Lush green, tender, long fruits (50–65 cm) with prominent ridges and delicate aroma. Good transport and cooking qualities Early long thin and straight fruited variety, tolerant to powdery mildew, suitable for rain fed areas

Soil and Climate (continued)

8–10 t/ha

50 t/ha

53 t/ha

26.0 t/ha

16 t/ha

6 17

ICAR-RCER, Patna

ICAR-RCER, Patna

KKV, Dapoli

Swarna Uphar

Swarna Sawani

Konkan Harita

Variety Swarna Manjari

Release detail Centre of release ICAR-RCER, Patna

Table 3 (continued)

Jharkhand and Bihar and adjoining areas

–

–

Jharkhand, Bihar and adjoining areas

Suitable for the area Jharkhand, Bihar, Odisha, Tamil Nadu, Maharashtra and Andhra Pradesh

2006

2006

Year 2006

Varietal characters Developed through hybridization followed by selection. Fruits are elongated in shape, medium size and weight (175 g), highly ridged, greenish colour, pulp soft and contain less fibre. Tolerant to powdery mildew. First harvest 65–70 days after sowing Developed through hybridization followed by pedigree selection. Fruits are elongated in shape, medium size and weight (200 g), long ridged at edible stage, pulp soft and contain less fibre. First harvest 65–70 days after sowing Swarna Sawani was developed through pureline selection from local collection. Plant is vigorous with 3–4 m vine length. Early flowering and fruiting and suitable for rainy season crop. It is tolerant to powdery mildew and downy mildew. Fruits (35–45 g) borne in clusters with 6–8 fruits/cluster This variety developed through selection. It gives first harvest in 45 days after planting. Fruits are dark green in colour, 30–45 cm long and tapering at both the ends. Fruits have good market value. A vine produces on an average 10–12 fruits 20–25 t/ha

20–30 t/ha

Yield 18–20 t/ha

18 An Introduction to Cucurbits

5. Sponge gourd Pusa Chikni IARI, New Delhi

2005

–

–

–

IIHR, Hesaraghatta, Bengaluru

Arka Vikram (F1)

Gujarat

–

AAU, Anand, Gujarat

Gujarat Anand Ridge Gourd1

UP and Uttarakhand

–

GBPUA&T, Pantnagar

Pant Torai-1

–

–

PAU, Ludhiana

Punjab Sadabahar

It is suitable for cultivation in rainy and spring-summer seasons. Fruits are smooth, dark green and cylindrical. Single plant bears 15–17 fruits. Flowering starts in 60 days after sowing

The plants of this variety are medium sized with dark green leaves. The fruits long 3–5 cm thick, slim green, ridged, tender, slightly curved and rich in protein. This variety can be sown from May to July The main shoot is 5 m long. Fruits are 15–20 cm long and club shaped. It takes about 65 days to first harvest. It is specifically suitable for rainy season This variety is medium sized and elliptical shape with green fruit skin colour. The variety has less mosaic and downy mildew disease reaction Hybrid developed by crossing the inbreeds, IIHR-6-1-1  IIHR-53-1-3. Early flowering hybrid (46 days for first picking), green, long, tender fruits, excellent cooking quality, nutritionally rich in antioxidant activity and minerals like potassium, calcium, iron, zinc and manganese. Crop duration 120–135 days

(continued)

20–23 t/ha

34.0 t/ha

15 t/ha

10 t/ha

10 t/ha

6 Soil and Climate 19

IARI, New Delhi

ICAR-RCER, Patna

Pusa Sneha

Swarna Prabha

Variety Pusa Supriya

Release detail Centre of release IARI, New Delhi

Table 3 (continued)

2006

2004

Year 2002

Uttar Pradesh, Jharkhand and Bihar

Delhi and NCR

Suitable for the area –

Varietal characters Its vines are 2.5–2.8 cm long with 4–5 branches. Leaves are dark green, smaller in size with six lobed petiole, tip pointed and simple. Fruits are pale green, smooth, 15–20 cm long, straight and slightly curved at the stem end, pointed distal end, non-hairy, flesh tender, suitable for spring-summer and kharif season. Fruits become ready for picking at 50–55 days after sowing in springsummer and 44–48 days after sowing in kharif season Fruits medium long (20–25 cm), smooth, almost straight and dark green with blackish green narrow stripes having tender flesh and hard skin, suitable for long distance transportation. Maturity in 45–50 days, tolerant to high temperature, suitable for spring-summer and rainy seasons in northern plains Developed through pure line selection. Fruits are medium length (20–25 cm) and weight (150–200 g), light greenish colour, pulp soft and contain less fibre. Tolerant to powdery and downy mildew and resistant to leaf minor under field condition. First harvest 50–60 days after sowing

20–25 t/ha

12 t/ha

Yield 13–14 t/ha

20 An Introduction to Cucurbits

CSAUAT, Kanpur

Azad Taroi-2

IARI, New Delhi

IIHR, Hesaraghatta, Bengaluru

Pusa Vishwas

Arka Suryamukhi (Winter squash)

IARI, New Delhi

IIVR, Varanasi

Kashi Divya

6. Pumpkin Pusa Vikas

MPKV, Rahuri

Phule Prajakta

2001

1990

–

Orissa, Bihar, Uttar Pradesh, Punjab, Chhattisgarh, AP, MP and Maharashtra

Delhi and NCR

–

–

1991

Uttar Pradesh, Delhi, Bihar, Uttarakhand, Chhattisgarh, West Bengal and Madhya Pradesh

–

2012

2002

Vines semi-dwarf to dwarf (2.0–2.5 m long); leaves soft with light green or yellow spots; fruits small weighing 2 kg, flattish round; flesh yellow, rich in vitamin A Vigorous vegetative growth; leaves dark green with white spots including veins; fruits light brown, spherical with thick golden-yellow flesh, weight 5 kg; maturity in 120 days Pure line selection from IIHR-79, a foreign introduction. Fruits round with pressed ends. Rind colour orange red with white stripes when mature. Flesh is firm and orange-yellow in colour. Fruit stalk round with flared ends. Average fruit weight 1–1.5 kg. Resistant to fruit fly. A 100 days duration crop. Keeping and transportation quality of fruit is good

It is a selection from local germplasm. Fruits medium-sized, green, straight, slender, tapering at ends and flesh colour-pure white. This variety has crop duration of 145–150 days. Suitable for summer and kharif season Developed through pedigree selection. Fruits are medium sized (15–16 cm long), cylindrical, light green in colour, average fruit weight 80–90 g, high TSS content Profuse fruiting, suitable for summer and rainy seasons

Soil and Climate (continued)

34 t/ha

40 t/ha

30 t/ha

14–16 t/ha

29–35 t/ha

13–15 t/ha

6 21

IIVR, Varanasi

ICAR-RCER, Patna

KAU, Vellanikkara

Kashi Harit

Swarna Amrit

Ambili

Variety Arka Chandan

Release detail Centre of release IIHR, Hesaraghatta, Bengaluru

Table 3 (continued)

2001

2009

2006

Year –

–

Uttar Pradesh, Bihar, Jharkhand, Tamil Nadu Karnataka and Kerala

UP, Punjab and Jharkhand

Suitable for the area –

Varietal characters Pure line selection from IIHR-105, a local collection from Rajasthan. Fruit round with pressed blossom end. Rind colour green with white patches when immature which turns to light brown colour with self-coloured patches on maturity. Thick, bright orange flesh, firm, sweet (TSS 8–10%), rich in carotene (3333 IU). Fruit weight 2–3 kg, solid cavity This variety is derived from the cross between NDPK-24  PKM through pedigree selection. Vines are short, leaves dark green with white spots. Fruits are green, spherical, weight 2.5–3.0 kg at green stage; yield completes in 65 days of crop duration Developed through pure line selection. Fruits are round flat, dark green with average weight of 2.5–3.0 kg. First harvest 70–75 days after sowing Plants are spreading type; fruits are flatround and medium (6 kg weight), green with shallow furrows on surface. This variety has 95–110 days of crop duration

34–36 t/ha

50–60 t/ha

30–35 t/ha

Yield 33 t/ha

22 An Introduction to Cucurbits

NDUA&T, Faizabad

NDUA&T, Faizabad CSAUAT, Kanpur

Narendra Amrit

Narendra Abhooshan Azad Pumpkin-1

IARI, New Delhi 7. Summer Squash Punjab PAU, Chappan Ludhiana Kaddu

NDUA&T, Faizabad

Narendra Agrim

Pusa hybrid 1

AAU, Gujarat

Anand Pumpkin-1

Punjab, Kerala, Delhi, parts of northern plains –

1994

Punjab, Tarai region of UP, Uttarakhand, Bihar and Jharkhand

UP

UP

Delhi, Punjab, Haryana and Gujarat

–

1992

1984

1968

1983

2012

Plants are bush type and have non-lobed leaves. Fruits are green, medium in size, disc shaped. This is an early maturing variety, ready to first harvest in about 60 days after sowing. Single fruit weight 40–50 g. Plants are resistance to downy mildew

The fruits are medium sized, globular in shape with deep yellow flesh. Fruits possess higher TSS, carotene, total soluble sugars and protein. Fruits are small, round and stripe less dark green. Suitable for summer crop. Single green fruits weigh 3 kg, while mature fruits are of 6 kg weight. The mature fruits have papery skin, thick flesh of about 7 cm with small seed cavity. Early maturity (55 days). Fruits are round in shape and light green mottled in colour. Suitable for summer crop, mature fruit weight 5–6 kg. Fruits are round in shape with dark green striped and highly attractive Plants are spreading type, leaves green hairy, early fruiting, close fruit bearing, green fruit with yellowish stripes, flesh thick, less no. of seeds, fruit spherical flat Fruits flattish round, medium size, weighing 4.75 kg; flesh golden yellow

(continued)

52 t/ha

45–50 t/ha

70 t/ha

30–40 t/ha

24–25 t/ha

6 Soil and Climate 23

IIHR, Hesaraghatta, Bengaluru

Pusa Alankar (hybrid)

Patty Pan

IIVR, Varanasi

IIVR, Varanasi

Kashi Surbhi

Kashi Ujwal

IARI, New Delhi

IARI, New Delhi

Variety Early Yellow Prolific

8. Ash gourd Pusa Ujjwal

Release detail Centre of release IARI, New Delhi

Table 3 (continued)

2006

2009

2004

1972

1972

Year 2005

Punjab, Uttar Pradesh, Bihar Jharkhand, Karnataka, Tamil Nadu and Kerala

Punjab, Uttar Pradesh, Bihar and Jharkhand

Karnataka, Tamil Nadu and Kerala

–

–

Suitable for the area –

Fruits are oblong, ellipsoid, rind greenish white while flesh is white with average fruit weight of 7.0 kg. Its fruits are ideal for long distance transportation Fruits oblong, ellipsoid, rind greenish white, flesh white; average fruit weight 10–12 kg; fruits are suitable for long distance transportation Variety developed through selection. Fruits are round shaped, medium in size (Average weight 7–9 kg), suitable for candy/petha preparation

Varietal characters Plants are bush type and early in flowering. Fruits medium sized, warted and tapering towards stem end. Skin light yellow turns orange-yellow on maturity Fruits are green with shining light green stripes, long (25–30 cm); sown during March–April in hills and January– February in plains. Fruit matures in 45–50 days An introduction from USA. White, disc shaped fruits with notches along the margin. Fruit weight 350–400 g. Duration 75–80 days

Kharif: 48–50 t/ ha Summer: 41–43 t/ha Kharif:60–70 t/ ha Summer:51–55 t/ ha 50–80 t/ha

55 t/ha

20–30 t/ha

Yield 25–28 t/ha

24 An Introduction to Cucurbits

KAU, Vellanikkara

KKV, Dapoli

IIVR, Varanasi

ICAR-RCER, Patna

ICAR-RCER, Patna

Swarna Alaukik

Swarna Suruchi

10. Pointed gourd Swarna Rekha ICAR-RCER, Patna

Manushree

9. Snake Gourd Konkan Sweta

Kashi Dhawal

2011

2006

2006

2001

1986

2006

Jharkhand, Bihar, Odisha, West Bengal and Eastern UP

Jharkhand, Bihar, Odisha, West Bengal and Eastern UP

Jharkhand, Bihar, Odisha, West Bengal and Eastern UP

–

–

Uttar Pradesh, Punjab, Bihar and Delhi

Developed through clonal selection. Fruits elongated in shape, striped green, contain soft seed Developed through clonal selection. Fruits are elongated in shape, light greenish in colour, suitable for table and sweet preparation Developed through clonal selection. Fruits are oval in shape having blunt end on both side, light greenish in colour, suitable for table and sweet preparation

Fruits are medium-long (90–100 cm) and white in colour. Fruits have good flesh if harvested timely, otherwise it becomes hollow. This variety has crop duration of about 120–130 days Fruits are ready for harvest in the eighth week. Fruits are white attractive, uniform medium long (65–70 cm), green markings at the pedicel end. Average fruit weight is 750 g with 67 cm length.

This variety is derived from a local collection. The vine length is 7.5–8 m. Fruits are oblong, flesh white, thickness 8.5–8.7 cm, seed arrangements linear, average weight 11–12 kg crop duration 120 days. This is suitable for preparation of Petha sweets due to high flesh recovery

Soil and Climate (continued)

25–30 t/ha

20–25 t/ha

30–35 t/ha

57–62 t/ha

15–20 t/ha

55–60 t/ha 6 25

IARI, New Delhi

IARI, New Delhi

Pusa Barkha

IARI, New Delhi

IIHR-CHES, Bhubaneswar

Pusa Sanyog (F1)

11. Cucumber Pusa Uday

Arka Neelachal Kirti

Variety Kashi Alankar

Release detail Centre of release IIVR, Varanasi,

Table 3 (continued)

2012

1999

2004

2012

Year 2010

North Indian plains

HP, J&K and Uttarakhand

Delhi and NCR

–

Suitable for the area UP, Bihar, Jharkhand

Fruits medium in size (13–15 cm long), light green in colour with whitish green stripes (origination from blossom-end and running up to one-third of the fruit length), straight, non-prickled and soft skinned. Maturity in 48–52 days Hybrid developed by cross between EC-5082 and Green Long (of Naples). Very early fruits 28–30 cm long, cylindrical, attractive, dark green with yellow spines, crisp flesh. First picking in 50 days First extra early improved variety of cucumber for Kharif season cultivation. Field tolerant to high humidity, high temperature and downy mildew disease.

Varietal characters Developed through clonal selection. Fruits are spindle shaped, light greenish in colour, fruit length 6–7 cm with avg. weight of 25–27 g A high yielding variety (15–20 kg/vine, 280–290 fruit/vine, fruit weight 45–55 g) developed through selection. Fruits are soft seeded with solid core, moderately tolerant to anthracnose, downy mildew and Fusarium wilt

18–20 t/ha

20 t/ha

16 t/ha

28–32 t/ha

Yield 19–25 t/ha

26 An Introduction to Cucurbits

IARI, New Delhi

IARI, New Delhi

GBPUA&T, Pantnagar

KKV, Dapoli

MPKV, Rahuri

MPKV, Rahuri

ICAR-RCER, Patna

Japanese Long Green

Straight Eight

Pant Khira-1

Sheetal

Himangni

Phule Shubangi

Swarna Poorna

2004

2006

1999

1992

2006

Bihar, Jharkhand, Odisha, Uttar Pradesh and Pradesh

–

Maharashtra

–

UP and Uttarakhand

–

Suited to hills and lower hills

It is an introduction. A temperate cultivar suited to hills and lower hills. Plants are early, prolific bearing, first picking starts in 45 days after sowing. Fruits are yellowish green, 30–40 cm long, whitish green with light green and crisp flesh. This variety essentially requires staking for straight fruits Early cultivar suited to hills, white spined fruit medium long, thick straight and cylindrical with round ends, skin medium green The fruits are long (20 cm), cylindrical with light white stripes. The fruits attain first picking stage in 50–60 days Fruits are green, medium in length (25 cm), average weight 300–350 g and girth is 19.6 cm. The vine measures up to 2.7 m with 10 branches/vine. It bears 24 fruits/plant and its duration is about 92 days Fruits are white in colour and resistant to bronzing, suitable for kharif season. Crop duration 100–110 days Fruits are green in colour. Tolerant to powdery mildew, suitable for kharif season Developed through pure line selection. Fruits are cylindrical long in shape, medium size (300 g), light green colour with no placental hollowness. Tolerant

Soil and Climate (continued)

30–35 t/ha

20 t/ha

19 t/ha

15 t/ha

6 27

ICAR-RCER, Patna

ICAR-RCER, Patna

IARI, New Delhi

GBPUA&T, Pantnagar

Swarna Ageti

Swarna Sheetal

Pusa Seedless Cucumber-6

Pant Parthenocarpic Khira-2

Variety

Release detail Centre of release

Table 3 (continued)

2015–2016

2006

2006

Year

UP and Uttarakhand

Suitable for protected cultivation

Jharkhand, Bihar, Uttar Pradesh, Delhi, Maharashtra, Andhra Pradesh, Himachal Pradesh and Kerala

Bihar, Jharkhand, Uttar Pradesh, Delhi, Andhra Pradesh and Himachal Pradesh

Suitable for the area to powdery mildew. First harvest 55–60 days after sowing Developed through mutation breeding. Fruits are cylindrical long in shape, medium size (200 g), green colour with no placental hollowness. Tolerant to powdery mildew. First harvest 45–50 days after sowing Developed through hybridization followed by pedigree and recurrent selection. Fruits are cylindrical long in shape, medium size (250 g), greenish white in colour with no placental hollowness. Tolerant to powdery mildew. First harvest 60–65 days after sowing First extra early (40–45 days for first fruit harvest) improved variety of parthenocarpic gynoecious cucumber. Fruits are attractive, uniform, dark green, glossy, cylindrical, straight, slightly ribbed, non-hairy, non-warty, slightly striped at blossom end and has tender skin and crispy flesh. Average fruit length, width and weight are 14.24 cm, 3.45 cm and105 g, respectively A parthenocarpic cucumber variety. It is suitable for poly house cultivation. No. of female flower per vine is 551. Average fruit weight is 630 g

Varietal characters

210 t/ha

126 t/ha during winter season

25–30 t/ha

30–32.5 t/ha

Yield

28 An Introduction to Cucurbits

IARI, New Delhi

IARI, New Delhi

Pusa Madhurima

IARI, New Delhi

Pusa Madhuras

12. Muskmelon Pusa Sharbati

2015–2016

1975

1978

–

Northern India

– This variety developed through pedigree selection from the cross Kutana X American Cantaloupe (PMR-6). An early cultivar maturing in 85 days, leaves 5 lobed, green, pubescence and medium long petiole. Salmon orange flesh is firm and thick with small seed cavity, moderately sweet (11–12% TSS) It is a selection from a Rajasthan collection with roundish flat fruits weighing a kg or slightly more. Vigorous vines, leaves entire green pubescent with large petioles. Salmon-orange flesh, juicy and sweet (12–14% TSS) and poor keeping quality. This is a unique shaped muskmelon variety with high yield and increased shelf life. Its fruit is ovate to obovate shape with average weight of 775 g. Fruits get ready for harvest in about 80 days. The rind colour is creamish yellow with green sutures. Flesh is thick, green, juicy and crispy with medium musky flavour and high sweetness (TSS 120Brix). Fruit surface is grooved with moderate netting and is slipable at maturity. Fruits attain nipple shape at peduncle end. Its leaves are weakly lobed and shows andromonoecious sex expression

Soil and Climate (continued)

22.45 t/ha

12–16 t/ha

15–17 t/ha

6 29

PAU, Ludhiana

PAU, Ludhiana

Punjab Sunheri

Punjab Rasila

Variety Hara Madhu

Release detail Centre of release PAU, Ludhiana

Table 3 (continued)

1987

1975

Year 1987

–

–

Suitable for the area –

Varietal characters It is a late cultivar developed from a local collection of Haryana. Vines are 3–4 m long and vigorous. Fruits are round, tapering towards the stalk with open prominent green sutures, average weight 1 kg, do not slip from the stalk, thin rind, smooth and pale yellow at maturity; flesh is green, thick, very juicy with 12–15 % T.S.S.; poor keeping quality A derivative from the cross Hara madhu x Edisto. Early maturing variety producing round to elliptical fruits with pale green, thick skin; salmon orange and thick flesh, moderate sweetness (11–12% TSS). Fruits are devoid of distinct sutures at maturity. Average fruit weight is 1 kg. It slips easily from the stalk. Its rind is thick, netted and dull yellow at maturity It is developed from a cross between C. melo var. momordica ‘phut’  Indian cultivar. Fruits are round, green thick, juicy and it takes 80 days for fruit picking and about 10 days earlier than Hara madhu. Fruit weighing about 600 g, TSS around 11%. Resistant to powdery mildew and moderately resistant to downy mildew 16 t/ha

Yield

30 An Introduction to Cucurbits

ARS, Durgapura, Rajasthan

IIHR, Hesaraghatta, Bengaluru

IIHR, Hesaraghatta, Bengaluru

AAU, Anand, Gujarat

AAU, Anand, Gujarat

Durgapura Madhu

Arka Rajahans

Arka Jeet

Gujarat muskmelon-1

Gujarat muskmelon-2

1975

–

–

–

–

1975

–

–

1987

2001

A very early cultivar confined to Jaipur region of Rajasthan. Fruits are oblong weighing to 500–600 g, Pale green rind, light green flesh, very sweet 13–14% TSS, seed cavity big Plants are with densely hirsute stem, light green foliage with shallow lobes and bear 2–3 fruits, weighing about 1.25–2.0 kg. Fruits are round to slightly oval, medium-large, creamy white skin, netted with shallow vein, tracks at full slip stage. Mid-season variety bearing and fruits has transportable quality. It is tolerant to powdery mildew, keeping quality excellent An early cultivar selection from Bati strain of Uttar Pradesh. Relatively dwarf habit. Fruits are flat small weighing about 300–500 g. Orange to orange brown skin, white flesh, big seed cavity, very sweet (12–14%TSS). Excellent flavour and high vitamin C content. It is a selection from local collection from Sabarkantha district in Gujarat. Fruits are small, tasty, lemon yellow, smooth without suture and 5–6 fruits/ plant. Flesh is light green with 2.1 cm. The average weight of fruit is 0.982 kg with a diameter of 10 cm It is a selection from local collection from Nagpur area of Maharashtra. Flowering starts at 32 days after sowing. Fruits are medium in size (diameter 11.5 cm), tasty, 4–5 fruits/plant and average (continued)

14–17 t/ha

13–15 t/ha

6 Soil and Climate 31

Release detail Centre of release

AAU, Anand, Gujarat

IIVR, Varanasi

IARI, New Delhi

Variety

Gujarat muskmelon-3

Kashi Madhu

Pusa Rasraj (F1)

Table 3 (continued)

1987

1996

2006

Year

Delhi, UP, Punjab, Haryana and Bihar

UP, Punjab and Jharkhand

–

Suitable for the area weight of fruit 1.3 kg. Skin is orange green with slight netting and no suture. Flesh is capucine orange with 2–6 cm thicken Fruits are medium-sized, round to slightly oval, yellowish brown spots on mature fruits with green strips. Flesh green, juicy, very sweet, TSS 12%, average fruit weight 800 g Plants have medium vine and leaves sparsely lobed and dark green, fruits are round, with open prominent green sutures, weight 650–725 g, half slip in nature, thin rind, smooth and pale yellow at maturity, flesh salmon orange (mango colour), thick, very juicy, T.S.S. 13–14% and seeds are loosely packed in the seed cavity. Post-harvest life is long with good transportability, tolerant to powdery and downy mildew and medium maturity It is F1 hybrid (Monoecious 3  Durgapura Madhu). Average fruit weight is 1–1.2 kg; producing sweet flesh (11–12% TSS), take 75–80 days for first harvest. This monoecious hybrid is vigorous and produces slightly oval,

Varietal characters

25 t/ha

20–27 t/ha

11–13 t/ha

Yield

32 An Introduction to Cucurbits

14. Long melon Pusa Utkarsh

13. Snapmelon Pusa Shandar

Punjab Hybrid (F1)

IARI, New Delhi

IARI, New Delhi

PAU, Ludhiana, Punjab

2015–2016

2004

–

North Indian plains

–

–

First early maturing variety of long melon for cultivation in spring-summer season. Fruits sets ready for first harvest in 45–50 days after sowing. Fruits are slightly curved, medium long (length 52 cm), thin (diameter 2.4 cm), light green, smooth non-prominent ridges, shiny with tender skin, crispy flesh and free from bitterness. Each fruit weighs 130–145 g at marketable stage. Seeds light tan in colour

Fruits are oblong, medium in size with creamy white skin, thick and light pink flesh. Recorded 32% higher yield over best local check. Maturity in 45–50 days

smooth and non-stripped fruits. Suitable for both garden land river bed cultivation It is a hybrid between a male sterile line (ms1) and Hara Madhu. Vines are long (2–2.5 m) vigorous and luxuriant growth. Early maturing variety. Fruits are globular with distinct sutures. Average fruit weight is 800 g and slips from the stalk. Rind is quite thick, netted and creamy yellow. Flesh is thick, orange and juicy. Suitable for distant transportation

(continued)

29–30 t/ha

38 t/ha

6 Soil and Climate 33

2004

Asahi Yamato

IARI, New Delhi

1978

HAU, Hisar

Karnal Selection

1999

Year 1992

15. Watermelon Sugar Baby IARI, New Delhi

GBPUA&T, Pantnagar

Pant Kakri-1

Variety Arka Sheetal

Release detail Centre of release IIHR, Hesaraghatta, Bengaluru

Table 3 (continued)

HP, J&K and Uttarakhand

Odisha, Chhattisgarh, MP, Maharashtra, Karnataka, Tamil Nadu, AP and Kerala

PAN India

–

Suitable for the area –

It has medium long vines. Fruits are round with black rind, deep pink flesh with 11–13% TSS, brown small seeds and each weighing 2–5 kg. Crop duration 85 days Mid-season, vines medium with deeply cut, lobed leaves, fruits medium sized, 6–7 kg, round, pale green, smooth,

Varietal characters Fruits are medium to long (length 22 cm and girth 7.8 cm) with light green skin colour covered with soft hair. Each fruit weighing 90–100 g at marketable stage. Free from bitter principles with crisp texture. Seeds light colour The vines are vigorous with long light green straight fruits. It is free from common diseases and insects. The first green immature fruit picking is possible in 50 days after sowing. Seed to seed stage is about 90 days. A prolific bearer, fruits are tender light green, long thin, flesh crisp with good flavour

20 t/ha

15–17 t/ha

9–10 t/ha

30 t/ha

Yield 35 t/ha

34 An Introduction to Cucurbits

IIHR, Hesaraghatta, Bengaluru

IIHR, Hesaraghatta, Bengaluru

ARS, Durgapura, Rajasthan

ARS, Durgapura

Arka Manik

Arka Muthu

Durgapura Meetha

Durgapura Kesar

1986

–

–

–

–

1990

–

–

non-striped skin flesh deep red, sweet, T.S.S. 9–11%; maturity in 95–100 days Developed by modified back crossbreeding method from cross IIHR-21 X Crimson Sweet followed by selection in the advanced generation. Fruits oval with light green rind colour and green to dark green stripes. Deep crimson flesh with granular texture, pleasant aroma, very sweet, TSS 12–15%. Average fruit weight 6 kg. Seeds small with dark brown specks on the testa. Triple resistant to powdery mildew, Downey mildew and anthracnose Selection from IIHR-81-1-1. It has unique character of dwarf vine (vine length 1.2 m), shorter inter nodal length and early maturing type (75–80 days). It has round to oval fruits with dark green stripes and deep red flesh. Average fruit weight 2.5–3 kg with TSS ranging from 12 to 14 Brix Fruits are round with light green and thick rind, good keeping quality, weight varies from 7 to 8 kg; flesh is dark with 11 % T.S.S., seeds with black tip and margin; gives yield in 125 days of crop duration Fruit weight is 4–5 kg, green skin with stripes. The flesh is yellow and moderately sweet. Seeds are large and yellow

Soil and Climate (continued)

40–45 t/ha

40–45 t/ha

85–90 t/ha

60 t/ha

6 35

IARI, New Delhi

Pusa Bedana (Triploid)

Arka Jyoti (F1)

Arka Akash (F1)

IIHR, Hesaraghatta, Bengaluru IIHR, Hesaraghatta, Bengaluru IIHR, Hesaraghatta, Bengaluru

Arka Aiswarya (F1)

Variety Improved Shipper

Release detail Centre of release PAU, Ludhiana

Table 3 (continued)

– –

–

–

–

–

–

2002

Suitable for the area –

Year 1975

Varietal characters Fruits are medium to large weighing 6–10 kg, round, with characteristic tripartite blossom end. Flesh is red with moderate sweetness (8–9% TSS). Rind is thick and dark green. Seeds are uniformly light brown Hybrid between IIHR-86-3 X Arka Manik, high yielding with high TSS (10–110 Brix). Fruits oblong Hybrid between IIHR-60-1 X Arka Manik, high yielding with high TSS (11–120 Brix). Fruits oval round Fruits are round to oval, dark green with blue angular stripes, average weight of 5–6 kg; flesh is bright crimson, granular texture with 12–13% T.S.S.; good keeping and transport quality; first picking starts after 90 days of sowing Vine growth vigorous. Fruits have dark green skin with faint stripes, somewhat triangular shape, tough rind, red flesh with white remnants of false seeds, T.S.S. 12–13%, 5–6 kg, produces 3–6 fruits/vine, very good keeping quality; maturity in 115–120 days 48 t/ha

90–100 t/ha

80–90 t/ha

Yield

36 An Introduction to Cucurbits

2001

IIHR, Hesaraghatta, Bengaluru

Arka Tinda

–

2015–2016

IIHR, Hesaraghatta, Bengaluru

16. Round melon (Tinda) Pusa Raunak IARI, New Delhi

Arka Madhura (Triploid)

–

North Indian plains

–

First early maturing variety of round melon for spring-summer season cultivation. Fruits become ready for first harvesting in 55–60 days after sowing. It produces 8–10 fruits per vine. Young fruits at marketable stage are attractive green, shiny, uniform, flattish round in shape, 5 cm in diameter. Flesh is white, tender, less-seeded and has good cooking quality. Each fruit is medium in size and weighs 60 g at marketable stage. The seeds are black in colour with ridged border Developed by hybridization between Rajasthan Local and T8 (Punjab) followed by pedigree method of selection. It is an early summer season variety. Fruits round with lush green shining skin covered with soft hair when young and tender (60 g). Crop duration 90–100 days

Triploid seedless watermelon hybrid between Tetra-1 X Arka Manik. Fruits round with dark green rind colour with light green broad stripes. Crimson red flesh with pleasant aroma without seeds, TSS 140 Brix. Average fruit weight 6 kg. Crop duration 100–110 days

(continued)

9.5–10 t/ha

8 t/ha

50–60 t/ha

6 Soil and Climate 37

IGKV, Raipur, Chhattisgarh

IIHR-CHES, Bhubaneswar

Arka Neelachal Khunkhi

IGKV, Raipur, Chhattisgarh

PAU, Ludhiana

Indira Kundru35

17. Ivy gourd Indira Kundru05

Punjab Tinda

Variety Hisar Tinda

Release detail Centre of release HAU, Hisar

Table 3 (continued)

2012

1993

1983

1991

Year 1995

–

Chhattisgarh

Chhattisgarh

–

Suitable for the area –

Fruits are light green and oval shaped (4.30 cm fruit length and 2.63 cm fruit diameter) with white strips. It is very high yielding variety, producing about 21.08 kg fruits per plant. Suitable for table purpose Fruits are long and light green in colour having 6.0 cm fruit length and 2.43 cm fruit diameter. It is very high yielding variety, producing about 22.0 kg fruits per plant. Suitable for table purpose An improved dual purpose (salad/ vegetable) variety developed through selection. It yields 18–20 kg/vine (800–850 fruits), extra large fruit, fruit weight (23–25 g). The variety is moderately tolerant to anthracnose, downy mildew and Fusarium wilt

Varietal characters Early and high yielding, fruits round medium in size tender and tolerant to downy mildew and root rot wilt Fruits are medium in size, and the fruit surface is shining and pubescent. Flesh is white, less-seeded, tender and has good cooking quality. It takes about 60 days from sowing to marketable maturity

35–40 t/ha

41–45 t/ha

40–45 t/ha

4.5–5 t/ha

Yield 7.5–10 t/ha

38 An Introduction to Cucurbits

KAU, Vellanikkara

Sulabha

2001

2012

–

–

Source: IARI (2016), Pandey et al. (2011), Anonymous (2017a, 2017b)

IIHR-CHES, Bhubaneswar

Arka Neelachal Sabuja A high yielding (40–50 kg/vine) variety developed through selection with 900–1000 fruits per vine. Hardy plant type, moderately tolerant to anthracnose, downy mildew and Fusarium wilt. Fruits are tolerant to bruising It is a clonal selection of CG-23. Fruits are long (9.25 cm), pale green, with average fruit weight is 18.48 g. It takes 37 days from planting to first flowering. The first harvest can be done in 45–50 days after planting 60 t/ha

70–80 t/ha

6 Soil and Climate 39

40

An Introduction to Cucurbits

friable soil with enough space for root development is required for better growth and yield of cucurbits. The soil should be well manured with lot of vertical and horizontal growing room. 9. The soil should be mildly sandy with clay content of 15% to 30%. Heavier soil is not suitable for cucurbit cultivation, as it remains moist for longer period, which invites various diseases (Deyo and O’Malley 2008). 10. All the cucurbits are sensitive to acid soils. Soil should have a pH not lower than 5.5 and if it is below 5, then there should have provision of liming before sowing. An ideal soil pH for cucurbit cultivation is 6–7. Watermelon is slightly tolerant to soil acidity. 11. Alkaline and saline soils are also similarly unsuitable for growing cucurbits. Bitter gourd and Ash gourd are tolerant to soil salinity, whereas, Snake gourd is the most sensitive cucurbit in this respect.

7

Package of Practices for Cultivation of Different Cucurbits

7.1

Agronomy

Most of the cultivated crop species in this genus are annual in nature and seed propagated excepting Sweet Gourd, Pointed Gourd, Ivy gourd and Chayote, which are perennial in nature and vegetatively propagated by root or vine cuttings. The standard cultivation methods like sowing time, spacing, seed rate, etc. for the cultivated cucurbitaceous vegetables are detailed in Tables 4 and 5.

7.2

Nutrient Management

All gourds, cucumber and pumpkin respond well to manuring and fertilizer application. The doses of fertilizers and manures depend upon the soil type, climate and variety. Fertilizer requirements for cucurbits are relatively less compared to other vegetable crops (Table 6). Full dose of FYM, phosphate and potash should be applied at the time of land preparation. It is better to apply half dose of nitrogen at the time of vining and rest at the time of initial fruit set. Apart from fertilizer application in soil, there is scope of liquid fertilizer application. There are number of fertilizers, which may be applied in liquid form upon leaves of the plant to supplement the nutritional requirement according to crop stage. In the early stage of growth NPK 18:18:18 or 19:19:19 or 20:20:20 or 24:24:0 is beneficial. In cucurbit vegetables, excessive vegetative growth reduces female flower production and thereby yield. Spraying of NPK 0:52:34 or 0:0:50 as 0.3% aqueous solution helps in checking the vegetative growth and induces female flower production and yield.

7

Package of Practices for Cultivation of Different Cucurbits

41

Table 4 Crop-wise cultivation parameters of cucurbits Annual crops raised through seed Name of the crop Bottle gourd

No. of seeds per gram 5–10

Spacing (cm) Row to Hill to row hill 200–300 100–200

Seed rate (kg/ha) 4–6

Bitter gourd

5–10

150–250

60–120

4–5

Ribbed or ridge gourd Sponge gourd Pumpkin

10

150–250

60–120

3.5–5

10 8–15

150–250 200–300

60–120 100–200

2.5–3.5 3–5

Winter squash Summer squash Wax/ash gourd Snake gourd Cucumber

5–12 8–15 10 5–10 30–45

150–250 100–150 150–250 150–250 150–250

90–150 60–120 60–120 60–120 60–90

5–8 5–8 5–7 5–6 2.5–3

Muskmelon Snapmelon Long or serpent melon Watermelon

35–45 35–50 35–50

150–250 150–250 150–250

60–120 60–120 60–120

3–7 3–5 2.5–3.5

6–20

250–350

90–120

3.5–5

30–50

150–250

60–120

3.5–5

Jan.–Feb.; May–June; Oct.–Nov. Jan.–Feb.

Cuttings required (no./ha) 2500–3500 2500–3500 2000–2500 2000–3000 2000–3000

Sowing time in Northern Hemisphere Jan.–Feb.; May–June Jan.–Feb.; May–June Oct.–Nov.; Jan.–Feb. Jan.–Feb.; May–June Jan–Feb.; May–June

Round melon/Indian squash

Sowing time in Northern Hemisphere Jan.–Feb.; May–June; Oct.–Nov. Jan.–Feb.; May–June; Oct.–Nov. Jan.–Feb.; May–June; Jan.–Feb.; May–June; Jan–Feb.; May–June; Oct.–Nov. May–June; Oct.–Nov. May–June; Oct.–Nov. Jan.–Feb.; May–June Jan.–Feb.; May–June Jan.–Feb.; May–June; Oct.–Nov. Nov.–Feb. Nov.–Feb. Nov.–Feb.

Table 5 Crop-wise cultivation parameters of cucurbits Perennial crops raised through cuttings Spacing (cm) Name of the Row to row Hill to hill crop Spine gourd 150–250 90–150 Sweet gourd 150–250 90–150 Pointed gourd 200–300 100–200 Ivy gourd 200–250 100–200 Chayote 150–250 100–200

When the crop is at middle of its age, application of water soluble fertilizer NPK 13:0:45 @ 3 g/lt either as spray or through drip in the root zone is effective in revitalizing the crop and increasing the overall yield.

42

An Introduction to Cucurbits

Table 6 Manure and fertilizer requirements of cucurbit vegetables Crop Bottle gourd Bitter gourd Sponge and ridge gourd Ash gourd Snake gourd Pointed gourd Pumpkin and squash Cucumber Muskmelon Watermelon Ivy gourd

7.3

FYM (q/ha) 180–250 150–200 120–180

Nitrogen (kg/ha) 95 100 90

Phosphorus (kg/ha) 60 50 40

Potash (kg/ha) 80 50 30

120–180 120–180 150–200 180–250 120–180 150–200 180–250 120–180

90 80 90 100 100 100 100 50

50 40 60 50 65 60 60 25

60 40 60 50 65 60 60 25

Intercultural Operation

In cucumber, Luffa and snake gourd, bitterness in edible fruit is a very common problem, occurred due to synthesis of bitter alkaloid ‘cucurbitacin’ making the produce unconsumable. Synthesis of cucurbitacin occurs only when the plants go through any kind of biotic stress (like excessive insect pest attack or heavy weed infestation) or abiotic stresses (like drought, heat waves, cool waves, waterlogging, hardpan in rhizosphere, soil salinity, acidic soil etc.). So, to have a good harvest, proper care has to be taken in every respect, to avoid any kind of stresses during crop growing period.

7.3.1 Irrigation • Irrigation is important for better yield. Though, most of the cucurbits are deep rooted and fetches their required water from the sub-surface strata, yet, for commercial cultivation and to obtain better yield, soil moisture level should always be maintained at 10–15% above permanent wilting point. • Generally, winter crops need irrigation at 10–15 days interval and summer crops should be irrigated at 7–10 days interval depending upon the soil type and environmental condition. In extreme dry situation, irrigation at every third or fourth day is required for better crop growth and yield. • Cucurbit crops respond very well to micro-irrigation, and the combination of drip irrigation and mulching resulted best, particularly in cucumber, watermelon and muskmelon. In bottle gourd and ridge gourd, 48% and 17% higher yield is recorded, respectively, through drip irrigation compared to furrow irrigation. 7.3.2 Use of Plant Growth Regulators • Spray of plant growth regulators helps a lot in modifying sex expression and increased fruit set. The most effective plant growth regulators are Ethrel, Maleic

7

• • •

• •

•

•

Package of Practices for Cultivation of Different Cucurbits

43

Hydrazide (MH), TIBA (2,3,5-Triiodobenzoic Acid), Gibberellic acid (GA) and Alpha Naphthalene Acetic Acid (α-NAA). Other chemicals like Boron, Calcium, Silver Nitrate, Silver Thiosulphate and Molybdenum are also effective in sex modification in cucurbits. Spraying of aqueous solution of these chemicals is most effective when applied upon seedlings twice, once at two and again at four true leaf stage. Exogenous application of plant growth regulators can alter the sex ratio and sequence, if applied at 2 or 4 leaf stage, which is the critical stage for suppression or promotion of either sex (Shinde et al. 1994). The increase in yield varied from 60 to 100%. In pumpkin, three spray of ethrel at 250 ppm at 3–4 leaf stage and 15 days after first spray increases growth parameters, female flower production and yield (Sakthinathan et al. 2017). In bottle gourd, two sprays with Ethrel (100–150 ppm) or MH (at 400 ppm) or TIBA (at 50 ppm) or Boron (at 3–4 ppm) or Calcium (at 20 ppm) have recorded more than 100% increase in yield over the control. Application of growth regulators like MH at 50–150 ppm, CCC (Cycocel) at 50–100 ppm, Ethrel at 25 ppm and GA at 60 ppm at 2–4 leaf stage increases female flower population in bitter gourd. Seed treatment with boron at 3–4 ppm gives higher yield (Verma et al. 1984). In Snake gourd application of ethephon at 250 ppm increases number of female flowers and thereby yield (Cantliffe 1976). In cucumber, application of ethrel at 150–200 ppm twice, at two and four true leaf stage increases number of female flowers and thereby yield. Growth regulators like GA3 at 1500–2000 ppm or chemical like silver nitrate at 200–300 ppm is used in gynoecious cucumber to induce male flower, which is essential for population maintenance (Pessarakli 2016). In Muskmelon, sponge gourd and ridge gourd, application of ethrel at 250 ppm at two and four true leaf stage increases the fruiting as well as yield. In gynoecious Muskmelon, silver thiosulphate at 300–400 ppm induces male flower, which is essential for population maintenance. To increase female flowers and yield in Watermelon, chemicals like TIBA (50–150 ppm), Boron (3–4 ppm), Molybdenum (3–4 ppm) and Calcium (20–25 ppm) are found beneficial.

7.3.3 Pollination Management Cucurbit flowers are unisexual, hence pollination is completely dependent on insect pollinators like honey bee, blue banded bee, cuckoo bee, metallic sweat bee, Carpenter bee, bumble bee, solitary bee, stingless bee and other insects. In any circumstances, if visit of pollinator insects is reduced, then the fruit setting is drastically hampered, resulting to poor fruit setting, yellowing and fruit drop. Sometimes, incomplete pollination in some crops (like cucumber, ridge gourd, bitter gourd, etc.) leads to deformed fruit, which is not marketable at all. Indiscriminate use of chemical pesticides not only kills these pollinators, but also limits visit of these beneficial insects in the crop field due to its obnoxious odour. So, in cucurbits cultivation, to obtain better and quality production, every care and caution have to

44

An Introduction to Cucurbits

be taken in selection of pesticide and its application. Artificial pollination is a better way to mitigate the problems associated with natural pollination. Artificial pollination can be encouraged through different ways. • To ensure pollination, fruit setting and yield, bee hives at the rate of 2 to 3/acre can be installed in cucurbit crop fields. In pointed gourd, visit of bee is rare and natural pollination happens by insects like nitidulid beetle (Haptoncus sp.), pumpkin beetles (Aulacophora foveicollis Lucas), flea beetle (Monolepta signata O.), epilachna beetle (Epilachna dodecastigma (Wied.)), etc. (Das et al. 2009). • In dioecious crops (pointed gourd, sweet gourd), use of one row of male plant after every nine (9) rows of female plants along with installation of bee hive ensures pollination and fruit setting. Parthenocarpic fruit setting is common in the other dioecious crop like ivy gourd. In pointed gourd also, parthenocarpic fruit setting has been recorded in some local germplasms (Mondal and Maitra 2011). • When crop field is smaller, then hand pollination is a better option for these dioecious crops. • During early morning fresh male flower has to be plucked. The fresh pollen from this flower has to be shed carefully upon freshly opened pistillate flowers. Single staminate flower can be used to pollinate 5 to 6 female flowers. • To make the system easier, a pollen mixture can be made using fresh pollen (of 80 to 100 flowers), soluble boron powder (2 g) and glucose (4–5 g), all mixed in one litre of clear water. Two drops of this pollen mixture should be applied upon the stigma head of freshly opened female flowers, essentially during early morning. Boron enhances effectivity and glucose increases longevity of the pollen cells. This system of pollination reduces human labour and drudgery of hand pollination. • To overcome pollination problem in other monoecious cucurbits (bitter gourd, cucumber, ridge gourd), hand pollination or pollination using pollen mixture can be made. As, in monoecious cucurbit crops, female flowers borne simultaneously with male flowers, hence hand pollination to individual pistilate flower is a tedious job. • To simplify the artificial pollination process, pollen mixture (as in pointed gourd, made using the pollen of respective cucurbit crop) can be sprayed over the freshly opened female flowers, early in the morning. This method is very much effective and acceptable for large scale cultivation of melons and gourds. This spray method is not applicable to Cucurbita sp., due to their bell shaped flower structure which restricts reach of the spray droplets to the stigma head.

7.3.4 Staking • Most of the cucurbits are viny crop excepting few bush varieties of summer squash, muskmelon and watermelon. Staking/Bower helps in better flowering and fruiting of these viny cucurbits. • Size of bower/stake depends upon the growth habit of the crop. Vigorous growing crops like bottle gourd, pumpkin, etc. require high and tough bower, whereas crops like pointed gourd, bitter gourd set well in low bower.

8

Harvesting

45

• Vertical bower is very much effective for bitter gourd cultivation in broad bed-furrow system and land embankment system of cultivation, a predominant method of vegetable cultivation in the Indian Sundarbans. Bitter gourd, being light weight crop, fits best in the vertical bower system. Here, two rows of vertical bower are made at a distance of 100 cm to a height of 180 to 200 cm. The top of two bowers are covered using nets and ropes. When the crop covers the entire bower, it looks like a green tunnel. • In low-lying areas, particularly in paddy fields, multi-tier cropping is a good option using cucurbit crops like bottle gourd, pumpkin, ash gourd, etc. Small heap of soil of 70 to 100 cm are made in the paddy field at a spacing of 300 to 500 cm, before transplanting of paddy. Crops are raised upon these heaps. Bower is made all over the paddy field and the crops are spreaded over it. Thus cucurbit and paddy are grown simultaneously. Here, no irrigation is required for the cucurbit crops. • Ariel cultivation or no-land cultivation is another system of agriculture, where cucurbits fit best. Crops like Bottle gourd, Pumpkin, etc. are seeded in the pond embankment. Bower is made over the entire pond and crop is spreaded over it. Thus the crop gets enough space to spread and gives very good yield. In this method, a good harvest is realized, virtually without disturbing any agriculture land. • Some crops like watermelon, muskmelon, snap melon, pumpkin, bitter gourd, pointed gourd, ridge gourd, cucumber, etc. are usually cultivated without bower, by trailing the vines over ground. In such cases, paddy straw mulching is very effective in getting quality harvest. Out of these crops, watermelon, muskmelon and snap melon are never grown over bower.

8

Harvesting

Harvesting stage of cucurbits varies according to crop. In few crops the immature fruits are consumed, whereas in some cases the mature fruits are harvested. Ripe fruits are preferred in some cases. Crop-wise yield of different cucurbits is presented in Table 7. Some important aspects for harvesting of cucurbits are described hereunder. 1. Bottle gourd and Luffa are harvested at immature stage, usually at 12–15 days and 5–7 days after anthesis, respectively. Delay in harvesting makes the fruit fibrous, tough and unsuitable for human consumption. In all the cases, first harvest is ready usually at 60 days after sowing. Next harvesting should be done at 3–4 days interval. 2. In Bitter gourd, immature and tender but fully grown fruits are harvested, usually at 60–70 days after sowing. Regular harvesting of tender fruits at 2–3 days interval increases fruit number and total yield. 3. In Ash gourd both the immature and mature fruits are consumed. Immature fruits are harvested 6–8 days after anthesis, which are consumed as culinary vegetable.

46

An Introduction to Cucurbits

Table 7 Crop-wise yield potential

4.

5.

6. 7.

8.

Name of the crop Bottle gourd Bitter gourd Spine gourd Sweet gourd Ribbed or ridge gourd Sponge gourd Pumpkin Winter squash Summer squash Wax/ash gourd Snake gourd Pointed gourd Cucumber Muskmelon Snapmelon Long or serpent melon Watermelon Round melon/Indian squash Ivy gourd Chayote

Yield potential (t/ha) 20–50 10–20 10–20 10–20 10–20 10–25 20–35 25–30 20–30 15–30 12–25 15–25 15–25 12–25 15–25 10–20 25–45 8–12 10–15 15–25

Mature fruits are harvested at 30–40 days after anthesis and are used in preparation of candy (usually called Petha). It usually starts fruiting 60–80 days after sowing. Pointed gourd and Ivy gourd fruits are harvested when the fruits are fully grown, still immature, determined by change of the colour from dark green to light green. Harvesting should be done twice a week. Pumpkin and winter squash are usually harvested at mature ripe stage; though immature fruits are also consumed. Mature fruits are harvested at 75–180 days after sowing. Fully mature fruits are dark brown or pale yellow in colour and can be stored for long period in normal/ambient storage condition. Summer squash fruits are harvested at one-third maturity, when the fruits are tender with glossy skin, usually at 60–80 days after sowing. Muskmelon and snap melon fruits are ready to harvest 30–35 days and 26–28 days, respectively, after anthesis at full ripe stage. Long melon is harvested at immature stage. Watermelon becomes ready to harvest 40–45 days after anthesis. The harvestable maturity in watermelon is very important with respect to its quality, as it is consumed as dessert. Harvestable maturity is judged by the following parameters: a. Dull sound in beating the fruit by fingers in contrast to metallic sound of immature fruit. b. Tendrils at fruit axil get withered. c. Yellowing of the portion of fruit skin touched with the soil.

Insect Pests and Non-insect Pests of Cucurbits

Cucumbers, muskmelons, watermelons, squashes, gourds and pumpkins are commonly grown cucurbits in most parts of the world. These crops are attacked by a variety of insect pests at different growth stages that cause defoliation of leaves, damage roots or flowers, contribute to poor crop stand, transmit diseases and generate wounds that help the invasion of fungal pathogens. Some of the important insect pests and non-insect pests are fruit fly, red pumpkin beetle, hadda beetle, pumpkin caterpillar, snake gourd semilooper, bottle gourd plume moth, stem gall fly, serpentine leaf miner, stem borer or clear winged moth, flea beetle, aphids, stink bugs, leaf footed plant bug, stem boring beetle, blister beetle, melon thrips, red spider mite and root knot nematodes. Apart from this, vertebrate pests particularly the different species of rat cause damage to the crop.

1

Insect Pests

1.1

Fruit Fly

Fruit flies belonging to the family Tephritidae are well known throughout the world due to their transboundary nature of problem. Devastating effects of this pest on the horticultural industries have placed them on top of the world’s list of key insect pests (Enkerlin 2003). Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Section: Schizophora Family: Tephritidae Subfamily: Dacinae # Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_2

47

48

Insect Pests and Non-insect Pests of Cucurbits

Tribe: Dacini Genus: Bactrocera The family Tephritidae consists of over 4000 species, of which nearly 700 species belong to Dacine fruit flies while nearly 250 species have economic importance. Some important species under the genus Bactrocera includes cucurbitae, dorsalis, zonata, tryoni, correcta, diversa, tau, ciliatus, latifrons.

B. cucurbitae

B. dorsalis

B. zonata

B. correcta

B. diversa

B. tau

B. latifrons

B. tryoni

B. ciliatus

Identification Species name B. cucurbitae

B. dorsalis

Morphology 1. Predominantly orange-brown species 2. Hyaline wings 3. Costal band broad and almost covering apical part of cells r2+3 and r4+5 4. Anal stripes well developed 5. Hind cross veins thickly margined with brown and grey spots at the apex 1. Clear wing membrane with a narrow costal band (not reaching R4+5) 2. Scutum generally black with lateral vittae and medial vitta wanting 3. Yellow scutellum and abdomen with a medial dark stripe on T3-T5 (continued)

1

Insect Pests

B. zonata

B. correcta

B. diversa

B. tau

B. latifrons

B. ciliatus

B. tryoni

49

4. Populations from the Indian subcontinent and Africa have extensive pale markings but specimens from Myanmar mostly have dark scutum 1. Predominantly pale orange brown to red brown species with pale yellow band on 3rd tergite 2. Costal band incomplete and anal band wanting 1. Brightly coloured little fly 2. Predominately black with lateral yellow stripes 3. Very similar to B. zonata but distinguished by colour of the thorax and facial black spots which are being united to form a black transverse band 4. The whitish cross-band on the second abdominal segment is less developed i. Scutum predominantly black with lateral yellow stripes (vittae) ii. Face of male entirely yellow without facial spots while face of female with a black transverse line above the mouth opening 1. Scutum orange brown and marked with black and having lateral and medial yellow stripes (vittae) 2. Wings with a costal band expanded into an apical spot 1. Scutum predominantly black with lateral yellow stripes (vittae) 2. Abdomen is orange coloured 3. Costal band of wings extended up to apical spot 1. Smaller than B. cucurbitae 2. Predominantly orange species 3. Mid femur yellow or orange-yellow 4. Wings with a costal band expanded apically to form an apical spot 5. Prominent dark brown oval spot on either side of 3rd tergite 1. The fly is brown marked with yellow 2. Transparent wings marked with brown 3. On the thorax a broad, creamy, often pale dorsal band runs down the scutellum, and there is a well-defined narrow pale yellow stripe on each side

Distribution The pest is native to India and distributed widely in temperate, tropical and subtropical regions of the world. The pest causes serious damage to several commercial crops in Bangladesh, Cambodia, Hong Kong, India, Indonesia, Japan, Malaysia, Myanmar, Nepal, Pakistan, Sri Lanka, Taiwan, Thailand, Vietnam and Philipines. Host plants The Tephritid was reported to attack as many as 70 host plants while in other reports the insect was found to feed on over 125 plants belonging to Cucurbitaceae and other families. Based on the extensive surveys carried out in Asia and Hawaii, cucurbitaceous plants were found to be the most preferred host for melon fruit fly among 81 plant species surveyed. Some of the preferred host plants under the family Cucurbitacae have been presented here under.

50

Insect Pests and Non-insect Pests of Cucurbits

Host plants Bitter gourd (Momordica charantia), muskmelon (Cucumis melo), snap melon (C. melo var. momordica), snake gourd (Trichosanthes anguina and T. cucumerina), luffa (Luffa acutangula, L. aegyptiaca), balsam-apple (M. balsamina), cucumber (C. sativus), melon (C. melo), pumpkin (Cucurbita maxima, C. pepo), watermelon (Citrullus lanatus), wax gourd (Benincasa hispida, white-flowered gourd (Lagenaria siceraria), Momordica cochinchinensis, African horned cucumber (Cucumis metuliferus), pointed gourd (Trichosanthes dioica), Ivy gourd (Coccinia grandis)

Cucumber

Gherkin

Watermelon

Source Bhatia and Mahto (1969), Clausen et al. (1965), Doharey (1983), Kapoor and Agarwal (1983), Syed (1970)

Bottle Gourd

Ridge Gourd

Pumpkin

Seasonal Abundance The melon fruit fly remains active throughout the year. However, during the severe winter months, they have a tendency to hide and remain crowded under dried leaves of bushes and trees while, during hot and dry season, the flies take shelter under humid and shady places and feed on honeydew of aphids infesting the fruit trees. The lower developmental threshold for adult was recorded as 8.1  C (Keck 1951) while for both lower and upper developmental thresholds for eggs were 11.4 and 36.4  C, respectively (Messenger and Flitters 1958). High temperature, long period of sunshine and plantation activity influence the B. cucurbitae abundance in the Northeastern Taiwan (Lee et al. 1992). The infestation increases at temperatures below 32  C with a relative humidity ranges between 60% and 70% (Dhillon et al. 2005).

1

Insect Pests

51 Adult

Pupa

Cucurbit fruit fly, Bactrocera cucurbitae

Eggs

Larvae

Biology Egg: Eggs are white in colour, slightly curved, elongated, tapering at one end but rounded at other end. The incubation period varied on different host plants and was ranged between 4–5 days. Egg viability on cucumber and pumpkin was recorded 91.7% and 85.4%, respectively, at 27  1  C (Samalo et al. 1991). Maggot: The maggots are apodus, acephalous, dirty white, wriggling creatures, thicker at posterior end but tapering anteriorly. The maggot has three instars and whole larval period varies from 3–6 days depending on prevailing temperature and host plants. The full grown maggot comes out of the fruit by making one or two exit holes and jumps to the ground by curving and springing its body in the air for pupation in the soil. Survival of the maggots on cucumber and pumpkin has been reported to be 86.3 and 80.9%, respectively (Samalo et al. 1991). Pupa: Pupa is barrel-shaped brownish grey in colour with pronounced body segments. Similar to maggot, puparia of B. cucurbitae differ from that of B. dorsalis and B. zonata by the presence of dark transverse line across the middle of posterior end. Pupation occurs in the soil at 0.5–15 cm below the soil surface depending upon the soil texture and moisture. Pre-pupal period varies from less than 6–24 h while pupal period recorded to vary from 6–9 days during rainy season and 15 days during the winter. Pupal survival on cucumber and pumpkin has been reported to be 81.4 and 73.0%, respectively (Samalo et al. 1991). Adult: Adult flies emerge from pupa during morning hours and mate at dusk where males are more active than females which lay eggs singly or in clusters of four to ten on soft fruits generally in the evening hour. The point of oviposition is covered by exuding gummy substance that cements and makes it water proof. A total of 1000 eggs with an average of 300 eggs may be laid by a female which can lay for a period of one week or more. The longevity of male and females was observed 15.0 to 28.5 days and 21.7 to 32.7 days, respectively. Adults hibernate during winter and become active in hot weather. Adults spend considerable time on low, succulent, leafy vegetation surrounding cultivated areas and sometimes at a considerable

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Insect Pests and Non-insect Pests of Cucurbits

distance from host plants. During hot days they are found to take rest on underside of leaves or in shaded areas. Flight is most common in the morning hour as well as in late afternoon. Adults feed mostly on juices from decaying fruits or nectars. Mean single generation time was estimated 71.7 days while net reproductive rate and intrinsic rate of increase was 80.8 births per female and 0.06 times, respectively (Vargas et al. 1997). Bhatia and Mahto (1969) reported that the insect completed the life cycle in 36.3, 23.6, 11.2 and 12.5 days at 15, 20, 27.5 and 30  C, respectively. There are 8–10 generations in a year. Economic Importance Crop Cucurbit vegetables Bitter gourd and watermelon Bitter gourd Cucumber Muskmelon Snake gourd Sponge gourd

Economic loss (%) 30–100 30 60–80 20–39 76–100 63 50

Source Shooker et al. (2006) Singh et al. (2000) Shivalingaswami et al. (2002)

Among several species of the genus Bactrocera, melon fruit fly B. cucurbitae is considered to be most damaging pest to both fruits and vegetables. In a study, adult fly population causing 10% fruit infestation was recognized as economic threshold level. Fruit infestation by melon fruit fly recorded between 41–89% in bitter gourd by different workers but in snake gourd and pumpkin the infestation level was 90% and 60–87%, respectively, in Solomon Islands (Hollingsworth et al. 1997). However, in India, the extent of damage caused by melon fruit fly was 31.27% and 28.55%, respectively, in bitter gourd and watermelon (Singh et al. 2000). Because of high fecundity and mobility, each female fly is capable of destroying large numbers of fruits in its lifespan. Nature and Symptoms of Damage The female adults may lay eggs inside the corolla, tap root, leaf stalk or even within the stem but prefer to lay eggs in young, green and soft-skinned fruits. A watery fluid oozes from the puncture and later changes into brown resinous deposit. As a result of oviposition necrosis may develop around the point of puncture. Sometimes pseudopunctures (punctures without eggs) have also been observed on the fruit. The larvae, after hatching, feed the pulp tissue and make feeding galleries. Attacked fruits fail to develop properly, and drop or rot on the plant.

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Adult fly oviposits on fruit

Marks of oviposition

Premature ripening

Fruit fly strikes but maggot fails to develop in cucumber

Maggots are inside the fruits

Management • Cucurbits are very good remunerative vegetable crops. The fruits are generally picked up at short intervals for either self-consumption or marketing. Hence, broad-spectrum insecticides with high residual action should be restricted to control this noxious pest. Rather, judicious use of biorational or new generation soft insecticides with low residual toxicity having short waiting periods is much recommended along with other pest control tactics. • Elimination of breeding source i.e. damaged or over-riped fruits from the field by burying deep into soil is highly effective in managing the population of pest. • Protein baited traps should be used to monitor the size of population. • Poison bait with cuelure traps and mashed sweet gourd in bitter gourd crop was recorded to reduce the fruit fly infestation by 40–65%. • In endemic areas, sowing date will be as such that the peak fruiting synchronizes with low fly population which is generally less prevalent during hot dry season. • Ploughing and up turning of soil after harvest not only exposes the pupae to sun but also to the natural enemies like birds and other insectivores that keep the pest population under control. • High humidity hot air treatment of C. pepo fruits at a temperature of 45  C for 30 min followed by storing fruits at 7–8  C is very much effective against the pest. • Bagging of fruits with two layers of paper bags at 2–3 day intervals minimizes the fruit fly infestation. • Leaf extract of Ocimum sanctum containing major volatiles such as eugenol (53.4%), beta-caryophyllene (31.7%), and beta-elemene (6.2%) placed on cotton pads can be used in monitoring the adult insect population. Besides this, melon fruit fly can be controlled by planting O. sanctum as border crop sprayed with protein bait containing biorational insecticides like spinosad, Abamectin, etc.

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Insect Pests and Non-insect Pests of Cucurbits

• Ribbed gourd as trap crop may be sprayed with carbaryl 0.15% or malathion 0.1% on congregating adult flies that generally take rest on underside of leaves. • Each pot containing 10 ml of the bait prepared by mixing methyl eugenol and malathion 50 EC at 1:1 ratio, and placed in the field at 25 pots/ha was found effective to control the adult fly population. • Keeping 5 g of wet fishmeal mixed with 0.1 ml of dichlorvos in perforated polythene bags (20  15 cm) at 5 traps/ha was found to be effective in managing the adult fruit fly population. The trap should be charged with insecticide in every week and fishmeal should be renewed at 20 days interval. • The biocontrol agents such as Opius fletcheri, Fopius arisanus may be included in the IPM programme of B. cucurbitae. • An interesting farmers’ practice in Sundarbans areas of West Bengal (India) to control fruit flies is wrapping of fruits with white transparent polythene just after hand pollination. • Mexican strain of nematode, Steinernema carpocapsae applied at 500 infective juveniles/cm2 soil exhibited a very effective control of pupal population in the field. • Host plant resistance is an important component in integrated pest management programmes. Some of the resistant genotypes for melon fruit fly have been presented hereunder. Crop Bitter gourd

Genotype IHR 89, IHR 213 Hisar II, Ace 3 Ace 23, Ace 33 BG14

Pumpkin Bottle gourd Sponge gourd Ridge gourd Round melon

IHR 35, IHR 40, IHR 79-2, IHR 83, IHR 86 NB 29 NB 22, NB 25, NB 28, Pusa smooth purple long NS 14

Remarks Resistant, thick and tough fruit rind Resistant Resistant Resistant and high yield High resistant

Source Pal et al. (1984) Srinivasan (1991) Thakur et al. (1992, 1996) Nath (1966)

High resistant Moderate resistant Moderate resistant

NR 2, NR 5, NR 7

Moderate resistant

Arka Tinda

Resistant

Mahajan et al. (1997)

• Shipment of infested plant material from one area or country to other places is one the major mode of spread of insect pests and this can be kept under control by strict quarantine of imported vegetables and their treatment at quarantine stations.

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55

Pumpkin Beetles

Pumpkin beetles are the leaf beetles belonging to Galerucinae, a large subfamily of Chrysomelidae, containing about 15,000 species in more than 1000 genera. The Genus, Aulacophora contains several species of which some economically important species are foveicollis, lewisii, cincta, similis, coffeae, flavomarginata, femoralis, lewisii, frontalis, abdominalis and intermedia. However, out of the several species of this genus, the red pumpkin beetle, A. foveicollis (Lucas) is the commonest beetle found in India. The insect species is polyphagous pest but cucurbits are the most preferred host. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Chrysomelidae Subfamily: Galerucinae Genus: Aulacophora (Raphidopalpa)

A. foveicollis

A. lewisii

A. cincta

Identification Insect species A. foveicollis

A. lewisii

A. cincta

A. intermedia

Morphology 1. Adult beetles are 6–8 mm in length and have slender body 2. Elytra are pale orange-yellow to deep pale brown in colour and outer surface of the elytra are uniformly covered with fine punctures 3. The posterior part of the abdomen bears soft white hairs 1. Adult beetles are shorter in size than A. foveicollis and body length ranges between 5–6 mm 2. Colour of elytra is blackish blue 1. More or less similar in size and appearance with A. foveicollis 2. Elytra are greyish-yellow to brownish-green in colour with glistening yellow red border 1. Size of the body is almost similar to A. foveicollis 2. Elytra are black in colour

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Insect Pests and Non-insect Pests of Cucurbits

Distribution Red pumpkin beetle, A. foveicollis is widely distributed in India but is more common in north-western parts. The species has also been reported from Greece, south Europe, Algeria, Cyprus, Aden, Iraq, Sri Lanka, Nepal, Burma and Pakistan. Other insect species such as A. similis are recorded from southern and south-eastern Asia while A. coffeae from Malaysia, A. flavomarginata from Malaysia and Indonesia, A. femoralis from Myanmar and Vietnam, A. lewisii from Malaysia and Vietnam while A. frontalis from Singapore, Thailand, Vietnam and Laos. Host Plants The pest is polyphagous species but cucurbits are the most preferred host. Among the cucurbits, cucumber is the most accepted one. Cucurbitacins, present in cucurbits, play a major role in host acceptance while triterpenoid like glucoside in bitter gourd acts as a feeding deterrent. Some of the most preferred hosts are Cucumis sativus (cucumber), C. melo (muskmelon), Cucurbita maxima (giant pumpkin), Lagenaria siceraria (bottle gourd), Luffa aegyptiaca (ridge gourd), Citrullus lanatus (watermelon), Trichosanthes dioica (pointed gourd) and Benincasa hispida (ash gourd). Seasonal Abundance Both larvae and adults of A. foveicollis were reported to remain most active at the temperature range between 27  C to 32  C while the pest is unable to survive beyond 35.2  C (Pavlakos 1943; Al-Ali et al. 1982). The beetle became active from the last week of February after overwintering (Rajak 2000) and the increased population caused maximum damage during March to May. In Madhya Pradesh, India high beetle population (75 beetles/5 sweepings/week) was observed during the month of April but as low as 30 beetles/5 sweepings/week during October (Shinde et al. 1994). Again, the pest was found to remain active throughout the year in Tripura, India with a maximum (104 adults/30 leaves) and minimum (34 adults/30 leaves) beetle population during December and August, respectively (Roy and Mukhopadhyay 1980). In Pakistan, it has been found to infest from first fortnight of May and reached peak during the first week of June (Saljoqi and Khan 2007). Biology Egg: Eggs are spherical in shape and initially yellowish pink in colour but change into orange colour within 2 days. Incubation period ranges between 6–15 days depending upon environmental condition or more specifically on temperature. Chaudhary and Alikhan (1990) observed the highest number of viable eggs/ female and shortest developmental period from egg to pupa in A. foveicollis at 30  C and 70% r.h. and lowest number of viable eggs at 35  C and 90% r.h. Grub: Freshly hatched grub is dirty white in colour but later looked creamy pale yellow with brown heads and legs. Body is slender, elongate, cylindrical and slightly broader towards posterior region. It measures about 10–12 mm long when full grown. It has four instars and the developmental period lasts for 13–25 days and has subterranean life.

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Pupa: Fully developed grub stops feeding and moves into the soil where it constructs almost water proof oval shaped whitish earthen cell for pupation at a depth of 15–25 mm. The grub remains motionless within the cocoon and later change into pupa which is exarate type, greenish yellow in colour with hypognathous head, wider at the thoracic region and narrower towards the caudal region. Pre-pupal and pupal stages vary from 2–5 and 7–17 days, respectively. Adult: Adults are strong fliers, very active in hot weather, and take flight quickly when disturbed. Female beetle starts laying eggs in clusters of 8–9 after about 7 days of emergence in moist soil usually around the host plant and does not prefer to lay eggs in dry and waterlogged soil. Fecundity of female is about 150–300. The adults live for about a month. In frigid temperatures, adults undergo overwintering. The insect completes 6–8 overlapping generations a year from March to October and duration of life cycle ranges from 32–65 days.

Economic Importance The pest causes severe damage to cucurbitaceous crops especially at seedling stage. If the pest is not controlled timely, damage becomes so severe that replanting is needed. Losses caused by the pest are estimated to be 35–75% at seedling stage (Yamaguchi 1983) but the damage rating gradually decreases with the increases of leaf canopy. The pest also delays marketing of the produce of different cucurbits and thereby reduces the income of the growers.

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Nature and Symptoms of Damage Immediately after hatching, the grubs feed on the roots, stems and fruits that come in contact with soil. The damaged roots and underground stems may rot due to infection by the saprophytic fungi. Adult beetles are more destructive that feed voraciously on the leaf lamina by scrapping off the chlorophyll and making irregular holes or leaves with netlike appearance. They also attack the flowers and feed mainly on petals. However, sometimes anthers, pollens, stigma and ovary are also seen to be attacked by the pest which renders the flowers incapable of fruiting. The maximum damage is done during the cotyledon stage. Early sown cucurbits are severely damaged by the pest. The attacked plants may shrivel and necessitating resowing under severe infestation. The young and smaller fruits of the infested plants may dry up, whereas the bigger and mature fruits become unfit for human consumption. Sweet gourd was the most suitable and bitter gourd was the least suitable host for red pumpkin beetles. Management • Ploughing fields just after harvesting of crops is effective in killing the hibernating adults while deep summer ploughing is very helpful to control the pest population by exposing the pupae to sun as well as natural enemies.

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• Collect the debris and burn or bury it after harvest. • It will be better to avoid the crop sowing before the month of November. • Fast growing varieties are more likely to outgrow the damage caused by the beetles. • Provide conditions for healthy rapid plant growth, especially for seedlings by using adequate manures and water along with balanced dose of fertilizers. • Mechanical collection and killing of adult beetles in the morning hour are advisable when incidence is low. • Dusting crop plants with ash is used to repel the pest. • Drenching the soil with insecticides like Chlorpyrifos 20 EC at 2.5 ml/l at root zone may be used to kill the grub. • Indoxacarb 14.5 SC at 0.5 ml/l or Carbaryl 50 WP at 4 g/l or Chlorpyrifos 20 EC at 2.5 ml/l may be applied if infestation is severe. Avoid synthetic pyrethroids as some of these categories of insecticides are reported to have phytotoxic effect on cucurbitaceous plants. • Spraying of Beauveria bassiana (108 conidia/g) at 1 kg/ha may be done twice to thrice at 10–14 days intervals. • Biocontrol agents such as egg parasitoid Trichogramma spp., larval parasitoid Brachymeria tachardiae, pupal parasitoid Trichospilus pupivora should be conserved naturally to increase their efficacy against the pest.

1.3

Hadda Beetle

H. vigintioctopunctata

H. dodecastigmata

The genus Henosepilachna (Epilachna) has nearly 500 phytophagous species. Two species viz vigintioctopunctata and dodecastigma are group of closely related herbivorous ladybird beetles that have diversified greatly in external morphology and host plant use. Polyphagous nature of these species has turned them out as

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destructive pest of many cultivated and wild crops particularly under the family Solanaceae and Cucurbitaceae. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Coccinellidae Subfamily: Epilachninae Genus: Henosepilachna (Epilachna) Identification Insect species H. vigintioctopunctata

H. dodecastigma

Morphology 1. Beetles are about 8–9 mm in length and 5–6 mm in width 2. The beetle is nearly round, convex dorsally, flattened ventrally 3. Head partly hidden beneath pronotum 4. Glossy, deep red and usually having 7–14 black spots on each elytron and one or more on each side of the thorax 5. Legs and antennae are relatively short 6. Upper surface covered with fine, short hairs 7. Tarsi 4-segmented but appear 3-segmented; 2nd segment from base strongly lobed underneath; 3rd segment very short and small, and 4th segment bears claw 8. Each tarsal claw bears three distinct teeth and basal tooth is subrectangular 9. Tip of the abdomen is pointed 10. Newly emerged adults entirely yellow, but as body hardens, dark spots develop over 6–12 h. Antennae longer than width of frons, but shorter than head width; last 3 segments form asymmetrical club 11. Postcoxal plates on 1st visible sternite of abdomen rounded and incomplete externally 12. In the male, hind margin of 6th visible sternite is concave but deep median split in female 1. Beetles are deep copper coloured and six black spots on each elytron 2. Body is hemispherical and smooth 3. The mean length and width of male and female adults was recorded 5.85  0.32, 6.85  0.23 mm and 4.55  0.42, 5.05  0.15 mm, respectively 4. Tip of the abdomen is slightly rounded

Distribution Epilachna beetles have been reported from China, Sumatra and the USA on different crops. Henosepilachna vigintioctopunctata (Fab.) is a widespread Oriental-

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Australasian species and its natural range extends from Pakistan east to the Pacific islands. However, it appears to be absent from the Philippines and New Guinea. In India, the beetle is present in higher hills and in plains of Jammu and Kashmir, Punjab, Himachal Pradesh, Uttar Pradesh, Karnataka and Bengal while Henosepilachna dodecastigma (Wied.) is very common in Bangladesh and has also been recorded from major important vegetable cultivated in South-East Asia, Australia, America and the East Indies. Host Plants The polyphagous pest is reported to cause severe damage to many agricultural crops belonging to the families Solanaceae, Cucurbitaceae, Fabaceae, Convolvulaceae and Malvaceae. The crops under Cucurbitaceae such as bitter gourd, cucumber, melon, watermelon, pumpkin, ribbed gourd, snake gourd, rock melon, squash, etc. are mostly attacked by the pest. Among cucurbitaceous vegetables, bitter gourd is the preferred one. Seasonal Abundance As the beetle can attack and survive on a large number of plant species under different families, it is found to be active almost throughout the year except the winter month when the last instar grub as well as the adult beetle goes for hibernation. However, prevalence and degrees of infestation by the pest vary from season to season, place to place and host plant species. The beetle is most active during morning and evening hours. The pest is most abundant in rainy season during the month of July to August (Sukla and Upadhyay 1985). In Japan, under severe cold conditions, the overwintered adults of H. vigintioctopunctata appeared in early May and adults of the first generation in late June to early July while the second generation was noticed during the month of August (Takeda et al. 1980). High population of H. dodecastigma was recorded by Tripathi and Misra (1991) during the period from late July to October but low in December to January in NorthEastern part of Uttar Pradesh, India. In another study, Ghosh and Senapati (2001) recorded the incidence of the beetle from April to middle of October with a peak during middle of September in Terai region of West Bengal, India. Venkatesha (2006) noticed peak population of the beetle during the month of August in Bangalore (Karnataka, India). Hossain et al. (2009) recorded the peak period of infestation of the beetle during July and August in Bangladesh.

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Insect Pests and Non-insect Pests of Cucurbits

Biology

Egg: The eggs are yellow, cigar-shaped and about 1.5 mm long and are arranged side to side on underside of leaves. Incubation period lasts for 3–4 days in summer months and in 4–9 days in winter Grub: The grubs are oval, fleshy and yellow in colour bearing hairs and spines on the body surface and about 6 mm in length. A fully grown grub measures about 8 mm in length. The grubs generally restrict their feeding to the epidermis of the leaves. There are four instars and duration of total larval period is 9–18 days Pupa: The last instar grubs pupate on infested parts specifically on the leaves of plant. The last larval skin acts as pupal case. The pupae are hemispherical, dark in colour and smaller in size of less than a centimetre. Pre-pupal period is 1–2 days while pupal period varies from 3–6 days depending upon environmental factors. Adult: The young beetles of the new generation feed intensively for 1–2 weeks to build up their fatty tissue. Latter, adult beetles hibernate in heaps of dry plants or in cracks and crevices in the soil. They resume their activity during March-April and live openly on the leaves, eating the soft tissues between the veins. However, during hot summer days their population declines considerably. After copulation, females start laying eggs in the month of March-April. Pre-oviposition period is 5–6 days. Eggs are placed on the undersides of leaves perpendicularly with the leaf surface in batches of ten to sixty-five and a female may lay eggs around 300 or more. Longevity of males and females recorded on different food plants ranged from 4–6, and 5–8 weeks, respectively. The pest completes 7–8 generations during March-October.

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Economic Importance The damage caused by the pest is generally restricted to three crop families viz Solanaceae (potato, tomato, aubergine and pepper), Cucurbitaceae (cucumber, melon, watermelon and pumpkin) and Fabaceae (soya and haricot beans). However, the potato plants were found to be the most preferred host plant for growth and development as well as for reproduction of overwintered beetles. Heavy infestation by this pest resulted in yield loss of potato tubers estimated 25%. Young plants are severely affected while older plants may sustain in spite of considerable foliage damage. Nature and Symptoms of Damage

Both grubs and adult beetles feed on leaves by scraping away the epidermal cells between the main veins. The leaves become skeletonized or looked lace-like in case of heavy infestation. The damaged leaves die, turning brown and curling as they dry before falling off. Management • Mechanical collection and destruction of all stages of the beetle i.e. egg, grub, pupa and adult from the infested plants. • Shaking plants to dislodge grubs, pupae and adults in a pail of kerosenated water early in the morning is effective. • Thorough irrigation of infested crop has been recorded to minimize the pest population. • Introduction of egg parasites such as Tetrastichus ovulorum and Chrysocharis appannai to the crop field may be done. The larval parasites viz Solindenia vermai, Pleurotropis epilachnae, Tetrastichus sp., Uga menoni and the pupal parasite like Pleurotropis foveolatus should be encouraged. • Azadirachtin 0.03% may be applied on leaves during early stages of infestation. • Combination of diflubenzuron and chlorpyrifos at 1 l/ha when sprayed on the crop reduced infestation by 95%.

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Insect Pests and Non-insect Pests of Cucurbits

Pumpkin Caterpillar

Adult

Larva within the leaf fold

The insect species Diaphania indica (Saunders) is commonly known as pumpkin caterpillar or cucumber moth or cotton caterpillar. The insect is mainly an old world moth species. However, the moth is native to southern Asia and occurs in many tropical and subtropical regions. The pest seems unable to establish in cooler climates. But, the transient populations have the potential to cause damage throughout the summer. This species is considered occasional pest of cucurbits and some other plants. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Lepidoptera Family: Crambidae Subfamily: Spilomelinae Genus: Diaphania Identification Insect species D. indica

Morphology Adults are about 13–16 mm long with a wingspan of 24–33 mm. A white patch banded by brown which exhibits a purple iridescence on wings. A well-developed tuft of light brown hairs at the tip of abdomen is present in female but it is vestigial in male. The tuft is formed by long scales which are carried in a pocket on each side of the 7th abdominal segment. The head, first two thoracic segments and a section further down the body are brown, but the central portion and section near to the tuft are generally white

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Distribution The insect species is distributed in India, China, Japan, South Korea, Bangladesh, Saudi Arabia, Yemen, sub-Saharan Africa, USA (Florida) and Northern Territory of Australia. Host Plants The insect primarily feeds on plants belonging to the crop family, Cucurbitaceae. The crops such as squash (Cucurbita pepo), melon (C. melo), pumpkin (C. moschata), cucumber (Cucumis sativus) and watermelon (Citrullus lanatus) are mostly affected. Seasonal Abundance Incidence of the pest depends upon changes in cropping pattern and geographical location including environmental conditions. The pest attacks cucurbit crops especially squash in late season (Zehnder 2011) and feeds primarily on foliage. However, Vanisree et al. (2005) recorded peak infestation of the pest at maximum flowering stage of cucumber. Morning humidity played an important role in population abundance of pumpkin caterpillar. Biology Egg: Eggs are oval and flattened in shape and look initially white but quickly turning yellow. The incubation period is completed within 2–3 days. Larva: The larva is bright green and about 2.5 cm long. Two longitudinal white stripes are present dorsal part of body. The average larval period is 11.9 days.

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Insect Pests and Non-insect Pests of Cucurbits

Pupa: The dorsal longitudinal white stripes on larval body are not found on pupa which is generally dark brown in colour. Pupation takes place inside a cocoon among the leaves. The average pre-pupal and pupal period is recorded 1.3 and 9.4 days, respectively.

Adult: Female moth lays eggs at night in a cluster of 2–6 on different plant parts like buds, stems and underside of leaves. Moths are active only at night. After mating female moth searches suitable site for oviposition. Average period of

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pre-oviposition, oviposition and post-oviposition was recorded 2.0, 5.1 and 1.5 days, respectively. A total of nearly 200 eggs laid by a female moth during her life period and adult longevity is slightly more than a week. The mean developmental period from oviposition to adult emergence ranged from 23–33 days. Economic Importance The pest feeds primarily on foliage. Indirect yield loss was estimated around 23% due to foliage damage while direct yield reduction due to fruit damage was ranged between 9–10% in squash (McSorley and Waddill 1982). Snake cucumber was found to harbour larvae the most, while pumpkin was the least preferred. The fruit damage was around 90% and 60% in little gourd and bitter gourd, respectively. However, in pointed gourd the damage was restricted to leaves and was estimated around 25–30% (Mohaned et al. 2013). Nature and Symptoms of Damage

On hatching, the young larvae nibble the chlorophyll of foliage. Later, it folds the leaves by binding together with silken threads and scrapes the green matter. In severe outbreaks, most of the foliage gets destroyed and gives a lacelike appearance as only leaf veins remain intact. It can also feed on ovaries and even bore into young developing fruits at the proximal end. Management • In early stages of infestation, handpicking of caterpillars and their mechanical destruction helps in keeping the pest population under check. • Pheromone traps may be used in dusty condition or in high moth population density. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken into consideration. • Larval parasitoid such as Apanteles spp., Common mynah (Acridotheres tristis) and cattle egret (Bubulcus ibis) should also be encouraged to increase their efficacy. • In severe cases of infestation Carbaryl dust 5% is effective or spray insecticides like Malathion 50 EC at 500 ml/ha or Dimethoate 30 EC at 500 ml/ha.

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Insect Pests and Non-insect Pests of Cucurbits

1.5

Snake Gourd Semilooper

Anadevidia peponis (Fabricius) is a moth of the family Noctuidae. This is a serious pest of snake gourd all over India. It is a defoliator of cultivated plants especially Cucurbitaceous crops viz. cucumbers and bottle gourds in Japan. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Lepidoptera Family: Noctuidae Genus: Anadevidia (Plusia) Identification Insect species A. peponis

Morphology The adult is a dark brown stout moth with the wingspan of 40 mm. Palpi with short third joint. Hind femur of male not tufted with long hair. Body greyish brown without rosy tinge. Forewings with bronze patches instead of coppery, where the postmedial line sinuous

Distribution The pest is found in south-east Asia, including Japan, India, Taiwan and New South Wales in Australia. Host Plants The larvae feed on cucurbitaceous plants particularly the plant species viz Citrullus lanatus, Cucumis sativus, Cucurbita moschata, Cucurbita pepo, Sechium edule, Momordica charantia and Trichosanthes cucumerina. Biology

Eggs

Larva

Pupa

Adult

Egg: Eggs are spherical in shape, beautifully sculptured and greenish white in colour. Incubation period is 4–5 days. Larva: The larva grows to a length of about 30–40 mm and looks greenish white. Dorsally, the larva having sub-dorsal longitudinal white stripes with short black

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pointed spines. Humped last abdominal segments are characteristic morphological feature of the insect. Larval period lasts for 24–30 days. Pupa: Pupation takes place in the leaf fold within a thin cocoon. Pupal period lasts for 7–8 days. Adult: Adult female lays eggs singly on tender leaves. Life cycle is completed in about 6 weeks. Nature and Symptoms of Damage

Caterpillar cuts edges of leaf lamina, folds it over and feed within the leaf fold. The damage is often serious if young plants are attacked. In severe infestation, the plants are found totally defoliated by the insect. Management • Collection and destruction of the caterpillars. • Biocontrol should be encouraged as the caterpillars are seen to be parasitized naturally by Apanteles paragame, A. plusiae and Mesochorus plusiaephilus. • Dusting Carbaryl 5% is effective for the management of this pest when population reaches or crosses ETL.

1.6

Bottle Gourd Plume Moth

Plume moths belong to the family Pterophoridae which contains nearly 600 species worldwide. The insect is mostly inconspicuous members of Lepidoptera. However, the pest Sphenarches caffer (Zeller) is commonly found on bottle gourd in South India. The larva may be seen as a leaf skeletonizer or flower feeder or stem borer. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Lepidoptera

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Family: Pterophoridae Genus: Sphenarches Some other important species are S. anisodactyl, S. bifurcates, S. bilineatus, S. cafferoides, S. gilloni, etc. Identification Insect species S. caffer

Morphology The adult is a tiny moth with a wingspan of about 10 mm. Both fore and hind wings are composed of feather-like plumes. These are buffed with brown marks. When resting, the moth sits with its abdomen curved up into the air and its wings held at right angles to the body with the plumes folded

Distribution The pest is widely distributed in West, South and East Africa, Maldives Islands, Indian subcontinent, Phillipines, Japan, Indonesia, Australia and Tonga Islands in Oceania and West Indies. Host plants The pest is polyphagous in nature and found to cause damage to pigeon pea, peas, cocoa, lablab, Cucurbita pepo and other cucurbits. Among the cucurbits, it has been reported damaging bottle gourd and Luffa sp. Biology

Last instar exuviae

Larva with bore hole

Pupa with last larval skin

Adult

Egg: Eggs are oval in shape, bluish green in colour with reticulate designs. Incubation period lasts for 3–4 days. Larva: Caterpillars are yellowish green in colour, cylindrical and about 7–9 mm long when full grown. They have short spines all over the body with a lateral brown stripe on either sides and clothed with long capitates hairs. There are five instars and larval period is completed within 10 days. Solitary nature of the larva is generally found particularly in latter stages. Pupa: Greenish brown in colour and have spines on the body. The pupa is generally attached by cremaster to a silken pad spun by the mature larva. Mean duration of pre-pupal stage is approximately 1 day. Duration of pupal stage is 7 days.

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Adult: Adults are inconspicuous and live almost 2 weeks. Eggs are laid singly on buds and leaves. A female insect can lay up to 100 eggs. Nature and Symptoms of Damage

Larvae feed on leaves making small holes and also feed on flowers and fruits of various plants. Numerous holes on leaves are found to be caused by the older larvae. Management • Collection and destruction of both larvae and pupae. • Timely sowing of the crop. • Proper maintenance of field sanitation. • Encouragement of larval parasites like Apanteles ruidus and A. paludicola. • Spore suspension of Bacillus thuringiensis kurstaki or Spinosad may be sprayed to achieve effective control of the pest.

1.7

Stem Gall Fly

The gall midge Lasioptera spp. is one of the serious pests of bitter gourd causing an economic yield loss. Two species of gall midges have been reported on Momordica charantia L., namely L. falcata and L. bryoniae. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Family: Cecidomyiidae Genus: Lasioptera

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Identification Insect species L. falcata

Morphology Minute, delicate dipteran insect. Adults are slender, dark brown and mosquito-like insect. They are identified from other flies by the presence of relatively long hairlike antennae, and long legs. The antennae are particularly well developed in males. Few veins present in the short-haired wings

Distribution It is very common at Coimbatore and other localities in South India. In Bangladesh it is commonly known as gall gnats or gall midges. Host Plants Bitter gourd, cucumber, tomato, squash and vegetable marrow. Biology

Eggs

Maggot

Pupa

Adult

Egg: Eggs are elongate and freshly laid one is transparent but becomes yellow after 36 h. Incubation period is 96 h. Maggot: The neonate maggots are transparent and about one millimetre long. The maggots have distinctly divided 11 body segments with a Y-shaped structure called the “Sternal spatula” on the ventral surface of the second segment. The head-capsule is well developed and mouthparts are of biting type. Early instars are white but turn yellow colour when fully grown. The duration of larval period is about 7–11 days. Pupa: Pupation takes place inside the larval cavity within the galls. The puparium is transparent initially which subsequently turn yellow and become dark brown with the development of wing pad and antenna 24 h before adult emergence. Ventral side of pupariam turns orange with black stripes at the distal abdominal segments. Adult: Adults emerged from the puparium leaving pupal case semi-atrophied on the gall. The female lays eggs by piercing the plant tissue and deposits the eggs inside the tender shoots or tender leaf petiole in patches of five. Adult is mosquito-like fly and the mated female starts laying eggs immediately after mating. The average fecundity of a gravid female was recorded 98.3. Male gnats fly in swarms, usually toward evening, dancing up and down a few feet from the ground. The insect can complete its life cycle in and around 21.5 days.

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Nature and Symptoms of Damage

The maggots bore inside the distal shoots and their feeding induce the formation of gall. Long and tubular galls are found on the distal young shoots and remains on the affected plant for extended periods of time. The galls might be due to increasing in cell size (hypertrophy) or cell number (hyperplasia). Gall formation affects the growth of plant. Once gall formation is initiated, many galls will continue to form even if the insect dies or undergo pupation. Management • Removal and destruction of affected shoots in early stage of infestation is the only effective management practice of the pest. • Chemical application may be a useful tool but often ineffective since the precise timing of application is critical. It must be timed to coincide with initial activity of the insect before gall formation begins. • Horticultural mineral oil can also be applied before insect activity begins.

1.8

Serpentine Leaf Miner

Liriomyza trifolii (Burgess) is commonly known as serpentine leaf miner. It is highly polyphagous and has been recorded from 25 families. It was first described as Oscinis trifolii in the family Chloropidae from flies attacking the leaves of Trifolium repens (white clover) in Indiana, USA. Later, it was transferred to the family Agromyzidae in the genus Agromyza by Coquillet in 1898, then to Liriomyza by de Meijere in 1925. There are 376 species currently recognized in the genus Liriomyza.

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Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Family: Agromyzidae Genus: Liriomyza Identification Insect species L. trifolii

Morphology Minute size insect measuring less than 2 mm in length. The head is yellow with red eyes with yellow hind margins. The insect has greyish black mesonotum and yellow femora. Abdominal terga are mostly black while ventral surface of the body is yellow. The wings are more or less transparent. Females bear elongated abdomen and more robust than males

Distribution It is generally recognized that all the countries bordering the Mediterranean have L. trifolii in varying degrees and that it occurs in all mainland states of the USA. However, expanded traffic in flower crops appears to be the basis for the expanding range of this species. As a vegetable pest, however, its occurrence is limited principally to tropical and subtropical regions. The pest was accidentally introduced into India from American subcontinent along with chrysanthemum cuttings. Host Plants It is a major pest of ornamental and vegetable crops, including beans (Phaseolus), Capsicum, carnations, celery, chrysanthemums, Dendranthema, clover, Cucumis, Gerbera, Gypsophila, lettuces, lucerne, potatoes, Senecio hybridus and tomatoes in North America, Africa and Europe. In India, it was initially recorded on 55 plant species (Viraktamath et al. 1993) and later on about 79 species (Srinivasan et al. 1995) that included pulses, oil seeds, vegetables, fodder and fibre crops. Cowpea is one of the important legume crops affected by this pest.

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Biology

Ovipositing female fly

Maggot

Pupa

Egg: Eggs are oval in shape and measuring about 1.0 mm long and 0.2 mm wide. Eggs are clear but become creamy white before hatching. Incubation period is 3 days. Maggot: Initially, the maggots are almost colourless but turn into greenish to yellowish with the advancement of age. Maggots having three instars and when fully grown they attain an average length of about 2.25 mm. The mature maggot cuts a semicircular slit in the upper surface of mined leaf from which it emerges and drops to the soil for pupation. Larval period varied from 4 to 25 days. Pupa: The mature maggot forms a puparium few centimetres below the soil. The puparium is reddish brown having a length of 1.5 mm and a width of 0.75 mm. Pupal period lasts for 9 days. Adult: Adult emerges out from the puparium, generally in the early morning hours. Mating occurs during the day. Gravid female oviposits on lower surface of leaves just below the epidermis. Initially, females lay more number of eggs at a rate of 30–40/day, but it decreases with the advancement of time. Fecundity varied with 110–140 eggs in different hosts. Population is meagre during the cooler months but often attains high and damaging levels by mid-summer. In warm climates they may breed continuously, with many overlapping generations per year. Under Indian conditions, adults lived for 3–6 days. Male and female longevity varied from 4.7 and 6.0 days in cowpea. Total life cycle period is almost a month. Nature and Symptoms of Damage

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Puncture due to oviposition by adult female may result in stippled appearance on foliage, especially at the tip and margin of leaf. However, the major form of damage is caused by maggot by mining leaves. The mine becomes noticeable about 3–4 days after oviposition and becomes larger in size as the larva matures. The pattern of mining is irregular. Both leaf mining and stippling can greatly depress the level of photosynthesis in the plant. Extensive mining resulted in premature leaf drop which also promotes sun scalding of fruits. Management • Destruction of weeds as alternate host and deep ploughing of crop residues are recommended because adult flies experience difficulty in emerging if they are buried deeply in soil. • Cultural practices such as mulching and staking of vegetables are also helpful in reducing the pest population as these practices exhibited a negative influence on leaf miners population. • Parasitoids often provide effective suppression of leaf miners in the field if broadspectrum, persistence insecticides are avoided. • To effectively manage L. trifolii, growers in southern Florida typically use translaminar biorational insecticide like abamectin and new generation insecticide such as Cyromazine, a dipteran triazine insect growth regulator, which acts as moulting disruptor.

1.9

Stem Borer or Clear Winged Moth

The clear winged moth, Melittia cucurbitae (Harris), also known as squash vine borer is often mistaken for a bee or a wasp because of its movements and bright orange scales on hind legs. Unlike many moths, they are diurnal fliers. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Lepidoptera Family: Sesiidae Genus: Melittia Identification Insect species M. cucurbitae

Morphology The adults have stout bodies and are about 3.8 cm in length with a wingspan from 3.2 to 3.8 cm. The adult body is reddish with black bands encircling the abdomen. The fore wings are metallic green. The hind wings are clear with dark veins and fringed with reddish brown hairs

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Distribution It occurs east of the Rocky Mountains from Canada to South America and India also. Host Plants It is a serious pest of vine crops, commonly attacking summer squash, winter squash and pumpkins. Cucumbers and melons are less frequently affected. In home gardens, entire crops may be lost sometimes in the year of high borer population. Seasonal Incidence It is active during middle of June through the July. Biology

Egg: Eggs are small, disk-shaped and reddish brown in colour. Incubation period ranged between 9 to 11 days.

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Larva: The larvae bore into stems within hours of hatching leaving small, almost invisible entrance holes with yellowish frass. The larvae are white to cream-coloured caterpillars with brown heads. Larvae feed for approximately 25–27 days. After feeding for about a month the borers exit from the stem and burrow about 1–2 inches into the soil for pupation.

Pupa: Pupation takes place in earthen cocoon in the soil and the pupa undergoes overwintering.

Adult: Females lay eggs one at a time on stems or leaf stalks at the base of plants or vines. Surprisingly, it is a daytime flyer and can sometimes be seen hovering in front of flowers for feeding on nectar, or around cucurbit plants and vines. One to two overlapping generations completed per annum.

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Nature and Symptoms of Damage

The female typically lays eggs at the base of leaf stalks. After hatching, the caterpillar remains within the leaf stalk and starts feeding the inside tissues. As a result of larval feeding, leaves begin to turn yellow and eventually brown around the leaf margins and finally dried to fall down. The larvae soon migrate to the main stem and the plants start to wilt or even die due to severe attack. Larval excreta (frass) resemble wet sawdust, protruding from small hole is an indication of larval presence inside the stem. Management • Destruction of mature larvae or pupae in the plants or soil by tilling in crop debris soon after harvest is the primary cultural practice for preventing a build-up of pest. • Altered time of planting is helpful in avoiding the peak period of pest population. • Row covers can be used up until blooming to prevent adult movement from underneath. • Covering the vine with soil at various points along its length inducing rooting which ultimately help in continuous supply of nutrient to developing fruits despite the loss of original stem. • The adult borers are attracted to yellow colour. So, yellow pan trap may be used to monitor their population. • Steinernema carpocapsae or S. feltiae applied to the stem and soil provided control similar to a conventional insecticide in many trials. • Activity of parasitoid, Apanteles spp. should be encouraged. • Pesticides are ineffective after the larvae are inside the plant. Hence, spray timing is critical for effective chemical control of the pest because larvae begin to tunnel into stem within hours of hatching and once entered inside the vine, they remain protected from outside intervention. Synthetic pyrethroids are mostly used by the farmers. However, new generation insecticide like spinosad can be used.

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Insect Pests and Non-insect Pests of Cucurbits

Flea Beetle

The Flea beetles are small, jumping insect of leaf beetle family (Chrysomelidae) having attractive colour and often metallic colours predominate. Their name, ‘flea beetle’ arose from the behaviour to jump when disturbed. However, they can also walk and fly. The most common flea beetle species is Phyllotreta cruciferae Goeze. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Chrysomelidae Genus: Phyllotreta Identification Insect species P. cruciferae

Morphology Adult beetles are 1.5–2.0 mm in length, elongate, oval shaped and metallic bluish green in colour. Antenna is black. Prothorax is wider than its length but scutellum is small. Elytron is closely covered with punctures. The beetles have enlarged hind femora which help them to spring when disturbed

Distribution It has been reported from Europe, Egypt, Middle East, Asia, Russia and North America. In India, the species is commonly found on cole crops. Host Plants The insect is very common pest of cruciferous vegetables. However, due to its polyphagous nature, the insect is found to infest many other crops including cucurbitaceous vegetables. Seasonal Incidence The pest is found almost throughout the year in different host plants. In India, the peak period of infestation is during March-April after which the pest migrates to root crops like radish, turnip, etc. However, in cucurbits it was recorded from the end of June to September with a peak at August in Dapoli, Maharashtra, India.

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Biology

Egg: Eggs are yellow, oval, about 38–0.46 mm in length and 0.18–0.25 mm in wide. Incubation period is ranged between 5–10 days. Grub: Grubs are small, whitish, slender, cylindrical worms bearing brown head and anal plate. Duration of grub stages is around 9–15 days. Pupa: Pupae are black in colour and pupation takes place in the soil. Pre-pupal and pupal stages last for 2–4 and 8–14 days, respectively, depending upon environmental condition. Adult: Sexually mature female lay eggs singly or in groups of 3–4 adjacent to the host plants on soil. A single female can lay 50–80 eggs in her lifetime. In a single year the insect has been recorded to complete 7–8 overlapping generations. Nature and Symptoms of Damage

Immediately after hatching the grubs feed on roots. However, the damage to roots is not so serious on cucurbitaceous vegetables. The adult beetles feed externally on leaves, stems and petals of plants, making typical ‘shot hole’ symptoms particularly

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during seedling stage of the crops. Sometimes, under heavy infestation the small round holes coalesce to each other. Management • The larvae overwinter in soil and can be killed by hoeing, ploughing like cultural operations. • Removal of all old debris and weeds from previous crops may be effective in managing the pest population because such materials serve as early-season food for flea beetle larvae. • Diatomaceous earth or neem oil may be used to repel most flea beetles. Some horticultural oils are also used to repel the insect. • Trap crop like Basil can be planted in different places along with the main crop to repel the insect. • Physical barriers such as row covers are safe and easy methods of controlling flea beetles. These prevent the insects from jumping onto the leaves and munching away on the foliage. • White sticky traps can be used to prevent free movement of the insect. • A layer of thick mulch around plants is very useful to limit the insect’s transformation from larvae to adult in the soil. • Insecticidal dust is effective in controlling the pest. Insecticides like spinosad, permethrin, carbaryl, bifenthrin are commonly used to control the pest population.

1.11

Aphids

Aphids are small sap-sucking insects and members of the super-family, Aphidoidea. They are among the most destructive insect pests on cultivated plants. They cause damage to plant directly by desapping and indirectly by spreading the diseases as vector of many plant diseases. About 5000 species of aphid have been described and all are included in the family Aphididae. However, around 400 species of aphid are found to attack food and fibre crops, and many of them are considered serious pests of agriculture. The aphid species such as Bean aphid (Aphis fabae Scopoli), Green peach aphid (Myzus persicae Sulzer), Melon aphid (Aphis gossypii Glover) and Potato aphid (Macrosiphum euphorbiae Thomas) are reported to infest cucurbitaceous plants. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Homoptera Family: Aphididae Genus: Myzus, Aphis (Common genera)

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Identification Insect species A. gossypii

M. persicae

Morphology Soft bodied, delicate and pear shaped insect. Apterous, parthenogenetic females are 1 to 2 mm in length. Body is quite variable in colour but light green mottled with dark green is most common. The legs are pale with the tips of tibiae and tarsi black. The head and thorax are black and the abdomen yellowish green except for the tip of the abdomen, which is darker. The wing veins are brown. The cornicles are also black. The oviparous female is dark purplish green. Whitish, yellow, pale green and dark green forms are also found Alate aphids have a black head and thorax, and a yellowish green abdomen with a large dark patch dorsally. They measure 1.8–2.1 mm in length. The cornicles are moderately long, unevenly swollen along their length, and match the body in colour

Distribution It is cosmopolitan pest and found throughout the world except extremely cold region of Asia and Canada. Hosts Plants More than 700 species of host plants have been infested by aphid throughout the world. Among cucurbitaceous plants, melons are highly prone to attack by this insect. Biology

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A. gossypii: Mode of reproduction is usually viviparous and parthenogenetic and sometimes oviparous. The mature female directly gives birth to offspring in place of laying eggs and that too without fertilization. A single apterous female produces 8–22 nymphs/day. These mature within 3–4 days and total life cycle occupies about 7–9 days. The alate forms generally appear after several generations; especially when there is overcrowding, deterioration of plant condition and/or change in the environmental condition particularly the temperature. The nymphs that give rise to winged females may be pinkish. The dispersants typically produce about 20 offsprings, which are always wingless. This cycle is repeated throughout the period of favourable weather. M. persicae: Nymphs initially are greenish, but soon turn yellowish, greatly resembling viviparous adults. Females gave birth to offspring 6 to 17 days after birth, with an average age of 10.8 days at first birth. The length of reproduction varied considerably, but averaged 14.8 days. The average length of life was about 23 days under caged conditions. The daily rate of reproduction averaged 1.6 nymphs per female. They often deposit a few young and then again take flight. There exist both alate and apterous forms in a single population. However, the apterous forms are more common and abundant. Nature and Symptoms of Damage

The aphids feed the plant gregariously. Both nymphs and adults suck the sap from lower surface of leaves, tender twigs, shoots, etc. Due to desapping the affected plants turn yellow, leaves become curled, wrinkled and deformed in shape and ultimately dried up. Vigour and vitality of the plant get affected badly which resulted in reduced yield. As a result of aphid infestation copious quantities of honey dew are found on infested parts, which favours the development of sooty mould fungus (Capnodium spp.) and thick black layer covering on leaves due to spore formation of sooty mould ultimately hinder photosynthetic activity of the infested plant. The infested fruits covered with black sooty mould fetch poor market price also. The aphid also transmits viral diseases and the loss due to the disease is irreparable. The main disease transmitted by aphid on cucurbits is Cucumber Mosaic Virus (CMV).

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Management • Infested crops should be destroyed immediately after harvest to prevent excessive dispersal. • Overwintering hosts like weeds should be destroyed. • Avoid continuous cropping. • Row covers can be used to inhibit development of aphid populations. • Time of planting should be adjusted as such that the crop may pass the vulnerable stage during aphid infestation. • Yellow sticky traps of yellow pan traps may be used to monitor the aphid populations. • Systemic or contact insecticides may be applied on affected plants particularly during the initial stages of aphid infestation.

1.12

Blister Beetle

The blister beetle gets its name from the defensive secretion of body fluid containing cantharidin causing blister if comes in contact with skin. There are nearly 7500 species under the family Meloidae having been known worldwide. The Meloidae is one of the most interesting of all Coleoptera families on account of the remarkable biology as the members of this family are hypermetamorphic. The first instar larva is active and campodeiform, while the subsequent larval instars are sedentary and scarabaeiform. Adult beetles are commonly found to feed gregariously on floral parts. They are mostly diurnal and often highly coloured. Mylabris pustulata Thunberg is a cosmopolitan blister beetle found throughout India and reported to feed on cucurbitaceous plants. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Meloidae Genus: Mylabris Identification Insect species M. pastulata

Morphology 1. Adult beetles can be recognized by morphological characteristics such as soft body, bright colouration, rather elongate, head deflexed with narrow neck, pronotum not carinate at sides, heteromerous tarsi and smooth integument 2. Head, thorax and abdomen are black in colour while elytra having a round orange spot and two transverse wavy orange bands across the wings on black background 3. They are commonly confused with members of the family Oedemeridae (false blister beetles) and subfamily Lagriinae (long-jointed beetles) of Tenebrionidae

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Distribution It is a polyphagous pest widely distributed in Africa and Asia. Host Plants The insect was reported to feed on a wide range of plant species belonging to the family Cucurbitacae, Asteraceae, Leguminosae, Compositae, Umbelliferae, Solanaceae, Fabaceae, Malvaceae, Convolvulaceae and Solanaceae. Seasonal Incidence They emerge out of the soil around August and are active till early December. However, peak activity is usually observed from August to October in South India. Biology Egg: Eggs are light yellowish in colour and cylindrical in shape. Incubation period is about 3 weeks. Grub: Larval development is hypermetamorphic, with four distinct phases. The first instar grub is called triungulin (more recently planidium) because of the peculiar shape of pretarsus. Young grubs are white in colour. Cannibalism is prevalent among larvae. However, on hatching they feed generally on egg pods of various grasshoppers found in the soil and also predates upon soft bodied insect like aphid. After first moult, they become scarabaeiform and enter a period of rapid growth (first grub phase) that lasts until the end of fifth or sixth instar. The full grown larvae become heavily sclerotized and change into coarctate form of immobile pseudopupae. In this phase the grubs lack any functional appendages as the musculature undergoes profound degeneration and they may undergo hibernation during which the respiration is reduced in such a low level that survival of the insect may extend to more than a year. In congenial weather when physiological development resumes, the muscles regenerate and after ecdysis the larva becomes scarabaeiform (second grub phase) again. Interestingly, in response to adverse environmental conditions, second grub phase may return to coarctate phase. Pupa: The second grub phase very soon pupates inside the soil tunnel. Adult: Female adult beetles lay eggs in masses of 60–80 at 2–3 cm depth in soil of cultivated land. Adults commonly live 3 months or more. Females typically mate and oviposit periodically throughout their adult lives.

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Economic Importance Damage caused by the adult beetles is only due to their gregarious nature of feeding. They feed on pollens, petals of flowers and flower buds. The resultant effect is the poor fruit setting. However, the insect is not considered as major pest of cucurbits. Apart from its pest status, the insect is found beneficial from pest management point of view because triungulins are recorded to feed on egg cases (oothecae) of grasshoppers while other instars are found to prey on soft bodied insect like aphids. Thus, the species may often be beneficial to agriculture as a larva, helping to control grasshopper populations, yet be a pest as an adult.

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Nature and Symptoms of Damage Damage to the crops is only caused by the phytophagous adults through their biting and chewing type of mouthparts. They mainly attack the floral parts and are generally attracted to yellow and pink flowers. Management • It is difficult to control the beetle because of their rapid mobility. However, hand collection and prompt destruction of the beetle is an effective measure to keep the population under check. But, this practice should be done during early morning hours as the beetles remain less active. • Cultural methods such as regular weeding, sanitation, polyculture, strip cropping and trap cropping, crop rotation may be followed to reduce the population buildup of pest. • Alternate host plants (non-crop) should be destroyed prior to blooming stage. • Ant-like flower beetles (Coleoptera: Anthicidae), false ant-like flower beetles (Coleoptera: Pedilidae) and some plant bugs (Hemiptera: Miridae) may be encouraged to control blister beetles naturally. • Insecticides like Beta-cyfluthrin proved effective against the beetle on sponge gourd. Besides this, Azadirachtin 0.03%WSP or Emamectin benzoate 5% SG or Spinosad 45% SC or Phosalone 0.07% may also be used.

1.13

Leaf Footed Plant Bug

Leptoglossus is a genus of true bugs in the leaf footed bug family that have leaflike dilations in hind tibia. The bug is a polyphagous pest. However, cucurbitaceous crop particularly the bitter gourd is considered to be most preferred host plant of L. australis (Fab.). Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hemiptera Family: Coreidae Genus: Leptoglossus Identification Insect species L. australis

Morphology The insect is black in colour and about 20 mm long. Antennae are filiform and four segmented. The flagellar segments are alternately with black and yellow in colour. Mesonotum having a spine on either side. A minute yellow spot is present in the centre of each forewing and on hind tibia

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Distribution The pest has widespread distribution including Asia and Oceania. It is recorded from Australia, American Samoa, Fiji, French Polynesia, Guam, Federated States of Micronesia, North Mariana Islands, Palau, Papua New Guinea, Samoa, Solomon Islands, Tonga, Vanuatu, Wallis and Futuna. The pest is also recorded from a number of African countries, South China, Phillipines and Indonesia. Host Plants Bitter gourd, snake gourd, melon, cucumber, pumpkin and other cucurbits. Seasonal Incidence Population levels change from year to year depending on weather and parasitism of eggs. Seasonal fluctuations in the number of bugs can also be related to rainfall, food availability and the prevalence of natural enemies. Cold winters kill many adults, and major outbreaks often occur after mild winters due to low incidence of natural enemies during this period. Overwintered adults live from September/October until late spring. When weather gets warm, typically in March in the San Joaquin Valley and April in the Sacramento Valley, adults disperse to find food sources while in Japan overwintered adults were recorded to breed from May to June in Japan. Adults may feed initially on the seeds of winter weeds and later move into gardens, landscapes, and farms in search of early-season fruit and a place to lay eggs. Biology

Egg: Eggs are cylindrical in shape and light brown in colour that hatch within 6–7 days. Nymph: The insect passes through five nymphal stages that may be completed within 40–50 days. Young nymphs are reddish while in latter instars they become darker. Full grown nymphs are 12–16 mm long. Wing pads appear after third instar and hind tibia also flattened out to become leaf like structure.

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Adult: Overwintering leaf footed bugs can lay over 200 eggs over a 2-month period in the spring. Eggs are generally laid on leaves, stems or even on the tendrils, in batches of about 30. The bugs overwinter as adults, typically in aggregations located in protected areas, such as in woodpiles, barns or other buildings, palm fronds, citrus or juniper trees, under peeling bark, or in tree cracks. Adults are strong flyers. Adult males live longer than female. The lifespan of male and female is 14 and 10 days, respectively. During the spring and summer, there are typically two to three generations of leaf footed bugs. In the fall, all bugs develop to adults that overwinter in aggregations. Economic Importance

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Population of the bugs seldom reaches to EIL, hence, it is not considered as major pest of cucurbits. Nature and Symptoms of Damage Both nymphs and adults congregate on terminal shoots and cause damage to the plant by desapping from the shoots. As a result, affected shoots get withered and sometimes may die if infestation reaches sufficiently high while feeding on tender fruits causes them to shrivel, rot and drop prematurely. Sometimes, dark spots are noticed on the affected fruits at point of puncture. Management • Removal of overwintering sites like woodpiles, culls of fruit of pomegranates and other fruits. • Elimination of weed plants that serve as alternate food source for the pest is very useful in reducing the pest population. • Covering plants with a row cover made up of polypropylene or polyester may be done before the bugs arrive and lay eggs on plants. • The egg masses deposited on underside of leaves should be destroyed. • Bugs that are hidden inside dense foliage layers or fruit clusters may be handpicked or brushed off into soapy water in the morning hour during the early stages of infestation. • Hymenopteran egg parasite, Gryon pennsylvanicum and tachinid fly, Trichopoda pennipes that parasitize the adult bugs should be conserved for better natural control. Leaf footed bugs are naturally predated by many birds, spiders and assassin bugs also. So, these natural enemies should be preserved by discarding the use of persistent broad-spectrum insecticides as well as by assuring pollen and nectar sources for them. • Loose barks of many trees may be treated with insecticides as the bugs overwinter inside those sites. • In severe cases, insecticides can be considered as a last resort to control the pest in the field. The insecticides are more effective against small nymphs. Therefore, it will be better to apply insecticides when small nymphs are present at sufficiently high level.

1.14

Stink Bugs

Stink bugs earned the name from their tendency to release unpleasant odour when disturbed or attacked. It is believed that the odour helps protect the bugs against predators. The buggy smell has often been compared to strong herbs and spices like cilantro and coriander. Some commonly found stink bug species are Aspongopus brunneus Thunb, A. janus (Fab.), A. observes (Fab.).

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Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hemiptera Family: Dinidoridae Genus: Apspongopus Identification

A. janus Insect species A. janus

A. brunneus A. viduatus

A. brunneus

A. viduatus

Morphology Stink bugs are described in different ways. They are characterized as flat, medium sized and shield-shaped insects. Adults of A. janus are about 30 mm in length, pronotum and base of the elytra is bright red while the head and wing membrane are black in colour. Their legs extend from the sides for which they appear even larger The adults of A. brunneus are pale brown in colour and slightly smaller than A. janus The insect is medium in size and is generally oval, but rather flat in shape. Colour dark brown to blackish except for the yellowish colour anterior part of hemelytra. Male and female are much alike except that female’s final abdominal segment is carved while in male it is sticking out straight

Distribution The species A. janus is widely distributed throughout India while A. brunneus is usually found in south India and A. obscurus is more prevalent in North-East India. However, black watermelon bug is reported from many of African countries, Turkey and Mediterranean basin.

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Host Plants The Apspongopus species have often been found to infest cucurbitaceous vegetables, especially Cucumis sativus, Cucurbita maxima, Lagenaria siceraria, Citrullus lanatus, Cucurbita pepo, Momordica charantia while black watermelon bug, A. viduatus (Fab.) (Coridius viduatus) is also found to infest squirting cucumber (Ecballium elaterium (L.)). Seasonal Incidence In south China the adult stink bugs occur from early spring to late fall and eggs have been found from mid-May through late August while in Uttar Pradesh (India), population of the pest increases in late summer (August) through fall (October). The increased population is stimulated by moderately high temperature and relative humidity but decreases with the decrease of relative humidity associated with sudden rise of temperature. In Namibia, heavy infestation of A. viduatus is recorded in irrigated areas during the winter months but in rain fed regions it appears during the rains. In the dry season the bug undergoes for aestivation in shady, low lying places. Biology Egg: The barrel-shaped eggs are attached side-by-side and hatched out in 9–10 days. Nymph: After hatching the tiny nymphs begin to feed the plant. They undergo a series of moults until they become adult. There are five nymphal instars which may be completed within 24–28 days depending upon prevailing environmental conditions. Adult: The gravid female lays 20–30 eggs typically in rows on underside of tender leaves and can lay about 500 eggs or more in her lifetime. After last moult, the nymphs become adult and copulation takes place within 2–3 days of adult emergence. The gravid females start laying eggs after a period of 4–5 days of pre-oviposition and egg laying continues for almost 2–3 weeks. Post-oviposition period is nearly one week. The adult lifespan is about four and seven weeks for male and females, respectively. During the winter adult bugs undergo hibernation in cracks and crevices and become active again during early spring. The insect has been reported to complete three generations in a year. Economic Importance Stink bug (A. viduatus) is a serious pest of watermelon. Gregarious feeding by both nymphs and adults may result in wilting, shedding of young fruit and secondary disease infection.

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Nature and Symptoms of Damage

In general, adult stink bugs feed on fruits while nymphs feed on leaves, stems and fruits. They may be found clinging to the leaves and tender shoots of the plants in cluster. As a result of desapping the plants become devitalize and growth and development of the attacked plant severely retarded. Management • During early stages of infestation, collection and manual destruction of the leaves and twigs containing congregating insects and their eggs is effective to suppress the population build-up of the pest. • Clean cultivation such as removal of rubbish from the field is effective in reducing the pest population because the bugs may pass off season within such materials. • Destruction of wild cucurbits is always suggested to cut off the alternate source of food. • Insecticides, like lambda-cyhalothrin 5 EC at 1 ml/l or systemic insecticides like Fipronil 5 EC at 1 ml/ha or Imidacloprid 17.8 SL at 3 ml/10 l may be recommended or any dust formulation may be applied against the resting insects.

1.15

Stem Boring Beetles

Stem boring beetles are also known as cucurbit longicorn beetle or flat-faced long horned beetles. The insect is grouped under Lamiinae and has long antennae less than half of their body length. Different species of longicorn beetles viz Apomecyna saltator Fab., A. alboguttata Thomson, A. histrio Fab. and A. perotetti Fab. are found to infest cucurbitaceous vegetables. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta

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Order: Coleoptera Family: Lamiidae Genus: Apomecyna Identification

Insect species A. saltator

A. alboguttata A. histrio

Morphology 1. Brown coloured beetles are about 12–18 mm long 2. Dense pubescent on dorsal side and sparsely on ventral of the body 3. Long antennae are about two-thirds the length of the body 4. Head is bent downward while thorax and elytra are marked with a number small to larger white spots. These spots run into each other to appear as large white irregular patches on each elytron, one is little below the base and the other between the apex and the middle region These are to some extend smaller in size, about 8–10 mm in length, dark brown in colour with round white spots on thorax and elytra It has a pair of white spots on elytron similar to those of A. saltator but differ in design. At the base of each elytrum there is an oblique row of four white spots between the middle and apex. Adults are able to make cacophony (sharp squeaking noise) by rubbing the inner surface of hind margin of pronotum on a small oval shaped, smooth and highly polished raised surface on mid-dorsal region of mesothorax

Distribution They are widely distributed in the Afrotropical, Oriental, Australasian regions, Hawaii and India. The species A. saltator is found all over India whereas A. perotetti is more common in southern tract of India. Another species, A. histrio has been recorded only from Bihar, India.

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Host Plants Stem boring beetle is a pest of various cucurbits but infrequent pests of cucumbers, pumpkins, squashes, watermelons and gourds. Seasonal Incidence After passing overwintering, the adults come out from dried vines usually during May. They become active and found to infest crops during summer and monsoon months. Biology Egg: Eggs are elongated oval in shape and creamy white in colour with reddish tinge. Incubation period is 5–6 days.

Grub: Grubs are brownish in colour having flattened head and thorax. Abdomen is soft and distinctly segmented. The grubs are about half an inch long when full grown. There are six larval stages and larval period extended up to 22–23 days. In extreme cold months, the insects undergo hibernation in grub stage. Pupa: The full grown larva pupated within the tunnel in a fibrous cocoon. Pupae are pale yellowish in colour and exarate type. Pupal period lasts for 6–8 days. Adult: The adult beetles emerge by biting their way out of the stem and feed by gnawing the leaf petioles and softer parts of the stems. Mating takes place immediately after emergence. During mating the females move about freely and keep on feeding, carrying the copulating males on their back. Eggs are laid by the sexually

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mature female singly in the epidermis of stems of cucurbit vines. Total life cycle comprises 35–46 days and adult longevity is 33–39 days. There are 3–4 generations per annum. Nature and Symptoms of Damage Immediately after hatching the grubs bore into the long trailing stems of cucurbitaceous plants usually at or near the node and make tunnel inside along the central pith. As a result of their feeding the affected stem swells up and the feeding tunnel is filled with glutinous waste material. Occasionally, irregular holes on leaf lamina are also seen as a sign of feeding damage caused by the adult beetles. Under very severe infestations, young plants may die while older plants experienced very poor yield. Management • In Indian condition the pest is a minor one for cucurbitaceous crops. No control measures are usually adopted against the beetle. • Seedlings should be carefully examined for grubs and adults in the roots and shoots to avoid the planting of infested materials. • Cutting and destroying of affected vines are highly effective in preventing population build-up and spread of the pest. • The remains of harvested plants should be destroyed immediately after harvest to prevent larvae and pupae from starting new infestations. • Many insecticides provide satisfactory control. Insecticides such as chlorpyrifos 20 EC at 2.5 ml/l or fenvalerate 20 EC at 1 ml/l may be applied to get effective control.

1.16

Melon Thrips

Melon thrips, Thrips palmi Karny is a polyphagous species which can attack several fruits and vegetables crops. However, the species is best known as a pest of Cucurbitaceae and Solanaceae. They have the ability to spread long distances on infested seedlings and other plant materials. High levels of melon thrips infestation can result in yield loss due to scarring on fruit. Besides direct damage caused by feeding plants they can also hamper the growth of affected plants by spreading tospoviruses. They are generally found on the undersides of leaves, fruit (under calyx) and in flowers. On cucurbits, this pest is more commonly found towards the tip of a runner. Nomenclature Kingdom: Animalia Phylum: Arthropoda Class: Insecta

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Order: Thysanoptera Family: Thripidae Genus: Thrips Identification Insect species T. palmi

Morphology Adults are minute, pale yellow-green to orange and cigar-shaped. They are difficult to distinguish from western flower thrips and onion thrips. The setae do not originate within the triangular arrangement of ocelli which bear red pigment. Females averaging slightly larger than males

Distribution Melon thrips has been recorded from Asian countries such as Bangladesh, Brunei, China (numerous provinces, including Hong Kong), India (numerous states), Indonesia (Jave, Sumatra), Korea (North and South), Malaysia, Myanmar, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan, Thailand and others to Pacific Ocean islands, North Africa, Australia, Central and South America, and the Caribbean. Host Plants Among cucurbits, watermelon, pumpkin, squash and cucumber are considered as major host plants. Seasonal Incidence Population of melon thrips are noticeable throughout the year. However, multiplication of the pest is favoured by warm weather. However, the pest population decreases with the senescence of crop even in presence of prevailing warm weather. In southern Florida, high population was recorded on both autumn and spring vegetable crops while in Hawaii, the pest is abundant on different vegetable crops during the summer season. Biology Egg: The eggs are colourless to pale white in colour and bean-shaped. Duration of the egg stage is normally 3–4 days.

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Nymph: The nymphs are smaller in size but resemble the adults in general body form. They lack wings. There are two nymphal instars which feed in groups, particularly along the leaf midrib and veins, and usually on older leaves. Nymphal development is determined principally by prevailing temperature and host plant quality. Generally, after 4–5 days the nymphs undergo for pupation in soil within the small earthen chamber. Pseudo-pupa: It looks similar to nymphs with having developing wing pads but is inactive, unlike the later. The insect has two instars during the so-called pupal period. Before the formation of pupa they pass pre-pupal stage which is nearly inactive. Both instars are nonfeeding stages. The insect completes both pre-pupal and pupal stages within 2–3 days.

Adult: Unlike the nymphal stage, the adults tend to feed on new young leaves after emergence. Both mated and virgin females deposit eggs which are generally deposited in leaf tissue, developing flower buds and fruits in a slit cut by the female. One end of the egg protrudes slightly. A female may lay a total of about 200 eggs with an average of 50 eggs per female. Adult longevity is 10–30 days for females

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and 7–20 days for males. Total life cycle is completed in about 11–14 days in the tropics. Economic Importance

The insect species is a major pest of vegetables and some other important crops. The pest causes severe injury to infested plants. The most serious but indirect damage caused by the pest is transmission of tospoviruses such as capsicum chlorosis virus (CaCV) that can cause serious yield losses, particularly when crops are infected early. In Hawaii, thrips were observed to attain higher densities on cucumber plants infected with watermelon mosaic virus (Culliney 1990). However, the insects are reported to be less damaging to cucumber fruit as they prefer to feed on foliage. Densities from one to 10 per cucumber leaf have been considered to be the threshold for economic damage in some Japanese studies. However, studies in Hawaii suggested a damage threshold of 94 thrips per leaf early in the growth of the plant (Welter et al. 1990). Nature and Symptoms of Damage Both nymphs and adults suck the plant sap by their rasping and sucking mouthparts. At low levels, there may be no visible sign of damage. When population increases, melon thrips produce silvering, yellowing, bronzing and scarring on affected plant areas. As a result of their feeding leaves become crinkle and die. Apart from this, flower buds may drop from the plants, growing tips may become stunted, discoloured and deformed while fruits may abort or develop scar tissue. Heavily infested fields sometimes acquire a bronze colour. Management • Population monitoring by sticky or water pan traps may be used. Blue and white are attractive colours for thrips, and have been used to trap melon thrips.

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• Physical barriers such as fine mesh and row cover material can be used to restrict entry by thrips into greenhouses, and to reduce the rate of thrips settling on plants in the field. • Organic mulching is reported to interfere with the colonization of crops by winged thrips. • Weeding along the headlands, irrigation channels and fallows near cropping land is effective. • Avoid sequential plantings of susceptible crops. • Maintain a buffer zone of 25 m or more using reflective mulches that reduce the number of thrips entering the cropping area. • Avoiding overuse of broad-spectrum insecticides, it is not advisable to apply insecticides if natural enemies like predatory bugs, Orius mexidentex, Carayonocoris indicus and other species are present in the field.

2

Mite Pests

2.1

Red Spider Mite

The phytophagous mites are very minute and recorded to feed on a wide variety of plant species. Among the different families of mite, Tetranychidae (spider mites), Tenuipalpidae (false spider mites), Eriophyidae (gall mites) and Tarsonemidae (broad/yellow mites) are economically most important because they have the potentiality to cause havoc damage to crop plants. Vast population of mites are seen on ventral surface of tender leaves protected under silken webs in ill managed crop field. Spider mites belong to the family Tetranychidae, include about 1200 species of which red spider mite or two spotted spider mite, Tetranychus urticae Koch has a cosmopolitan distribution and considered to be most destructive to cucurbitaceous vegetables in hot dry weather condition.

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Nomenclature Kingdom: Animalia Phylum: Arthropoda Subphylum: Chelicerata Class: Arachnida Sub-class: Acari Order: Acarina Family: Tetranychidae Genus: Tetranychus Identification Insect species T. urticae

Morphology 1. The mites are extremely small, barely visible with the naked eye. Adult females are only 0.3–0.5 mm long, while males are slightly smaller than female 2. Abdominal segmentation is distinct and having 12 pairs of hair on the dorsum 3. Two black spots which increase in size with age and finally cover the entire dorsum

Distribution T. urticae was originally native only to Eurasia, but has acquired a cosmopolitan distribution. Host Plants Besides cucurbits, the pest can attack the other vegetables like beans, eggplant, cruciferous vegetables, okra, onion, peas, potato, sweet potato and tomato. Seasonal Abundance Peak population of mites is usually observed during postmonsoon period and their activity declines with the fall of temperature. However, during rainy season, all developmental stages are killed except the eggs which ultimately contribute rapid population build-up of spider mite in postmonsoon period till winter.

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Biology

Egg: The eggs are spherical, minute of about 0.1 mm in diameter. Incubation period ranged from 2 to 30 days. Larva and Nymph: Freshly hatched larvae are almost spherical in shape, 0.1–0.2 mm in diameter and look light amber coloured. Latter, they become elongated in shape and turn greenish. The larvae have three pairs of legs with two small dark specks dorsolaterally each on either side. The immature stages resemble the adults except in size. Protonymphs are deep green in colour. Interestingly, they have four pairs of legs and are slightly larger than the larvae (0.2–0.3 mm in diameter) with longer bristle on dorsum. Males are elongate in shape, while females are ovate. Deutonymphs are slightly bigger than the protonymphs and are only found in females. In case of deutonymphs the genitalia are clearly visible. Duration of developmental stages correlated with prevailing environmental condition. Larval and nymphal period varied from 1 to 6 and 2 to 9 days during May to October in males and females, respectively. However, in the cooler months particularly during November to February developmental stages become prolong.

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Adult: Adult females lay spherical translucent eggs under the webbings on ventral surface of leaves. Females lay more eggs if they are fertilized. Pre-oviposition and oviposition period varied from 1 to 2 and 8 to 12 days, respectively, during March to September. However, oviposition period continues to nearly 20 days during the cooler months from October to December. Life cycle was noticed to complete within 4–8 and 6–10 days during April to October in males and females, respectively. Parthenogenesis is very common and males are the parthenogenetic population.

Nature and Symptoms of Damage Spider mites have needle-like mouthparts and feed by piercing and sucking the leaves of host plants. Both mature and immature stages cause damage to plant by sucking sap from tender parts. During desapping they also release toxin that kill the plant cells. At first, the damage shows up as a stippling of light dots on the leaves. But, in latter stage yellowing or bronzing appearance of leaves is noticed and the plant may suffer from premature leaf drop. Damage is usually worse when compounded by water stress. Besides, the thick webs formed by them also hamper the normal activity of leaves.

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Management • Regular monitoring is very important. Young leaves to be carefully checked with the help of magnifying lens for the presence of mite population. Yellow or distorted leaves should also be checked thoroughly as these may be symptoms of mite infestation. • Dusty conditions often lead to mite outbreaks. Apply water to pathways and other dusty areas at regular intervals. • Adequate irrigation is important, because water-stressed plants are less tolerant to mite damage. • Spider mites have many natural enemies, which limit their numbers. So, it is always beneficial to encourage the population of predatory mite species such as Galendromus occidentalis and Phytoseiulus mite. Besides, some important predatory insects are six spotted thrips (Scolothrips sexmaculatus), lady beetle (Stethorus picipes), larvae of cecidomyid fly (Feltiella acarivora), pirate bugs, big eyed bugs and lace-wing larvae. • Sprays of water, insecticidal oils or soaps can be used for management. • Broad-spectrum insecticide should be avoided as use of such chemicals frequently causes mite outbreaks. • New generation acaricides like clofentezine, hexythiazox, Etoxazole, chlorfenapyr, pyridazinone, bifenazate, etc. may be recommended.

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3

Vertbrate Pest

3.1

Rats

Rats are the most notorious pests of many crops particularly those are grown in rainfed condition. Different commodities kept in storage are also severely damaged by rats if not monitored regularly. An overall damage caused by the rats is more pronounced than whatever they eat. On the basis of their shelter, rats can broadly be divided in to two groups; (a) House rats, viz. Rattus rattus (House rat) and Mus musculus (House mouse), (b) Field rats, viz. Bandicota bengalensis (Lesser bandicoot), Tatera indica (Indian gerbil), Nesokia indica (Short tail mole rat), Rattus meltoda (Soft fur field rat) and Mus booduga (Field mouse). Besides this, species like Rattus norvegicus (Norway rat), Rattus rattus rufescens and Bandicota indica (Large bandicoots) have also been reported from both field and houses.

Nomenclature Kingdom Phylum Sub-phylum Class Order Family Sub-family Genus

Animalia Chordata Vertebrata Mammalia Rodentia Muridae Murinae Rattus, Mus, etc.

Biology Life span Age at puberty Oestrous cycle Duration of heat Mating habit

1–3 years 6–16 weeks 3–7 days 9–24 h Promiscuous (continued)

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Gestation period Breeding season Litter size Postpartum heat Breeding potential/pair/year

18–30 days Round the year 1–22 4–96 h 800–1500

Reason for Outbreak (a) Prolonged drought/dry spell followed by heavy rains. (b) Failure of monsoon in preceding year. Rodent Pests Species and their Distribution in India Name of species Bandicota bengalensis Millardia meltada Mus booduga Rattus nitidus Rattus rattus brunneusculus Bandicota bengalensis Millardia meltada Tatera indica Meriones hurrianae Tatera indica Millardia meltada Bandicota bengalensis Rattus rattus Rattus rattus wroughtoni Funambulus palmarum Funambulus tristriatus Rattus rattus Mus musculus

Habitat/distribution Irrigated fields Semi-irrigated fields Irrigated fields Jhum fields in north east Jhum fields in Mizoram Irrigated fields Irrigated dry fields Rainfed fields Desert soils in Indian desert Irrigated dry fields Irrigated dry fields Irrigated fields Throughout India South India Andhra Pradesh and Tamil Nadu Kerala and Karnataka Residential premises and farm level storage

Rodent Management • It has been noticed that the rats restrict their activity within 5–10 m radius around the burrow. Hence, this kind of information should be kept in mind during rat management. • Management of rats is effective when carried out on a large scale. Unlike other pests, rats should be killed as much as possible because they breed so fast that population reaches the same level within a very short period of time. • The cooperative efforts will not be effective unless as a scheduled programming is done with a system approach. • The heaps of trash, garbage and sweepings should not be left for a longer period near the field, houses and go downs. It is very essential to maintain sanitation in rat infested areas so that they may not harbour themselves in search of food and shelter.

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• The traps are employed in the places where rat infestation is small and chemical control like poison baiting, fumigation is impracticable. There are many types of traps, viz., cage traps, wooden traps, wire traps, snap traps and bamboo traps which are commonly used in the country. The traps should be cleaned by water after each installation. Each time fresh bait materials like breads, fruits that are attractive to rats should be used. • Poison baiting can be done by using single dose acute poison (e.g. zinc phosphide) or multiple dose chronic poison (e.g. warfarin, ratanfin, rodafrin, etc.) or newer rodenticides like single dose chronic poison (e.g. Vacor or RH-782, silmurin, bromadiolone—a second generation anticoagulant). These newer rodenticides found to be most effective against the rats which do not developed any bait shyness. However, pre-baiting is required prior to single dose acute poison baiting. • Some indigenous knowledge that are very much popular in rural India particularly in Southern part of West Bengal such as discarded tube light generally placed within the crop field to frighten the rat in twilight resembling snake. Discarded tyre of bicycle (black coloured) painted with white band are also placed in the crop field to frighten the rat as it mimics snake. Dead ‘apple snail’ (Pila sp.) shell rattle (Jhumjhumi) is used to minimize the infestation of rodents in crop field, which is made of eight to ten dead and dry ‘apple snail’, bound with a rope on a stick. About 60–75 rattles are hung per hectare of crop field. The sticks are dug into the soil. The stick heads are connected with a single nylon rope, coconut coir rope or jute rope. One end of the rope is kept at one side of the field preferably on the roadside or to the farmers’ house. Approximately, 50 m long distance can be covered through a single rope having been attached with 8–10 numbers of snail rattle. Farmers, whoever in the family happens to pass by, make sound by shaking the rope usually at least once every 3–4 h interval. Rodents are scared from sudden sound and they leave the crop field (Mondal et al. 2017).

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Preparation of 1.0 kg of Pre-Bait and Poison Bait Pre-bait Poison bait for single dose acute poison Poison bait for single dose chronic poison

Thorough mixing of cereal (980 g) and oil (20 g) Mixing of cereal (960 g), oil (20 g) and Zn3P2 powder (20–25 g) Mixing of cereal (960 g), oil (20 g) and bromadiolone bait concentrate 0.25% (20 g)

Placement of Bait Within the Burrows 1. Methods followed for single dose acute poison baiting: (a) Pre-baiting to be done @ 8–10 g/burrow 2–3 days prior to poison baiting. It is very useful in acclimatizing the rodents to feed on new food at a specific place. (b) Poison baiting to be done for only 1 day after successive pre-baiting @ 6–8 g/ borrow. 2. Methods followed for single dose chronic poison baiting: (a) Bromadiolone (0.005%) @ 15–20 g/burrow Recommendation of Poison Baiting or Fumigant 1. Rain fed crops: Zinc phosphide (2%) baiting. 2. Irrigated crops: Zinc phosphide (2%) baiting followed by bromadiolone loose bait (0.005%) or Bromadiolone loose bait (0.005%) baiting followed by bromadiolone. 3. Aluminium phosphide or Celphos tablet fumigation may be done @ 2 pellets/ burrow in case of very severe infestation. Calendar of Operation for Rodent Management in Crop Fields Day 1

Plugging of burrows and estimation of poison bait as well as maintenance of sanitation (continued)

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Day Identification of live burrows and pre-baiting 2–3 Day 4 Zinc phosphide baiting (2.0%) Day 5 Collection and burying of dead rodents Day 7 Plugging of burrows/de-plugging of bandicoot burrows Day 8 Bromadiolone (0.005%) baiting (loose bait/wax cake) After 10 days, all burrows to be plugged for assessing the success of control operation (Source: Tripathi and Choudhary 2006)

3.2

Other Vertebrate Pests

3.2.1 Birds Birds play an important role in pollination, killing different pests such as insects, rodents, etc. for their food. Apart from their several beneficial roles, they also reported to cause damage to many crops, and now pestiferous nature of birds thought to be an emerging concern in agriculture. They can cause considerable damage to variety of crops during vulnerable stages in different agro-ecological regions of the country. The extent of bird damage to any crop depends upon several factors, viz. food habits, density of local bird population, total area under the crop, cropping pattern, physiological stages of crops, location of the field, season, habitat and physiological status of the birds. A field’s vulnerability is more related to its position, with some areas being at greater risk than that of protected one. There are as many as 63 species of birds belong to 19 families have been reported to cause damage to several crops. Of these, the grey partridge, blue rock pigeon, house sparrow, rose ringed parakeet, weavers, munias, doves and some other species are agriculturally most important for their nature to inflict damage to crops. If the attack by the birds occurs at very early stages, the whole plant may die due to damage to the cotyledon and lesion on the stalk. Cucumber and Ridge gourd grown in small patches of coastal Karnataka have been reported to damage by birds like Blue rock pigeon (Columba livia) at sowing to seedling stages where damages caused by the pest accounts to almost 17%, while damage by the small green barbet to cucumber recorded almost 38% at fruiting stage. Similarly, quail are known to eat the seedlings. Goldfinches usually focus on sunflowers but they are found to damage on squash and other cucurbits also. Some birds even consumed petals, detached androecia and damaged the reproductive parts. Management In general, for most vegetables, cultural practices that require no additional labour are effective fully or partly, e.g. floating row cover can protect the emerging seedlings from quail. Most bird conflicts can be resolved by modifying habitat. The most direct approach is applying exclusion techniques. Well-placed bird netting will either prevent or discourage most birds from causing damage to crops.

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The traditional management techniques for the birds include erecting a machan (a especial type of hut, structure made generally by bamboo and thatched with straw) nearby crop fields; visual or acoustic bird-scaring methods such as streamers, owl decoys, hawk silhouettes, scare-eye balloons, bangers, scarecrows, kites, etc.; drum beating; recorded distress calls; pyrotechnics (explosions); habitat manipulation; block plantation; reflective ribbon for bird scaring; reflective paper plate or bird resistant hybrids are suggested to protect vegetables from bird damage at sowing and germination stages. However, birds often habituate to frightening techniques. Therefore, they should only be used when damage levels are low. On the other hand, chemical repellents found to be not much effective to limit bird damage. In severe cases, avicides may be used to control different pestiferous birds. However, killing the birds needs the prior legal approval for Wild Life Protection Act. Some of the promising avicides are Starlicide (3-chloro-p-toluidine hydrochloride), DRC-1339 (3-chloro-4-methylaniline hydrochloride), CPT (3-chloro-4-methyl benzenamine CAS 95–74-9).

3.2.2 Non-rodent Mammal Pests Common mammalian pests other than rodents are bat, blue bull, rhesus monkey, langur, wild boar, sloth bear, black buck, dear, Indian hare, jackal, Indian bison and elephant. Although at national level the losses caused by them to the crops are not significant but at farmers level the magnitude of damages crosses the tolerable limit. The reasons behind their pestiferous nature are the rapid and continuous loss of their habitat due to the expansion of agriculture, industry, mining and roads inside the forests. Blue Bull Blue bull, Boselaphus tragocamelus (Artiodactyla: Bovidae) is indigenous to India, with its distribution restricted to western and northern India. It is the biggest antelope in the country. An adult animal is reported to consume 13–15 kg plant material per day and the depredation of crops like moth bean, sorghum, pearl millet, green gram, coriander, cumin and several fruits and vegetables by this particular animal has become a serious problem in the states of Rajasthan, Haryana and Punjab. Elephants The Asian elephant, Elephas maximus has an estimated food requirement of 125 kg green leafy matter and grains per day. They generally meet up their food requirement from the wild forages. Due to the unsustainable growth of the human population in the recent past, encroachment in elephant territory has resulted in frequent conflict between the two mammals. In recent years, the problem reached its peak throughout the tropics because of reduced, fragmented and deteriorating habitat. These conflicts are manifested as killing/injuring people, crop raiding, damaging property and harming livestock. In a report, the damage caused by the animal in crop field is in order of paddy (66%)>potato (16%)>vegetable (10%)>wheat (5%)>maize (1%).

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Monkeys Three species of monkeys, viz. rhesus monkey (Macaca mulatta), bonnet monkey (M. radiata) and Hanuman langur (Semnopithecus entellus) though living in forest edges, are almost totally dependent on the human environment for their food. This habit makes them a crop pest in the process. They can eat everything which is palatable, e.g. sown seeds, sprouting seedlings, young plants, maturing green vegetables and fruits. They are reported to consume 184 different types of food items including all natural foods, cultivated plant parts and food items. Unconventional and Sporadic Vertebrate Pests There are a few herbivorous and omnivorous mammals that become sporadic pests. These include some species of bears, wild boar, jackal, hare, etc. Sloth Bear Melurus ursinus (Carnivora: Ursidae)

Sloth bear is indigenous to India; their diet mainly consists of fruits such as mangoes, jamoon, ber, wild figs, fruits of banyan, etc. However, in several places in India, particularly in southern part of Karnataka encroachment of agriculture up to forest edge/foothills has reduced food availability and forcing them to depredate on agricultural corps. Wild Boar, Sus scrofa (Artiodactyla: Suidae)

Wild boar has been found throughout India, is an unrecognized pest of crops wherever wilderness borders cultivation, more so around national parks and hilly regions. In search of food, they dug the soil around the crop plants and thus cause damage to underground parts of crop including the roots. Golden Jackal, Canis aureus (Carnivora: Canidae)

Golden jackal lives close to towns, villages and cultivated areas at the fringe of forests. Although they feed on crops such as corn, sugarcane, melon and vegetables, their role in scavenging having much more important than as pest. Management Most of the mammalian pests are considered as endangered species, so their management to protect the crops will be without hampering the ecological balance. Following are some preventive management practices that may be applied against them. • In many places, farmers guard their crop fields during day time to prevent damage caused by animal like langur, etc. • Sometimes, the farmer used a device of throwing stones to repel the pests. • In many instances, the farmers employ their pet dogs to chase pest like monkeys. • Erecting human effigies in the field and fire lighten up nearby also practiced by the farmers to scare the pest. • Barbed wire fencing around the crop field may be used to keep away certain pests. Most of the Indian farmers use nylon net fencing around the crop field.

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• Low voltage electric fencing may be installed to give a jolt to invading pests. However, this method is not practical and economical for the marginal farmers of India. • Fire torches with drum beating or applying potash bomb to scare and repel animal like elephant is also practiced by the farmers. • In rare cases, shooting with gun is recommended.

Deaseas of Cucurbits and Their Management

One of the key setbacks for the cultivation of cucurbit vegetables is the pathogenic infestation. Besides, some abiotic causes are also involved in lowering crop yields in terms of both quality and quantity. The biotic diseases, by which cucurbits are suffering at their different growth stages, are fungi, bacteria, virus, phytoplasma, nematodes, etc. The abiotic factors are related to excess or deficient supply of nutrients, adverse climatic and soil conditions, etc. Some of the economically important diseases are downy mildew, powdery mildew, damping-off, fruit and vine rot, cottony leak, gummosis, Phytophthora blight, anthracnose, Cercospora leaf spot, phoma blight, collar rot, charcoal rot, Fusarium wilt, white rot, root knot, bacterial wilt, watermelon bud necrosis and leaf distortion virus, mosaic, phyllody, etc. that becoming most destructive in cucurbits (Pandey et al. 2002). Among diseases, viruses causing mosaic symptoms appear to be more serious in the monsoon months. Besides, downy mildew and powdery mildew are rampant, former one appear in pre-monsoon and monsoon months and the later in late winter to spring (Chowdhury 1998). Most of the diseases are of national importance and cause significant losses of the crops. The disease may be spread between countries and within the states of the country through import of seeds/planting materials from foreign countries. It was reported that 1795 number of seed samples of cucurbitaceous crops were imported from Algeria, Australia and Canada to India through NBPGR, New Delhi during the period of 1992–1997 (Majumdar 1998).

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Fungal Diseases of Cucurbits

An exhaustive list of diseases of cucurbits caused by fungi including fungus-like organisms are presented hereunder in tabular form (Table 1).

# Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_3

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Table 1 Diseases caused by the fungi and fungus-like organisms in field condition Sl. No. 1.

Name of the disease Seed rot and damping-off

2.

Powdery mildew

3.

Downy mildew

4.

Anthracnose

5.

Fusarium wilt

6. 7. 8.

Fruit and vine rot of pointed gourd Alternaria leaf blight Pythium fruit rot (cottony leak)

9.

11. 12. 13. 14. 15.

Net blight/web blight/ leaf blight/ belly rot Fusarium root rot (Crown and foot rot) Belly rot Rhizoctonia fruit rot Stem rot/collar rot/southern blight Rhizoctonia root rot Charcoal rot of fruits

16. 17. 18.

Cercospora leaf spot White mould Choanephora fruit rot

19.

Fusarium fruit rot

20.

Helminthosporium Leaf spots

10.

Causal organism Pythium aphanidermatum (Edson) Fitzp., P. debaryanum Hesse, P. myriotylum Drechsler, P. butleri Subram., Rhizoctonia solani Kühn, R. bataticola (Taubenh.) Butler, Phytophthora parasitica Dastur, Fusarium spp., Fusarium equiseti (Corda) Sacc., Acremonium spp., Thielaviopsis basicola (Berk. and Br.) Ferraris and some other fungi Erysiphe cichoracearum DC., Sphaerotheca fuliginea (Schl.) Salmon Pseudoperonospora cubensis (Berk. and Curt.) Rostow Colletotrichum orbiculare (Berk. and Mont.) Arx. (¼C. lagenarium (Pass.) Ellis and Halsted Fusarium oxysporum Schlecht. emend. Snyder and Hansen, F. o. f.sp. benincasae Gerlagh and Ester, F. o. f.sp. cucumerinum Owen, F. o. f.sp. lagenariae Matuo and Yamamota, F. o. f.sp. luffae Kawai et al., F. o. f.sp. melonis Snyd. and Hansen, F. o. f.sp. momordicae Sun and Huang, F. o. f.sp. niveum (Smith) Snyder and Hansen Phytophthora melonis Katsura Alternaria cucumerina (Ell. and Ev.) Elliot Pythium spp., Pythium butleri Subramaniam, P. aphanidermatum (Edson) Fitzp. Rhizoctonia solani Kuhn Fusarium solani f.sp. cucurbitae Snyder and Hansen Rhizoctonia solani Kuhn Rhizoctonia bataticola (Taub.) Butler Sclerotium rolfsii Sacc. Rhizoctonia bataticola (Taub.) Butler Macrophomina phaseolina (Tassi) Goid. [¼Macrophomina phaseoli (Maubl.) Ashby] Cercospora spp., Cercospora citrullina Cooke Sclerotinia sclerotiorum (Lib.) de Bary Choanephora cucurbitarum (Berk. and Ravenel) Thaxt. Fusarium equiseti (¼ Fusarium roseum f.sp. gibbosum), Fusarium graminearum, Fusarium semitectum, Fusarium solani f. sp. cucurbitae, Fusarium spp. Helminthosporium rostratum Drechsler, Phyllosticta cucurbitacearum Sacc. (continued)

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Table 1 (continued) Sl. No. 21.

Name of the disease Marginal leaf blight

22.

Choanephora fruit rot

23. 24. 25. 26.

Alternaria leaf spot Corynespora blight/target spot Grey mould Collapse of melon

27.

Phoma blight

28. 29. 30. 31.

Crater rot (fruit) or black canker Phytophthora root rot Black root rot Verticillium wilt

32. 33.

Sudden wilt Gummy stem blight (vine decline)

34. 35.

Septoria leaf blight Lasiodiplodia vine decline/fruit rot

36. 37. 38. 39. 40. 41. 42. 43.

Monosporascus root rot Net spot Purple stem Pink mould rot Phomopsis black stem Ulocladium leaf spot Scab/gummosis Plectosporium blight

44. 45.

Blue mould rot Myrothecium canker (black canker) Rhizopus soft rot (fruit)

46. 47.

48 49.

Cephalosporium root and hypocotyl rot, stem streak and dieback Alternaria fruit rot of pointed gourd Phyllosticta Leaf spots

Causal organism Exserohilum rostratum (Drechsler) Leonard and Suggs Choanephora cucurbitarum (Berk. and Ravenel) Thaxt., Alternaria alternata f.sp. cucurbitae Vakal. Corynespora cassiicola (Berk. and Curtis) Wei Botrytis cinerea Pers. Monosporascus eutypoides (Petr.) Arx (¼ Bitrimonospora indica Sivan., Talde and Tilak) Phoma exigua var. exigua Sacc. (¼ Ascochyta phaseolorum Sacc.) Myrothecium roridum Tode:Fr. Phytophthora spp., Phytophthora capsici Leonian Thielaviopsis basicola (Berk. and Br.) Ferraris Verticillium albo-atrum Reinke and Berthold, V. dahliae Kleb. Pythium aphanidermatum (Edson) Fitzp. Didymella bryoniae (Fuckel) Rehm (¼ Mycosphaerella melonis (Pass.) Chiu and Walker), Phoma cucurbitacearum (Fr.: Fr.) Sacc. Septoria cucurbitacearum Sacc. Lasiodiplodia theobromae (Pat.) Griffon and Maubl. (¼ Diplodia natalensis Pole-Evans) Monosporascus cannonballus Pollack and Uecker Leandria momordicae Rangel Diaporthe melonis Beraha and O’Brien Trichothecium roseum (Pers.) Link Phomopsis sclerotioides Van Kesteren Ulocladium consortiale (Thüm.) Simmons Cladosporium cucumerinum Ellis and Arthur Plectosporium tabacinum (Beyma) Palm, Gams and Nirenberg Penicillium spp., P. digitatum (Pers.:Fr.) Sacc. Myrothecium roridum Tode Rhizopus stolonifera Vuillemin (¼ Rhizopus nigricans Ehrenberg) Acremonium spp. (¼ Cephalosporium spp.)

Alternaria alternata (Fr.) Kiessler Phyllosticta cucurbitacearum Sacc. (continued)

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Table 1 (continued) Sl. No. 50.

1.1

Name of the disease Fruit rot caused by other pathogens

Causal organism Diplodia natalensis Pole-Evans, Diplodia gossypina Ellis and Everh., Mycosphaerella melonis (Pass.) Chiu and Walker, Fusarium solani (Mart.) Appel and Wr., F. moniliforme Sheld., F. oxysporum Schlecht. emend. Snyder and Hansen., Fusarium equiseti (Corda) Sacc., F. gibbosum W.C. Snyder and H.N. Hans., F. graminearum Schwabe, Myrothecium roridum, Colletotrichum capsici (Syd.) Butler and Bisby, Helminthosporium hawaiiense Bugnic., Curvularia pallescens Boedijn, Alternaria tenuis Nees, Myrothecium roridum Tode:Fr., Sclerotium rolfsii Sacc., Rhizopus sp., Phoma sp., Cladosporium tenuissimum Cooke

Root Diseases

1.1.1 Seed Rot and Damping-Off This seedbed disease is prevalent throughout the cucurbits growing areas of the world. Cucurbit seeds need warm soils to germinate and develop properly (18  C at 5 cm depth). Seeds sown in warm and wet soils are at risk of seed rot and dampingoff caused by a number of fungus-like organisms and fungi that live in soil including Pythium, Phytophthora, Rhizoctonia, Fusarium, etc. The disease is responsible for poor germination and poor stand of seedlings. Symptoms The pathogens, causing damping-off attack seeds, seedlings and root of the cucurbit plants in fields and greenhouses. The disease generally occurs in two phases— (1) pre-emergence damping-off and (2) post-emergence damping-off. In this case of pre-emergence damping-off seeds and radicals rot before the seedlings emerge out of the soil, while the newly emerged seedlings are killed suddenly at ground level, causing them to collapse or topple over in post emergence damping-off. Seedlings emerge with soft brown water-soaked areas on the cotyledons. Stems of such newly emerged seedlings become thin and wire-like at collar region, which causes the young seedlings to topple over. Very fine cobweb like fungal mycelial growth appears on infected portion of seedlings. When relatively older plants are attacked by the pathogens are not always killed; water-soaked, blackish-brown lesions develop on roots and stems on infection resulting returded plant growth. Dampingoff pathogens may also cause root rot. Often, plants survive from damping-off might show symptoms of root rot. Roots can have a watery grey appearance, particularly the finer feeder roots because of the development of secondary thickening in the cells of stems and main roots. Infected plants are unlikely to grow into a mature normal plant (Singh 1987; Nath 2004; Chattopadhyay and Mustafee 2008).

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The Pathogen(s) The disease caused by quite a few fungus-like organisms and fungi live generally in soil are Pythium aphanidermatum, P. debaryanum, P. myriotylum, P. butleri, Rhizoctonia solani, R. bataticola, Phytophthora parasitica, Fusarium spp., Fusarium equiseti (teleomorph—Gibberella intricans), Acremonium spp., Thielaviopsis basicola and some other fungi (Nagaich and Singh 1960; Aulakh 1971; Sinha 2001; Agrios 2000; Chattopadhyay and Mustafee 2008). The most important damping-off causing pathogen is Pythium spp., which consists of slender, much branched, hyaline mycelium and coenocytic hyphae. The diameter of main hyphae is up to 5 μm. The hyphae penetrate the cell walls of the hypocotyl and ramify within and between the tissues of the cortical parenchyma. The sporangia and oospores are formed in the parenchymatic tissues of the host. Sporangia are spherical when terminal or oval or barrel shaped when intercalary. Size of sporangia varies from species to species. A prominent beak is formed on the sporangium, followed by the formation of a vesicle into which the sporangial contents are emptied. The protoplasm is divided to form reniform zoospores within the vesicle with two lateral flagella. The zoospores when released swarm for a few minutes and later form cyst. The cysts afterward germinate by producing the germ tubes. From the mycelium of the pathogen oogonia and antheridia are formed. Oogonia are round shaped, and may be terminal or intercalary, while antheridia are club-shaped. One or two antheridia are found attached to a single oogonium. Antheridium produces a fertilization tube which enters the oogonium; the nuclei of the antheridium move through the tube towards the nuclei of the oogonium, unite with them, and form the zygote. The thick-walled oospores are formed from fertilized oogonium, which afterward germinate by the formation of germ tube. The fungi multiply by zoospores as well as oospores. Oospore are resistant to adverse temperatures and moisture and serve as the survival and resting stage of the pathogen. Sexual reproduction is isogamous. Disease Cycle Most of the pathogens, causing seed rot and damping-off, are common soil inhabitants. Some of them produced resting structures (like Pythium and Phytophthora—oospore, Rhizoctonia—sclerotia) in soil. Pythium spp. survive in soil in short time period through dormant mycelium, sporangia or zoospores, while by oospore they can be survived in soil in several months. In favourable weather conditions oospores germinate to produce zoospores that disseminate rapidly in field in presence of high soil moisture and initiate infection by attacking the seedlings. The pathogen infects several weeds, and also survives on decaying plant materials. These are the primary sources of inoculum. Survival by resting structures is more important than saprophytic persistence. In contrast to the species of Phytophthora, Pythium spp. have a high degree of competitive saprophytic ability. They can be disseminated by infected transplant, rain and irrigation water, rain splashed soil, movement of soil, agricultural implements and through many other human activities (Mehrotra 1980; Singh 1987; Chattopadhyay and Mustafee 2008).

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Epidemiology Young seedlings (juvenile state) are mainly susceptible to the disease. Tissue hardening prevents the aged seedlings from the attack of damping-off pathogens. Heavy inoculums load, high soil moisture, relatively high temperatures (24–29  C), poorly aerated ill drained soils and overcrowding favour rapid development of the disease. Root rots of older plants are also common in moist hot conditions, especially under plastic mulches. Light soils containing a good proportion of sand are loose where damping-off incidence is less than the heavy and compact soils. Such conditions are very common in heavy and compact soil. High soil moisture makes the soil nutrient available to the oospores which germinate to produce zoospores. It also helps in rapid spread of zoospores which attack the tiny seedling before their tissue hardening. The disease becomes more severe in poorly aerated and poorly drained soil. In case of Pythium spp., temperature above 18  C favour germination of germ tubes, whereas temperature between 10 and 18  C induce germination by means of zoospores. The two fungi, Pythium spp. and Rhizoctonia spp. are responsible to cause damping-off in nursery beds. Pythium spp. primarily cause pre-emergence damping-off at fairly cool temperature, whereas Rhizoctonia spp. cause late pre-emergence and early post-emergence damping-off at slightly higher temperature. The disease appears in a wide range of temperature, i.e. 10–35  C with 60–70% relative humidity, and the disease may cease at 4  C (Mehrotra 1980; Singh 1987; Nayar and More 1988; Agrios 2000). Management The disease is usually sporadic outbreaks and difficult to manage due to its soil borne and complex nature. There are lots of management options, but no option is effective alone. Direct control of Pythium spp. on field condition is difficult and expensive. A comprehensive disease management programme should be followed to minimize the disease situation. • The disease may be checked by removing of previous year crop residue from the field. • Field should not be in shady place. Availability of sunlight throughout the day reduced disease incidence. • Management of seedling diseases involved especial attention to cultural practices. Nursery beds should be prepared in a well-drained field having preferably light soil. Well decomposed manures need to be applied in the nursery soil. The heavy application of urea to the nursery soil is highly effective for the reduction ofPythium population in the soil (Nayar and More 1988). • Physical disinfection of field soil through summer ploughing and soil solarization (if possible) is an important practice to minimize the disease. • In greenhouse condition, the disease causing pathogens can be eliminated by heating of soil. The common methods used for heating are steam treatment and pasteurization.

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• Soil inoculation with bio-antagonists (viz. Trichoderma viride or Pseudomonas fluorescens) through well decomposed organic manure before sowing is efficacious. • Crop rotation is an important practice but due to its wide host range, this practice is not help much for managing the disease. • Use of fungicidal seed protectants (like Thiram 75% WP, Copper Oxychloride 50% WP, Mancozeb 75% WP or Metalaxyl 35% WP at 3–4 g/kg seed) depending upon the pathogen associated with the damping-off or bio-inoculation of seed with Trichoderma viride and Azotobacter chroococum provides some sorts of protection against damping-off (Nath 2004; AICVIP 1997–1998). Seed treatment with Trichoderma viride formulation at 4 g + Metalaxyl 35% at 6 g/kg seed is recommended for the disease (Gour et al. 2008). • Overcrowding should be avoided. It is better to maintain proper spacing (Anonymous 1996). • Raised seed beds on well-drained soil is highly preferable (Anonymous 1996). • Care should be taken during transplanting of cucurbit seedlings when seedlings raised in plastic trays or pots. Disturbance of the plants root system or damage of the seedlings at collar region can make congenial condition for infection of the damping-off pathogens. • Light but frequent irrigation is essential. Careful irrigation management is important; drip irrigation is more effective than other method of irrigation. Overwatering is harmful and creates congenial condition for the disease development. • Drenching of seedlings with appropriate fungicides like copper oxychloride 50% WP at 4 g/l water can reduced the disease severity (Anonymous 1996). Soil drenching with 1% Bordeaux mixture or 0.2% Captan 75% WP or 0.3% Copper oxychloride 50% WP can help to prevent the serious disease (Gour et al. 2008). • Spraying of systemic fungicides like Metalaxyl 35% WP (1.5 g/l), Azoxystrobin 23% SC (0.3 ml/l) or combination of contact and systemic fungicides like Carbendazim 12% + Mancozeb 63% WP (2 g/l), Metalaxyl 8% + Mancozeb 64% WP (2.5 g/l), Cymoxanil 8% + Mancozeb 64% WP (2.5 g/l), etc. is quite helpful. Repeated application of the same fungicides should be avoided.

1.1.2 Phytophthora blight Phytophthora blight, caused by Phytophthora capsici Leonian, is a serious threat for production of cucurbits worldwide. Different cucurbits like cucumber, melon, watermelon, pumpkin and squash are susceptible, and the host range includes 50 different plant species in more than 15 families (Leonian 1922; Erwin and Ribeiro 1996; Zitter et al. 1996; Babadoost 2005; Egel 2017). Phytophthora capsici on cucurbits was first reported in 1937 in California and Colorado. The disease commonly occurs in temperate, subtropical and tropical environments, and causing up to 100% yield loss. Outbreaks of the disease are seriously threatening the production of cucurbit crops (Hausbeck and Lamour 2004; Babadoost 2005).

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Symptoms The disease can appear on cucurbit plants at any stage of crop growth, i.e. from seedlings to maturity. The pathogen can infect almost all above ground parts of the crops, viz. vines, leaves and fruit. However, in cucumbers and watermelons symptoms usually seen on fruit, but not on foliage. In contrast, lesions readily form on the leaves and stems of pumpkins and squash. Cantaloupe are less sensitive to the disease than the others, and symptoms may appear on foliage or fruit. Different kinds of symptoms like pre- and post-emergence damping-off, vine blight, leaf spot and fruit rot are associated with the disease (Hausbeck and Lamour 2004; Babadoost 2005; Egel 2017). The causal pathogen causes pre- and post-emergence damping-off in cucurbits under wet and warm soil conditions. In case of pre-emergence damping-off, death of seedlings is common due to the development of watery rot on the hypocotyl at or near collar region. In case of post-emergence damping-off, mature plants show symptoms of crown rot. Sometimes, a sudden wilting of the plant occurs very quickly. Infected plants often die within a few days after the first appearance of the disease symptoms, in general. A light to dark brown, water-soaked lesion develop at collar region of the stem that become enlarge and soft, and ultimately the infected stems collapse and die. No distinct symptoms appear on the taproot and lateral roots of infected pumpkin plants. Vines of cucurbits can be affected at any stages of crop growth. Water-soaked, dark olive coloured lesions develop on vines that become enlarge and dark brown in a few days. The infected vines collapse rapidly after girdling the stem, which results death of foliage just above the point of infection. Petioles as well as leaf blades of plants can be affected by this disease. Dark brown, water-soaked lesions develop on petioles, resulting in rapid collapse of the petiole and leaf death. Primarily, chlorotic areas develop on the leaf blades that become water soaked and dark green with an olive-green border. Size of the spots ranges from 5 mm to more than 5 cm in diameter. These leaf spots expand rapidly, merge and may cover the whole surface of leaf under warm and humid conditions. Fruit rot can occur at any stages of crop growth from fruit set to harvest. The fruit that is in contact with the ground or the fruit having contact with infected leaves or vines are more prone to infected with the disease. Fruit rot typically starts as a watersoaked lesion that became enlarge in time, and the infected portion of the fruit covered with white mycelial growth. Fruit infection progresses rapidly, resulting in complete collapse of the fruit. Fruit rot also can develop after harvest, during transit or in storage. The Pathogen The causal pathogen is Phytophthora capsici Leonia. The pathogen produces sub-spherical, ovoid, obovoid or pyriform, papillate sporangia on sporangiophores and biflagellate, single-celled zoospores asexually. Pedicellate sporangia can be dispersed in wind-driven rain. The size of sporangia varies from 32.8–65.8 μm  17.4–38.7 μm. Sporangia have long pedicels, ranging from 35 to 138 μm. Under

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moist conditions, zoospores are produced inside sporangia. Mycelia are coenocytic. The pathogen also produces thick-walled chlamydospores asexually, which may be terminal or intercalary on the mycelium. Chlamydospores can range in diameter from 22 to 39 μm. The pathogen grows well at 10–36  C temperature, with optimum of 24–33  C. This pathogen grows rapidly on lima bean agar. The growth patterns of colonies can vary from cottony, petaloid, rosaceous to stellate (Papavizas et al. 1981). P. capsici produces amphigynous antheridia and spherical or sub-spherical oogonia, sexually. The pathogen is predominantly heterothallic with two mating types known as A1 and A2. The pathogen also produces oospores as sexual spores and are predominantly plerotic (Stamps 1985; Islam et al. 2005). Disease Cycle Phytophthora capsici is a soil borne plant pathogen. There is no report to survive and spread the pathogen through true seeds. However, it spreads through soil, water, wind-driven rain, planting material, etc. It survives between crops as oospores in soil and mycelium in plant debris. Oospores are the resting structures that can survive in the soil for several years in absence of host. Oospores germinate and produce sporangia and zoospores. Zoospores are released in water, disseminated by irrigation or surface water, and are able to swim for several hours. Zoospores first lose their flagella and then encyst and form a cell wall, germinate and infect plant tissues. Profuse sporangia are produced on infected tissues, mostly on affected fruit. Sporangia are disseminated through water or in wind-driven rain in the air. Sporangia may either germinate directly and infect the host plant or germinate and give rise to zoospores that are released in water and infect the plant. The pathogen grows within the host and produces sporangia on the surface of the infected tissues. The disease develops rapidly in congenial environmental conditions. Though the pathogen produces chlamydospores on culture media, their role in pathogenic survival and diseases development is unknown (Erwin and Ribeiro 1996; Hausbeck and Lamour 2004; Babadoost 2005; Egel 2017). Epidemiology Soil moisture plays an important role for disease development by the pathogen. The pathogen produces abundant sporangia when soil pores are drained, and zoospores are released when soil is saturated (i.e. soil pores are filled with water). The disease is generally accompanied with substantial rainfall and excessive irrigation. Poorly drained soil creates favourable condition for disease development. Frequent irrigation increases the incidence of the disease. Warm and humid conditions are congenial for development of the disease (Erwin and Ribeiro 1996; Hausbeck and Lamour 2004; Babadoost 2005: Egel 2017). Disease Management No single method is effective to provide adequate control of the disease. Various disease control options can be integrated to manage this destructive disease.

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• The most effective method is to prevent movement of the pathogen from infested to non-infested field. Farm equipment should be cleaned thoroughly after use to avoid spread of the pathogen from infested to non-infested field. It is better to avoid using water sources that receive run-off water from an infested field. Presence of the pathogen in irrigation sources can be tested through baiting techniques. Planting materials should not be collected from the disease infested fields (Ristaino and Johnston 1999). • The selected field should have good drainage facility. Application of excessive irrigation should be avoided. As the pathogen survives in soil for several years, crop rotation is impracticable. So, fields without having a previous history of the disease should be selected for planting. It is recommended to select only fields that have not had a history for cultivation of cucurbits, brinjal, peppers and/or tomatoes for at least 4 years. Fields should be selected that are well isolated from fields infested with P. capsici (Ristaino and Johnston 1999). • Cucurbit crops should be planted on raised beds. Regular scouting of field, especially after major rainfalls, and particularly in down areas of the field is very much important to know the disease situation. The infected plants should be collected carefully from field and destroyed. Through growing of cover crops and/or mulching with plant materials including rice/wheat straw, dried water hyacinth, etc. the disease incidence can be reduced by managing the dispersal of the pathogen (Ristaino and Johnston 1999). • Soil inoculation with Trichoderma viride and/or Pseudomonas fluorescens through well decomposed organic manure before sowing is efficacious. Bio-inoculation of seed with Trichoderma viride provides some sorts of protection against damping-off. Seed treatment with fungicide (like Copper Oxychloride 50% WP, Mancozeb 75% WP or Metalaxyl 35% WP at 3–4 g/kg seed) can protect seedlings of cucurbits against P. capsici for up to 5 weeks after planting (AICVIP 1997–1998; Babadoost and Islam 2003; Nath 2004). • Drenching of seedlings with appropriate fungicides like copper oxychloride 50% WP at 4 g/l water can reduce the disease severity (Anonymous 1996). Spraying of fungicides like Metalaxyl 35% WP (1.5 g/l), Azoxystrobin 23% SC (0.3 ml/l), Dimethomorph 50WP (2 g/l) or combination of contact and systemic fungicides like Metalaxyl 8% + Mancozeb 64% WP (2.5 g/l), Cymoxanil 8% + Mancozeb 64% WP (2.5 g/l), etc. at weekly intervals can provide effective protection against foliar blight and fruit rot. Repeated application of the same fungicides should be avoided. There are some reports for development of resistance against metalaxyl and mefenoxam, so the sensitivity of P. capsici populations should be tested before selection of fungicide for applications (Lamour and Hausbeck 2000). • Identification of genetic resistance to this disease has proven difficult, but certain rootstocks appear to be more tolerant than others (Davis et al. 2008). Takahashi and Kawagoe (1971) found that certain rootstocks reduced phytophthora blight on cucumbers, and Wang et al. (2004) showed improved cucumber tolerance to this disease through grafting. The best control option at present is to combine grafting with tolerant rootstocks with cultural practices to mitigate disease pressure (Davis et al. 2008).

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1.1.3 Fusarium Wilt Fusarium wilt is an important disease of cucurbits causing a considerable loss in every year. Occurrence of the disease is very common on a number of cucurbit vegetables like watermelon, muskmelon, bottle gourd, etc. Several Fusarium species and physiological races were identified on cucurbits from different parts of the world. Fusarium wilt of melon (Fusarium oxysporum f.sp. melonis) was first reported as a disease of melon in the USA in New York in 1930, although pathogenicity was not confirmed until the disease was described in Minnesota in 1933. Though the pathogen is not uniformly distributed all over the melon-producing regions of the world, it is very widespread. In India, Fusarium wilt was first reported from the Maharashtra in 1955 and now it occurs in almost all the states. The disease is reported to be serious in Punjab (Waraitch et al. 1976). The disease is rated as one of the serious diseases of muskmelon that is capable of causing up to 90% or more mortality (Sohi and Sharma 1998). Symptoms Fusarium wilt of watermelon is caused by the fungus Fusarium oxysporum f.sp. niveum. The fungus also attacks summer squash but not muskmelon or cucumber. The plants are attacked by the pathogen in all the stages of its growth. Germinating seeds become soft and rot in the soil. Wilting of cotyledons is common. Plants infected early in their development (i.e. in seedling stage) often damp-off at the soil line. Small leaves of infected young plants lose their green colour, droop and wilt or show stunted plant growth. Primarily the older plants exhibit temporary wilting (flagging down of leaves) only during the hot period of the day but will die within a few days. The wilting normally progresses slowly. Wilt symptoms develop in one or more lateral vines, starting at the tip. A light brown discolouration of the vascular tissue (area just beneath the epidermis) in the collar region is an important internal symptom along with gummosis and tyloses in xylem vessels. In wet weather condition, appearance of white to pink fungal growth on surface of the infected stems can be observed. Microscopic observation of this growth reveals the presence of mico and macrospores of Fusarium. Fusarium wilt of muskmelon is caused by the fungus Fusarium oxysporum f.sp. melonis. The fungus also infects Crenshaw melon and honeydew melon. Mature plants are mostly affected. But, the disease may appear in any stages of plant growth. Young seedlings show hypocotyl rotting and damping-off on infection. Whereas the older leaves of mature plants show marginal yellowing that will progress to a general yellowing in time, followed by wilting of one or more vines. In some cases, sudden collapse occurs without any yellowing of the foliage. On stems near the crown of the plant, a linear, necrotic streaks or lesion may develop externally that generally extend up on one side of the vine. Streaks are light brown in colour at first, turn yellowish tan, become dark brown with age. One vine of a plant may wilt and collapse leaving the other vines healthy. A gummy, reddish exudate from these lesions may occur, but this may also be caused by gummy stem blight and insect injury. Vascular discolouration is a key diagnostic evident. Mature plants often wilt

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severely (collapse) late in the season because of the fruit load stress. A white to pink fungal growth develop on infected stems during wet weather. Palodhi and Sen (1979) studied the role of tyloses in wilting. Fusarium wilt and root rot of cucumber caused by Fusarium oxysporum f.sp. cucumerinum produces pre- and post-emergence damping-off of seedlings and wilting of mature plants. Young infected plant shows dark brown cortical lesions followed by soft decay of collar tissues at the base of the stem. Wilting symptom first develop on single lateral vine followed by total collapse of infected plants. Xylem vessels show necrosis up to the seventh node. Fusarium wilt collapse should not be confused with sudden wilt of melon. Sudden wilt is a disease complex associated with plant stress brought on by heavy fruit set, cool evening soil temperatures followed by warm and sunny days, feeder root loss caused by soil borne fungi (may include Verticillium and other species), and virus infection (primarily cucumber mosaic and watermelon mosaic, but also papaya ring spot W strain and zucchini yellow mosaic virus). The Causal Organism Fusarium oxysporum Schlecht. emend. Snyder and Hansen with the following formae speciales (f.sp.) responsible for wilt of different cucurbits. Fusarium oxysporum f.sp. melonis Snyd. and Hansen Fusarium oxysporum f.sp. niveum (E. F. Smith) Snyder and Hansen Fusarium oxysporum f.sp. benincasae Ying C. Wu and S.Z. Wang Fusarium oxysporum f.sp. cucumerinum Owen Fusarium oxysporum f.sp. lagenariae Matuo et Yamamota Fusarium oxysporum f.sp. luffae Kawai et al. Fusarium oxysporum f.sp. momordicae Sun and Huang The fungus produces septate mycelium, which is hyaline at first, turn cream coloured with age and finally show acherous strands throughout the colony. Chlamydospores are formed in older mycelium. Single celled, hyaline, ovoid to ellipsoid micro conidia (6–15  2.5–4.0 μm) are produced in abundance. Relatively less numbers of fusiform, mostly two to three septate and hyaline macroconidia (25–33  3.5–5.6 μm) are produced. In case of Fusarium oxysporum f.sp. melonis (Fom) four races (called races 0, 1, 2 and 1,2) have been accepted worldwide based on specific resistance genes found in melon differentials that the pathogen overcomes. The only described race of Fom in the USA is race 2. In 1985, race 1 was reported from Maryland, and in 1987, race 0 was discovered in Texas. In 1992, race 1 was recovered from collapsed melon fields in New York. But race 2 still remains the most widely distributed race in the USA. In contrast, race 1 is the most common race in Europe and the Middle East. Until recently, race 1,2 had only been reported from France, but is now known to occur in Maryland. Through the early breeding efforts of Henry Munger, two Fusarium wilt resistant varieties (Iroquois in 1944 and Delicious 51 in 1951) with Fom-2 resistance gene were released to meet the early needs of New York growers.

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Disease Cycle The causal fungus survives from season to season in soil as mycelium as well as chlamydospores (thick-walled modifications of the mycelium), in old infected vines or on seeds. Once it is established in soil it remains viable for an indefinite period. The pathogen is both externally and internally seed borne. Internal infection is limited to the area immediately beneath the seed coat and does not infect the embryo. The fungus can live on dead plant material (saprophytically) or on the roots and stems of other plants, such as tomatoes and several weeds. These serve as the primary sources of inoculum for the next disease cycle. Infection occurs through the root tip by direct penetration, natural openings or through wounds. Root-feeding larvae of the striped cucumber beetle may increase the incidence of wilt. Eventually, the fungus invades and plugs the plant’s water conducting vessels (xylem vessels), reducing water movement and leading to plant wilt and death. The pathogen can be spread to other fields in soil by farm equipment or flooding. It can also be spread by infected plant material or contaminated seed. Epidemiology Environmental and soil conditions are important for infection and in symptom expression. For Fusarium oxysporum f.sp. niveum, the disease incidence and severity increase during warm, dry weather. Seedling injury is severe at 20–30  C temperature (Sohi and Sharma 1998). Wilt development is also favoured by a temperature of about 27  C. No infection occurs at temperature below 15  C and above 35  C. Optimum temperature for growth of the fungus in culture medium is 27  C. At high soil temperatures, plants become infected but may not wilt; rather they develop severe stunting. Low soil moisture is congenial for the pathogen and accentuates the wilting symptom. High nitrogen, especially NH4—nitrogen, and light, sandy, slightly acidic soil (pH 5–5.5) favour disease development. In case of Fusarium oxysporum f.sp. melonis, the optimum temperature for growth of the fungus in culture medium is 26  C but the disease can develop at any temperature below the temperature in which muskmelon can grow. Optimum temperature for disease development is 21  C which is lower than that for watermelon wilt. Maximum symptom expression occurs at 18–22  C (Sohi and Sharma 1998). The fungus remains alive as a saprophyte for about 150 days at high inoculums density. Saprophytic activity is highest at 60% moisture holding capacity of soil along with 5–6 soil pH, and 25–35  C temperature. High nitrogen in soil is congenial for the disease development. Addition of cellulosic materials to soil reduces the survival of the pathogen in soil (Kannayan and Prasad 1975). Ramaswamy and Prasad (1975) stated that higher doses of nitrogen increase the disease intensity, whereas higher doses of potassium reduce it. Kesavan and Prasad (1974) recorded the presence of more cucurbitacin in resistant varieties of muskmelon than in susceptible ones, but direct correlation has not been established. Sohi and Sharma (1998) also reported the favourable temperature for growth of the pathogen Fusarium oxysporum f.sp. cucumerinum, causing wilt and root rot of cucumber is below 20  C.

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Management Chemical control of this soil borne and root disease is very difficult. A holistic management practice is necessary for sustainable management of the disease. • Resistant varieties, along with rotations with non-hosts, offer the most reliable control of this disease. Resistant varieties should be planted in the same field only once every 5–7 years and susceptible varieties no more than once every 15 years. Radhakrishnan and Sen (1985) reported Durgapura Madhu and Punjab Sunehri as resistant varieties of muskmelon. Some important watermelon varieties showing resistant against the disease are Charleston Gray, Iowa Belle, Garrisonian, Crimson Sweet, Sweet Princess, Jubilee, etc. (Sitterly 1972). • Use of disease free seed and destruction of diseased debris can keep the disease under check. • Liming the soil to increase the pH about 6.5–7.0 decreases wilt severity. • Addition of cellulosic materials (straw) to soil reduces the survival of the pathogen in soil (Kannaiyan and Prasad 1975). • Seed borne inoculum can be reduced by hot water treatment at 55  C for 15 min (Sohi and Sharma 1998). By treating the seed with Benomyl or Carbendazim 50% WP at 1–1.5 g/kg seeds or Trichoderma harzianum at 6 g/kg seeds the disease may be kept under check. • The disease can be checked to some extent by drenching the soil with Captan 50% WP (0.2–0.3% solution). This should be repeated twice or thrice. • Soil application Trichoderma viride formulation 2 kg in mixing with 50 kg of farm yard manure per acre can effectively manage the disease (Gour et al. 2008). • Grafting for Fusarium resistance started in Japan in the 1920s to control F. oxysporum f. sp. niveum Snyder and Hansen (Davis et al. 2008). The common rootstocks used for controlling Fusarium wilt of watermelon are Cucurbita moschata, bottle gourd (Tateishi 1927; Sato and Takamatsu 1930; Kijima 1933; Murata and Ohara 1936; Sakata et al. 2007) and squash interspecific hybrids (Cucurbita maxima  Cucurbita moschata) (Davis et al. 2008). Besides, the rootstocks of Citrullus spp. (Huh et al. 2002), Cucumis spp. and Cucurbita spp. (Igarashi et al. 1987; Trionfetti-Nisini et al. 1999; Hirai et al. 2002; Komada and Ezuka 1974; Pavlou et al. 2002; Tjamos et al. 2002; Imazu 1949; Bletsos 2005; Xu et al. 2005; Lin et al. 1998) are commonly used for preventing Fusarium wilt of cucumber, melon and bitter gourd, in addition to watermelon. Grafting melon onto squash interspecific hybrids can provide resistance to F. oxysporum f. sp. melonis race 1,2 (Hirai et al. 2002; Trionfetti-Nisini et al. 2002; Crinò et al. 2007).

1.1.4 Fusarium Root Rot Fusarium root rot of cucurbits, also known as foot rot or crown rot, attacks almost all the cucurbits. Root rot of squash was first described from South Africa in 1932. In 1939, widespread reports were received from New York, Connecticut and Massachusetts regarding a serious disease of summer squash, which was subsequently traced to a particular lot of seed grown in Oregon. The disease has also been reported in Australia and Canada. While its distribution in the USA is limited, it still

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remains a concern for cucurbit growers. The crown and foot rot phase of the disease has occurred sporadically in New York since 1939, but in 1995 the fruit rot phase was experienced in two widely separated counties. Symptoms The above ground symptoms of this disease are similar to those of vascular wilt caused by Fusarium oxysporum with which it may be confused. The first symptom generally noticed in the field is wilting of the leaves. Within some days, the entire plant may wilt and die. If the soil is removed around the base of the plant, a distinct necrotic rot of the crown and upper portion of the taproot is evident. The rot develops first as a light-coloured, water-soaked area that becomes gradually darker. It starts in the cortex of the root, causes cortex tissue to slough off and eventually destroys all of the tissue except the fibrous vascular strands. Infected plants break off easily about 2–4 cm below the soil line. The fungus normally is limited to the crown area of the plant. The main and lower portions of the taproot are not affected, except under extremely wet conditions. Similarly, the stem is not affected, except for the lower 2–4 cm immediately above the soil line. The above ground symptoms of this disease may be confused with vascular wilt caused by Fusarium oxysporum. But there is sudden wilting of the plant in mild season with dark brown cortical soft decay at the base of the stem. The below ground parts of the infected plants are found disintegrated. Frequently there is invasion of insects in such roots, and secondary infection by other organism likely fungi may also be found. Profuse sporulation occurs on infected tissues during humid weather condition (Sohi and Sharma 1998). Plants showing symptoms develop numerous sporodochia and macroconidia (spores) giving the mycelia a white to pink colour on the stem near the ground surface. Fruits are attacked at the fruit-soil interface; the severity of the fruit rot depends on soil moisture and the stage of rind maturity at the time of infection. The Pathogen The disease is caused by Fusarium solani f.sp. cucurbitae Snyder and Hansen. Perfect stage of the fungus is Nectria haematococcus Berk and Br. (¼Hypomyces solani Reinke and Berth.) (Sohi and Sharma 1998). In culture the mycelial growth is sparse to floccose, greyish white with typically a bluish to bluish-green discolouration of the substrate. There is always the presence of a sclerotial plectenchyma. Spore layers are pionnotal, off white, cream or blue-violet. Microconidia are formed abundantly on the aerial mycelium. They are hyaline, cylindrical, may become one septate and measure 9–18  2–4 μm. The conidiophores producing macroconidia are less than 50 μm in length, branched and a few septate. The macroconidia are cylindrical to falcate, usually straight and habitually slightly wider at the apex with usually short and fairly blunt apical cell. They measure 40–100  5–7.5 μm. In its perithecial stage the fungus produces pale orange to brown perithecia which measure 130–200 μm in diameter. The asci are cylindrical, becoming clavate, with rounded apex and central pore. They measure

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60–80  8–12 μm. Ascospores are ellipsoid to obovate, 11–18  4–7 μm in size. There is a single central septum. Two races of the fungus have been described. Race 1 is distributed worldwide and causes root rot, stem rot and fruit rot. It is responsible for the disease in New York. Race 2 causes only fruit rot and has been reported only in California and Ohio. Recent work, however, has separated these two races into different mating populations which most probably mean that the two races represent different species. F. solani f.sp. cucurbitae forms all three asexual spore types (microconidia, macroconidia and chlamydospores) typical of Fusarium by which the fungus can overwinter. Disease Cycle The fungus is both internally or externally seed borne. However, it actually survives for only one to 2 years in seed. Infection does not appear to affect seed viability or germination. Although the fungus produces abundant chlamydospores, it apparently survives for only 2–3 years in soil, which is much less than Fusarium oxysporum or even other formae speciales of F. solani. Plants and fruit of any age can be infected. Muskmelon, squash melon and bitter gourd are most severely affected by this disease than pumpkin. The pathogen exhibits host specificity for all cucurbits. Larger pumpkins are more susceptible than smaller sized varieties. The smaller sized varieties matured sooner in the field, and the time of infection and environmental conditions may not have been conducive for fruit infection to occur. Epidemiology The disease severity primarily depends on soil moisture and inoculum density. Optimum temperature for growth of the fungus is 28  C. Management • Removal of diseased plants from the field is helpful for reducing disease inoculum from the field. • The disease can be avoided through use of healthy and disease free seeds. • Fusarium root rot can effectively be controlled by soil drenching with copper fungicides like copper oxychloride 50% WP at 0.4% (Maity et al. 2004). • Seed treatment with systemic fungicides like Carbendazim 50% WP at 2 g/kg seed or Trichoderma harzianum at 6 g/kg seeds can kept the disease under check. Hot water treatment of seed at 55  C for 15 min (Roychaudhury and Verma 2000) is also effective. • A 4-year crop rotation with non-host crop is adequate for managing the disease (Roychaudhury and Verma 2000). • Spraying of the crop with Captan 50% WP at 0.2% is beneficial. • Cultivation of resistant varieties is recommended.

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1.1.5 Rhizoctonia Root Rot Rhizoctonia root rot or collar rot is an important disease of cucurbits. Rhizoctonia root rot of cucurbits was reported from Punjab by Jhooty and Grover (1971). Collar rot of muskmelon has been reported by Suhag and Duhan (1980) from Haryana with 50% mortality of the crop. Symptoms The disease causes light green to yellow green, minute and sunken lesions at the collar region. The depressed infected area extends upwards and may girdle the vine within 15 days, leading to its collapse. On pathogenicity test, Jhooty and Grover (1971) recorded that the fungus is pathogenic to 10 different cucurbits, causing both pre- and post-emergence rots. Older plants are less susceptible than younger. Suhag and Duhan (1980) reported that the infection usually appears in the field when the muskmelon plants attain 40–50 days of age and at that stage the disease gradually starts to spread. Causal Organism The disease is caused by Rhizoctonia bataticola (Taub.) Butler. The hyphae are septate and thick, which present both inter- and intracellularly in the host tissue. The fungus produces sclerotia that are near about 100 μm in diameter in maturity. The sclerotia are black and irregular. The fungus produces superficial, dark coloured, abundantly branched stout mycelium. In artificial medium, young colonies of the fungus are white to dull white. Mycelium is stout and septate. Sclerotia are black in colour. The septa are typical dolipore type. The lateral branches from the main hyphae are invariably constricted at the point of origin and septum occurs in the branch near the junction with main axis. Branching almost invariably occurs near the distal septum of the cell in the young advancing hyphae but at any point in older hyphae. Disease Cycle The pathogen is soil borne and can survive as sclerotia on infected crop debris that germinate to infect the fresh vines. The pathogen is capable to survive as saprophyte on dead organic matter. It has wide host range, infects several other crops like cotton, tobacco, sesamum, potato, brinjal, mulberry, jute, etc. Epidemiology The disease spreads rapidly from April to June, when day temperatures range between 30 and 40  C (Sohi and Sharma 1998). Management Detailed studies are required to develop the suitable management practices. • Proper nutrient management including micronutrient, especially nitrogen, zinc, iron and boron is essential to reduce the disease incidence. • Removal of infected plants/plant parts and debris (Anonymous 1996)

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• Soil amendment with green organic manure, oil cakes, neem cake can reduce the disease inoculum in soil. • The disease can be controlled biologically by soil application of Trichoderma viride at 8 kg/ha in mixing with organic manure. • Seed treatment with Trichoderma viride at 6 g/kg, carboxin 37.5% + thiram 37.5% WP at 0.25% may be helpful for reducing the disease incidence. • Spraying of mancozeb 63%WP + carbendazim 12% WP (0.25%) once or twice is effective in controlling the disease. • Crop rotation with non-host crops is recommended.

1.1.6 Other Root Diseases Verticillium Wilt The disease is caused by Verticillium dahliae Kleb. and V. alboatrum. Verticillium is a common soil borne pathogen that affects cucurbit crops in many regions (Davis et al. 2008). Grafting for controlling the Verticillium wilt was studied by several workers for cucumber, melon and watermelon (Alabouvette et al. 1974; Paplomatas et al. 2002). Most of the cases, the rootstocks were tolerance not immune to V. dahliae, and grafting onto these rootstocks can delay expression of disease for up to 20 days (Paplomatas et al. 2002). Grafting in combination with additional control strategies will give effective control of Verticillium wilt (Davis et al. 2008). There are some reports which demonstrate the effectiveness of combining grafting with other control methods in cucurbit crops (Ioannou 2001). Blackroot Rot Phomopsis sclerotiodes Kesteren commonly causes black root rot in greenhouse-grown cucumbers (Cappelli et al. 2004), and has also been shown to cause disease in melon, pumpkin, bottle gourd and watermelon (Shishido et al. 2006). The pathogen can survive in soil, soil-less media and even on plastic containers, which makes difficult to control the pathogen (Davis et al. 2008). Grafting was shown to be an effective control measure for greenhouse-grown cucumbers, even surpassing chemical control treatments in some occasions (Wiggel and Simpson 1969). Monosporascus Root Rot and Vine Decline Monosporascus root rot and vine decline, caused by the soil borne pathogen Monosporascus cannonballus Pollack and Uecker, is a serious monocyclic disease of melon (Lobo 1990; Buzi et al. 2002; Ferrer 2003) and watermelon (GarcíaJiménez et al. 1994; Gennari et al. 1999; Buzi et al. 2004). The pathogen infects the roots of plants, mostly the secondary and tertiary roots. The primary symptoms are necrosis of the small roots and development of lesions on the larger roots, characteristically around the root junctions, however, the most intense symptom is the collapse of the vine late in the season (Martyn 2007). Root colonization and necrosis continues throughout the life of the plant. In severe cases, larger roots, including the taproot, become infected. Fruit and foliage are not infected directly, although they manifest symptoms related to root infection, water stress and plant decline (Martyn 2002; Waugh et al. 2005). The primary diagnostic sign of the pathogen is the formation of black, spherical, erumpent perithecia on the roots,

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easily visible with the unaided eye or hand lens. Perithecia are the sexual reproductive structures of the fungus and develop along the entire root length. When mature, the perithecia rupture, spilling the ascospores into the soil. Ascospores (40–50 μm diameter) are spherical, multi-layer and multinucleate (typically having eight nuclei, although occasionally they may have 16), typically only one ascospore is formed per ascus instead of the usual eight (Pollack and Uecker 1974; Martyn 2002). The pathogen favours hot and dry climates. In in vitro condition, optimum vegetative growth of the pathogen occurs at 25–35  C, while perithecia are formed at 25–30  C. The fungus may survive for several days at temperatures up to 55  C, but is killed within 90 min at 60  C. Mycelial growth occurs over a pH range of 5–9, and inhibited completely at pH 4 and below. Slightly or moderately alkaline and saline soils favour the disease development. The fungus survives as dormant mycelium in the soil or plant debris that initiates infection on the roots. Germinating ascospores are also responsible to initiate infection. The ascospores may survive for many years in a dormant state. The fungus continues to colonize the root tissue and invades the xylem causing the plant to form tyloses. While the fungus invades the xylem, it does become systemic in the plant. But, the pathogen is not a true vascular wilt pathogen. The pathogen can spread through movement of contaminated soil, crop debris, rain splashed soil, irrigation water, contaminated agricultural implements, etc. There is no evidence that the pathogen is seed borne or systemic in the plant (Martyn and Miller 1996a, b; Martyn 2002). The disease is difficult to control. It can be managed through interested approach like selection of disease free field, field sanitation, crop rotation with non-host crops, use of mulch materials, soil solarization, cultivation of resistant varieties and use of biological weapons, etc. (Batten et al. 2000; Cohen et al. 2000; Dias et al. 2004; Radewald et al. 2004; Egel et al. 2008; Martyn 2002). Grafting is part of an integrated approach for controlling the disease that will reduce the disease severity depending on the rootstock/scion combination, time of year and primary inoculum levels (Edelstein et al. 1999; Cohen et al. 2005). Though one of the main problems is lack of true resistance in melon rootstocks to M. cannonballus, but, the large root systems and vigour of the rootstock allow the scion for crop development in presence of the pathogen (Cohen et al. 2000). Grafting along with additional control strategies to reduce pathogen populations appears to be a key factor in reducing the disease severity of Monosporascus vine decline (Davis et al. 2008). Watermelon tolerance to this disease has improved through grafting onto tolerant rootstocks (Peris 2004).

1.2

Leaf Diseases

1.2.1 Powdery Mildew Powdery mildew is one of the most common and destructive diseases of cucurbit vegetables throughout the world including India. It is known to occur on the cucurbits since the year 1800. Six species of powdery mildew fungi have been reported worldwide on various hosts. Among them, occurrence of Erysiphe cichoracearum DC. and Sphaerotheca fuliginea (Schl.) Poll. [Synonyms:

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Podosphaera fuliginea (Schltdl.) U. Braun and S. Takam., Podosphaera xanthii (Castagne) U. Braun and Shishkoff] is very common and widespread in distribution. In Asia, the disease is reported to occur in Iran, Iraq, Saudi Arabia, Isreal, Malaysia, Singapore, China, Japan, Taiwan and India. In India, the disease was reported first time by Butler in 1918 on various hosts from Uttar Pradesh and Bihar on the basis of conidial characters of the pathogens. The disease is also reported in Malaysia and Singapore on pumpkin (Thompson 1933). Jhooty (1967) claimed that the disease was caused by S. fuliginea in Punjab and Northern India. Khan et al. (1976) reported the widespread occurrence of powdery mildew of cucurbits due to S. fuliginea in Kashmir. The disease occurs most severely during dry seasons than the wet weather condition. Regular occurrence of the disease caused by S. fuliginea was also reported by Mustafee (1998) in different parts of India, viz. Haryana, Punjab, West Bengal, Tamil Nadu, Uttar Pradesh, Jammu and Kashmir, Assam, Karnataka and Maharashtra. The disease caused by E. cichoracearum has been reported on Momordica balsamina, Trichosanthes dioica (Butler and Bisby 1931), Lagenaria vulgaris (Rajendran 1965), Coccinia cordifolia, Coccinia indica (Khan et al. 1972; Sohi et al. 1981), Benincasa hispida (Khan et al. 1972). Although the fungus attacks all the cucurbits. It is especially destructive on pumpkin (Cucurbita moschata) and bottle gourd (Lagenaria siceraria). The bitter gourd (Momordica charantia) is the least affected crop. Both the powdery mildew causing fungi occur commonly on cucumber also. The fungus, E. cichoracearum also attacks potato and tobacco seedling, lettuce, sunflower, mango, castor, Antirrhinum orontium, Hyssopus officinalis, Sedum suprium and Sonchus asper (Stone 1962), although the strains may be quite different (Singh 1987). According to CMI description, Kapoor (1967) described that S. fuliginea exclusively attacks cucurbits, while E. cichoracearum attacks to the members of compositae and other non-cucurbitaceous hosts too. Symptoms The disease appears on all the above ground parts of the crops mainly foliage and green stems (vines), and rarely on fruits. It is characterized by the appearance of tiny, white to dirty grey superficial spots (sometimes with a reddish brown tinge) mostly on the upper surface of leaves, also found on the lower surface and vines. The disease appears primarily on older leaves or on the shaded portion of plant. The spots become powdery (talcum like growth) as they enlarge, consisting of superficial mycelium, conidiophores and conidia. The superficial powdery mass may ultimately cover the entire affected green surface of the host. The affected leaves turn yellow and become necrotic. In case of severe infection, the affected leaves and stem may dry-off and arrested the further growth of the plant, which leads to premature death of the vines. While powdery mildew primarily infects leaves and vines, infections rarely take place on pointed gourd, cucumber or melon fruit. Squash fruit are not directly infected. Regardless of direct infection of the fruit, infected plants produce fewer and smaller fruit(s). The fruits remain undersized and sometimes are deformed. The yield and quality of the fruit are reduced significantly. Infected plants produce fruits with incomplete ripening, poor storability and poor flavour. In India, mostly in the winter season crops, minute, dark brown to black pin-head bodies

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appear late in the season rarely intermixed with the white powdery mass. These are the cleistothecia (ascigerous stage) of the fungus. Powdery mildew is most severe after fruit set and in densely planted fields in warm, rain-free growing areas. The Pathogen Cleistothecia of six species of Erysiphaceae were recorded on cucurbits in different parts of the world. Erysiphe cichoracearum DC. and Sphaerotheca fuliginea (Schl.) Poll. (¼Podosphaera fuliginea (Schltdl.) U. Braun and S. Takam., Kingdom— Fungi, Phylum—Ascomycota, Class—Leotiomycetes, Order—Erysiphales, Family—Erysiphaceae, Genus: Podosphaera, Species: P. fuliginea, Subspecies: P. fuliginea) are two most regular and most commonly distributed species all over the world. There are two situations, viz. two pathogen disease situation and one pathogen disease situation prevails throughout the world on the basis of identity of causal organism (Sharma 2005). Two pathogen disease situations refers that the same disease is caused by two pathogens separately. This situation should not be confused with diseases caused by two pathogens in combination like disease complexes, which involves the intimate association of two or more pathogens. Two pathogen disease situations have been established in USA, U.K., Germany, Italy, Hungary, Bulgaria, ex-U.S.S.R., Japan, Israel and India. E. cichoracearum dominates over S. fuliginea in the USA, U.K., Germany and Bulgaria, while S. fuliginea is predominant in Italy, Japan, Israel and India. In Bulgaria and ex-U.S.S.R., both are more or less equally important (Sharma 2005). One pathogen disease situation by Erysiphe is found in Canada, France, Norway, Sweden, Austria, Switzerland, Mozambique, Egypt, Malta, Fizi, Kenya, Bolivia, Brazil, Peru, Nicaragua, West Indies, Iraq, Saudi Arabia, Malaysia and Singapore. One pathogen disease situation by Sphaerotheca is recognized in Netherlands, Greece, Turkey, Czechoslovakia, Rumania, Australia, New Zealand, South Africa, Sudan, Malawi, Iran, China and Taiwan (Sharma 2005). In India, the disease is caused by E. cichoracearum as well as S. fuliginea (Sharma 2005). Both the fungi produce two spore types: the white powdery spores present on the plant surface are conidia and those produced in tiny round fruiting bodies (cleistothecia) are ascospores. The fungus, E. cichoracearum produces well-developed superficial, evanescent but sometimes persistent and effused mycelium with well develop haustoria in host cells. Unbranched, erect conidiophores arise from mycelial web that produced single celled, hyaline, ellipsoidal or barrel-shaped conidia (25–45  14–26 μm) in chains at their apex abundantly and disseminated mainly by wind. The fungus is probably heterothallic. The fungus produced gregarious or scattered globose cleistothecia (90–135 μm in diameter) in autumn that contain ovate to broadly ovate, rarely subglobose, and more or less stalked asci (60–90  25–50 μm). Each cleistothecium contains 10–25 numbers of asci. Usually two, rarely three ascospores (size of each ascospore is 20–30  12–18 μm) form in each oval or sub-cylindrical ascus. Appendages are numerous, myceloid, basally inserted, hyaline to dark brown,

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interwoven with mycelium, 1–4 times as long as the diameter of cleistothecium (ascocarp), rarely branched (Mehrotra 1980; Gupta et al. 2001; Khatua and Saha 2004; Sharma 2005). The fungal plant pathogen, S. fuliginea causes serious infection in gourd, squash, pumpkin, cucumber and melons. Powdery mildew caused by S. fuliginea is a serious disease in northern India (Jhooty 1967). Sohi and Nayar (1969) obtained perithecial stage of S. fuliginea on several varieties of Luffa leucantha and Cucumis sativus under glasshouse conditions from Aligarh in Uttar Pradesh. Khan et al. (1976) reported the widespread occurrence of powdery mildew of cucurbits due to S. fuliginea in Kashmir. Sexual stage of the pathogen has also been reported on Cucurbita moschata from Himachal Pradesh (Sohi and Nayar 1969), Lagenaria leucantha and cucumber from Uttar Pradesh (Khan et al. 1976). Whereas both the pathogens, E. cichoracearum and S. fuliginea occur commonly on cucumber (Mital and Akram 1985). The conidial stage of S. fuliginea has been noticed on Lagenaria siceraria, Luffa aegyptiaca, Cucumis melo, Cucumis melo var. utilissimus (Jhooty 1967) and many other cucurbits. When the pathogen inoculated artificially, a large number of cucurbits have been found susceptible in Uttar Pradesh, Himachal Pradesh and Karnataka (Khan et al. 1972; Sohi 1984). The fungus produces intercellular, hyaline mycelium (rarely brown when old) usually evanescent but sometimes persistent forming white circular to irregular patches on the host surface, with haustoria. At the tip of the conidiophores (short and simple) the fungus produces long chains of conidia that are ellipsoid to barrel shaped and 25–37  14–25 μm in size. Cleistothecia produced by the fungus are scattered to densely gregarious, 66–98 μm in diameter. Appendages are variable in number, usually as long as the diameter of cleistothecium, myceloid, brown, tortuous, interwoven with mycelium. Each cleistothecium contains single broadly elliptic to subglobose ascus with 50–80  30–60 μm in size. Ascospores are ellipsoid to nearly spherical, 17–22  12–20 μm; each ascus contains eight numbers of ascospores (Sharma 2005). On the basis of cross inoculation method, Kaur and Jhooty (1985) reported three distinct types of isolated of the fungus (S. fuliginea) on different cucurbits. On the basis of four differential hosts (viz. PMR-45, PMR-59, PMR-6 and Edisto-47), they also observed the widespread occurrence of race-3 of the fungus in Punjab (Kaur and Jhooty 1986). Distinct physiological specialization of these pathogens causing powdery mildew disease has been reported by different scientists. Blumer (1967) distinguished 13 formae speciales of E. cichoracearum based on single species or a single section of a genus. Jaczewski (1927) distinguished 84 formae of S. fuliginea. Appearance of biotypes and extent of specialization has not been investigated thoroughly in India (Seshadri 1986). The fungus, Sphaerotheca fuliginea (Schl.) Poll., usually occurs in the conidial state, particularly on cucurbitaceae, and has often been confused with Erysiphe cichoracearum. The conidia on germination form a characteristic forked germ tube distinguishing them from those of E. cichoracearum, which on germination produce appressoria (Zaracovits 1965). The patches formed by this fungus are not white but reddish brown. The cleistothecia are different in structure from those of Erysiphe (Mehrotra 1980).

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Disease Cycle Complete disease cycle of the pathogen is not well understood. The fungus produces conidial and perfect stages. Probably, the fungus survives in conidial stage on wild cucurbitaceous hosts and other collateral hosts, and the wind borne conidia cause secondary spread. The conidia are capable of germinating even under dry condition with low humidity and therefore the secondary infection occurs very rapidly. Heavy dew favours penetration by the germ tube. Penetration is confined to the epidermal cells where spherical haustoria are present. With maturity of the host plant and as the disease advances, the fungus produces sexual organs, resulting in the formation of the cleistothecia containing ascospore, which enable the fungus to survive in the field off-season, when susceptible host plants are grown, the ascospores germinate to cause fresh infection (Mehrotra 1980; Sharma 2005). In India, cleistothecia of both Erysiphe and Sphaerotheca were reported on different cucurbits from field as well as greenhouse condition. Cleistothecia are produced in nature only during late winter or early summer, whereas cleistothecia of Sphaerotheca in greenhouse condition develop during December to January. Temperature and host physiology play an important role in the production of cleistothecia (Sharma 2005). There are some reports regarding the production of perithecia in nature on some cucurbits in Indo-Gangetic plains, but their role in perpetuation of disease seems to be doubtful, because of the existing adverse weather condition during summer in this region. Chance of over summering of cleistothecia due to intense high temperature during summer and heavy rains during rainy season appears to be remote (Sharma 2005). The pathogen overwinters through various means. The possibility of overwintering or over summering of the fungus as mycelium in buds is excluded as the majority of the cucurbits are cultivated as annual crops. In subtropical and tropical parts, overwintering may not be a problem and the fungus may survive well as cleistothecia on a number of congenial hosts mainly gourds climbing on the house hut tops during winter in rural India. Cucurbits are grown in fields or kitchen gardens as vegetable crops all over the year in India. However, the fungus may not be able to establish on them due to intense heat of summer followed by heavy rains. The cucurbits are grown as key vegetable crops during summer in hilly tracts of Himalayas. The fungus may over summers on these summer crops in the hills and blowing each year to the plains during winter. The inoculum during summer may also be blown from plains to hills. Moreover, some shade plants provide protection to some cucurbits, and the fungus may survive on these cucurbits during summer in plains itself (Sharma 2005). In Punjab, Jhooty (1967) observed that the vegetative mycelium and conidia are maintained on sheltered cucurbits and these are important in disease cycle. Some collateral or alternate hosts most likely play the same role in the annual recurrence of the disease, as the pathogen has a wide host range. Thus, the mode of perpetuation and recurrence of the disease are still unsolved (Sharma 2005).

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Epidemiology Unlike many other fungal diseases that need leaf wetness for infection, moisture on plant surfaces actually inhibits the powdery mildew fungus. High humidity, however, is required for infection. Older leaves are more susceptible. Densely planted crops, plants crowded by weeds, plants in shaded sites, and over fertilized cucurbit plants are more likely to be infected with the disease. The disease is also favoured by sultry (i.e. hot and humid weather) weather, moderate temperature and reduced light intensity. The disease occurs most severely during dry seasons than the wet weather condition. The disease mainly appears in late winter to spring season. For good conidial germination, a temperature ranges of 22–31  C with optimum of 28  C, and low RH of 20 percent for less than 2 h is essential (Sohi 1984; Chowdhury et al. 1998). Management • Seed treatment (Jhooty and Behar 1972) and soil drenching with systemic fungicides like Benomyl (Roy 1973a) may protect the young seedlings from the disease. • The wild cucurbits should not be allowed to grow near the cultivated cucurbitaceous crop field (Singh 1987; Gour et al. 2008). • Destruction of diseased plants, especially late in the off-season is important to avoid the formation of sexual stage of the pathogens. • Diseased crop debris should be destroyed properly (Singh 1987). • Good air movement around the crop fields through proper spacing, staking of plants and weed control is very much important. • Search for disease resistance in host plants is most important. The following resistant sources are important to avoid the severity of the disease. Sources of powdery mildew disease resistance melon are PMR 45 (race-1 resistant), Seminole (race-2 resistant), Georgia-47 (moderately resistant), Planter’s Jumbo (highly resistant to race-1 and race-2), Campo (resistant to an unidentified race), PI 124111, PI 79376, PI 134198 and PMR 450, whereas this is for cucumber are PI 200815, PI 197087, PI 200818, C. hardwickii, wise 2757 (USA) that are very much important for researchers to develop resistant varieties (Swamy et al. 1981; Amin et al. 1982; Seshadri 1986). In case of cucumber, resistance is governed by one gene in cultivars Palmetto and Ashley, two genes in cultivars Poinsett and Cherokee and three genes in cultivar PI 197087 (Barnes 1961, 1966). Many researchers have screened germplasm to identified sources of resistance to the disease. As many as 31 Indian and 10 exotic germplasm of muskmelon reported to be highly resistant to the disease (Swamy et al. 1981). Waraitch et al. (1977) reported some resistant varieties of muskmelon, namely PMR 5, PMR 6 and Arka Rajhans. Other reported important resistant varieties of muskmelon are Diguria and Haragola (Amin et al. 1982). Arka Manik is one of the highly resistant varieties of watermelon under Bangalore condition (Seshadri 1986). SR-91 and V-1 are two important cultivars of muskmelon resistant to sulphur injury in California (Seshadri 1986).

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• Fertilizer should be applied based on soil test results. Over doses of nitrogenous fertilizers may increase the disease severity. • Fungicides should be applied when a single spot of powdery mildew is first found. In earlier years, this disease used to be controlled by sulphur dusting (15–30 kg/ha), but most of the cucurbits are susceptible to sulphur injury, especially when it is done during the hot days. Elasol (0.5%) has been used as a substitute of sulphur (Singh 1987). Fortnightly sprays of fungicides like Dicofol 18.5% EC (0.2%), Carbendazim 50% WP (0.1%), Thiophanate methyl 70% WP (0.1%), Tridemorph 80 EC (0.05%), Benomyl 50% WP (0.1%), etc. have been found useful in controlling this disease (Mustafee 1998; Khatua and Saha 2004). A safe protective controlling measure of Erysiphe cichoracearumis 1% Bapolysulphide with 24–25  C temperature and 80% relative humidity in greenhouse condition. Spraying of colloidal sulphur and Thiram is effective against Sphaerotheca fuliginea. Spraying of Kerathene, Cosan, Calixin, Benomyl or Bavistin at 5–6 days’ intervals at least thrice have been reported to be effective for controlling powdery mildew of cucurbits (Mandloi and Khare 1969; Waraitch et al. 1975; Mehrotra 1980; Seshadri 1986; Maity et al. 2004). Suhag and Mehta (1982) have compared 0.1% Karathane, Bavistin and Calixin and 0.2% Sulfex for the control of Sphaerotheca fuliginea on bottle gourd, summer squash and pumpkin. The disease can be managed effectively, if these fungicides sprayed just after initiation of first symptoms. Copper oxychloride 50% WP (0.4%) or Mancozeb 75% WP (0.2%) has also been recommended to spray at 8 days’ interval. About 3–4 sprays will be enough to manage the disease. About 2–3 sprayings of sulphur 80% WP at 0.2% can also be used at an interval of 5–6 days (Sinha 1990). • Several phylloplane fungi including Penicillium fellutanum have been reported to inhibit spore germination of E. cichoracearum on Cucurbita maxima that can be used as bio-antagonists (Srivastava and Suman 1986). • A phytoalexin has been isolated from the endocarp of detached open pea pods inoculated with E. cichoracearum (Mehrotra 1980) can be an alternative management option for the disease.

1.2.2 Downy Mildew Downy mildew was first reported and described from Cuba in 1868 (Walker 1952). It has now been reported from several parts of the world. It is an important fastmoving fungal disease affecting most of the cucurbits like sponge gourd, ridge gourd, muskmelon, cucumber, ash gourd, pointed gourd, long melon, bottle gourd, bitter gourd, snake gourd, round melon, vegetable marrow, pumpkin and Cucumis callosus, etc. (Bains and Jhooty 1976b; Bains and Vidyaprakash 1985; Sohi and Sharma 1998). The disease was reported to occur on Luffa sp. and Trichosanthes sp. (pointed gourd) from Pusa (Bihar) and West Bengal (Bilgrami et al. 1979; Khatua et al. 1981; Mondal et al. 2014b) and melons from Punjab (Mehrotra 1980). It is most frequently found on cucumber. The disease is fairly common in northern India, where it becomes serious during latter part of the rainy season. The

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disease is serious in muskmelon in Punjab and ridge gourd in West Bengal (Seshadri 1986). Symptoms Downy mildew symptoms are found almost exclusively on leaves. Lesions vary considerably but usually appear first as small slightly chlorotic to bright yellow areas on the upper leaf surface in the crown area of the plant resemble those of mosaic mottling. The pale green areas are separated by islands of darker green. One or more spot may be formed on a single leaf. As lesions expand and number of lesions increases, they may become necrotic and brown, eventually coalescing and killing the entire leaf. Heavy infection will lead to the browning of leaves and eventual death of the entire vine, and plants will appear scorched if cool and wet weather persists. Usually, the central leaves are attacked first and are followed by other leaves until entire plant is wilted or weakened. Young leaves are less susceptible than older ones. Infection occurs more readily on lower surface than on upper surface. Premature defoliation caused by downy mildew will reduce fruit size and predispose fruit to sunscald injury. Fruits are not directly attacked. But, in case of severe infection, a few smaller size fruits develop are often misshapen. Margins of the lesions are usually irregular, sometimes ‘blocky’ or angular in appearance and tend to be limited by leaf veins that can be confused with the bacterial disease angular leaf spot. This type of symptoms is most distinct in cucumber. On the lower surfaces of the leaves, lesions will be water soaked and slightly sunken, and are less vivid in colour. In moist weather (high humid) condition, downy mildew will only sporulate profusely on the underside (bottom lesions) of leaves producing light to dark grey or purplish-brown spores in white, fuzzy fungal growth (downy appearance). The growth is scanty and hardly discernible. But on pointed gourd, downy growth of the fungus is not found even in humid weather or rainy day (Mondal et al. 2014b). On watermelons, an exaggerated upward leaf curling is very common. Lesions are usually small on the leaf of snake gourd and ash gourd. The Pathogen Downy mildew is caused by the fungus-like organism, Pseudoperonospora cubensis (Berk. and Curt.) Rostow. It is an oomycete, is not a true fungus, and is often referred to as a water mould due to the fact that it thrives in wet or very humid conditions. It is an obligate parasite because it requires living host tissue for its growth and reproduction, and the pathogen is unable to culture in artificial media. According to Butler (1918a), ‘This parasite is an interesting example of a fungus, described on what seems to have been a wild plant, in an isolated part of the world, and considered of no economic importance, which by its gradual spread to other countries and the damage that it has caused on new hosts has won for itself a position amongst the major enemies of cultivated plants’. Mycelium of the pathogen is hyaline, coenocytic and intercellular, develops abundantly in the mesophyll, but also penetrates palisade tissues. Haustoria are

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small, ovate and intercellular sometimes with finger like branches. Sporangiophores are 180–400 μm in length, dichotomously branches in their upper third (or intermediate between dichotomous and monochotomous branching habits); emerge in groups of 1–5 through stomata. The soporiferous tips, on which the sporangia are borne singly, are subacute. Sporangia are pale greyish to olivaceous purple, ovoid to ellipsoidal, thin walled, with a papilla at the distal end, measuring 20–40  14–25 μm. Sporangia germinate by production of biflagellate zoospores, rarely by infection hyphae. Oospores are not common in the species but when produced are thick walled, smooth and light yellow (Gupta et al. 2001; Khatua and Saha 2004; Mondal et al. 2014b). They measure 19–22 μm in diameter and 1.5–3.5 μm thick. In India, presence of oospore on certain cucurbits has been reported from Madhya Pradesh, Punjab and Rajasthan (Mahrishi and Siradhana 1984). Bains and Jhooty (1976b) observed that the organism causing downy mildew on muskmelon did not infect ash gourd and pumpkin, whereas the reverse was possible. Bains and Prakash (1985) and Bains and Sharma (1986) have proposed the existence of races on the basis of different rates of disease spread and the reaction of different isolates of pathogen on 18 cucurbit hosts. Bains and Sharma (1986) reported the occurrence of two new races from Punjab. Disease Cycle The pathogen survives both as mycelium and sporangium from one season to another, since oospores are not common. Sporangia survive in cold weather (Khatua and Saha 2004). Cucurbit crops including wild species affected by downy mildew and old infected crop trash are the primary source of inoculum. Airborne sporangia from these infected cucurbits cause primary infection. Secondary infection within a field may be spread mostly by air currents, as well as rain splash, workers and agricultural implements. The sporangia can be carried by cucumber beetles (Lange et al. 1989). After release, the zoospores on germination produce germ tube or germinate directly and the germ tube penetrates the host surface and cause infection (Khatua and Saha 2004). The incubation period is 4–12 days, depending on the temperature and photoperiod. Oospores are not generally observed on the host plants. But, Khosla et al. (1973) reported oospores on pointed gourd in Madhya Pradesh and Bains et al. (1977) on Melothria maderaspatana in Punjab. These oospores are important source of perpetuation of the pathogen. Butler (1918b) had reported the possibility of perpetuation of the organism on wild hosts in certain regions. Perpetuation of the fungus in the form of active mycelium on self-sown or cultivated sponge gourd plants growing in sheltered places were observed by Bains and Jhooty (1976a) from Punjab at Ludhiana during severe winter, and they recorded sporangial production from November to February. In south Indian condition, the downy mildew fungus perpetuates on various cucurbit hosts without facing any difficulty due to monoculture of the crop as well as prevailing milder climate. At Solan, Himachal Pradesh, the disease is only noticed on snake gourd and ash gourd without forming oospores (Sohi and Sharma 1998). The pathogen is able to survive from season to season and cause infection because of the great diversity of climate

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and season in different parts of India, and abundance of suitable wild hosts would probably ensure the continuous supply of primary inoculum of the parasite (Butler 1918a). Epidemiology Infection of the pathogen generally occurs through stomata. The disease is favoured by prolonged periods of cool and wet weather. Moist conditions such as rain, fog and heavy dews required for successful development of the disease. Disease is more common in areas with high rainfall. According to Chowdhury (1998), the disease appears mainly on cucurbits during pre-monsoon and monsoon months. The incubation period of the disease is one week at 22–28  C. The pathogen can infect the plants at temperature between 10 and 27  C, with optimum day temperature of 25–30  C and night temperature of 15–21  C. The optimum temperature for infection is 20  C. However, the temperature above 35  C arrested the further invasion of the host. Relative humidity of more than 75% favour the disease development. For sporulation (i.e. for production of sporangia), at least 6 h of wet period (100% relative humidity) at the leaf surface and temperatures of 5–30  C after 6 h of dry period is essential. At 15–20  C temperature, optimum sporangial production takes place. Germination of sporangia requires free moisture and started within 1 h and reaches the maximum in 2 h at 20  C. Maximum dispersal of sporangia occurs between 6 and 10 a.m. Planospores remain motile for longer period at 10 and 15  C than 30 and 35  C. A film of moisture on leaf surface is necessary for the infection to occur (Bains and Jhooty 1978a; Lange et al. 1989; Khatua and Saha 2004). Sporangia production of the muskmelon isolate of Pseudoperonospora cubensis starts before midnight and sporangia mature by 3 a.m. In saturated atmosphere maximum sporulation occurs at 18–28  C. When the plants are exposed to 35  C for more than 9 h and to 40  C for more than 3 h before sporulation there is no sporangia production during the subsequent 12 h irrespective of other favourable environments (Bains and Jhooty 1978a). Bains and Jhooty (1978b) reported a sharp relationship between mineral nutrition of muskmelon and the disease development. Low nutritional status pre-disposes the muskmelon plants to infection. The disease development is less on plants grown in high phosphorus, low potash and high nitrogen situation. It was an important observation by them that nutrition of plants also affects sporulation of the pathogen but there was no correlation between sporulation and disease intensity. Jhooty et al. (1978) observed that the relative resistance of upper surface of leaves of muskmelon is due to lesser number of stomata in comparison with lower surface. Chemical composition of leaves of wild muskmelon is an additional factor for resistance. Khatua and Saha (2004) reported that the downy mildew of pointed gourd usually appears in December and become severe in February and March. Spread and development of the disease is arrested after middle of April when temperature become hot and humidity become low (Mondal et al. 2014b).

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Management The disease is very difficult to manage once it gets started. Some possible management options are described below. • Wild cucurbits from vegetable growing areas should be destroyed as they serve as secondary host. • Seeds should be sown in sunny sites with good airflow. • It is better to use drip irrigation and avoid overhead irrigation. Wider row spacing encourages good air movement around the plants. • Close monitoring of crop fields should be recommended to identify the disease early in its cycle and the growers must be alert to weather conditions that may cause an early infection. • Removal of severely affected vines or leaves from the field followed by spraying of fungicide (1% Bordeaux mixture) prevents spread of the disease (Mehrotra 1980). • Spraying of preventive fungicides can be recommended for management of this disease. Mancozeb 75 WP (0.2%), chlorothalonil 75 WP (0.2%), zineb 27% SC (0.2%) and copper oxychloride 50% WP (0.4%) at 8 days’ interval gives good control of the disease as protectant but failed to check established infection (Chadha 2001; Gour et al. 2008). Mancozeb (Dithane M-45) and zineb (Dithane Z-78) protect the leaves for 9 days after spraying while copper oxychloride (Tricop-50) gives protection only for 5 days (Bains and Jhooty 1978c). Khatua et al. (1981) reported the effectiveness of metalaxyl for checking this disease on cucumber. Spraying of mancozeb 75% WP (0.1%) and metalaxyl 35% WP (0.05%) mixture starting with the onset of favourable weather at 10 days’ interval are very effective. Cymoxanil 8% + mancozeb 64% WP and chlorothalonil 75% WP as tank mixture also provide effective control for downy mildew of cucumber (Robak 1995). Spraying the field with 2:2:50 Bordeaux mixture is effective (Choudhury 1990; Roychaudhury and Verma 2000). Dusting with tribasic Copper sulphate (5% copper content) at 20–25 kg/ha early in the season, and 45–60 kg/ha when the vines are larger is recommended to manage the disease (Choudhury 1990). Metalaxyl 8% + mancozeb 64% WP (0.3%), copper oxychloride 50 WP (0.4%) and mancozeb 75% WP (0.25%) is very much effective under field condition. Spraying of Mancozeb (0.3%) at 15 days intervals has been recommended to control downy mildew of melon under Ludhiana condition. Mancozeb 75% WP, Zineb 75% WP or Fosetyl-AL 80% WP (0.3%) at 10 days intervals was recommended for management of the disease of cucumber under Bangalore conditions (Rai et al. 2008). Spraying of Metalaxyl 8% + Mancozeb 64% WP and Copper oxychloride 50% WP at the recommended dosages reported effective (Bhattacharya et al. 2006). Mustafee (1998) reported that fungicides like Fosetyl-Al 80% WP, i.e. Aliette (0.2%) and mancozeb 75% WP (0.3%) can be recommended for controlling downy mildew of cucurbits. Retarded growth of vine of pointed gourd was reported due to spraying of hexaconazole and propiconazole (Saha 2002; Khatua and Saha 2004; Mondal

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et al. 2014b). Alternate use of protective and systemic fungicides reduces the chance to develop resistance against pathogen. • Resistant cultivars should be preferred for growing and avoiding the disease. Wild melon Cucumis callosus is resistant to this disease that can be used as source of resistance by the researchers. Georgia, MM-7 and Mathuria are reported as moderately resistant cultivar. The germplasm showed resistance to both downy and powdery mildew disease is IHR 142, IHR 157, IHR 180, H 190, H 226 and H 240 (Sohi and Sharma 1998). PMR Cantaloupe 45, PMR 6, PMR 7, PMR 8, Campo, Jacumba, etc. are reported as resistant muskmelon varieties. Some important resistant varieties of cucumber are Palmetto, PR 27, Santee and Palomar (Choudhury 1990).

1.2.3 Anthracnose Anthracnose was first described on gourd in Italy in 1867. In India, the disease has been reported from Punjab on long melon and gourd (Mundkur 1937). The disease has also been observed on several other cucurbit hosts. Prakash et al. (1974) reported that the cultivation of watermelon, muskmelon, snake gourd, round melon, cucumber, ash gourd and bottle gourd has been limited to a great extent due to the disease. The disease has reported from almost all cucurbits growing countries of the world. It is very serious in watermelon, muskmelon, bottle gourd, cucumber, snake gourd, etc. while bitter gourd, squash and pumpkin are less infected cucurbits. Havoc losses occur on fruits of watermelon grown in temperate countries. As much as 90% yield losses takes place in bottle gourd and watermelon during rainy season, reported by Sohi (1975) from India. About 69–70% of fruits show infection in muskmelon, watermelon and bottle gourd (Sohi and Sharma 1998). Amin and Ullasa (1981) have recorded 63% yield loss in watermelon. Ullasa and Amin (1986) recoded as high as 99% loss of marketable fruits. Losses in storage or during transport can occur when freshly harvested fruit becomes infected. The disease is severe in rainy season and in regions of heavy summer rains as in West Bengal (Seshadri 1986). This is a very common disease throughout the world but causes most significant losses in the tropics and subtropics (Agrios 2000). Symptoms Symptoms of the disease vary according to the host. All above ground plant parts are affected and plants can become infected at any stage in their development. The spots on the older leaves (foliage) begin as small, water-soaked, yellowish areas that enlarge (1–2 cm) rapidly and turn reddish brown to tan in most cucurbits but dark brown to black on the watermelon (Maity et al. 2004; Agrios 2000; Mehrotra 1980). Cucumber leaf spots are comparatively bigger than the watermelon leaf spot and often have a yellow halo. Spots are often circular to angular. Afterward, spots may coalesce to create extensive blighting. These areas become dry and tear away, typically giving the foliage a ragged appearance. Often the leaves at the centre of a plant are attacked first, leaving the stem and runners bare. Tan to black, elongated, slightly sunken streaks (cankers) form on petioles and stems that can girdle the vine, causing death of the tissue beyond the lesion. On cucumber (kheera) leaves, the

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spots commonly start on a vein and expand into brown spots which are angular or roughly circular. Growing leaves may be distorted and coalescing spots may cause death of the entire leaf. On muskmelon, the petioles are attacked so that often defoliation occurs. On pumpkin, symptoms include small, tannish-brown spots on the upper leaf surface that become pinkish-orange in colour. Shape of the lesions may be circular or spindle shaped, which are limited to the veins of leaves. Older lesions eventually turn brown and often fall out leaving a ‘shot holes’ on infected areas of the leaf (Agrios 2000; Singh 1987; Seshadri 1986; Mehrotra 1980). Saha et al. (2002) recorded the disease in the month of August on pointed gourd grown on scaffold. Individual vines are dry up due to infection on the stem. Stem lesions are brown in colour and 2–4 cm in length without superficial mycelia growth. Fruit pedicel may also be infected by the disease, which causes the fruit to turn dark, shrivel and die. Fruits, if infected early, may turn black, shrivel and die. This disease is most characteristic on fruits reaching maturity. On such fruits, the spots are roughly circular and water soaked. Spots turn dark green to brown in colour and become sunken with variable in size (0.6–10 cm in diameter and 0.8 cm in depth) depending upon the age of the plant and weather condition. The lesions may develop in field condition, in transit or in storage condition that expand rapidly and coalesce to form larger ones. Fruit lesions on watermelon can be cracked and irregularly shaped. On pumpkin, lesions are mostly circular, sunken and measure 0.2–0.5 cm in diameter or larger. On butternut squash the lesions are similar but may be larger and more elongated (Agrios 2000; Singh 1987; Seshadri 1986: Mehrotra 1980). Appearance of irregular discolouration on cucumber fruits is another important characteristics symptom observed by Laxminarayana and Reddy (1976). Under humid conditions, the centre of these spot darkens and develops tiny black specks on cuticle where salmon-pink spore masses are seen due to reddish gummy exudation from acervuli. Severely affected fruits are often tasteless or even bitter in taste. In these cases, secondary infection by soft-rotting bacteria and fungi are common, which get easy entry through the broken rind of fruits (Agrios 2000). Maity et al. (2004) described the fruit rotting symptoms of watermelon. The tender fruits are rot on infection. The infection may spread inside the older fruits infecting seeds that become rotted in case of severe infection. Causal Organism This fungal disease is caused by Colletotrichum lagenarium (Pass.) Ellis and Halsted [¼Colletotrichum orbiculare (Berk. and Mont.) Arx.]. The sexual or perfect stage (teleomorph) is Glomerella lagenarium. Colletotrichum lagenarium can infect a plant successfully at any stage of growth. When moisture is present, the spore germinates and a penetration tube enters the plant within 3 days. Invaded tissues die and form a canker followed by the production of spores which are then ready to repeat the infection process (Ferreira and Boley 1992). Young mycelium is hyaline and septate that becomes dark with age. Acervuli are brown to black and variable in size. Setae are brown, thick walled, two to three

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septate and 90–120 μm long. Colletotrichum produces conidia at the tip of conidiophore in acervuli (the canker). Individually the conidia are hyaline, oblong to ovate oblong, single celled and measures about 13–19 μm  4–5 μm. Masses of conidia attain a pink or salmon colour. Conidia are released from the acervuli and come into contact with susceptible plant and/or fruit hosts and germinate when water is present and temperatures are optimal (20–32  C). The conidia germinate by producing germ tube and penetrate host tissues directly by forming dark, thick-walled appressorium (Singh 1987; Ferreira and Boley 1992). Laxminarayana and Reddy (1976) recorded the organism infecting cucumber is Colletotrichum capsici (Syd.) Butler and Bisby. Saha et al. (2002) also recorded the same organism from infected pointed gourd. The pathogen has also been reported to cause leaf spots and blight of Cucumis melo var. momordica (Mehrotra 1980). The organism, Colletotrichum capsici forms acervuli. Acervuli on stems are rounded or elongated, intra and sub-epidermal, disrupting outer epidermal cell walls of host. Setae are brown, 1–5 septate, rigid, hardly swollen at the base, slightly tapered to the paler acute apex, up to 250 μm in length. Conidia are hyaline, falcate with acute apex and narrow truncate base, aseptate, 16–30  2.5–4.0 μm, formed from unicellular hyaline to faintly brown cylindrical conidiophores (Khatua and Saha 2004). Three races of Colletotrichum have been reported by the researchers from different parts of the world (Seshadri 1986). Disease Cycle The causal agent is primarily soil borne but it may also be seed borne if fruits are attacked and the fungal mycelium reaches the seed. The fungus can overwinter as mycelium on or in seed and on residue from diseased plants in and on the soil, and in weeds of the cucurbit family (Ferreira and Boley 1992; Agrios 2000; Gour et al. 2008). The pathogen can also overwinter in old cucurbit vines. The fungi produced spores (conidia) on infected leaves and fruit. These spores are easily spread by splashing rain, irrigation, activities of workers, agricultural equipment and insect activities. This soil borne fungus is splashed with soil particles onto healthy leaves during rainfall or overhead irrigation. Epidemiology Germination and growth of the fungus occurs best at 22–27  C. The conidia (spores) are released and spread only when the acervuli are wet and are generally spread by splashing water and blowing rain or by coming into contact with insects, other animals (including humans) and tools (Ferreira and Boley 1992). If moisture is present, spore germinates and penetration occurs effectively within 3 days. In next few days numerous fruit bodies form on the lesions. The pathogen can tolerate temperatures up to 45  C and unable to infects the host below the temperature of 18  C. Warm temperatures (20–30  C), high humidity (frequent rains, poor drainage and 100% relative humidity for at least 18 h) and high rainfall favour rapid development and spread of the disease. Temperatures between 20 and 30  C are most conducive for infection with day and night temperatures ranges of 26–30  C

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and 18–20  C, respectively is most congenial for disease development (Sohi and Sharma 1998). Intermittent rains during August and September coupled with warm temperatures cause epidemics in watermelon, muskmelon, and bottle gourd. Disease development is not affected by plant population (Ullasa and Amin 1986). In high humid condition the disease and its further spread is very much difficult to check. Anthracnose can appear anytime during the season, but most damage occurs late in the season after fruit setting. The fungus occurs in epidemic form only when there is more than average rainfall. Seshadri (1986) pointed out that the disease is promoted by high humidity and moist weather condition, and is severe in rainy seasons and in regions of heavy summer rains as in West Bengal. Maity et al. (2004) reported that the disease mainly appears on watermelon in West Bengal during the end of February due to gradual rise of day temperature and deposition of dew on the leaf surface during the early morning. Management • Sowing of certified, disease free seeds of a variety resistant to the races of Colletotrichum (watermelon—races 1 and 3; cucumber—races 1, 2 and 3) are important to manage the disease in field condition (Ferreira and Boley 1992). • Cultivation should be done in well-drained soil free from surface run-off water. • Three to four years crop rotation programme with non-host crop should be practiced (Kennelly 2012). • It is better to plough down the field after harvest the crop. Plant debris should be collected for proper destruction at the end of the growing season. • Drip irrigation can be advised instead of overhead sprinklers, if possible. • Removal of weeds under cucurbits family and volunteer cucurbits plants is beneficial. • Continuous cropping of different cucurbit vegetables in tropical regions especially in riverbed areas should be discouraged (Sohi and Sharma 1998). • There is an increasing interest in controlling or curbing disease incidence by immunizing plants to some bacterial, viral and fungal plant pathogens by exposing them to C. lagenarium (Ferreira and Boley 1992). • The seeds should be treated with fungicides like captan or thirum 75% WP at 2.5 g/kg (Mustafee 1998), carbendazim 50% WP at 1.0 g/kg (Maity et al. 2004), benomyl 50% WP at 1.0 g/kg of seeds or bio-antagonist like Trichoderma viride at 6 g/kg of seeds (Gour et al. 2008). • The disease can be managed by the repeated spraying of recommended fungicides like benomyl 50% WP, carbendazim 50% WP and thiophanate methyl 70% WP (0.1%) (Prakash et al. 1974; Sohi and Sokhi 1976; Amin et al. 1979; Amin and Ullasa 1981; Ullasa and Amin 1986; Mustafee 1998; Maity et al. 2004) or Mancozeb 75% WP, Zineb 75% WP, Captan 50% WP (0.2%), etc. at an interval of 5–7 days. Khatua and Saha (2004) stated that one spray with mancozeb 75% WP (0.2%) or carbendazim 50% WP (0.1%) after removal of infected vines will check the disease. Spraying should be started at two leaf stage. Chlorothalonil 75% WP and Maneb are also efficacious against the disease (Zitter 1987). Spraying of Carbendazim 50% WP and Benomyl 50% WP at 0.2% at 15 days

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intervals has been recommended for controlling of the disease of watermelon under Bangalore condition (Rai et al. 2008). Gour et al. (2008) also recommended Copper oxychloride 50% WP at 0.3% for controlling the disease. • Cultivation of resistant varieties like PI 197087 (resistant to all three races), Poinsett (highly resistant), PI 175111 (moderately resistant) of cucumber; African Citron 8 (resistant to races 1 and 3), African Citron W-695 (resistant to race 2), Charleston Gray, Congo (resistant to races 1 and 3), Dunbarton, Garrisonian, Calhoun sweet, Fairfax, Blackstone, Iowa Belle, Crimson Sweet, Sweet Princess, Jubilee, etc. of watermelon are important to avoid the disease situation (Sitterly 1972). Arka Manik has reported as moderately tolerant watermelon variety under Bangalore condition.

1.2.4 Alternaria Leaf Blight Alternaria leaf blight is found primarily on watermelon and muskmelon, but may occur on cucumber, gourds, pumpkin and squash (Seebold 2010a; Gour et al. 2008). This disease affects foliage and sometimes fruit. Alternaria leaf blight does not commonly infect fruit but can reduce yield and quality through reduced plant vigour and sunscald of exposed fruit. The disease was recorded on muskmelon, watermelon, bottle gourd, snake gourd, cucumber and vegetable marrow in Punjab and Rajasthan (Khandelwal and Prasad 1979; Chahal et al. 1970). Bhargava and Singh (1985) recorded a wide range of disease intensity from Rajasthan on various cucurbits. The disease intensity varied from 30.2 to 90.7 percent on watermelon, 30.2–40.8% on bottle gourd, 12.5–60.3% on pumpkin, 12–22.2% on ridge gourd and 15.3–29.0% on bitter gourd. They also reported 77.7% yield losses on bitter gourd, 65.3% on bottle gourd, 80% on pumpkin, 69% on ridge gourd and 88.3% on watermelon. Symptoms Disease symptoms initially appear on mature leaves near the crown of the plant as small necrotic spots, which rapidly increase in number and size. The spots may be surrounded by a yellow halo. These lesions expand to form large, irregular brown spots with a concentric ring or target board pattern. Expanding lesions may merge to form large, blighted areas. The blighting symptom or burning effect is prominent especially on the watermelon. As symptoms progress, leaves curl and die, leading eventually to plant decline. There are some controversies regarding fruit infection by the pathogen. Fruit are not commonly infected but can suffer from sunscald due to leaf loss. Gour et al. (2008) reported that fruit infection on muskmelons causes circular, brown and sunken spots resulting in dry rot. Singh (1987) in his book also mentioned fruit infection of muskmelon due to the disease with dry rotting symptoms. So, to remove this confusion, the fruit rot phase of the disease needs more study.

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The Pathogen Leaf blight of cucurbits is caused by Alternaria cucumerina (Ell. and Ev.) Elliot. Conidia of this species are obclavate, dark, muriform and measure about 30–75 μm  15–25 μm in size (Singh 1987). Disease Cycle This fungus perpetuates as a saprophyte on decaying crop debris in soil. The disease dissemination occurs from plant to plant through conidia that are carried by wind and splashing water from diseased plants to disease free plants (Seebold 2010a). The long distance dissemination of the disease occurs through wind currents whereas the disease can be spread within the field by splashing water. The role of collateral hosts and seeds as carriers of the pathogen needs to be investigated appropriately (Sohi and Sharma 1998). Germinating spores can penetrate the host directly, as well as through wounds and natural openings. Epidemiology This fungus rarely attacks young, vigorously growing healthy plants. Wet rainy weather favours the disease development. The disease is more severe in wet and warm temperatures condition (Seebold 2010a). A temperature of 25–30  C and relative humidity of 92–100% are optimum for the growth and sporulation of the fungus (Khandelwal and Prasad 1979). Chopra and Jhooty (1974) studied biochemical changes in resistant and susceptible varieties of watermelon. Management The following management practices along with maintenance of plant vigour at high level are very much important to ward off the pathogen from the field. • Crop rotation with non-host crop for at least 2–3 years is helpful for reducing the disease incidence (Gour et al. 2008; Seebold 2010a; Kennelly 2012). • Good sanitation practices, such as cleaning up crop debris at the end of the growing season, proper drainage during growing season are important. • Use of drip irrigation instead of overhead sprinklers is helpful to manage the disease. • It is better to avoid heavy doses of nitrogenous fertilizer along with close spacing (Anonymous 1996). • Muskmelon cultivars that have some level of resistance should be cultivated; newer varieties are believed to be somewhat more resistant to alternaria leaf blight than older, traditional cultivars (Seebold 2010a). Honeydew melons are highly resistant to alternaria leaf blight (Kennelly 2012). • Borax wash (2.5%) at 45  C for 30 s or at 40  C for 2 min before packing of the fruits prevents fruit rot. Captan 50% WP and ziram 27% SC are also effective at low temperatures (Sohi and Sharma 1998). • Fungicides can be used to control the disease effectively. Preventive sprays are efficacious but are only essential in fields with a previous history of the disease. Three spray of Carbendazim 50% WP or Benomyl 50% WP at 0.2% at 15 days

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intervals for managing the disease of watermelon has been recommended under Bangalore conditions (Rai et al. 2008). The disease can be managed effectively by spraying Mancozeb 75% WP at 0.25% or Copper oxychloride 50% WP at 0.3% (Gour et al. 2008).

1.2.5 Net Blight This is an important disease of pointed gourd. The disease also locally known as suji dana haja (suji is a granulated but not pulverized product of Indian wheat, dana means seed, haja is a type of skin disease) due to the presence of small white sclerotial growth on leaves and stem. Sometimes farmers called it chak poka (chak means ‘beehive like shape’, poka means ‘insect’) because of appearance of symptom as beetle feeding on leaves (Khatua and Saha 2004; Mondal et al. 2014b). The disease was recorded first time from Nadia and North 24 Parganas of West Bengal, then several other pointed gourd growing belts of the state (Mondal et al. 2012). Symptom The disease starts as water-soaked angular spot, delimited by veinlets on lower side of the leaves. At that time, no symptom appears at the upper surface of the leaf. In time, such leaves dried up. During rains, rotting occurs in infected zone of the leaves and rotted tissues are washed out by rain leaving the network of veins. The first noticeable symptom of the disease in the field is drying of older leaves in patches. During rainy days or sunshine day following rains at night, dull white coloured small sclerotial growth along with thin hyphal filaments appear on the diseased tissue and nearby healthy tissue early in the morning. After sunrise, the hyphal and sclerotial growth apparently disappears. In advanced stages of the disease all the leaves dry up and axillary buds are destroyed leaving the stem bare (Saha 2002). The Pathogen The disease causing agent is a small sclerotia forming fungus Rhizoctonia solani Kuhn causes leaf blight of radish in the same season (Saha 2002; Khatua and Maiti 1982). The pathogen also causes leaf blight of bottle gourd was reported from Nadia district of West Bengal by Mondal et al. (2012). Superficial, dull white coloured, irregular and small sclerotia appears on the host that become dark brown in time. This is accompanied by thin, superficial, dark coloured, abundantly branched stout mycelium. The matured sclerotia are near about 100 μm in diameter. The hyphae are septate and present both inter- and intracellularly in the host tissue. In artificial medium, young colonies of the fungus are white which turn dull white having brown shade with age. Mycelium is stout and septate. Sclerotia are brown in colour. The septa are typical dolipore type. The lateral branches from the main hyphae are invariably constricted at the point of origin and septum occurs in the branch near the junction with main axis. Branching almost invariably occurs near the distal septum of the cell in the young advancing hyphae but at any point in older hyphae.

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Disease Cycle The fungus survives in soil and on infected crop debris as sclerotia that germinate to infect the fresh vines. The pathogen can also survive as saprophyte on dead organic matter. It has wide host range, infects several other crops like potato, groundnut, cowpea and different other oilseeds and vegetables, etc. Epidemiology The disease appears from August onwards particularly during the rainy days where crop is grown in soil beds. The pathogen favours hot (nearly 28–30  C) and humid climate for infection and disease development. The disease occurs more in alluvial and sandy soils. Management The disease is becoming a serous one. Proper management is needed for getting higher yield of the crop. The following practices can help to reduce the disease incidence. • Mixed cropping with Phaseolus aconitifolius and sorghum can reduce the disease incidence. • Enrichment of soil with decomposable organic matter like green manure, oil cakes, neem cake, etc. can bring down inoculum load in the soil. • Soil amendment with green organic manure especially tops of maize plants and a legume is efficacious. • Crop rotation with non-host crops is recommended. • Judicious application of nitrogenous fertilizer is important. Application of potashic fertilizer helps to reduce the infection (Anonymous 1996). • The disease can be controlled biologically by soil application of Trichoderma viride at 8 kg/ha in mixing with organic manure. • Spraying of mixture of mancozeb 75% WP (0.2%) and carbendazim 50% WP (0.1%) once or twice is effective in controlling the disease (Khatua and Saha 2004).

1.2.6 Cercospora Leaf Spots The disease is widespread all over the tropical and subtropical regions of the world. Almost all the cucurbit vegetables are found to be infected with leaf spot disease in India mainly caused by Cercospora spp. (Gour et al. 2008). Besides, there are some reports of other fungal plant pathogens causing leaf spot disease of cucurbits. In favourable weather conditions the disease become more severe. Sometimes the fungus causes devastating damage resulting in heavy loss in fruit yield (Rangaswami and Mahadevan 2004). In Europe, it is a destructive disease of cucurbits in greenhouse condition. Symptom Almost all the above ground parts are infected by this disease. Fruits are in general remains unaffected. The disease affects leave as well as young succulent stems and

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Table 2 Species of Cercospora infecting cucurbits in India Name of cucurbits Trichosanthes anguina L. Momordica charantia L. Luffa acutangula (L.) Roxb. Benincasa hispida (Thumb.) Cong. Lagenaria siceraria (Mol.) Standl. Citrullus vulgaris Schrad. Ex. Eckl. and Zeyh. Cucumis sativus L. Cucurbita maxima Duch.

Cercospora spp. Cercospora citrullina Cooke, C. trichosanthes var. anguinae Rang. and Chand. C. momordicae McRae, C. citrullina Cooke C. annamalaiensis Rang. and Chand. C. citrullina Cooke C. lagenariae Rang. and Chand. C. citrullina Cooke C. chidambarensis Rang. and Chand. C. citrullina Cooke

petioles. The symptoms initially appear as water-soaked areas on the leaf lamina. These water-soaked areas enlarge rapidly to become circular or irregular spots with pale brown, tan or white centres and purple to almost black margins. The spots are generally limited by the leaf veins and they vary in size, from a few mm to about 1 cm in diameter. A few to over a hundred spots may be seen on a leaf blade, depending upon the severity of infection. Spots are coalescing type, and form large blotches in advance cases. Severely infected leaves may dry up and ultimately the infected plants die. In snake gourd stem and fruits are also affected. In this case the fungus causes elliptical, greenish, sunken spots. Several such spots coalesce to cover and girdle the fruit, which rots eventually. The Pathogen The disease is incited several species of Cercospora. Among them, Cercospora citrullina Cooke is most common which attacks bitter gourd, pumpkin, cucumber, snake gourd, muskmelon, etc. Other species are C. trichosanthes var. anguinae, C. momordicae, C. laginariae and C. cucurbiticola, etc. Most prevalent species are Cercospora citrullina Cooke and C. lagenariae Rang. and Chand. (Gour et al. 2008). The species of Cercospora responsible to cause leaf spot disease of cucurbits in India are mentioned below (Rangaswami and Mahadevan 2004) (Table 2). The mycelium of Cercospora spp. is branched, septate and hyaline when young that become coloured with age. Hyphae aggregate below the stomatal cavity to form stromata. Conidiophores arise from these structures. Conidiophores are light brown to dark, septate, geniculate and bear conidia which are hyaline and usually needle shaped. Fruiting of C. citrullina is chiefly epiphyllous. Stromata may or may not be present, if present are small and brown in colour. Conidiophores are 2–30 in a divergent fascicle, pale to very pale brown, paler towards the apex, rather uniform in width or mildly attenuated towards the apex, occasionally swollen at some points, straight to slightly bent or curved, geniculate, multiseptate, simple or occasionally

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branched, subtruncate at the apex, 20–300  4–7 μm in size, conidial scars conspicuously thickened, 3–4 μm wide. Conidia are hyaline, acicular cylindric or slightly cylindro-obclavate or filiform, straight to curved, 1–17 septate, subacute to obtuse at the apex, subtruncate or rounded at the base, and 30–200  4–6 μm in size (Hsieh and Goh 1990; Mukhtar et al. 2013). Disease Cycle The common source of primary inoculum is infected crop debris. The pathogen may also be perpetuated on perennial weed hosts (Gour et al. 2008). These are the primary sources of inoculum. Secondary inoculum of the pathogen is wind borne conidia. Long distance dissemination of the pathogen occurs through moist wind. The new lesions develop on host within 7–10 days of penetration. Epidemiology High humidity along with a temperature range of 26–30  C is congenial for reproduction and successful infection by the pathogen (Gour et al. 2008). Management • The field and its surrounding should be kept free from perennial weeds to destroy the sources of inoculum. • Collection and destruction of the infected crop debris are helpful to reduce inoculum density. • Proper drainage and aeration facilities in crop field reduce chance of infection and rapid spread of the disease. • The seeds should be treated with Captan 50% WP (0.2%) before sowing. • Spraying of Captan 50% WP (0.2%), Mancozeb 75% WP (0.2%) or Ziram 27% WP (0.2%) at an interval of 10 days is effective.

1.2.7 Leaf Spot Causing Other Fungi There are several other fungi which cause leaf spots of cucurbits were reported by many scientists from different cucurbits growing areas of the world. • Helminthosporium rostratum Drechsler: This fungal plant pathogen causes leaf spot disease on cucumber (Krishnamurthy et al. 1972; Singh 1987). • Corynespora melonis (Cooke) Lindau.: C. melonis, an important fungus, causes leaf spot disease on cucumber (Krishnamurthy et al. 1972; Singh 1987). • Exserohilum rostratum (Drechsler): This fungus causes marginal leaf blight on cucurbits (Utikar et al. 1986). • Phyllosticta cucurbitacearum Sacc.: This fungus causes leaf spot of bottle gourd recorded from Nadia district of West Bengal (Mondal et al. 2012). • Rhizoctonia solani Kühn: This fungus causes leaf blight of bottle gourd recorded from Nadia district of West Bengal (Mondal et al. 2012).

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Stem Rot, Vine Rot or Collar Rot Diseases

1.3.1 Stem Rot Stem rot is becoming a destructive disease of cucurbitaceous vegetables causes mild to severe damage to the crops like pointed gourd, bitter gourd, cucumber, muskmelon, pumpkin and watermelon. Pointed gourd is mostly affected crop than other cucurbits. The disease is differently known as collar rot, southern blight, etc. The pathogen has wide host range, which also includes other vegetable crops, fruits, herbaceous ornamentals and tobacco, etc. Symptom The pathogen infects any portion of the pointed gourd vine in the field. The first sign of the disease is a mid-day wilting of the plant. The leaves turn yellow, and within a few days the plant completely wilts and dies due to girdling of the stem at the soil surface (Gour et al. 2008). It causes rotting of the stem portion that is in close contact with soil. The affected tissue becomes covered with white mycelial growth. In advancement of the disease, numerous small, round fungal structures known as sclerotia develop in the fungal mat on the infected tissue and on nearby soil. Severely infected vine may dry up. Maximum damage occurs when the fungus attacks the roots of root knot infected plants, causes root rot resulting into death of the entire plant. In severe cases fruit can be infected by this disease (Khatua and Saha 2004). Siddaramaiah et al. (1982) found development of water-soaked areas on the fruits of pumpkin due to soft rot caused by the fungal pathogen, Sclerotium rolfsii. Similar type symptoms were also recorded on ridge gourd by Laxminarayana and Reddy (1976) and on cucumber, muskmelon, pumpkin and watermelon by Seebold (2010b). The Pathogen Singh and Seth (1974) recorded Sclerotium rolfsii as collar rot causing fungus of pumpkin. Khatua and Saha (2004) also identified the pathogen as Sclerotium rolfsii Sacc. (Teleomorph: Athelia rolfsii (Curzi) Tu and Kimbrough). The soil borne pathogen produces silky-white hyphae with septate mycelium. These rapidly growing, silky-white hyphae of the pathogen tend to aggregate into rhizomorphic cords. Fan-shaped mycelial growth is the characteristics identifying feature of the fungus. The pathogen produces small and hard resting structure called sclerotia (0.5–2.0 mm diameter). The sclerotia develop after 4–7 days of mycelial growth. Initially sclerotia are felty white, small, poppy seed like and round shaped which quickly melanise to a dark brown, hard structure, like that of mustard seed. The sclerotia that form on a host surface are of smooth textured, whereas those produced in culture may be pitted or folded. Sclerotia are the protective structure, contain viable hyphae and serve as primary inoculum for the disease development (Aycock 1966; Punja 1985, 1988). The sexual stage of the fungus (Athelia rolfsii) occasionally produces basidiospores at the margin of lesions under humid conditions, but this form is not

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common. Reproduction and spread of the organism by this spore under field conditions is unknown (Punja 1985, 1988; Sarma and Singh 2002). Disease Cycle The pathogen has wide host range and can also survive as saprophyte on crop refuse. Sclerotia serve as the principle overwintering structures and primary source of inoculum for the disease. Persisting near the soil surface, sclerotia may exist free in the soil or in association with plant debris. Those buried deep in the soil may survive for a year or less, whereas those at the surface remain viable and may germinate at congenial situation by a number of germ tubes or hyphae and cause infection of the host in response to alcohols and other volatiles released from decomposing plant material. When host is unavailable, the germ tubes rapidly form sclerotia, thus, augmentation of the survival ability. The mycelium survives best in sandy soil, while the sclerotia survive best in moist and aerobic conditions found at the soil surface (Aycock 1966; Punja 1985, 1988). The pathogen survives in soil for many years and the disease spreads by different means, i.e. movement of infested soil or by surface water (Gour et al. 2008). Epidemiology High temperatures (above 28  C) and high humidity favour growth of the fungus and infection too. Aeration and moist conditions are essential for germination of sclerotia. Maximum mycelial growth occurs between 25 and 35  C. High soil moisture, dense planting and frequent irrigation promote infection (Punja 1985, 1988). The disease is more severe where undecomposed organic matter is left on and in the soil. Sclerotia enable the fungus to survive adverse conditions and can persist in the upper layers of soil for many years. This soil borne, polyphagous fungal plant pathogen has wide host range that serve as collateral hosts (Aycock 1966; Punja 1985, 1988). Since S. rolfsii does not produce spores, dissemination depends on movement of infested soil and infected plant materials. Use of contaminated equipment and machinery may spread sclerotia to uninfected fields. Sclerotia may also be disseminated through running irrigation water. Management Management of the disease is difficult because of soil borne nature and wide host range of the pathogen. The disease can be check by the following ways. • Deep plowing (at least 20 cm) serves as a cultural management tactic by burying sclerotia deep in the soil as well as complete decomposition of crop residues. Destruction of crop residues can help to reduce inoculum load. • Crop rotation using non-host or less susceptible crops like corn, sorghum, small grains, etc. can be practiced to reduce the inoculum load but it will not help much to minimize the disease situation due to its wide host range, soil borne and saprophytic nature (Gour et al. 2008; Seebold 2010b).

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• Soil solarization is effective to manage the disease by reducing inoculum. Covering soil with transparent polyethylene sheets during the hot season increases soil temperatures and kills sclerotia. Soil solarization in combination with the application of Trichoderma harzianum is more effective to manage the disease. • Seed treatment with Trichoderma viride at 4 g/kg seed will help in reducing the disease. Soil treatment with T. viride recorded effective too (Kulkarni and Kulkarni 1994; Virupaksha Prabhu et al. 1997; Singh et al. 2013), while soil application of Azotobacter chroococcum and Pseudomonas fluorescens during transplanting/sowing and 25 days after transplanting at 10g/plant recorded effective (Mahato and Mondal 2014). Seed treatment with Trichoderma viride at 4 g/ kg seed followed by soil application of 2 kg T. viride mixed with 50 kg farm yard manure per acre is effective in managing the disease (Gour et al. 2008). Seed treatment with carbendazim 50% WP at 1.0 g/kg seed can protect the seedling from rotting due to the pathogen. Soil application of Trichoderma viride at 8kg/ha by mixing with organic manure (preferably neem based) is efficacious. • Mahato and Mondal (2014) observed effectiveness of vermicompost at 5 t/ha for managing the pathogen causing collar/stem rot disease. • Removal of infected plants and fruits from the field can prevent the fungal infection (Seebold 2010b). • There are some reports about the use of black plastic mulch in controlling the disease. • It is better to avoid over irrigation of the field during early stage (seedling stage) of crop growth (Anonymous 1996). • Application of plaster of paris (CaSO4.1/2 H2O) on the soil after removal of the infected vines is very much effective to check the disease in field condition. Application of plaster of paris at 2.5 g/infected area of plant reported efficacious (Mondal and Khatua 2013; Mahato and Mondal 2014). • Mondal and Khatua (2013) recorded some fungicides having inhibitory effect on sclerotial germination of the fungus, viz. Carboxin 37.5% + Thiram 37.5% WP, Chlorothalonil 75% WP and Metalaxyl 8% + Mancozeb 64% WP at 0.2%, 0.2% and 0.25%, respectively. Mahato et al. (2014) reported some fungicides (Carboxin 37.5% + Thiram 37.5% at 0.2%, Metalaxyl 8% + Mancozeb 64% WP at 0.25%, Chlorothalonil 75% WP at 0.2%, Mancozeb 75% WP at 0.25% and Cymoxanil 8% + Mancozeb 64% at 0.25%), plant oil (Karanja oil at 5% v/v) and plant leaf extract (Murraya exotica 10% v/v) having good in vitro sensitivity against the pathogen. Spraying of carbendazim or Benomyl 50% WP at 1.0 g/l of water is helpful for reducing the disease incidence.

1.3.2 Sclerotinia Rot The disease was recorded on ridge gourd from Arunachal Pradesh (Bag 2000), and on pointed gourd from Birbhum district of West Bengal by Khatua et al. (2014). The disease on pointed gourd was reported first time from India by Khatua et al. (2014).

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Symptoms The first noticeable symptom of the disease in field condition is drying of new vines. Drooping of tips of some vines is also noticed. On careful observation fade green lesions are found on the internodes of those vines. Such vines, if kept in moist condition white mycelial growth come up and spread over the vines within 3 days. In pointed gourd, infection spread to the leaf also. Prominent white mycelial growth is seen on infected ridge gourd fruits in field condition. Infected pointed gourd fruits become reddish brown and thin mycelial growth cover the infected area. If infected fruits are kept in moist condition prominent white mycelial growth covered the fruits of both pointed gourd and ridge gourd and the rotting of those fruits occurs completely. On the rotted fruits abundant small to large, elliptical, circular and irregular sclerotia are formed (Khatua et al. 2014). Pumpkins and some varieties of winter squash are most severely affected by the disease. In this case, the disease does not cause leaf spots but infects both stems and fruit. Water-soaked lesion appears on the infected fruits and stems where fluffy white cottony fungal growth is commonly seen. Fruit are often infected through the blossom end of the fruit, especially when the blossom remains attached after pollination, and becomes rotted and watery. Sclerotia may be found inside these rotted fruit. The disease may occur both in the field and post-harvest condition. Stem infections often start where cotyledons are fading or where the plant has been wounded. Small hard and black coloured sclerotia eventually develop that generally embedded in the cottony growth. The Pathogen The causal pathogen, Sclerotinia sclerotiorum (Lib.) de Bary produce white mycelium with hyaline, much branched consisting of closely septate hyphae. The pathogen grows both inter and intracellularly to the host and form black coloured, spherical to elongated large sclerotia on host surface and inside the infected host tissues. The size of mature sclerotia varies from 2–10  2–5 mm. On artificial medium, the fungus produces white fluffy mycelial growth. Black sclerotia near spherical to irregular in shape generally formed within 4 days of incubation at 25  C. The sclerotia are silvery white in initial stages of development but turned dark later. No host specificity was recorded by Khatua et al. (2014). At limited food supply condition, sclerotia germinate to produce funnel-shaped cups known as apothecia that become darker with age. These apothecia produce ascospores, which discharged at maturity and cause infection. Disease Cycle In absence of the hosts, the fungus persists in soil through formation of sclerotia or in infected plant debris. Sclerotia may form within the infected host tissue, on host surface and in soil. They can survive in soil and in plant debris for 5 or more years. These sclerotia germinate to form funnel-shaped cups, i.e. apothecia, in which numerous cylindrical asci are formed. Each ascus generally contains eight ascospores. The ascospores are released in environment through an apical pore of

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ascus at maturity. Ascospores formed from these structures either directly infect the host or they grow on fallen flowers and produce mycelium. This mycelium can cause infection and help in secondary spread of the disease. The pathogen has wide host range. Sclerotia and ascospores are act as the primary sources of inoculums. Epidemiology The disease appears mostly in humid weather condition. The pathogen has wide host range. The pathogen infects different vegetables like French bean (Phaseolus vulgaris L.), Dolichos bean (Dolichos lablab L.), pea (Pisum sativum L.), bottle gourd (Lagenaria siceraria (Molina) Standl.), cauliflower (Brassica oleracea L. var. capitata) along with many other plants on artificial inoculation in laboratory condition (Khatua et al. 2014). Broccoli (Brassica oleracea L. var. italica) is also a host of this pathogen was reported by Kumar et al. (2003). The pathogen favours low temperature. The condition congenial for germination of sclerotia is mostly prevails in December and January. Optimum temperature for infection is 15.5–21  C (Singh 1987). Management Management is much difficult as the pathogen has wide host range. • Care should be taken to remove and destroy diseased plant parts and infected fruits from the field by which survival potential of the pathogen can be reduced (Khatua et al. 2014). Removal and destruction of infected plants from the field should be done before the formation of sclerotia. Infected fruits and other plant materials should not be kept for preparation of composting. • Deep summer ploughing should be done in such a way that surface soil is buried deep. Sclerotia buried deep fail to produce apothecia (Singh 1987). • Crop rotation with wet rice culture, i.e. cultivation of rice under flooded condition helps in destruction of sclerotia (Singh 1987). • The fungus is soil borne and the pathogen survives in soil through sclerotia. As germination of these sclerotia continues over a period of months producing ascospore showers, it is difficult to control the disease through application of fungicides. Spraying of ziram and carbendazim has some effect to reduce the disease incidence (Singh 1987). • Wider row spacing is recommended for managing the disease. • No resistant varieties are available, but plants with an open growth habit have less disease than plants with dense leaf coverage.

1.3.3 Gummy Stem Blight This is an important fungal disease of cucurbits having worldwide distribution and often accompanied by leaf spot and black fruit rot. The disease appears both in field and storage condition and cause significant damage to the crops. Among the cucurbits, squash, watermelon, cucumber, muskmelon and pumpkin are mostly affected by the disease.

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Symptoms The disease appears all the above ground parts of the plants in congenial weather condition. The pathogen, causing gummy stem blight, generally attacks the leaves and stems of watermelon, cucumber and muskmelon, and the fruits of squash and pumpkin. Due to the disease, different kinds of symptoms appear on the hosts’ surface. Damping-off occurs when the fungus is carried in the seed and cause killing of seedlings. Leaves, petioles and stems are infected by the disease and pale brown or grey spots develop on infection. These spots become enlarge to form larger spots. Infected leaves turn yellow and die. The spots usually start at the joint on stems, become enlarge and form crack from where exudation of amber-coloured gummy sap occurs. The stem dried out from the point of infection; eventually the whole plant shows wilting symptoms and dies. On fruit, the spots primarily appear as yellowish, irregularly circular areas that turn grey to brown in time, and may have a droplet of gummy exudate in the centre. The spots ultimately turn black. In some cases, the spots are superficial and spread over much of the fruit surface. On butternut squash, superficial and galloping type of black rot is common. Black rot spots appeared on winter squash are comparatively bigger in size. In storage condition, the fungus penetrates through the rind and spreads throughout the squash and even into the seed cavity (Agrios 2000). Sohi and Sharma (1998) also recorded a numbers of cucurbit vegetables suffering from such types of fruit rot disease. The Pathogen The fungal plant pathogen, causing gummy stem blight is Didymella bryoniae (¼Mycosphaerella melonis (Pass.) Chiu and Walker), produces huge conidia and ascospores, which are short-lived after released in the environment. It produces chlamydospores as resting structure by which the pathogen generally overwinters in absence of hosts. The fungus also produces closely spaced groups of palecoloured pycnidia and dark, globular perithecia that are sometimes arranged in rings, and are visible with the necked eye (Agrios 2000). Seshadri (1986) mentioned Mycosphaerella citrullina as gummy stem blight causing pathogen of watermelon, cucumber and muskmelon. Sohi and Sharma (1998) recorded Mycosphaerella melonis causing fruit rot of different cucurbits. Disease Cycle The fungus overwinters in diseased plant residues as chlamydospore and in infected seeds. These are the primary sources of inoculum. Conidia act as secondary inoculum and spread through wind and dripping or splashing water. Beetles, mainly striped cucumber beetles, serve as a vector of the disease, which also spread conidia from diseased plant to others (Agrios 2000). Epidemiology High humidity and warm weather condition is favourable for development of the disease. Leaf wetness or high humidity is essential to release of conidia of the pathogen and its germination. For production of perithecia require warm and humid weather condition (Agrios 2000).

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Management The disease is difficult to manage because of its diverse nature. • • • •

Disease free clean and treated seeds can be used to avoid the seed borne infection. Long crop rotation with non-host crop is effective. Diseased crop residues should be removed from the field. Care is needed to avoid infection in storage. Careful handling reduces the chances of wounding of stored fruits. Curing of squash at 23–29  C for 2 weeks to heal the wounds and subsequent storage at 10–12  C are very helpful (Agrios 2000). • Frequent application of fungicides such as benomyl 50% WP (0.1%), mancozeb 75%WP (0.25%) or chlorothalonil 75% WP (0.2%) is efficacious to check the disease in field condition. • Grafting melon onto squash interspecific hybrids can provide resistance to Didymella bryoniae (Fuckel) Rehm (Crinò et al. 2007). It was pointed out that while gummy stem blight is typically considered a foliar disease, D. bryoniae is a soil-inhabiting fungus, and one of the primary sources of infection is through the crown. It was speculated that providing resistant root stock on susceptible scions prevents primary sources of infection, resulting in reduced disease incidence (Davis et al. 2008).

1.4

Fruit Rot Disease

1.4.1 Alternaria Fruit Rot The disease is prevalent in diara area. It was observed in pointed gourd in a local variety Tinsokwa. Sahu Kritagyan and Singh (1980) recorded approximately 5% fruit infection on pointed gourd by the disease. Symptom Black uniformly spreading lesions appear on pointed gourd fruit. The fungus gradually forms a cavity in the infection court, which later appears as sunken lesions. Finally, it produces deep brown spore mass. Later the infection extends deep inside the flesh. The fruit becomes pale yellow leaving a deep brownish-black target board like spot on the skin and dries up due to loss of turgidity. Brownish mycelia are observed inside the rotten fruits. Whole fruit including seeds are found to rot emitting unpleasant odour (Sahu Kritagyan and Singh 1980; Khatua and Saha 2004). The pathogen also causes severe leaf spot disease on cucumber. In this case, lesions ranged in size of a pin point to over 5 cm in diameter, with necrotic tissue on most of their area and a surrounding yellow zone (Vakalounakis and Malathrakis 1988). Laxminarayana and Reddy (1976) recorded fruit infection of cucumber along with appearance of characteristics round, pale brown lesions on fruit. They also recorded appearance of brown coloured spots on ridge gourd for the disease.

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The Pathogen The fruit rot of pointed gourd is caused by the fungal pathogen, Alternaria alternata (Fr.) Kiessler. Conidia of the fungus are obclavate, dark, muriform and measured 30–75  15–25 μm in size. Alternaria tenuis Nees is also recorded as fruit rot causing fungus of cucumber and ridge gourd. The fungus causes round, pale brown lesions on fruits (Laxminarayana and Reddy 1976). Disease Cycle This pathogen hardly ever attacks young, vigorously growing plants. They live from one season to the next in infected crop debris and wild cucurbits (Sahu Kritagyan and Singh 1980). Epidemiology The pathogen, Alternaria alternata grow satisfactorily on PDA medium at temperatures between 5  C and 40  C and spore germination occurs in the range less than 10  C to over 37  C. Optimum temperature in both cases is near about 26  C (Vakalounakis and Malathrakis 1988). Management There are some chemical and non-chemical control measures, which may help to reduce the disease incidence. • A single post-harvest water dip of 20 min at 48  C will reduce the incidence of alternaria fruit spot (Nishijima 1993). • Spraying of chlorothalonil 75% WP or mancozeb 75% WP once every two weeks can reduce the disease by about 50%. However, an orchard spray program alone does not provide adequate economic control necessary for surface shipment to export markets. The water dip will be helpful for reducing the incidence (Nishijima 1993). • In greenhouse condition, Iprodione 50% WP at 0.1%, prochloraz-manganesecomplex, chlorothalonil 75% WP at 0.2%, dichlofluanid, guazatine, maneb and etem were reported to be effective for controlling the disease caused by A. alternate (Vakalounakis and Malathrakis 1988).

1.4.2 Rhizoctonia Fruit Rot The disease was recorded by Som and Bandyopadhyay (1981) during kharif season of 1979 in a pointed gourd field of Bangaon sub-division, West Bengal where jute was cultivated previously. The loss was estimated to be 20–25% (Khatua and Saha 2004). Fruit rot of bitter gourd was also recorded by Vyas and Panwar (1976). The disease is also known as belly rot mainly affects cucumber and rarely some other cucurbits (Seebold 2010b).

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Symptom The disease appears as yellowish orange discolouration on the skin of green pointed gourd fruit, which later changes to light brown water-soaked spots spread on the fruit surface that become necrotic. These spots enlarge and gradually cover whole fruit, which ultimately rots and shrivels with the loss of moisture. The affected tissue becomes hard and dotted with sclerotia of the pathogen. The pulp of the fruits becomes brown to black along with mycelial growth and formation of sclerotia. The fungus does not produces any pycnidia on fruit pulp (Som and Bandyopadhyay 1981; Khatua and Saha 2004). Vyas and Panwar (1976) recorded light brown, watersoaked spots on bitter gourd due to the disease. Laxminarayana and Reddy (1976) observed characteristics discoloured, water-soaked spots on cucumber. Whereas drying of fruit followed by rotting of rind and sponginess of pulp on pumpkin was noticed by Gangopadhyay and Sharma (1976). The fungus also causes belly rot of cucumber. Belly rot is hardly found on other cucurbits. This type of rot develops on the fruits come into contact with soil. Yellowish brown, superficial discolouration appear on young infected fruit, which become sunken irregular spots on the underside or ‘belly’. Large water-soaked decayed areas may develop on mature fruit (Seebold 2010b). The Pathogen Som and Bandyopadhyay (1981) identified the causal pathogen of fruit rot of pointed gourd as Rhizoctonia bataticola (Taub.) Butler. Similar findings were also furnished by Khatua and Saha (2004). While, Rhizoctonia solani Kuhnas causal pathogen for fruit rot of different cucurbits, viz. bitter gourd, cucumber and pumpkin was mentioned by many scientists (Vyas and Panwar 1976; Laxminarayana and Reddy 1976; Gangopadhyay and Sharma 1976). R. solani is responsible for causing belly rot of cucumber and some other cucurbits (Seebold 2010b). Superficial, dull white coloured, irregular and small sclerotia appears on the hosts that become dark brown in time. This is accompanied by thin, superficial, dark coloured, abundantly branched stout mycelium. The matured sclerotia are near about 100 μm in diameter. The hyphae are septate and present both inter- and intracellularly in the host tissue. In artificial medium, young colonies of the fungus are white which turn dull white having brown shade with age. Mycelium is stout and septate. Sclerotia are brown in colour. The septa are typical dolipore type. The lateral branches are at 90 angles to the main hyphae and here is a cross-wall, and invariably constricted at the point of origin and septum occurs in the branch near the junction with main axis. Branching almost invariably occurs near the distal septum of the cell in the young advancing hyphae but at any point in older hyphae. Disease Cycle The pathogen is soil borne and also survives in infected crop debrisas mycelium and sclerotia. The fungus is capable of growing saprophytically on dead organic matter in the soil. It has wide host range infects jute, potato, brinjal, tobacco, etc. The

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infected fruits bear sclerotia that are resting structure of the fungus, disseminated through irrigation water, splashing rains, movement of soils or many other human activities from infected plant or field to another. With receiving sufficient moisture and temperature the sclerotia germinate to infect healthy fruits. Warm temperatures, high humidity and excessive moisture favour infection and disease development. Under favourable conditions, symptoms can become evident within 24 h of infection and entire fruits may decay in 72 h (Seebold 2010b). Epidemiology The fungus favours warm soil temperatures 12–32  C for growth and infection. Moderate to high soil moisture favours growth of the fungus and development of the disease. Management The disease can be controlled by employing the following methods: • Deep ploughing of soil before sowing is essential to minimize the disease. • Collection and proper destruction of infected fruits from the fields is most important to reduce the disease incidence. • The disease can be avoided by crop rotation with non-host crops. • Proper fertilizer management is necessary to reduce disease incidence. • Drip irrigation is better than flood irrigation to restrict the spread of the disease inoculum. • No effective biological control strategies have been developed for Rhizoctonia fruit rot. But, soil amendment with green organic manure along with Trichoderma viride can reduce disease inoculum considerably in soil. • Black plastic mulch or straw mulch can be used as physical barrier between the fruit and the soil. Staking or scaffolding can be done instead of mulch materials. Varieties highly susceptible to Rhizoctonia fruit rot should be avoided, especially if plastic mulch is not used. • Recommended fungicides (carbendazim 50% WP at 0.1%, ziram 27% SC at 0.3%, chlorothalonil 75% WP at 0.2%, Oxycarboxin 20% EC at 0.15% or Validamycin 3% L at 0.2%) can be applied to protect the crop from the infection of the pathogen.

1.4.3 Fusarium Fruit Rot Fruit rot is a very common problem of cucurbits caused by a number of Fusarium spp. The disease is particularly devastating on pumpkin. Decay of fruits can occur in the field or in storage condition after harvest (Seebold 2010b). Fruit rot of pointed gourd have been observed to be most serious problem in Ganga-diara area of Bihar, which causes approximately 15% loss (Kritgyan and Singh 1980). Nevertheless, the extent of affected fruits and fruit dropping due to Fusarium were invariably associated with varieties and different agroclimatic condition of Ganga-diara area (Khatua and Saha 2004).

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Symptom The first indications of the disease under field condition are water-soaked patches on fruits. The skin of the infected portion becomes soft and succulent, resulting in disintegration of tissues. Slight swelling of skin around the infection court surrounds the brownish spots. In advanced stages of disease development, the fungus produces white growth on the yellowish brown affected region. The fruit loses turgidity, becomes yellowish and that infected fruit rot entirely without exudation. Discolouration of internal tissues and seeds occurs and the pulp turns into a light brown thick viscous fluid that gradually dry up. In certain cases, both end of the affected fruits become deep brown to black in colour. On splitting open, the affected fruits emit unpleasant odour (Kritgyan and Singh 1980; Khatua and Saha 2004). Appearance of brown dull spots on sponge gourd (Prasad and Ambasta 1987) and ash gourd (Upadhyay and Roy 1987) are important characteristics symptoms for infection of the fungal plant pathogen, Fusarium. Similar type symptoms on tinda was observed by Mathur and Mathur (1958) and Kore and Kharwade (1987). Gangopadhyay and Sharma (1976) recorded drying of fruit followed by rotting of rind and sponginess of pulp on pumpkin due to the disease. The Pathogen Several species of Fusarium are known to cause fruit decay in cucurbits (Seebold 2010b). The pathogen causing fruit rot of pointed gourd and sponge gourd is Fusarium equiseti (Corda) Sacc. (Kritgyan and Singh 1980; Khatua and Saha 2004; Prasad and Ambasta 1987). Upadhyay and Roy (1987) observed Fusarium solani (Mart.) Appel & Wr. and F. moniliforme Sheld. as fruit rotting pathogen of ash gourd, whereas, Fusarium oxysporum Schlecht. emend. Snyder & Hansen was recorded as fruit rot causing fungus of pumpkin and tinda by many scientists working in this field (Gangopadhyay and Sharma 1976; Mathur and Mathur 1958; Kore and Kharwade 1987). Culture of the fungi, when first isolated are white with a floccose white mycelium tinged with peach but after 7–10 days it changes to beige and finally deep olive buff. From below the initial peach colour it changes to vinaceous fawn and finally dark brown. Only macroconidia are produced; these developed sparsely at first from simple lateral phialides but production increased with the formation of compact penicillately branched conidiophores after about 10 days. Conidia are falcate, with a well-developed pedicellate foot cell and an attenuated apical call which curves inwards. Mature conidia have 4–7 thin but distinct septa and measure 22–60  3.5–5.9 μm. Chlamydospores are intercalary, solitary, in chains or knots, globose, 7–9 μm in diameter (CMI description of pathogenic fungi and bacteria No. 571, 1978; Khatua and Saha 2004). Disease Cycle The pathogen is soil borne and overwinter as mycelium in plant debris or as thickwalled chlamydospores (Seebold 2010b). The chlamydospores can survive in soil for a long period. The pathogen can also survive in infected plant debris

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saprophytically. The disease inoculum disseminates through irrigation water, splashing rains, movement of soils or many other human activities from infected plant or field to another. Infection generally occurs through wounds. Epidemiology The disease is favoured by high soil moisture with poor drainage condition. The disease incidence is more in light soils (sandy and sandy-loam) than heavy soils (clay and clay-loam). Management A holistic management approach should be taken to minimize the disease incidence. • Crop rotation with non-host crops for several years reduces the disease intensity (Seebold 2010b). • Physical barriers can be provided to minimize contact of the fruit with soil (Seebold 2010b). • Proper field sanitation, i.e. removal and destruction of affected fruits from the field. • Management of irrigation to restrict the dissemination of pathogenic inoculum. • Use of antagonistic microorganism in soil like Trichoderma harzianum or T. viride can reduce the inoculum load from the soil. • Proper curing of fruits should be done (Seebold 2010b). • Carefully handling of fruits is important during harvest to avoid wounding (Seebold 2010b). • Spraying of fungicides (mancozeb, metalaxyl+mancozeb, cymoxanil+mancozeb, etc.) used for controlling of fruit and vine rot disease will check the disease successfully (Khatua and Saha 2004).

1.4.4 Pythium Fruit Rot or Cottony Leak Disease One of the important and very common diseases of cucurbits in India is fruit rot incited by Pythium spp. (Mitra and Subramanian 1928). The disease is differently known as blossom end rot (Sohi et al. 1976) and cottony leak (Singh and Chohan 1977). It occurs in almost every locality and field during the rainy season (July to August). In Punjab, 50% or even more fruits of muskmelon and watermelon occasionally rot after rains because of cottony leak (Singh and Chohan 1977). In Karnataka, the disease affects nearly all of the cucurbits; however, it is a major problem in bottle gourd. The disease has reported to occurs on sponge gourd, snake gourd, pointed gourd, cucumber, squash, bottle gourd and bitter gourd. Fruits not only affected at field condition but also during transit and in storage. Symptoms The disease appears as luxuriant cottony mycelial growth on the affected fruits which looks like wrapped in cotton. The fruits in contact with soil suffer most. The first noticeable symptom observed on fruits surface as small, water-soaked lesions, which gradually turn dark green and develop into a watery soft rot. Under

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humid atmospheric condition, the diseased tissues are covered by a profuse, whitish, fluffy mycelial growth. In certain cases, the whole fruit surface may be covered by mycelial growth. In watermelon, the decay often starts at the blossom end and progress towards stem and cover the entire tip region. On the margin of the cottony growth the skin of fruit looks dark green and water soaked. The area, which is without any aerial growth of the fungus, indicates the 'killing in advance' activity of the pathogen. The tissues in the interior of the fruit become watery, turns brownish and soft, and the decaying matter emits a bad odour. The disease is common in the field where the fruit lying on the ground or hangs near the soil level. The disease also spreads during transit and storage. On the fruits, infection generally occurs when there is some injury to the skin, by soil particles, excess wetness around fruits, or insect bites or injuries during intercultural operation. General symptoms of cottony leak of cucurbits were clearly described by Seebold (2010b). Chattopadhyay and Sengupta (1952) and Saha et al. (2002) recorded detail symptoms of the disease on pointed gourd. The Pathogen Several species of Pythium are associated with the disease. The causal organism is a fungus-like soil borne plant pathogen. Pythium butleri Subramaniamand P. aphanidermatum(Edson) Fitzp. are commonly associated with the fruit rot of cucurbits in Karnataka (Mitra and Subramanian 1928; Singh and Chohan 1977; Sohi et al. 1976), whereas P. debaryanum Hesse, P. ultimum Trow and many other fungi/ fungus-like organisms (viz. Fusarium spp., Rhizoctonia spp., Phytophthora spp. and Sclerotium rolfsii Sacc.) also cause the disease either singly or in association. The mycelium of the P. aphanidermatum consists of intracellular, much branched hyphae. The hyphae measure 2.8–7.5 μm, mostly 4.0–6.0 μm in diameter, produce much lobbed, branched sporangia, which may be less than 50–100 μm in length. Oogonia are spherical smooth walled, terminal on lateral hyphae, 19–29 μm in diameter. Oospores are aplerotic, single, with moderately thick wall and 17–19 μm in diameter (Gupta et al. 2001). Disease Cycle The pathogen, Pythium spp. survive in soil for long duration by means of oospore. The organism can live in soil in short time period through dormant mycelium, sporangia or zoospores, and also survives in wild cucurbit crops and several other weeds in absence of main hosts. Infected crop debris or decaying plant materials are the important sources of inoculum. These are the primary sources of inoculum. Survival by resting structures is more important than saprophytic persistence. In favourable weather conditions, oospores germinate to produce zoospores that disseminate rapidly in field in presence of high soil moisture and initiate infection to the host. The disease can be disseminated by infected transplant, rain and irrigation water, rain splashed soil, movement of soil, agricultural implements and through many other human activities (Mehrotra 1980; Singh 1987; Chattopadhyay and

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Mustafee 2008; Seebold 2010b). Infection usually occurs through wounds or where the fruit touches the wet ground (Seebold 2010b). Epidemiology Pythium aphanidermatum cause severe damage in hot and humid condition. Abundance of moisture and high temperature is very much congenial for disease development. Tender fruits are more susceptible than the mature fruits. Injury in fruit surface and excessive wetness around fruits favours easy entry of the pathogen into the hosts. The pathogen grows well at a temperature range of 15–40  C, with optimum growth at 30–35  C and 100% relative humidity (Sohi and Sharma 1998). Pythium butleri grows best between 30 and 35  C. Desai and Pathak (1969) reported that 30  C temperature is the optimum for fruit rot of cucurbits caused by P. butleri. Management Though some of the cucurbit fruits consumed directly, it is not always advisable to recommend application of fungicides to prevent infection of fruits. • The disease may be checked by removing of previous year crop residue from the field. • Field should not be in shady place. Availability of sunlight throughout the day reduced disease incidence. • Physical disinfection of field soil through summer ploughing and soil solarization (if possible) is an important practice to minimize the disease. • In greenhouse condition, the disease causing pathogens can be eliminated by heating of soil. The common methods used for heating are steam treatment and pasteurization. • Soil disinfection with fungicides is uneconomical. But, soil inoculation with bio-antagonists (viz. Trichoderma viride or Pseudomonas fluorescens) at 8 kg/ ha through well decomposed organic manure before sowing is efficacious. • Crop rotation is an important practice but due to its wide host range, this practice is not help much for managing the disease. • By changing the method of cucurbit cultivation like use of mulching or scaffolding can keep the fruits from contact with the soil that can reduce the chance of infection. • Use of fungicidal seed protectants (like Thiram 75% WP, Copper Oxychloride 50% WP, Mancozeb 75% WP or Metalaxyl 35% WP at 3–4 g/kg seed) depending upon the pathogen associated with the fruit rot or bio-inoculation of seed with Trichoderma viride and Azotobacter chroococum provides some sorts of protection against the disease. • Proper spacing should be maintained to allow vigorous growth of the plants. It is better to avoid overwatering. Light but frequent irrigation is essential. Careful irrigation management is important; drip irrigation is more effective than other method of irrigation.

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• Hygienic transportation and rage storage method may be employed to avoid the fruit rot disease.

1.4.5 Charcoal Rot of Fruits This is an important fungal disease of cucurbit vegetables. The disease occurs all over India wherever cucurbits are grown. Symptom The fungal pathogen attacks roots, stems and also fruits touching the soil. Initially symptom appears as slightly sunken, rose-coloured areas on fruits. In advancement of the disease, the entire fruits are affected. The surface of the fruit becomes dark brown or black encrusted with sclerotia. The flesh becomes black and densely impregnated with sclerotia. In advanced stages, the flesh turns characteristic charcoal. Infected seeds turn ash-grey and encrusted with sclerotia. On seedlings black coloured sunken cankers in a concentric ring pattern may appear on the hypocotyls at the time of emergence. The developing canker stunts the plant, and wilt. On older plants the crown leaves and runners may turn yellow after infection and eventually die. Characteristically, a water-soaked lesion will girdle the vine at the soil level and extend several centimetres up to the stem. Amber-coloured droplets may form in the affected part. Within a few days the lesion dries up and turns into light tan in colour (Gour et al. 2008). The Pathogen Jhooty and Singh (1971) identified Macrophomina phaseolina (Tassi) Goid. (¼Macrophomina phaseoli (Maubl.) Ashby) as the pathogen of charcoal rot produces dark brown to black lesions on muskmelon. Rao (1964, 1965) recorded same pathogens a causal agent of charcoal rot of ridge gourd and watermelon. The pathogen also infects pointed gourd (Chowdhury 1998). The mycelium of Macrophomina phaseolina is superficial or immersed, hyaline to brown, branched and septate. The pycnidial stage is uncommon but abundant on infected jute and field beans. In cultures, sclerotia are most common. Sclerotia are also formed on the infected host surface. The sclerotia are brownish-black, smooth, hard, round to oblong or irregular, variable in size approximately 100 μm to 1 mm in diameter. Pycnidia are more or less globose, membranous, or subcarbonaceous, dark brown, solitary or gregarious, immersed or erumpent, measure about 100–200 μm in diameter, and open by a small ostiole. Conidiophores develop from cells of the inner wall of the pycnidium. The conidia are cut off at the tip of the conidiophores. Conidia are hyaline, ellipsoid to obovoid and 14–30 μm  5–10 μm in size (Singh 1987). Disease Cycle The disease is soil borne. Sclerotia of the fungus survive in soil freely or embedded in host tissues. The fungus can overwinter in infected weeds or plant debris (Gour et al. 2008). Survival is longer in dead host tissues than in free condition in soil. Dry

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soil is better for sclrotial survival than wet soil. In wet soil, sclerotia and mycelium of the fungus survive not more than 7–8 weeks and 7 days, respectively. The pathogen is poor competitor in soil but readily colonizes plant debris. Population of the fungus increases in the field due to continuous culturing of the susceptible hosts. Infected transplants are also important sources of inoculum in the field. Sclerotial movement occurs in field through irrigation water, implements used for intercultural operation and other human activities (Singh 1987). Epidemiology The fungus favours dry condition with high temperature. The disease is not common in low temperature even though the fungus can grow. The disease appears in the field when the soil temperature rises to 28–35  C. Though the irrigation water helps to sclerotial dissemination in the field but due to lowering down the soil temperature sclerotia lose its capability to infect the host immediately. Gour et al. (2008) reported that the disease is favoured by high temperatures in moderately wet soil. Moisture and salt stress can predispose plants for infection. Management This is a minor disease and not common in cooler part of the world. It can be minimized by the following ways. • Disease free transplants should be used. Seeds/transplants should be treated with protectant fungicide like carbendazim 50% WP or carboxin 37.5 + thiram 37.5 % WP at 2 g/kg or bio-inoculation with Trichoderma viride at 4–6 g/kg to check the sclerotial dissemination and germination. • Removal and destruction of the affected fruits and plant parts from the field is helpful for reducing the disease incidence. • Soil temperature should be bringing down through irrigation water as per requirement to check the sclerotial infectivity and germination. • The incidence of the disease can be reduced by avoiding moisture stress and maintaining plants in good nutritional conditions (Gour et al. 2008).

1.4.6 Other Fruit Rotting Fungi A large number of fungi were reported as causal pathogens of fruit rot of cucurbits due to their succulent nature and direct contact with soil. Any one of them may become serious in congenial condition on particular hosts. Some of the fruit rot causing fungi of cucurbits are mentioned below: • Choanephora cucurbitarum (Berk. and Ravenel) Thaxt.: This is an important fruit rot causing fungus of cucurbit vegetables reported by Sohi and Sharma (1998). Choanephora fruit rot is usually observed on summer squash, but it may also affect cucumber and pumpkin. Symptoms commence as a soft, wet rot of flowers and the blossom end of fruit. Infected fruits decay rapidly, becoming soft and watery. A profuse, fuzzy fungal growth with large masses of black spores forms on infected tissues. The pathogen’s distinctive appearance (like

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• • • • •

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numerous small black headed pins sticking out of a pincushion) is diagnostic for this disease (Seebold 2010b). There are no effective available control measures for the disease. Fungicides (like copper fungicides, i.e. copper oxychloride 50% WP at 4 g/l or copper hydroxide 77% WP at 2.5 g/l) may reduce disease incidence; however, it can be difficult to protect developing blossoms throughout the season. Practices that reduce leaf wetness can be of beneficial. By avoiding overhead irrigation or time of overhead watering to allow for leaf drying (Seebold 2010b). Diplodia natalensis Pole-Evans: Sohi and Sharma (1998) also observed this fungus from rotten fruits of different cucurbits. Diplodia gossypina Ellis and Everh.: This fungus causes rotting of cucurbit fruits with production of characteristic symptoms (Sohi and Sharma 1998). Myrothecium roridum Tode: Vyas and Panwar (1976) recorded small, circular, olive-green patches due to the infection of the fungus on bitter gourd. M. roridum also causes dark brown patches on cucumber in favourable weather condition (Laxminarayana and Reddy 1976). Circular, necrotic lesions on muskmelon incited by this pathogen were also reported by Singh (1986). Helminthosporium hawaiiense Bugnic.: The fungus produces pale brown depression on cucumber (Laxminarayana and Reddy 1976). Rhizopus sp.: Dalela (1956) recorded this as soft-rotting fungi of pumpkin, whereas Rangaswami and Mahadevan (2004) described this pathogen as dry rot causing fungi. Phoma sp.: The fungus produces circular spots on fruits of ridge gourd (Laxminarayana and Reddy 1976). Cladosporium tenuissimum Cooke: On watermelon, water soaked, brown discolouration due to infection of this pathogen was reported by Narain et al. (1985). Cladosporium cucumerinum Ek and Arth.: This fungal pathogen causes scab disease of cucumber, which is prevalent in subtropical and temperate countries. The disease also appears on muskmelon, pumpkin and squash. Small, sunken spots develop on fruit; lesions may be covered with an olive-green mass of spores. While leaves and stems can be affected, the greatest losses occur when fruit are infected. Secondary pathogens may invade lesions, leading to fruit rot. The pathogen, Cladosporium cucumerinum, overwinters in cucurbit vines left in the field or garden, and in seeds. Spores produced by the fungus can spread through air currents to susceptible tissues. Wet conditions, including fogs and dews, along with moderate to cool temperatures, favour this disease (Seebold 2010b). The pathogen is virulent in cool growing seasons accompanied by intense fog and dew. Low night temperature is favourable for spread of the pathogen and development of the disease. Resistant varieties developed against the disease are Highmoor and Wisconsin SMR-15 (Seshadri 1986). Sowing of pathogen-free seeds, seed treatment, proper crop rotation practice and application of recommended fungicides are some important management options for the disease (Seebold 2010b). Colletotrichum capsici (Syd.) Butler and Bisby: Irregular discolouration occurs due to the infection of the pathogen (Laxminarayana and Reddy 1976).

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• Curvularia pallescens Boedijn: This fungus causes style end rot of cucurbits, and circular brown spots appear on the fruit surface (Laxminarayana and Reddy 1976). • Sclerotium rolfsii Sacc.: This fungus causes soft rot on ridge gourd (Laxminarayana and Reddy 1976). Siddaramaiah et al. (1982) found that the fungi Sclerotium rolfsii is responsible for causing soft rot of pumpkin that develop water-soaked areas on the fruits. • Erwinia spp.: This fungus causes soft rot of cucurbits. Little work has been done on the fruit rot disease caused by the above mentioned pathogens, so that the detail symptoms of such diseases are not available.

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Bacterial Diseases of Cucurbits

Cucurbit vegetables suffer from lots of bacterial diseases which cause mild to severe damage to the crops. Some of the important bacterial diseases of cucurbits are presented in Table 3.

2.1

Angular Leaf Spot

This bacterial disease primarily affects cucumber, but it may occur on muskmelon, squash, pumpkin, watermelon and other cucurbit plants. The disease is very common and destructive in cooler regions of cucurbits growing tracts. Mukherjee and Khatua (1998) reported that the disease is common in West Bengal condition. Table 3 Diseases caused by the bacteria including phytoplasma Sl. no. 1.

Name of the disease Angular leaf spot

2.

Bacterial wilt

3. 4.

Bacterial leaf spot Bacterial soft rot

5. 6. 7.

Brown spot Bacterial rind necrosis Bacterial fruit blotch/ seedling blight Phyllody Witches’ broom Little leaf

8. 9. 10.

Causal organism Pseudomonas syringae pv. lachrymans (Smith & Bryan) Young et al. Erwinia tracheiphila (Smith) Bergey et al. Ralstonia solanacearum (Smith) Yabuuchi et al. Xanthomonas campestris pv. cucurbitae (Bryan) Dye Erwinia carotovora subsp. carotovora (Jones) Bergey et al., E. aroideae (Townsend) Holland, Pectobacterium carotovorum subsp. brasiliense Nabhan et al. Erwinia ananas Serrano Erwinia spp. Acidovorax avenae subsp. citrulli (Schaad et al.) Willems et al. (¼ Pseudomonas pseudoalcaligenes subsp. citrulli) Phytoplasma Phytoplasma Phytoplasma

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Symptoms The disease occurs on most of the above ground parts like leaves, young green stems and fruits. The disease appears on the leaves as small water-soaked spots. The shape of older lesions tends to be irregular or angular as they enlarge and encounter veins. Under humid weather conditions, whitish bacterial ooze in the form of droplets may be found on the infected areas. It dries to form white crusts. The spots enlarge and become brown. Afterward, the tissues dry up and may fall off leaving irregular holes in the leaf. Water-soaked necrotic spots can also be developed on stems and fruits. On fruits, the spots are much smaller and nearly circular that may dry up and the tissues become white and crack. The fruit lesions are superficial but cracking may expose the fruit to the secondary attack of soft-rotting bacteria. The bacteria may move deep into the fruit and infect the seeds. The Pathogen Angular leaf spot is caused by Pseudomonas syringae pv. lachrymans (Smith & Bryan) Young et al. The bacterium was previously known as Pseudomonas lachrymans (Smith and Bryan) Carsner. The bacterium is rod shaped, aerobic, gram negative, motile and having more than one polar flagella. In iron deficient culture medium, the bacterium produces a diffusible yellow-green pigment. The bacterium produces slime in media containing 2–5% sucrose, does not hydrolyse starch, but utilizes pectate gel at pH 4.6–8.5. This bacterium does not reduce nitrate. Disease Cycle The bacterium can overwinter in seed and on infected plant parts left in the field. Seeds from diseased fruits carry the bacterium in the seed coat. Cotyledons are invaded after germination of the seed. The pathogen is disseminated by splashing rain, wind-blown rain, wind-blown soil, insects, farm equipment and field workers. Infection occurs through natural openings mainly stomata and wounds. Epidemiology The disease is favoured by warm temperatures (24–26  C), high humidity and rain. Optimum temperature for growth of the pathogen is 25–30  C but unable to grow at 41  C. Management Pathogen-free seed should be used to avoid the disease. It is better to obtain seeds from the crops grown in dry areas. • Hot water treatment can be done for cucumber seed. • Crop rotation with non-hosts for at least 2 years is helpful for managing the disease. • Management of irrigation systems is important to minimize leaf wetness and soil splash. Overhead irrigation should be avoided. • Intercultural operations and other works should avoid in the fields when plants are in wet situation.

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• Proper ventilation facility is important in managing this disease in greenhouse production. • Resistant varieties are important to avoid the disease. • Applications of copper based fungicides (Copper oxychloride 50% WP at 0.4% or Copper hydroxide 77% WP at 0.25%) may help protect plants when conditions are favourable for the disease. Copper based fungicides are not effective if epidemic have already been started. Spraying of Streptocycline 90:10 SP at 100 ppm reduce the spread of the disease in the field.

2.2

Bacterial Leaf Spot

Bacterial leaf spot is a serious disease that causes considerable damage to the cucurbit vegetables, especially cucumber. It is totally distinct from angular leaf spot disease and was reported from India as early as in 1931 (Singh 1987). The disease of pumpkin was also reported by Lamichhane et al. in the year 2010 and 2011 from Nepal with low incidence. They recorded 12% average yield loss of pumpkin. Symptoms The disease primarily appears as small, water-soaked areas on the under surface of the leaves. The upper surface of these areas of leaves looks yellow. The spots are inter-veinal in nature. In time, the spots emerge and become angular. The colour of the spots changes to brown. The spots are surrounded by a chlorotic halo. Several spots may coalesce to form larger spots. Afterward, the tissues dry up. Occasionally young stems and petioles are also attacked. On stems and petioles, the lesions are linear or streak like and brown in colour. The Pathogen The disease is caused by a gram-negative, rod shaped, flagellate (single polar flagellum) bacterium, Xanthomonas cucurbitae (ex Bryan) Vauterin et al. (¼Xanthomonas compestris var. cucurbitae (Bryan) Dye). The colonies on beef agar are mustard-yellow. Disease Cycle The bacterium is seed borne and also perenates in diseased crop debris. The diseased fruits carry the bacterium in the seed coat, i.e. seed infection occurs internally in the seed coat. After germination of the seed, cotyledons are infected. The pathogen is disseminated by splashing rain, wind-blown rain, wind-blown soil, insects, farm equipment and field workers. Infection occurs through natural openings mainly stomata and wounds like that of angular leaf spot of cucurbits. Epidemiology Optimum temperature for growth of the bacterium is 25–30  C and maximum temperature is 35  C. The thermal death point is 50  C.

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Management • To kill the bacterium in the seeds, hot water treatment (50  C for 30 min) is recommended. Care should be taken for this practice; otherwise germination percentage of the seed may be reduced. • It is better to obtain seed grown in dry areas. • Spraying copper fungicides reduces the spread of the disease in the field. Spraying of copper fungicides (Copper oxychloride 50% WP at 0.4% or Copper hydroxide 77% WP at 0.25%) or antibiotic like streptocycline 90:10 SP at 100 ppm reduce the spread of the disease in the field.

2.3

Bacterial Wilt

Bacterial wilt of cucurbits was first studied by E. F. Smith, caused by Erwinia tracheiphila (Smith) Bergey et al., is a devastating disease occurs worldwide including the USA, Europe, South Africa and Japan (Mehrotra 1980). In India, the disease is common in Haryana, Punjab, West Bengal, Assam, Orissa and Maharashtra (Mustafee 1998). Incidence of the disease in sweet gourd, watermelon and bottle gourd is rare in West Bengal condition (Mukherjee and Khatua 1998). Many species of the family Cucurbitaceae, i.e. cucumber, muskmelon, squash and pumpkin are reported to be infected by the disease. This pathogen can cause severe losses in cucumbers and muskmelons, while squash and pumpkins are less affected. Watermelon is not affected by the disease. The severity of the disease varies from occasional wilted plant to destruction of 75–95% of the crop. Bacterial wilt of bottle gourd (Lagenaria siceraria (Molina) Standl caused by a bacterium, Ralstonia solanacearum (Smith) Yabuuchi et al. was recorded from West Bengal (India) by Mondal et al. (2004, 2011, 2014a) with very low disease incidence (4.50%). Recently, bitter gourd (Momordica charantia L.) and ridge gourd (Luffa acutangula (L.) Roxb.) were also recorded from Kerala and West Bengal as hosts of R. solanacearum (Mathew et al. 2002; Mondal et al. 2016). Symptoms The disease produces two types of symptoms —(1) Sudden wilting of foliage and vines of the affected plant in field condition (2) Slime rot of squash fruit in storage condition. In the first case, symptom appears as drooping of one or more leaves of the vines with dull green appearance, and consequently, the infected plant shows wilting of all leaves and collapse of all vines. Wilted leaves of the affected plant shrink and dry up; affected stems primarily become soft and pale, but later shrink and become hard and dry. Wilt progresses down the vine until entire vine is wilted. In moderately resistant plants or under adverse situation, symptom progress slowly and may rarely be accompanied by excessive blooming and branching of the infected plants. Wilt progression varies by crop. Cucumber and melon wilt and die rapidly, whereas pumpkin takes up to 2 weeks to wilt completely. Summer squash may continue to produce wilting symptom several weeks after infection.

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If infected stems are cut and pressed between the fingers, droplets of white bacterial ooze appear on the cut surface. If infected vines are cut close to the crown of the plant and the cross sections pressed together, thread like strands of bacterial ooze can be seen when the two halves are gently pulled apart again. Measures have to be taken observing the presence of striped or spotted cucumber beetles in the field that are actually acts as vector. In case of the slime rot of stored squash fruit, the disease progress internally whereas the outer surface of the fruit may appear normal. In time, dark spots or blotches appear on the surface of the squash, which later coalesce and enlarge. The disease develops over several months in storage. These squash fruits may be infected secondarily by other soft-rotting microorganisms and are smashed entirely. The Pathogen The disease caused by Erwinia tracheiphila is a gram-negative, rod shaped, flagellate (peritrichous) bacterium. Ralstonia (¼Pseudomonas) solanacearum is also a gram-negative, rod shaped, flagellate bacterium. Disease Cycle The bacterium survives for only a few weeks in infected plant debris and also in weeds without producing any visible symptoms. The bacterium overwinter (hybernates) in the intestines of striped cucumber beetles, Acalymma vittata (F.) and spotted cucumber beetles, Diabrotica undecimpunctata Mannerheim which are actually responsible for transmission of the bacterium. During spring, the cucumber beetles that carry bacteria feed and cause leaves injury and deposit bacteria in the injury with their faeces. The bacteria enter the xylem vessels, multiply rapidly and spread to different parts of the plant. Obstruction of the xylem vessels of infected plant occurs due to the rapid multiplication of the bacteria and their polysaccharides, deposition of gum and formation of tyloses in the xylem elements, which allow less than one-fifth of the normal water flow. This extensive plugging of the vessels is the primary cause of wilting. The bacteria are spread to the healthy plants through contaminated mouthparts of different insects particularly by the striped and spotted cucumber beetles. After one feeding on a wilted plant each contaminated insect can infect several healthy plants though a relatively small percentage of beetles become carriers of the bacteria. The first wilting symptom appears on the field at 6–7 days after infection, and another 7 days is required to wilt the plant completely. The bacteria present in the xylem vessels of infected plants die within 30–60 days after the dead plants dry up. Fruit infection of squash plants generally occurs through infected vines and rarely through beetles feeding on the blossoms and the rind of developing squash. Management • If the disease appears in a few plants, careful rogueing and burning of such plants are essential to prevent its further spread.

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• Monitoring of cucumber beetles during growing season followed by proper management practices through insecticides and others provides the most effective control of bacterial wilt (Kennelly 2012). • Bactericides/antibiotics or other pesticides will not facilitate much in managing cucurbit plants infected with this destructive bacterial disease. However, soil application of bleaching powder at 15 kg/ha at least 15 days before sowing along with spraying of streptocycline at 250 ppm reported being effective against the wilt caused by R. solanacearum. Phosphate solubilizing bacteria like Bacillus megaterium can also be applied in soil with organic manures. • To circumvent squash rot in storage, fruits only from healthy plants should be picked, and it should be stored in a clean, fumigated warehouse (Agrios 2000). • Cultivation of resistant cucurbit varieties is most important to avoid the disease. Varieties with less cucurbitacin show less damage. Presence of cucurbitacins stimulates cucumber beetles and rootworms to feed on cucurbits (Hoffman and Zitter 1994). • Attractant-baited traps and attracticidal baits are promising for control of cucumber beetles. Attracticidal baits are mixtures of a feeding stimulant (cucurbitacins) and a small amount of insecticide; some baits also include a mixture of volatile attractants. In theory, the cucurbitacins stimulate the beetles to feed, and the volatile attractant draws them to the bait. The biggest advantage of attracticidal baits is that the amount applied per acre is very small relative to a standard foliar application. Traps being developed could be used for early detection of infestations and possibly for control if several traps are used per field (Hoffman and Zitter 1994). • Only a few species of parasitoids (tachinid fly and braconid wasp) or insect pathogens have been observed affecting cucumber beetles and their impact is not well documented. The larvae are attacked by predacious nematodes. One species of soldier beetle is considered an important predator (Hoffman and Zitter 1994).

2.4

Bacterial Soft Rot

Soft rot is a common disease of cucurbits. Generally, fruits are affected by the disease. It occurs mainly due to injury to fruits in field condition and also in poor transit and storage conditions (Singh 1987). Nearly 20–30% yield losses of cucumber were recorded due to the outbreak of bacterial soft rot occurred in Shandong, Shanxi, Hebei, Henan and Liaoning provinces in China during 2014–2015 with an account of 15–50% disease incidence in field condition and 90% disease incidence in greenhouse condition (Meng et al. 2017). Bacterial stem soft rot of cucumber was first reported from China by Meng et al. in 2017. The disease has a significant economic impact on cucumber production. Symptoms Initially whitish, thick liquid gummy exude appear on the surface of the infected tissues (i.e. leaves, stems, petioles and fruit) of cucumber plants. Water-soaked areas

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also develop in the infected stems. The basal portion of the stem becomes dark brown and turned to wet rot. Yellow watery spots (wet rot) develop at the edge of the infected cucumber leaves that progress gradually to the leaf centres. Brown rot in the fruit surface is another characteristics symptoms of the disease. In advanced cases, longitudinal cracking in the infected stems appear gradually and produce soft rot symptoms (Meng et al. 2017). The Pathogen The bacteria that associated with soft rot of cucurbits are Erwinia carotovora subsp. carotovora and E. aroideae (Singh 1987). Meng et al. (2017) reported that the soft rot of cucumber is caused by Pectobacterium carotovorum subsp. brasiliense. The bacterium, Pectobacterium carotovorum subsp. brasiliense is able to grow at 28 and 37  C, can tolerate 5% NaCl and form pits on crystal violet pectate (CVP) media. It is a gram-negative and facultative anaerobic bacterium. The bacterium can metabolize a number of carbon sources. The pathogen can produce acid from α-methyl glucoside, glucose and maltose and utilize acetic acid, acetic acid, cellobiose, d-melibiose, d-sorbitol, succinamic acid and thymidine (Duarte et al. 2004; van der Merwe et al. 2010; Meng et al. 2017). The soft rot symptoms develop on the stems of cucumber seedling at 24 h after inoculation, and on fruit and leaves at 4 days after inoculation. The bacterium causes soft rot in species of Brassicaceae (Chinese cabbage, mustard, broccoli, radish and cabbage), Solanaceae (green pepper, tomato and potato), spinach, celery and most Cucurbitaceae (cucumber, zucchini and watermelon) on artificial inoculation. The bacterium unable to infect balsam pear and luffa under Cucurbitaceae family (Meng et al. 2017). Management • The walls and floors of storage warehouses should be disinfected with either formaldehyde or copper sulphate. Injury to plant tissues should be avoided as much as possible, and the humidity and temperature of the storage facility should be kept low using an adequate ventilation system. These are some important practices for reducing the storage soft rot. • Sanitary growing practices should be adopted. Removal and destruction of plant debris from the field reduce the chances of infection. • The crop should be planted in well-drained soils maintaining proper spacing, which will help for adequate ventilation between plants. • Some varieties are resistant to the disease but none are immune. Resistant varieties can be used to protect the crop from infection of the disease. • Crop rotation is an important practice to avoid the disease. Rotating susceptible plants with non-susceptible ones like cereals can limit soft rot infection.

2.5

Bacterial Rind Necrosis

Bacterial rind necrosis is an important disease of watermelon and melon. This disease has been reported from Hawaii, Texas, Florida and California in watermelon and in melon in Texas.

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Symptoms The infected rind of watermelon (Citrulus vulgaris) exhibits small (0.3–1.0 cm) localized water-soaked necrotic spots; or larger greyish-brown, corky, quite hard necrotic spots. Primarily the symptoms appear in the interior of the rind. There are rarely any external symptoms on watermelon. In the case of severe infection, the necrosis may extend around the entire rind as well as the edible part of the fruit. In this case the infected fruit may be misshapen. No foliage symptoms appear in the disease affected plant. In melon, the internal symptoms are similar to those in watermelon. But external symptoms also appear in the form of circular, dark, water-soaked depressions in the surface of the fruit. Severely infected fruit is either unmarketable or is sold at low prices (Kontaxis and Kurupas 1975). Symptomless infection was also recorded by Kontaxis and Kurupas (1975). The Pathogen Various bacterial pathogens, such as Erwinia spp., have been reported as the cause of this disease (Kontaxis and Kurupas 1975). Cause and Disease Development Little is known about the conditions favouring infection and disease development. The rind necrosis is incited by bacteria that are normally residents of the healthy host. Under some predisposing environmental conditions, these resident bacteria multiply to a population high enough to cause disease. Management • Susceptible cultivars should be replaced by less susceptible or resistant one. Some important resistant cultivars are Charleston Gray, Sweet Princess, Grayhoma and Crimson Sweet, whereas Blue Ribbon is a susceptible cultivar. • The fields that have the previous record of the disease should be avoided.

2.6

Bacterial Fruit Blotch of Watermelon

Bacterial fruit blotch is an important disease of watermelon, muskmelon and pumpkin. This is a relatively new but common disease of cucurbits in the USA. The disease was first reported in the Mariana Islands in 1988. It appeared in commercial watermelon fields in Florida in 1989 and in Illinois in 2001. It is a sporadic disease but under congenial environmental condition, the disease becomes severe and may cause 100% loss of marketable fruits. Symptoms The characteristic symptoms of the disease on the upper surface of the watermelon fruit is appearance of dark, grey-green stains or blotches. The blotch is first noticeable as a small water-soaked area (>0.500 diameter), which become enlarge rapidly within 7–10 days so that much of the fruit surface is covered by the lesion. As the blotch increases in size, the area around the initial infection site becomes necrotic. In

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advanced cases, the rind epidermis ruptures or cracks from where amber-coloured sticky oozing is common. Fruit lesions rarely extend into the flesh and contaminate the seeds. Secondary infection by other rotting organisms cause decay and collapse of the fruit. Rapid expansion of fruit lesions generally occurs during few weeks prior to harvest. Watermelon seedlings also infected by the pathogens producing dark, water-soaked lesions on the undersides of cotyledons. As the cotyledons expand, the lesions become necrotic and often extend along the length of the midrib. On young true leaves dark brown lesions develop, which may have chlorotic halos. Infected seedlings usually do not collapse and die, but foliar lesions will increase slowly in a warm, moist environment. Leaves are also infected. Leaf lesions are small, dark brown, somewhat angular and often inconspicuous. The severity of symptom expression on individual leaves is slight. Infection does not result in wilt, defoliation, vine blight or vine collapse. In wet or humid weather, lesion margins appear water soaked. The Pathogen The disease is caused by the bacterium Acidovorax citrulli Willems et al. (¼Acidovorax avenae subsp. citrulli). It is a gram-negative, biotrophic bacterium. Two distinct groups of the bacterium have been reported on the basis of carbon source utilization, DNA fingerprinting profiles, whole cell fatty-acid composition utilization and pathogenicity assays. The group I strains are mainly associated with non-watermelon plants, whereas group II includes strains associated with watermelon. Disease Cycle The pathogen is seed borne. Contaminated seeds give rise to infected seedlings, which serve as an important source of secondary inoculum. In the field, the rainsplashed bacteria from older lesions creates infection in newly developed leaves and neighbouring plants. Leaf lesions are important as a primary source of inoculum for fruit infection. Bacteria associated with infected rind, move down into the flesh and become associated with the seeds. The pathogen may overwinter in infested crop residue, volunteer watermelon plants, contaminated seeds and infected wild cucurbits that provide primary inoculum for the subsequent crop. Moist and warm conditions are favourable for development and spread of the disease. The pathogen can be spread by wind-driven rain and mechanical means. A few primary infection sites in a field may result in infection of all plants by the time of harvest. Management The strategies for management of bacterial fruit blotch of watermelon should focus on preventing the introduction of the pathogen into the field. The following practices can help to minimize the disease situation.

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• Collection and sowing of uncontaminated seeds should be practiced. Hot water and bleach treatments are not effective in eliminating the contamination from infested seed. • Disease free transplants can be planted to avoid the disease. • Careful handling of transplants is important to avoid contamination. Irrigation with an overhead boom (i.e. sprinkler irrigation) may result in splash dispersal of the pathogen. Drip irrigation is helpful to minimize the dissemination of the pathogenic. Decontamination of seedling trays can be done using 0.5% sodium hypochloride solution. • Removal and destruction of volunteer cucurbits seedlings are done to eliminate inoculum sources. • Elimination of wild cucurbit plants should be done in and around the production fields. • Three years crop rotation with non-cucurbitaceous crops in the infested fields is important to manage the disease. • The disease can be avoided by using resistant varieties. Most of available commercial watermelon cultivars are susceptible to the fruit blotch disease. • Two to three times application of copper fungicides at an interval of 15 days may reduce the incidence of fruit blotch symptoms. Application should begin at initiation of flowering or earlier, and continue until all fruit are mature. Application of copper fungicides may cause marginal yellowing of the foliage so care should be taken during spraying.

3

Diseases Caused by Phytoplasmas

Like other plant pathogens, phytoplasma is also one of the important pathogens causing considerable damage to the cucurbitaceous vegetables. The pathogen causes different kinds of diseases like phyllody, witches’ broom, little leaf, yellowing, etc. The symptoms produced by the pathogen is more or less similar to those produced by virus. Some of the diseases of cucurbits caused by phytoplasma are described below in brief.

3.1

Phyllody

Phyllody is one of the most important diseases of cucurbits. Phyllody of bitter gourd and bottle gourd is common around Jaipur, Rajasthan (Misra and Gupta 1988). Fluorescent microscopy indicated association of phytoplasma (previously known as MLO) with the disease. Chow-chow is also infected by a graft transmissible disease and common in Kalimpong district of West Bengal (Ahlawat and Kulshreshtha 1977), but involvement of insect vector for transmission of the disease and aetiology of the pathogen have not been determined (Verma and Giri 1998). The disease is characterized by shortening of internodes and various parts of the flower turn into leafy structures. Some plants bear cluster of phyllody flowers. The

3

Diseases Caused by Phytoplasmas

181

leaves of the infected plants are distorted. Infected plants remain stunted and usually do not bear fruits. The disease infects almost all cucurbit vegetables. Phytoplasmas are pleomorphic, small, rounded, large globular and branch filamentous, one or two to several microns in length and their average diameter is 0.3–0.8 μm.

3.2

Witches’ Broom

Witches’ broom of bitter gourd was first noticed around Bangalore (Singh 1985, 1992). The incidence of the disease varies from 20 to 60% (Verma and Giri 1998). The disease is characterized by chlorotic little leaves, virescence, phyllody and proliferation of axillary buds. The fruits of late infected plants are small, thin and cylindrical. Such fruits are unmarketable. The cultivar Coimbatore Long is very susceptible (Verma and Giri 1998). Plants infected at early stages show total loss of yield and, even in late infection, the yield losses are 30–50% (Singh 1985). The causal agent is suspected to be phytoplasma. It transmitted through graft, but not by mechanical inoculation, whitefly or aphids (Verma and Giri 1998).

3.3

Little Leaf

Phytoplasma association with witches’ broom disease of bitter gourd was first described in Taiwan, and the pathogen was identified through electron microscopy (Chou et al. 1976). Afterwards, a phyllody disease on bitter gourd caused by aster yellows phytoplasma was also reported and the causal agent was identified by RFLP analysis in Thailand (Spoodee et al. 1999). Montano et al. (2000) also reported a phytoplasma disease of bitter melon in Brazil. Yellowing of infected plants and reduction in size of leaves are common, which appeared as witches’ brooms. The disease was reported to be associated with phytoplasma belonged to X-disease phytoplasma subgroup 16SrIII-J. Little leaf of bitter gourd was observed by Win et al. (2014), characterized by smaller, thickened, yellowish green and puckered leaves. The internodes of the affected plants are also thickened and shortened. Flowers of affected plants are deformed. Affected plants produce small sized flowers, which are unable to open fully at maturity and eventually withered within a few days. Win et al. (2014) detected the causal agent of little leaf of bitter gourd by polymerase chain reaction using universal phytoplasma primers, and classified by sequencing of 16S rRNA gene, ribosomal protein gene and protein translocase subunit gene and RFLP analysis. The 16S rRNA gene sequence analysis of bitter gourd little leaf phytoplasma showed 99.7–99.9% identity with members of ‘Candidatus Phytoplasma asteris’ associated with sesame phyllody, periwinkle phyllody and periwinkle little leaf diseases in Myanmar. Moreover, ribosomal protein and protein translocase subunit gene sequences of the bitter gourd little

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leaf isolate were 99.7–100%, and 99.9–100% identity among the sesame phyllody, periwinkle phyllody and periwinkle little leaf phytoplasma. Management • All the disease plants must be rouged out from the field. • Soil application of Fipronil 0.3G at 50–75 g ai./ha at the time of sowing the seed to control insect vector. • Application of leaf extracts of Vitex negundo var. purpurascens and Sesbania rostrata reduced phyllody incidence by 68% (Srinivasulu and Narayanaswami 1993). Spraying of systemic insecticides like Acetamiprid 20% SP (0.05%) or Imidacloprid 17.8% SL (0.05%) at 10 days’ interval is effective to manage the disease through controlling of insect vectors. • Disease symptoms can be suppressed by five sprays of 500 ppm oxytetracycline hydrochloride solution at 7 days’ intervals (Vyas 1981; Verma and Giri 1998). • A possibility of biochemical control by spraying manganese chloride has been indicated by Purohit and Arya (1980). It appears that manganese chloride oxidizes phenols and protects or inhibits the enzymes, bringing the auxins level to normal. Once hyperauxin is oxidized, the plant can gain its normal conditions.

4

Post-Harvest Disease

Production of vegetables has increased considerably in recent years, which is contemplated to create an export-oriented trade. Different vegetables are now stored in cold storage. Steps being considered to put cucurbits under such storage conditions that will increase their shelf life. Investigations need to be undertaken to identify appropriate measures for preventing spoilage of vegetables during transit and storage (Chowdhury 1998; Chowdhury et al. 1998). Cucurbits are grouped under perishables vegetables, and are suffering from a numbers of fungal and bacterial diseases both in field and storage conditions. The quality of perishable vegetables declines within 10 days of harvest, which subsequently speed up by the attack of microbes. Damage like blemishes or bruishes occur during harvest, handling or transportation of vegetables make them more prone to microbial invasion (Roy and Singh 2003). An account of 8–15% post-harvest loss in some cucurbits was recorded by different scientists. The microorganisms that are responsible for spoilage of vegetables lower the nutritive values in declining the amount of sugar during host–parasite interactions is perhaps due to breakdown of carbohydrates by the fungal enzymes, increases in the rate of respiration in the infected host tissue and utilization of host carbohydrates by the fungi for various metabolic activities. Proteins are also used by the microorganism to meet up their nutritional requirements for better growth and development. Besides, fungal infections lead to reduction in the concentration of ascorbic acid and somewhat minerals that actually bring about changes in their quantity and quality (Roy and Singh 2003). Some of the important post-harvest diseases of cucurbitaceous vegetables are (Table 4): Physiological ripening/yellowing is an abiotic post-harvest disease of cucurbits.

4

Post-Harvest Disease

183

Table 4 Post-harvest diseases caused by the fungi and fungus-like organisms Sl. no. 1. 2.

Name of the disease Cottony rot Cottony leak

3.

Soft rot

4. 5.

Stem end rot Brown rot

6. 7. 8.

11.

Calyx end rot Grey white rot Green mould rot Dirty grey rot Waxy rot or sour rot Anthracnose

12. 13.

Charcoal rot Black spot

9. 10.

4.1

Causal organism Fusarium spp. Pythium aphanidermatum (Edson) Fitzp., P. butleri Subramaniam and P. cucurbitacearum S Takim. Rhizopus spp., Mucor spp., Fusarium spp., Pythium butleri subram., Choanephora sp. Botryodiplodia theobromae Pat Botryodiplodia theobromae Pat., Aspergillus niger van Tieghem, A. flavus link, Alternaria spp., Fusarium equiseti (Corda) Sacc., F. oxysporum Schlecht. Emend. Snyder & Hansen, Macrophomina phaseolina (Tassi) Goid. Thielaviopsis paradoxa (De Seynes) Höhn. Sclerotium rolfsii Sacc. Aspergillus fumigates Fresenius, Aspergillus niger van Tieghem Rhizoctonia solani Kühn Geotrichum candidum Link, Fusarium sp. Colletotrichum capsici (Syd.) E.J. Butler & Bisby and C. lagenarium (Pass.) Ell. et Halst. Macrophomina phaseolina (Tassi) Goid. Curvularia ovoidea (Hiroë & Watan.) Munt.-Cvetk.

Cottony Rot Caused by Fusarium spp.

Different species of Fusarium, viz. F. oxysporum, F. solani, F. equiseti and F. moniliforme etc. have been reported as white cottony rot causing fungi from West Bengal, Bihar and other parts of India (Chattopadhyay and Mustafee 1967; Mandal and Dasgupta 1981; Prasad and Poddar 1977; Bilgrami et al. 1979). Among them, F. solani and F. oxysporum are more common and often cohabitating (Dasgupta and Mandal 1988). The disease is quite common all over the season but causes extensive damage during June-July. The rots start mostly from the poles, but may appear anywhere on the fruit surface. The rotted area depressed slightly that measures about 2–5 cm in diameter. Infected area become soft, dull and yellow, and covered with whitish to peach, floccose growth that occasionally invades the hollow centre of the fruit too. Rotted fruits emit a characteristic smell (Dasgupta and Mandal 1988). The fungi causing varieties of cottony rot, viz. white cottony rot, white rot, pink rot, spongy rot, scanty cottony white rot, fluffy white rot, cottony white rot, etc. White cottony rot is mainly caused by Fusarium equiseti, F. oxysporum, F. solani (Mart.) Appel & Wr. on pointed gourd and little gourd. These pathogens were reported from West Bengal and Bihar, respectively (Chattopadhyay and Mustafee 1967; Mandal and Dasgupta 1981; Prasad and Poddar 1977). Other Fusarium spp. was also recorded from different parts of the India (Bilgrami et al. 1979). The disease of little gourd due to F. semitectum Berk. and Ravenel has been earlier recorded from

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Karnataka (Hiremath and Govindu 1973). Fusarium equiseti (Corda) Sacc. is more prevalent species. White cottony rot is quite common all over the season but causes extensive damage during June-July and October-December. The rot starts from anywhere on the fruit surface but mostly from the poles as small water-soaked spots. Rotted area becomes to some extent depressed and measures about 2–5 cm in diameter. Infected area is soft, dull and yellow and covered by white to peach, floccose growth which sometimes invades the hollow centre of the fruits as well. Rotted fruits emit a peculiar offensive smell (Chattopadhyay and Mustafee 1967). One of the most important post-harvest diseases of tinda (Praecitrullus fistulosus (Stocks) Pangalo) is white cottony rot, and has been recorded from Rajasthan (Mathur and Mathur 1958), Andhra Pradesh (Rao 1966) and Madhya Pradesh (Chaurasia 1980). It is seed borne in nature (Suryanarayana et al. 1963). The disease appears on the rind as circular brown patches that spread rapidly. Afterwards, profuse white mycelial growth develops and covers the entire fruit surface. The whole fruit becomes soft and pulpy within 6–7 days. Internal rotting is common in injured fruits (Dasgupta and Mandal 1988). White or pink rot, a common post-harvest disease of long melon, caused by F. semitectum, F. oxysporum and F. solani have been recorded from Haryana and West Bengal (Mandal and Dasgupta 1981; Dasgupta and Mandal 1988). The disease occurs during April-June on fruit bores by insect larvae, or otherwise bruised. The rot starts around the injury as water-soaked lesions progressing both dry and humid conditions. Afterward, a pinkish or cottony white mycelia mass appears on the fruit surface as well as within the hollow centre while the skin remains intact. Emittance of an offensive smell can be recorded only with a secondary infection due to bacteria. Larvae bores provide the pathogen an easy access and thereby a multisite infection can develop in nature. High relative humidity favours the disease (Mandal and Dasgupta 1981; Dasgupta and Mandal 1988). Pink cottony rot of cucumber caused by F. moniliforme was also noticed during winter (Mandal and Dasgupta 1981). Infection starts from the weak pedicel end or around an injury. The rotted area is slightly depressed, progressing slowly on the surface with floccose pinkish growth covering the fruit surface either partially or fully, and finally transforming the fruit into a soft watery mass (Dasgupta and Mandal 1988). Spongy rot (white cottony rot) of pumpkin due to Fusarium oxysporum has been reported from Himachal Pradesh (Gangopadhyay and Sharma 1976), and due to F. solani from West Bengal (Mandal and Dasgupta 1980). F. solani f.sp. cucurbitae race 2 has become serious in the USA (Hall et al. 1981). The disease observed on stored ripe fruits during June-July with a characteristics oak brown soft area around the injured site. The flesh of the infected fruits becomes combed brown. Infection progress radially with distortion of the fruit skin and shrinkage of the flesh, which causes cylindrical hole of about 2.5–5.0 cm diameter. Scanty mycelia growth can be observed on this half-rotten fruits (Dasgupta and Mandal 1988). Scanty cottony white rot disease is common in phuti (Cucumis melo var. phuti). The rotting originates from the distal end of the fruit during April and May in the form of browning, depressed blemish covering measuring of about 5–6 cm in

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185

diameter. Scanty mycelia mass can be seen from the commencement on the blemish over a rather shallow rotting but deep softening of the inner tissue. The disease is more pronounced on injured fruits than uninjured one and rate of spread is very slow (Dasgupta and Mandal 1988). Taste of the infected fruit may vary from normal to extremely bitter depending on the species of the pathogen involved (Ryall and Lipton 1972). The disease caused by two fungal pathogens, i.e. Fusarium equiseti (mycelium with red, blue or violet tinge) and F. oxysporum (pink mycelium and spore mass). Both the species cause similar decay symptoms. The pathogen disseminates through contact (Dasgupta and Mandal 1988). Cottony white rot of bitter gourd is quite common in India. The disease caused by different species of Fusarium was reported from Maharashtra, Karnataka, West Bengal and Uttar Pradesh (Rao 1966; Hiremath and Govindu 1973; Chattopadhyay and Mustafee 1967; Dasgupta and Mandal 1988; Tandon and Varma 1964). Fusarium sp., F. equiseti, F. oxysporum, F. solani s.sp. cucurbitarum have been reported to be infected the crop. F. equiseti is the prevalent one (Dasgupta and Mandal 1988). Both young and matured bitter gourd fruits are infected by the disease throughout the year. Maximum damaged of the crop occurs during summer month. The disease initiates from the distal end that characterized by a little water-soaked circular to irregular rotten patch with withered ribs and skin. Slightly depressed rotted zone encircled by a dark zonation of about 1 cm in diameter, which finally measuring to about 5–6 cm in diameter is the important diagnostic symptoms. Under dry conditions the fruits become hard, but under favourable conditions internal tissue disintegrates with a brownish shade. The reddish slimy host tissue on the seed surface become disintegrated and separated. Seeds surface is invaded by a fungal spores mass. Afterword, whitish to dull white scanty of fluffy cottony mycelium develops on the fruit surface in a moist atmosphere. Secondary infection by the bacteria cause quick decay and leak out of juice from infected fruit without any unpleasant odour. Injured fruits are easily infected by the pathogen (Dasgupta and Mandal 1988). Fluffy white rot of kakrol or spiny gourd (Momordica dioica Roxb. ex Willd.) caused by F. semitectum and other Fusarium spp. has been reported from Madhya Pradesh and West Bengal (Gupta et al. 1982; Mandal and Dasgupta 1981). Injured fruits are suffered mainly that characterized by water-soaked spots with softening of the tissue. In advanced stages of infection fluffy cottony mycelial growth develops over the fruit (Dasgupta and Mandal 1988). Cottony rot of bottle gourd has been reported from different parts of India. The inciting agent is Fusarium spp. The reported species from Bihar are F. concolor, F. equiseti and F. semitectum (Roy 1973a, b), from Uttar Pradesh are F. semitectum and F. solani (Garg and Gupta 1983), from Punjab are F. semitectum, F. dematium and F. solani (Sohi 1984; Singh and Chouhan 1980), and from Haryana is F. equiseti (Sumbali and Mehrotra 1982). The characteristic symptom of the disease is discrete or coalescent water-soaked lesions that appear on the rind of mature and ripe fruits. Slightly depressed pinkish or white mycelial growth develops over the surface (Dasgupta and Mandal 1988). Light brown water-soaked area develops due to the

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Deaseas of Cucurbits and Their Management

infection of F. solani and brown to black area develops due to F. semitectum (Garg and Gupta 1983).

4.2

Cottony Leak

It is a common and most troublesome disease of pointed gourd, cucumber, snap melon and tinda in India. The disease continues to be serious during transit, storage and marketing. It is aggravated by bruises and many weak parasites become a part of the causal complex. The disease is common in occurrence under humid conditions during rains. Pythium aphanidermatum (Edson) Fitzp., P. butleri Subramaniam and P. cucurbitacearum S Takim. have earlier been reported in India, especially from Bihar and West Bengal (Mitra and Subramanian 1928; Mehrotra 1954; Vasudeva 1960; Chaudhuri 1975; Bilgrami et al. 1979; Mandal and Dasgupta 1981). Cottony leak of snap melon has been recorded from Tamil Nadu (Ramakrishnan and Ramakrishnan 1950; Bilgrami et al. 1979), and ridge gourd and bitter gourd from Maharashtra and West Bengal (Rao 1966; Mandal and Dasgupta 1981). In pointed gourd, rotting generally starts on infected fruits during March-September, being more serious on the physiologically weakened fruits while the cottony leak of cucumber is prevalent from April to August being severe during July to August (Dasgupta and Mandal 1988). The disease is quite common in ridge gourd during May to September but is severe during May to June whereas that was noticed on bitter gourd during July to August (Dasgupta and Mandal 1988). Infection appears suddenly in pockets of eight to ten fruits within bamboo basket in the form of watersoaked light green areas anywhere of the fruit surface, but certainly to be covered overnight by fluffy cottony white mycelial mass with contaminant growth inside as soft rot sets in (Khatua and Saha 2004). The disease can be noticed in high proportion during August-September on the long-transported produce of tinda. It manifests itself as a small water-soaked lesion on any part of the fruit surface, which progress rapidly but irregularly. Normal green colour of the fruit gradually fades out and the lesion becomes slightly brownish with a cottony fluffy overgrowth which covers the whole fruit within 36 h (Dasgupta and Mandal 1988). The infection is possibly carried over from the field. High humidity favours quick rotting. Mature fruits are more susceptible than young ones (Dasgupta and Mandal 1989). Fruit decay in storage and transit can be prevented by treatment of imazalil (2000 ppm) along with waxing of fruits. Aharoni et al. (1993) suggested treating fruits with hinokitiol, a volatile oil extracted from the Japanese Hika tree (Thujopsis dolabrata (Thunb. ex L. f.) Siebold & Zucc.).

4

Post-Harvest Disease

4.3

187

Soft Rot

4.3.1 Soft Rot Caused by Rhizopus spp. The disease was recorded on cantaloupe in the USA and the pathogen was identified as Rhizopus spp. (Ramsey and Smith 1961; Beraha and O’Brien 1979). Dasgupta and Mandal (1988) described the disease in their book, Postharvest Pathology of Parishables. According to them, over-ripe fruits of phuti are more affected than semiripe ones in the markets in West Bengal during March to May. Rotting becomes prominent as a water-soaked irregular depression of about 5–6 cm in diameter on the surface. Natural maize yellow colour of the fruit tarnishes into cadmium yellow in due course of decay. Inner edible pulp becomes to some extent softened and reddened. The disease is frequently first discovered at this stage when a finger pressed suddenly plunges into the soft flesh. In severe cases brown and thin mycelia mass invades the core of the fruit wherein the seeds are embedded. The rot progress very fast and putrefies the fruit within 3–5 days. The pathogen (R. oryzae Went & Prins. Geerl., R. stolonifer (Ehrenb.: Fr.) Vuill.) gains its entry through the natural cracks, which originate at the time of ripening and causes severe decay in storage. The cracks also provide easy access to the saprophytes to enter. R. stolonifer causes soft watery rot on bitter gourd that occurs during rains and was recorded from Karnataka and West Bengal (Hiremath and Govindu 1973; Mandal and Dasgupta 1981, 1982). The disease begins as a small, water-soaked area around an injury, progress rapidly become yellowish-brown and being covered by a stringy coarse fungal mass. In advanced case, the surface becomes very soft, and because of tissue disintegration watery rot sets in. Mycelial mass invades the seed coat. Infection develops in pockets consisting of a few fruits in the bucket if the primary foci remain unnoticed. The whole fruit is putrefied into a soft mass within a week under congenial conditions. Affected fruit emits a bad odour. Touch with the infected fruits is possibly responsible for fast dissemination of the disease (Dasgupta and Mandal 1988). Soft rot of long melon caused by R. rhizopodiformis was reported from West Bengal (Mandal and Dasgupta 1981). The disease is quite common in the markets during March, mostly on bruised and insect-injured fruits. At first, slightly discoloured lesion appears on the fruits, which becomes circular to oval in shape. The advancing margin of the lesion is light greenish-yellow and water soaked. The surface of the affected fruit becomes soft with sparse mycelial growth. Whereas, under humid conditions dense stringy mycelial mass partially covers the fruit surface in a short time and gets intermingled with the seed. A bad odour may emit from the infected fruit due to secondary bacterial infection (Dasgupta and Mandal 1988). 4.3.2 Soft Rot Caused by Mucor spp. Soft rot of ridge gourd has been described from Punjab and West Bengal (Singh 1974; Bilgrami et al. 1979; Mandal and Dasgupta 1981). The causal organism of the disease is Mucor hiemalis f.sp. luteus, M. circinelloides). This is not a common problem. Three to four days old fruits damaged by insects or physical means are affected severely during July-September. Mucor hiemalis also caused fuzzy

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Deaseas of Cucurbits and Their Management

yellowish rot of bitter gourd mostly during October to November (Dasgupta and Mandal 1988). Water-soaked patches appear around the injured part of the fruits followed by appearance of a yellowish fuzzy mycelial growth. The rotted portion becomes slightly shriveled, soft, dull in colour, and emit a bad odour. The rotting due to the Mucor spp. is slower than the cottony leak. The disease favoured by high humidity. In some cases, the disease associated with Fusarium spp. (Dasgupta and Mandal 1988).

4.3.3 Soft Rot Caused by Fusarium spp. Soft rotting due to Fusarium spp. reported earlier on snake gourd and ridge gourd (Rao 1966). Mandal and Dasgupta (1981) noticed the disease during July-August in West Bengal. The disease occurs rarely in snake gourd. Injured fruits are affected mainly, and a small water-soaked specks appears around the injury that progress rapidly both radially and into the edible tissue. The advancing margin is lavender green whereas the inner central has a small red zonation, about 2–3 mm in diameter. Afterwards, scanty, white or pinkish, floccose mycelium develops on the infected fruit surface. Cracking of fruits at the infected site can also be noticed. The fungus sporulates in the hollow centre of the fruit (Dasgupta and Mandal 1988). 4.3.4 Soft Rot Caused by Choanephora spp. Soft rot of little gourd/ Ivy Gourd (Coccinia grandis (L.) Voigt) caused by Choanephora sp. is a minor disease noted only during November particularly on the produce delayed in transit (Mandal and Dasgupta 1981). The infected fruits primarily show water-soaked spots of champagne colour. Rotting spreads quickly with dense mycelial overgrowth, extensive internal ramification and a characteristics odour. 4.3.5 Soft Rot Caused by Pythium spp. Soft rot of muskmelon caused by Pythium butleri Subramaniam is an important postharvest disease (Dasgupta and Mandal 1988). The disease was recorded from Punjab (Singh and Chohan 1977). During transportation and marketing the injured fruits suffer seriously. The disease primarily appears as minute dots, which gradually enlarge to a water-soaked area of about 2–4 cm diameter on the upper end of the fruit. While the colour turns from faded green to brown, the whole fruit becomes soft within 2–3 days and is covered by fluffy cottony white mycelium. Possibly the fungus is carried from the field.

4.4

Stem End Rot

Stem end rot of watermelon is caused by a fungal pathogen, Botryodiplodia theobromae Pat. The disease has earlier been recorded from the USA (Walker and Weber 1931). This serious disease occurs in West Bengal on semi-ripe fruits during May-June on the marketed produce. The infection initiates at the stem end with water-soaked appearance, which become a Naples yellow rim and an extreme ashy

4

Post-Harvest Disease

189

grey centre. Afterwards, the infected fruit rots very rapidly become wrinkled and dried up, with an ashy grey mycelial mass over the surface. The inner tissues turn Vandyke brown, emit a fermentative odour and leak a watery juice. Infection may be carried from the field or consequently through contact (Dasgupta and Mandal 1988). The pathogen, Botryodiplodia theobromae also caused brown pedicel end rot of snap melon during summer months (Mandal and Dasgupta 1981; Mandal and Dasgupta 1982). The infected fruit shows patches of small brown area at the pedicel end that coalesce to form large spots or lesion and progress with its brown coloured centre and yellowish water-soaked margin. Sparse ashy grey mycelial mass later turn brown, and grow outside and into the inner cavity entangling the seeds. The inner tissues become soft and watery. Such affected fruits emit characteristics fermentative smell. The juvenile tissues appear to be resistant (Dasgupta and Mandal 1988).

4.5

Brown Rot

4.5.1 Brown Rot Caused by Botryodiplodia spp. The disease is noticed on over-ripe fruits of Phuti (Cucumis melo var. phuti) in markets during May and June. The rotting is brown and progress fast radially and downwards. Later, the inner core is blackened and filled with blackish mycelium. Almost immediately, a quite fungus develops and covers the entire ripe fruit producing a mosaic effect. Severely infected fruits emit offensive smell. The fungal pathogen responsible for the disease is Botryodiplodia theobromae. Some other pathogens, which are associated with the disease, are Aspergillus niger, A. flavus, Alternaria spp., Fusarium equiseti and F. oxysporum (Dasgupta and Mandal 1988). 4.5.2 Brown Rot Caused by Alternaria spp. Brown rot of snake gourd, caused by Alternaria tenuissima has been reported from Uttar Pradesh (Singh 1974). Infection starts at the stem end as roughly circular grey spots of 0.3–0.4 cm diameter, which merge, become yellow to pink and finally turn brown. The tissues below the lesion may be dried up and hanged out from the healthy portion (Mandal and Dasgupta 1988). Brown spot due to Alternaria alternata develops on injured or uninjured bottle gourd as small circular to oval, dark coloured spots of 1.5–2.5 cm in diameter with depressed centre and raised margin that may enlarge up to 6 cm (Dasgupta and Mandal 1988). 4.5.3 Brown Rot Caused by Macrophomina spp. Brown rot of little gourd caused by Macrophomina phaseolina is a minor disease occurring in June-July on green to semi-ripe fruit (Mandal and Dasgupta 1981; Mandal 1981). The diseased fruit shows a sunken circular to oblong spot of approximately 0.5 cm diameter at the distal end. Infection is skin-deep but enlarges superficially with scanty whitish mycelial mass within the sunken area. Brown micro-sclerotia appear later with the area becoming blackish brown. The skin remains intact but the fruit either becomes hard or soft depending on the ambient

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Deaseas of Cucurbits and Their Management

moisture. Fruits near the ground level possibly get contaminated in the field itself (Dasgupta and Mandal 1988).

4.6

Calyx End Rot

Rao and Subramaniam (1975) were observed the disease on muskmelon in Maharashtra during March. The disease initially appears as irregular, slightly depressed, blackish, rotted lesions at the calyx end, which spread rapidly and the fungal growth covers the lesion surface. In early stage, the epicarp becomes yellow and finally turns brownish starting from the centre. The flesh becomes soft and loose, and emits fermentative fruity odour. The causal agent of the disease is a fungus, Thielaviopsis paradoxa (De Seynes) Höhn. (Dasgupta and Mandal 1988).

4.7

Grey White Rot

The disease of pumpkin is caused by Sclerotium rolfsii, noticed from April to August mainly on ripe and injured fruits (Mandal and Dasgupta 1981). The infected fruits show a circular, slightly depressed area of about 0.6–1.5 cm in diameter, progress slowly but occasionally enter tissue instead of expanding radially. It becomes somewhat soft, watery and dull. The pathogen possibly finds its avenue through insect bites or other injuries (Mandal and Dasgupta 1988). Ridge gourd and bottle gourd are infected with S. rolfsii as well. The disease is known as creepy cottony rot that has been reported from Rajasthan (Agarwal et al. 1980). The disease develops as small localized patches with superficial creepy shining white mycelial overgrowth, which is shortly strewn with copious sclerotia (Mandal and Dasgupta 1981). Grey white rot of bitter gourd, one of the worst post-harvest diseases, recorded in Karnataka and West Bengal (Singh 1973; Mandal and Dasgupta 1981). The disease occurs mainly on large sized bitter gourd between April and July. Small, slightly depressed, water-soaked areas appear on the fruit surface around a deep injury, which become ashy yellow and soft finally turn greyish to blackish. The growth of the fungus is limited in dry weather condition but conspicuous chalky white stranded mycelial mass creeps all over the fruit surface without forming sclerotia in high humid conditions. Infection may be initiated from the field that spreads by contact and develops in pockets. A bad odour emits from the infected fruit if secondary bacterial invasion takes place (Mandal and Dasgupta 1988).

4.8

Green Mould Rot

The fruits of watermelon injured during road transportation are almost regularly affected by the disease during May-June in West Bengal (Mandal 1981). The cracked fruits are mainly affected. The surface of the crack zone covers with

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greenish fungal growth. The red colour pulp of the fruit becomes fade. The rotting caused by the fungus, Aspergillus fumigates Fresenius is very slow and limited, both in natural infection as well as artificial inoculation. The causal agent is expected as a week pathogen (Dasgupta and Mandal 1988). Aspergillus fumigates causes disease on matured and injured fruits of bottle gourd as water-soaked area that soon covered by a fungal mass with conidia and conidiophores (Dasgupta and Mandal 1988). The long melon also infected with green mould causing rot during summer season. The fruits injured by larvae or otherwise bruised are affected mainly (Mandal and Dasgupta 1981). Infection starts as a soft area around an injury. The rot progress very fast and the conidial heads of the causal fungus (Aspergillus foetidus var. acidus Nakazawa et al., A. fumigates) appear on the injured surface. The rot either progress or arrested in high or low relative humidity, respectively (Dasgupta and Mandal 1988). Aspergillus niger van Tieghem causing disease on pumpkin called black mould rot. This is a minor disease that occurs on the cut pieces or on rat-browsed fruits of ripe pumpkin (Dasgupta and Mandal 1988).

4.9

Dirty Grey Rot

Dirty grey rot incited by Rhizoctonia solani occurs in ridge gourd during August to September and bitter gourd during October to December (Mandal and Dasgupta 1980, 1981). Infection on ridge gourd usually begin from the distal end showing a depressed area of about 4–5 cm in diameter with a slightly water-soaked advancing margin. Rotting progress rapidly and contaminate neighbouring fruits. Water congestion may be noticed within the affected areas, which subsequently develop straw colour. Dirty coarse mycelial mass develops afterwards rarely being intermingled with sclerotia measuring 0.3–0.5 cm in diameter, the pathogen is perhaps carried incipiently from the field by those fruits touching the ground. On bitter gourd, the rot initiates from anywhere on the surface of fruit as water-soaked patches of irregular area, progress fairly into dull blackish patches being covered by extrametrical, coarse, light yellowish mycelium generally without sclerotia or any unpleasant odour. The infection may be carried from the field (Dasgupta and Mandal 1988).

4.10

Waxy Rot or Sour Rot

This minor disease is caused by Geotrichum candidum Link recorded from Maharashtra (Rao 1966) and West Bengal (Mandal 1981). Waxy rot of tinda suffer most during July-August, whereas in pointed gourd and pumpkin during JuneOctober (Mandal 1981; Mandal and Dasgupta 1981). The disease is almost invariably associated with semi-ripe, physiologically weak or bruised fruits. Sour rot is also noticed only on a day-old left over stock of injured ridge gourd fruits in the

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market or kitchen store. Infected fruits lose its lustier (Mandal and Dasgupta 1981). Infection develops in patches as white powdery growth. Under humid conditions it becomes dirty and looks like a bacterial colony on the fruit surface. In this condition the infection progress fast and the infected fruit subsequently becomes soft. Such fruits ooze out juice that carry spore laden mass and emit strong offensive odour (Khatua and Saha 2004). Fusarium sp., when associated with this disease, produces scanty mycelia growth on the fruit surface. Both the organisms are individually pathogenic on tinda (Mandal and Dasgupta 1981). Bacillus spp. and yeasts also associated with the sour rot of pumpkin (Mandal and Dasgupta 1983).

4.11

Anthracnose

The infected cucurbit fruits show remarkable discolouration followed by appearance of water-soaked patches, in the initial stages. The infected regions become yellowish white, which gradually turned black. A large number of small pinheads like structures, i.e. acervuli appear on affected areas of the fruits. The spot turns pinkish white due to spore production in acervuli. The infected fruits finally fall off (Sahu Kritagyan and Singh 1980). The causal organism was isolated, identified and confirmed as Colletotrichum state of Glomerella cingulata (Stoneman) Spauld. & H. Schrenk (Sahu Kritagyan and Singh 1980). Anthracnose of snapmelon reported only from Karnataka caused by Colletotrichum capsici (Syd.) E.J. Butler & Bisby and C. lagenarium (Pass.) Ell. et Halst., is an important disease produce circular to semi-circular water-soaked lesions measuring up to 2.5–9 mm in diameter. These lesions may coalesce and became light yellowish-brown in colour and sunken (Dasgupta and Mandal 1988). Post-harvest anthracnose of bitter gourd has been recorded from Karnataka (Prakash and Singh 1977). The disease is caused by Colletotrichum lagenarium. The infected fruits show abundant small, circular, water-soaked, sunken or depressed area over the surface. The spots are straw to greyish brown in colour and merge into large elongate patches on the fruit. Afterward, the fruits crack open longitudinally, which comprise the most characteristic symptoms of the disease. Pink spore masses may develop over the surface but inner tissues remain free from infection (Dasgupta and Mandal 1988). Anthracnose of snake gourd was recorded in Uttar Pradesh (Singh 1973) as stem end rot that later renamed. Greyish, oblong to ovoid or irregular slightly sunken lesions appear on fruit surface, which frequently coalesce and spread longitudinally towards the distal end. The affected area turns light pink-green to yellow and finally become dark brown to black. Such fruits become soft, water soaked and rotten totally. Under humid conditions, the acervuli may be developed on the rotted tissue (Mandal and Dasgupta 1988). Anthracnose of bottle gourd incited by Colletotrichum lagenarium is a devastating disease, occurs worldwide both in field as well as in market (Madan and Grover 1977; Bilgrami et al. 1981). The disease appears as water soaked, circular to irregular, oval to oblong lesions that become brown to black and scabby.

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The lesions are coalescing. Under high humid conditions, pinkish spore mass may be appeared on old scabby lesions (Mandal and Dasgupta 1988). To avoid spoilage of fruits care should be taken to remove infected and injured fruits before transit and arrangement is to be taken to keep the fruit surface dry (Khatua and Saha 2004).

4.12

Charcoal Rot

This is a common and serious disease of snap melon and ridge gourd caused by Macrophomina phaseolina known in Punjab (Jhooty and Singh 1971; Bilgrami et al. 1979; Singh and Chohan 1972) and West Bengal (Mandal and Dasgupta 1981). Infection initiates generally from the distal end of the fruit as water-soaked area with varying shades of brown and later turns blackened. Abundant sclerotia develop as the rotting progress towards the pedicel end with shrinkage of the skin and tissue. Under moist conditions a skin-deep superficial blemish develops as depressed blackish growth associated with fast rotting. A dry spell can result in halting the disease (Dasgupta and Mandal 1988).

4.13

Black Spot

The disease is recorded on both injured and uninjured matured bottle gourd as brown to black spots with irregular margin on the rind. Eventually, the lesions covered with a velvety black fungal growth accompanied by shallow rots. The causal agent of the disease is Curvularia ovoidea (Dasgupta and Mandal 1988).

4.14

Physiological Ripening/Yellowing

It is one of the important post-harvest diseases of cucurbits, which causes deterioration of the harvested products in the marketing process in West Bengal. The disease is very much common in little gourd, bitter gourd, etc. In case of little gourd ripening starts mainly from the pedicel and progresses very fast, consequently reducing the market price significantly, and the fruits become insipid while, in bitter gourd and pointed gourd yellowing start mostly from the pedicel end until the entire skin becomes bright yellow. In the meantime, the inner mass turns red or yellow and the infected fruits may burst along the ridges from the distal end. Physiological yellowing may be due to hot dry weather is quite common in bitter gourd during March-April, however, that is in pointed gourd during March-September with a severe form during April-June (Mandal 1981; Dasgupta and Mandal 1988). Roy and Singh (2003) reviewed in detail about the post-harvest diseases of cucurbits in Indian condition and prepared an exhaustive list (Table 5).

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Table 5 List of fungi and bacteria causing post-harvest diseases on cucurbit vegetables Host Lagenaria siceraria

Luffa cylindrica

Momordica charantia

Pathogen Fusarium equiseti F. semitectum F. scirpi Botryodiplodia theobromae Drechslera australiensis Alternaria alternate F. equiseti F. scirpi A. alternate D. australiensis B. theobromae Myrothecium roridum Helminthosporium spiciferum Curvularia lunata Pythium aphanidermatum Aspergillus flavus Rhizopus stolonifer Alternaria alternate F. solani F. oxysporum A. tenussima D. spicifer A. alternate C. lunata

Trichosanthes dioica

Aspergillus flavus A. niger Rhizopus stolonifer Myrothecium roridum F. equiseti F. semitectum F. moniliforme P. aphanidermatum C. lunata D. australiensis B. theobromae Colletotrichum gloeosporioides

Symptoms Soft rot Dull yellowish water-soaked patches Soft rot Dry rot Blackish-brown lesions Circular blackish brown spots Soft rot Soft rot Deep green irregular spot Blackish brown water-soaked lesions Small black and soft lesions Dull-black water-soaked irregular spots Soft rot Greenish white water-soaked irregular lesions Water-soaked areas with white cottony mycelia mat Soft rot Soft rot Soft rot Dry rot Soft rot Soft rot Dull-black irregular patches Circular lesions, surrounded by water-soaked areas Small dull-black regular lesions with greenish tinge at the centre Greenish patches Soft rot White mycelial growth Fruit rot Soft rot Soft rot Soft rot Soft rot Soft rot Soft rot Soft rot (continued)

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Table 5 (continued) Host

Citrullus vulgaris var. fistulous

Cucumis melo var. momordica

Coccinia indica

Cucurbita moschata

4.15

Pathogen Alternaria alternate Aspergillus flavus A. niger Rhizopus stolonifer Rhizoctonia bataticola Cylindrocarpon tonkinense Curvularia lunata Alternaria alternate F. scirpi F. semitectum Rhizopus solani Myrothecium roridum Pseudomonas lachrymans F. moniliforme D. spicifera F. scirpi Colletotrichum dematium A. alternate B. theobromae Aspergillus flavus A. niger R. stolonifer Rhizoctonia solani F. oxysporum

Symptoms Soft rot Soft rot Soft rot Soft rot Soft rot Soft rot Blackish brown round patches Round to irregular dull brown erumpent patches Circular to irregular pale brown patches Dull yellowish water-soaked patches Fruit rot Fruit rot Bacterial spot Dull green oval to irregular water-soaked areas as well as soft rot Dull green to dirty black small patches Round irregular pale area Soft rot Small regular brown coloured spot Dry rot Green colonies Soft rot Luxuriant mycelial growth Fruit rot Fruit rot

Management of Post-Harvest Diseases

Post-harvest pathology has remained the weakest part of vegetables pathology, although many advances such as controlled temperature storage, controlled atmosphere storage, chemical treatments and improved packing and handling methods have substantially reduced post-harvest losses they still remain astonishingly high even in well-developed temperate countries (Booth and Burden 1983). In view of the seriousness of the problems particularly their loss efforts should be directed to development of safe technological package to check post-harvest losses due to diseases (Sengupta and Chowdhury 1998). Management of post-harvest diseases is

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very difficult. Many researchers tried to manage the diseases by different ways. But no one is effective alone. So, integrated management option is the best way. The following points should be remembered for effective management of the postharvest diseases of cucurbits: • To avoid spoilage of fruits care should be taken to remove infected and injured fruits before transit and arrangement is to be taken to keep the fruit surface dry (Khatua and Saha 2004). • Though the inoculum of most of the post-harvest diseases comes from field by contact with soil, so scaffolded cultivation or use of mulching materials can be an option to avoid the diseases. • Adhering soil on the fruit surface should be removed. • Refrigerated storage can reduce post-harvest losses. Refrigeration retards the rate of respiration and lengthens storage life. By modifying the oxygen and carbon dioxide content of the storage atmosphere physiological ripening, ageing, decay and some physiological disorders can be reduced (Booth and Burden 1983). • To control Pythium aphanidermatum infecting cucumber, post-inoculation treatment with undiluted autoclave culture filtrate of Acrophialophora nainiana and Stachybotrys atra are effective (Sharma et al. 1981; Dasgupta and Mandal 1988). • Paper wraps alone or impregnated with fungi static chemicals check the spread of pathogens associated with post-harvest diseases. Fruits can individually be wrapped in heat shrinkable polyethylene film, which prevents the spread of disease and transmission of spores (Roy and Singh 2003). • Fusarium spp. infecting long melon can be managed through pre- and postinoculation treatment with bleaching powder and Potassium permanganate @ 0.5–1.0% (Raina et al. 1968; Dasgupta and Mandal 1988). Other reports regarding the effective management of the fungus on different cucurbits are the use of carbendazim, mancozeb (Tandon et al. 1975), benomyl (Wade and Morris 1982) and imazalil (Carter 1981). Hot water treatment (24  C and 57  C) is also reported to be an effective practice (Carter 1981), whereas γ-irradiation recorded non-effective (Barkai-Golan et al. 1968; Dasgupta and Mandal 1988). • Aureofungin appeared best against the post-harvest disease of watermelon caused by Macrophomina phaseolina (Singh and Chohan 1979). • Post-inoculation treatment of Coccinia cordifolia with coprantol, thiourea and tetracycline against Colletotrichum lagenarium recorded effective. • Pre-harvest spraying with captan 50% WP (1.0%) can effectively manage the Alternaria cucumeriana (Gangopadhyay and Kapoor 1973; Dasgupta and Mandal 1988). • Pythium aphanidermatum can be managed effectively by post-inoculation cotton swab treatment with JF 3937 (Wahab and Sharma 1976), cotton swab and dipping treatment in multifungin, chloromycetin, aureofungin (50–200 μg/mL) and actidione (10–12 μg/mL) in dimethyl formaldehyde for 3 days (Sharma and Wahab 1970, 1973; Dasgupta and Mandal 1988).

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• Some non-hazardous chemicals are extensively used to manage pre- and postharvest diseases of perishable vegetables either by preventing sporulation or initiation of infection or by suppressing the development of pathogens and latent infection in the host tissues (Roy and Singh 2003). • Ojha (1983) and other researchers have tested some plant extracts against diseases of bottle gourd, pointed gourd and other perishable vegetables. Besides, antimicrobial properties of a large number of angiospermic plants have been evaluated and reported by many researchers (Roy and Singh 2003). • Attempts were made to manage the post-harvest diseases of perishables using antagonistic microorganisms with quite success. Antagonistic microorganisms reduced inoculums load directly or indirectly from the plant or fruit surface and keep the products safe from post-harvest rotting. Antagonists successful in controlling post-harvest diseases included a number of bacteria, viz. Bacillus subtilis, B. licheniformis, B. stearothermophilus, B. megaterium, B. amyloliquefaciens, Pseudomonas corrugate and the fungi, viz. Aureobasidium pullulans, Trichoderma viride and Penicillium funiculosum (Roy and Singh 2003). Management of post-harvest losses are very much important from both an economic and nutritional perspective, and that the problem is technologically and scientifically diverse. No single method is appropriate to reduce the post-harvest losses. So, impetus has to be paid to integration of different techniques for reducing both qualitative and quantitative post-harvest losses of cucurbits.

5

Viral Diseases

Virus diseases are one of the major challenges for cucurbit production. There are a large number of viruses which cause much damage and yield losses to different commonly grown cucurbits viz. pumpkin, cucumber, bitter gourd, ridge gourd, sponge gourd, bottle gourd, ash gourd, watermelon, muskmelon and pointed gourd, etc. worldwide. More than 70 viruses reported to infect cucurbitaceous crops throughout the world (Lecoq and Katis 2014). In India, these crops are naturally infected by more than ten viruses. The most common viruses that infect cucurbitaceous crops are Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), Melon necrotic spot virus (MNSV), Papaya ring spot virus (PRSV), Squash mosaic virus (SqMV), Watermelon mosaic virus-2 (WMV-2), Zucchini yellow fleck virus (ZYFV), Zucchini yellow mosaic virus (ZYMV) and Cucurbit aphid-borne yellow virus (CABYV) (Lecoq et al. 1992; Description of Plant Viruses 2010; Lecoq and Katis 2014). Mixed viral infections of cucurbits by CMV and potyviruses are often present and showed strong synergistic pathological responses, ultimately leading to plant death (Wang et al. 2002; Svoboda 2011). The viruses infecting cucurbitaceous plants reported from different parts of the world are tabulated below (Table 6).

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Table 6 Plant pathogenic viruses infecting cucurbitaceous vegetables Sl. no. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

Name of the disease Cucumber green mottle Cucumber mosaic Watermelon mosaic Zucchini yellows Chlorotic leaf spot Mosaic Mosaic Cucumber latent Tobacco ring spot Curly top Cucumber vein yellowing Lettuce infectious yellows Melon leaf curl Melon necrotic spot Muskmelon vein necrosis Squash leaf curl Squash mosaic Tomato spotted wilt Cucurbit aphid-borne yellows Zucchini yellow flecks Pumpkin yellow vein mosaic Squash vein yellowing Melon yellow spot

Name of virus Cucumber green mottle mosaic virus (CGMMV) Cucumber mosaic virus (CMV) Watermelon mosaic virus (WMV, WMV 1 & 2) Zucchini yellows mosaic virus (ZYMV) Bean yellow mosaic virus (BYMV) Potato virus Y (PVY) Papaya ring spot virus (PRSV-W) Cucumber latent virus (CLV) Tobacco ringspot virus Beet curly top virus (BCTV) Cucumber vein yellowing virus (CVYV) Lettuce infectious yellows virus (LIYVV) Melon leaf curl virus (MLCV) Melon necrotic spot virus (MNSV) Muskmelon vein necrosis virus (MkVNV) Squash leaf curl virus (SqLCV) Squash mosaic virus (SqMV) Tomato spotted wilt virus (TSWV) Cucurbit aphid-borne yellow virus (CABYV) Zucchini yellow fleck virus (ZYFV) Pumpkin yellow vein mosaic virus (PYVMV) Squash vein yellowing virus (SqVYV) Melon yellow spot virus (MYSV)

Source: Tomassoli and Meneghini (2006), Tomassoli et al. (1999), Lovisolo (1980), Tomassoli et al. (2010), Lecoq et al. (1992), Campbell et al. (1990), Gilbert-Albertini and Lecoq (1994), Alonso-Prados et al. (2003), Luis-Arteaga et al. (1998), Garcia-Jimenez et al. (1993), Juarez et al. (2005), Kiss et al. (2003), Muller et al. (2006), Lebada et al. (1996), Chod and Jokes (1991), Svoboda and Leisova-Svobodova (2011), Svoboda (2011), Korbin and Kaminska (1998), Borodynko et al. (2009), Pospieszny et al. (2003), Nath (2004), Roy and Mukhopadhyay (1980), Uppal (1934), Singh (1987), Capoor and Verma (1948), Vasudeva et al. (1950), Varma (1955, 1988), Vishwanath et al. (1980), Bandyopadhyay and Mukhopadhyay (1977), Huitron et al. (2011), Lecoq and Katis (2014)

Some unidentified viruses also infect cucurbits. Some cucurbits are also affected by phytoplasma diseases, which are however economically not very important. Recently, the incidence of viral diseases is increasing in trend. Earlier, the white fly transmitted viral diseases were of minor importance, while in recent times they are appearing in almost epidemic proportion (Verma and Giri 1998). Ghosh and Mukhopadhyay (1979a, b) described 18 different viruses infecting pumpkins. Among which some of the important viruses are bottle gourd mosaic virus, bottle gourd vein yellowing virus, cucurbit latent virus, watermelon mosaic virus, pumpkin enation mosaic virus, pumpkin mild mosaic, squirting cucumber mosaic virus. They also estimated the biochemical differences of the pumpkin plants (particularly buffer soluble proteins, reducing sugar and starch) infected by these

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different viruses. Almost all the cucurbitaceous vegetables are subjected to attack of mosaic virus affecting leaf and fruits (Chowdhury 1998; Chowdhury et al. 1998). According to Nath (2004) the cucurbits are mainly suffering from cucumber mosaic virus (CMV) and watermelon mosaic virus (WMV). Mukhopadhyay and Saha (1968) observed that CMV could be transmitted through seeds of Cucurbita moschata Duchesne ex Poir., whereas Ghosh and Mukhopadhyay (1979a) found that WMV was sap transmissible. Bandyopadhyay and Mukhopadhyay (1977) described a strain, cucurbit latent virus infecting muskmelon. Sarkar and Mukhopadhyay (1979) separated nine anisometric viruses of cucurbits by host reaction. Roy and Mukhopadhyay (1980) studied the epidemiology of watermelon virus-1 (WMV-1) in pumpkin and detected the virus in root, leaf debris and seeds. They recorded 86% transmission by Aphis gossypii in field (Mukhopadhyay and Nath 1998). Mukhopadhyay (1988, 1990) recorded Arka Chandan (National) and EC121270 (exotic) as resistant variety against cucurbit latent virus and WMV, while Tehuacan Smooth (exotic) showed resistance against bottle gourd mosaic virus, cucurbit latent virus and WMV. He identified Midnapore 1 (local) and Warte (exotic) as resistant sources only to bottle gourd mosaic virus. Pointed gourd crop is affected by CMV and particle of the virus was isometric in shape, confirmed by ISEM (Nath 2004). Bitter gourd was infected by Zucchini yellow mosaic virus and transmitted by Aphis gossypii Glover whereas ridge gourd was affected by several viruses (Nath 2004). Host range of the Zucchini yellow mosaic virus and papaya ring spot virus is restricted within cucurbits whereas watermelon mosaic virus not only infects cucurbits but also some weeds, and is transmitted by aphids. Aphids can acquire then transmit the virus within a few seconds. Once acquired, they lose it after a few plants. The squash mosaic virus infects cucurbits along with some other hosts under the family chenopodiaceae, which is reported to be transmitted by seeds and cucumber beetles (Kennelly 2012). Virus nature of the disease was confirmed through ISEM study and the particles of the viruses were found to be flexuous rod, and the viruses were under potyvirus (Nath 2004). Mukhopadhyay and Nath (1998) confirmed the prevalence of WMV in Cucurbita moschata, Luffa acutangula and Coccinia sp., CMV in Cucumis sativa, Trichosanthes dioica and Cleome viscose, and Zucchini yellow mosaic virus in Luffa acutangula and Coccinia sp. Different viruses infecting cucurbitaceous crops in West Bengal and their key characters are mentioned below (Table 7). The common detection techniques for viral diseases are (a) General methods— (1) Symptomatology, (2) Infectivity test, (3) Electron microscopic observation; (b) Specific methods—(1) Enzyme Linked Immuno-sorbent Assay (ELISA), (2) Dot Immunobinding Assay, (DIBA) (3) Immuno-sorbent Electron Microscopy (ISEM), (4) Complementary DNA (Cdna) Probe, (5) Polymerase Chain Reaction (PCR) (Majumdar 1998). Considering the importance of the virus diseases and for development of an eco-friendly holistic management option a comprehensive study on following lines deserves especial attention (Chowdhury 1998; Chowdhury et al. 1998):

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Table 7 Viruses infecting cucurbitaceous crops in West Bengal Diseases Cucumber mosaic virus Squash mosaic virus Cucumber green mottle mosaic virus Watermelon mosaic virus

Virus group Cucumovirus Comovirus Tobamovirus

Muskmelon vein mosaic virus

–

Yellow vein mosaic virus Cucumber stunt mottle virus

– Nepovirus

Cucumber necrosis virus

Tobacco necrosis virus –

Melon mosaic virus

Potyvirus

Key characters Isometric ssRNA aphid-transmitted Isometric ssRNA beetle-transmitted Anisometric ssRNA vector— unknown Anisometric ssRNA aphidtransmitted Anisometric ssRNA aphidtransmitted Whitefly-transmitted Isometric ssRNA nematodetransmitted Isometric ssRNA fungustransmitted –

Source: Mukhopadhyay and Nath (1998)

(a) Characterization and identification of virus or viruses affecting different crop species to find out whether one virus or number of viruses involved and their effect on symptoms expression. (b) Host range of individual virus or different viruses affecting cucurbit crops. (c) Perpetuation and spread of the virus/viruses concerned through involvement of vectors, role of seeds of virus affected plants and wild hosts in carryover the disease. (d) A number of cucurbits crops affected by mosaic disease. Identification of resistant sources, which is governed by a single dominant gene.

5.1

Mosaic Diseases

A variety of mosaic symptoms occur on different members of cucurbitaceae. In India, these are common on almost all cucurbits and often cause serious losses. The common mosaic is caused by the cucumber mosaic virus. In addition, cucumber green mottle mosaic virus and watermelon mosaic virus are also common in certain cucurbits and cause significant losses. Most of the cucurbits viz. cucumber, melon, snap gourd, long melon, pumpkin, watermelon, round gourd, bottle gourd, ridge gourd, sponge gourd, bitter gourd and snake gourd, grown in different parts of India are affected by virus diseases. Infected plants produced varied types of symptoms, which include (a) mild or severe dark green mosaic and (b) yellow-green or bright yellow mosaic mottling of the leaves, accompanied by blistering of green areas. In these cases, plants produced variously deformed leaves. Stunting of growth and reduction of leaves size are the common phenomenon that ultimately affects the yield (Rani et al. 1971; Cheema et al. 1999). Prevalence of these viruses (WMV in Cucurbita moschata, Luffa acutangula and Coccinia sp.; CMV in Cucumis sativa,

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Trichosanthes dioica and a weed Cleome viscosa; Zucchini Mosaic Virus in Luffa acutangula and Coccinia sp.) was confirmed through Electron Microscopic observations, Enzyme Linked Immuno-Sorbent Assay (ELISA) and ImmunoSorbent Electron Microscopy (ISEM) (Mukhopadhyay and Nath 1998).

5.2

Cucumber Mosaic Virus (Cucumovirus)

Introduction Cucumber Mosaic Virus (CMV) is a most widely distributed plant virus that has a very wide host range (Gour et al. 2008). The virus infects about 200 dicotyledonous and monocotyledonous plants belonging to about 40 families (Franski and Hatta 1980). According to Kennelly (2012) the virus infects more than 800 plant species. It attacks a greater variety of vegetables, ornamentals, weeds and other plants than any other virus (Agrios 2000). Among cucurbitaceous vegetables, cucumber, melons and squash are commonly infected by this disease. Summer squash is the most susceptible cucurbit (Agrios 2000). The CMV causes mosaic disease in cucumber (Uppal 1934; Bhargava and Bhargava 1977), muskmelon (Mayee et al. 1976; Sharma et al. 1984), pumpkin, summer squash, vegetable marrow (Reddy and Nariani 1963; Rao 1976; Bhargava and Bhargava 1977), snake gourd (Pillai 1971; Dubey et al. 1974; Joseph and Ramanathan 1978) and watermelon (Bhargava and Bhargava 1977), which was recorded from different parts of India. The disease rarely affects watermelon (Gour et al. 2008). Symptoms Cucumber mosaic affects most of the above ground plant parts by causing mottling or discolouration and distortion of leaves, flowers and fruits. Size of the infected plants may be reduced greatly or killed. Infected plants produce lower yield with inferior quality. The disease appears both in field and in greenhouse condition, and causes severe damage to the crops. Sometimes, one-third or one-half of the plants may be destroyed or total plants may have to be replaced by other crops depending upon its severity (Agrios 2000). The young seedlings are mainly attacked in field condition. Most of the cases, general field infections occur when the plants are about 6 weeks old. The disease symptoms appear in plants at 4–5 days after inoculation. The young developing leaves become mottled, distorted and wrinkled, and their edges begin to curl downward. Growth of the plants reduced drastically. Internodes and petiole being shorter, leaf size is reduced to only half of their normal size. Such plants produce a few runners, and also a few flowers and fruits. Ultimately, the plants show dwarf and form a rosette like clump. The older leaves of infected plants become chlorotic and thereafter necrotic areas develop along the margin, which later spread over the entire leaf. The dried or killed leaves hang down on the petiole or fall off, leaving part or most of the older vines bare (Singh 1987; Agrios 2000). The infected plants produce low quality fruits having pale green or white areas intermingled with dark green, raised areas. Rough, wartlike projections often appear

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on fruit surface and cause distortion of the fruits. Cucumbers produced by the plants in the latter stages of the disease are misshapen but have smooth grey-white colour with some irregular green areas. The infected plants produce cucumber which tastes bitter (Singh 1987, Agrios 2000). If a plant becomes infected after midseason, vine growth may not be reduced, but developing fruit may be bumpy and deformed (Gour et al. 2008). The Pathogen The pathogen is Cucumber Mosaic Virus (CMV) under Cucumoviruses group. The virus is also differently known as Cucumis Virus 1, Cucumber Virus 1, Cucumber Yellow Mosaic Virus, Spinach Blight Virus, Celery Virus 1, etc. (Singh 1987). The virus particles have been seen in the cytoplasm, nuclei and vacuoles of the host cell but not in mitochondria or chloroplasts (Singh 1987). CMV is characterized by isometric particles measuring 28–30 nm in diameter (Shankar et al. 1971; Giri 1985). The nucleic acid of the virus is single stranded RNA which constitutes 5% of the particle weight (Singh 1987). The virus exists in numerous strains that differ somewhat in their hosts, symptoms production, transmission and in other properties and characteristics (Agrios 2000). Some strains of the virus in India possess a satellite RNA that attenuates system development (Giri 1985). Datura stramonium L. is a good diagnostic and Chenopodium amaranticolor (Coste &A. Reyn.) Coste &A. Reyn. is a good assay host (Verma and Giri 1998). The particles appear spherical with smooth outline and darkly stained central region due to the penetration of the negative stain (Verma and Giri 1998). The virus is relatively unstable and unable to withstand temperature above 70  C for 10 min. Thermal inactivation point is in between 60 and 70  C. Dilution end point is 1:1000 to 1:10000. Infectivity is lost within 1–5 days at room temperature while the longevity in vitro at 34–39  C is 16–18 h (Singh 1987). Disease Cycle CMV overwinters in many perennial weeds, flowers and crop plants. Perennial weeds harbour the virus in their roots during winter and carry it to their top growth in the spring, from which the virus is efficiently transmitted in a non-persistent manner by different species of aphids viz. Aphis craccivora Koch., A. gossypii Glover and Myzus persicae Sulzer (Bhargava and Bhargava 1977; Dubey et al. 1974; Giri 1985; Joseph and Ramanathan 1978; Joshi 1977; Rao 1976; Raychaudhuri and Varma 1975a; Singh et al. 1976; Tripathi and Joshi 1985; Agrios 2000; Kennelly 2012). More than 60 species of aphids are responsible to transmit the virus (Singh 1987). These vectors can acquire the virus within 5–10 s of feeding but declines their ability to transmit the virus after 2 min, which is usually lost within 2 h. Besides, the disease also spreads in the field mechanically through sap during interculture operations and fruit picking (Agrios 2000). The virus is known to be transmitted through the seeds of several species of cucurbits, but in India, it is reported to be seed transmitted in only pumpkin and vegetable marrow (Mukhopadhyay and Saha 1968; Sharma and Chohan 1973; Singh 1987). Dodder transmission of the virus has also been reported (Singh 1987). In addition to

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cucurbitaceous hosts, the virus was recorded to be present in Amaranthus viridis, Physalis minima, Salvia plebeia and Solanum nigrum (Singh 1987). The virus causes systemic infection of most host plants. Older tissues and organs developed before infection are not affected by the virus whereas young active cells and tissues are affected with varying severity. The concentration of CMV in infected plants continues to increase for several days after inoculation, and then it started to decrease until it levels off or until the plant dies (Agrios 2000). According to Gour et al. (2008) the virus survives on weeds, ornamentals and other crops. Pickers may serve to spread the virus from one plant to another during harvesting.

5.3

Cucumber Green Mottle Mosaic Virus (Tobamovirus)

Introduction Cucumber green mottle mosaic virus (CGMMV) was first reported from Great Britain in Cucumis sativus by Ainsworth in 1935 (Okada 1986). In India, the disease was reported first time in bottle gourd (Capoor and Verma 1948; Vasudeva et al. 1950; Mandal et al. 2008). CGMMV is distributed in Europe and Asia (Eurasian region), and it is one of the few plant viruses that has been recorded in Antarctica (Polischuk et al. 2007; Mandal et al. 2008). It has rod shaped particles measuring 300  15 nm (Shankar et al. 1971; Raychaudhuri and Varma 1978a, b). The particles sediment as a major component at 192 S and two minor components at 104 S and 76 S. They contain approximately 5% nucleic acid (Raychaudhuri and Varma 1978a, b). The particles in leaf dip preparation can be grouped into three classes, indicating easy breakage of particles measure 158 nm in length. They are larger than those found in some other isolates of CGMMV (Fukuda et al. 1981). The virus is a strong immunogen and is distantly related serologically to Frangipani mosaic and TMV (Vani and Varma 1988). Several cucurbitaceous vegetables such as bottle gourd (Lagenaria siceraria), cucumber (Cucumis sativus), gherkin (Cucumis anguria), muskmelon (Cucumis melo) and watermelon (Citrullus vulgaris) are affected by the CGMMV (Mandal et al. 2008; Nagendran et al. 2015). High incidence of CGMMV i.e. 100% in bottle gourd, 80% in muskmelon, 75% in watermelon has been recorded in North Indian conditions (Raychaudhuri and Varma 1978a, b; Rao and Varma 1984). A loss of 10–15% was reported due to CGMMV infection in cucumber grown in greenhouses in Canada by Ling and his associates in 2014 (Nagendran et al. 2015) and in China (Shang et al. 2011). Serious outbreak of CGMMV in cucumber and watermelon is known as early as 1966–1969 in Japan (Komuro 1971). Subsequently, the disease appeared as a serious problem in different parts of the world i.e. in 1995 in Greece, 2002 in Korea and 2005–06 in China (Bem and Vassilakos 2000; Yoon et al. 2008; Chen et al. 2008). CGMMV being a potential threat to the production of cucurbitaceous crops has been recognized as a quarantine pest by the Government of China in May 2007 (Chen et al. 2008; Mandal et al. 2008).

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Symptoms The typical symptoms caused by CGMMV are systemic greenish mottle mosaic on foliage; however, the nature of the symptoms and loss depends upon the time of infection, type of host and the strain of the viruses associated with the disease. Early infection produces aggressive symptoms and causes severe losses. When the plant is attacked soon after emergence, the cotyledons are yellow and seedlings show symptoms of wilt. In case of older plants, symptoms appear first on younger leaves showing alternate green and yellow patches, which are of irregular in shape and enlarge rapidly, ultimately cover the entire leaf. The diseased leaves are mottled, deformed, small and sometimes curled downward. The veins and veinlets also turn yellow. Sometimes, there are shallow depressions on the leaves. Shortening of the internodes followed by dwarfing of the plant is common. The activity of the virus is reduced when the leaf ages. Young fruits are rough, mottled and deformed. Often these fruits are white and much smaller in size than normal ones. Fruit drop is also common. Yield is reduced by 25% even more if no management options are taken into account. In the epidermis of the infected plants characteristic structures can be seen easily with a microscope. CGMMV causes serious distortion and decomposition of fruits. In grafted watermelon plant it causes ‘Blood Flesh’ disease in Korea (Lee et al. 1990), ‘Konnyaku’ disease in Japan (Komuro et al. 1968). Infected cucumber, bottle gourd and cantaloupe plants consisted of young fully expanded leaves showed symptoms of mottling, systemic mosaic, mild to severe yellow mottling, vein clearing, blistering and growth stunting (Moradi and Jafarpour 2011). The aucuba mosaic strain of CGMMV causes yellow mottling on leaf and yellow streak or fleck on fruits of cucumber (Ainsworth 1935). On snake gourd symptoms appear as mosaic, mottling with reduction of leaf size and phylloid flowers (Nagendran et al. 2015). The Pathogen The pathogen is Cucumber Green Mottle Mosaic Virus (CGMMV) under the Tobamoviruses group. The virus is also differently known as Cucumis Virus 2 and Cucumber Virus 3. The particles of the virus are present in all tissues of the infected plant including pollen and occasionally seed embryo. Cytoplasmic inclusions are also found (Singh 1987). It has rod shaped particles measuring 300  15 nm (Shankar et al. 1971; Raychaudhuri and Varma 1978a, b; Singh 1987). The nucleic acid is single stranded RNA constituting about 6% of the particle weight (Singh 1987). The particles sediment as a major component at 192 S and two minor components at 104 S and 76 S. They contain approximately 5% nucleic acid (Raychaudhuri and Varma 1978a, b). The particles in leaf dip preparation can be grouped into three classes, indicating easy breakage of particles measure 158 nm in length. They are larger than those found in some other isolates of CGMMV (Fukuda et al. 1981). The virus is a strong immunogen and is distantly related serologically to Frangipani mosaic and TMV (Vani and Varma 1988). All strains of CGMMV are stable. In cucumber the type strain of CGMMV has thermal inactivation point (TIP) at 90  C, and TIP for watermelon strain at 90–100  C (10 min), while the Indian

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isolates have TIP of 95–88  C (Raychaudhuri 1977; Singh 1987). The dilution end point (DEP) is 1:1000000 for the type strain and 1:10000000 for watermelon strain. The Indian isolates have DEP of 1:10000. Infectivity is retained for several months at room temperature and for several years at 0  C (Singh 1987). Disease Cycle CGMMV is a sap transmitted disease through foliage contact and handling of plants during cultivation, and transmission through fungus is also suspected (Singh 1987). The virus does not have any specific vector, although cucurbit leaf beetle Aulacophora foveicollis Lucas is able to transmit the virus to the extent of 27% (Rao and Varma 1984; Vani and Varma 1988). Infective virus particles were detected in the regurgitated fluids and excreta of the leaf beetle feeding on the diseased leaves. This is not a seed transmitted virus disease in muskmelon, vegetable marrow and bottle gourd (Rao and Varma 1984; Vani and Varma 1988). However, in Japan and Netherlands, up to 8 and 5% seed transmission of the virus was reported in cucumber and watermelon, respectively, after 1 month of harvest but that will fall down to 1% after 5 months of seed storage. Seed transmission has also been recorded in bottle gourd (Van Koot and Van Dorst 1959; Komuro et al. 1971; Singh 1987). Contamination of seed is mostly external. Some species of dodder including Cuscuta campestries is able to transmit this virus (Singh 1987). Commercially important watermelon varieties are generally cultivated by grafting on the rootstock of bottle gourd or other cucurbits in China, Greece, Japan and Korea, where seed and graft transmission have been attributed to introduction and emergence of CGMMV (Mandal et al. 2008). Under field conditions, the virus is transmitted through contaminated tools, but not through soil or pollen (Rao and Varma 1984). The cutting knives used by growers for harvesting fruits from diseased plants can potentially contribute additional means of field spread of CGMMV during fruiting stage of crop. Under experimental condition, the CGMMV could be transmitted up to four healthy bottle gourd plants through serial cuttings by contaminated razor blade (Mandal et al. 2008). Nearly 18% transmission of CGMMV has been demonstrated in bottle gourd when soil was mixed with freshly dried infected plant debris. The infected plant debris possibly contributed as primary source of infection to a limited number of plants and successively the virus spreads through plant to plant contact (Rao and Varma 1984). Soil contamination occurs through infected crop debris where the virus remains infective (Singh 1987). The virus remains infective in the contaminated soil for at least 10 months (Varveri et al. 2002). Irrigation water plays an important role in the spread of the virus (Vani and Varma 1988). The host range of the virus is restricted to the members of Cucurbitaceae and Chenopodiaceae. Chenopodium amaranticolor is a good assay host (Verma and Giri 1998). The virus infects naturally bottle gourd, muskmelon and watermelon in India (Shankar and Nariani 1974; Raychaudhuri and Varma 1975a) whereas in other countries, it causes disease in cucumber. It is interesting that even though the virus infects Cucurbita pepo L. easily by mechanical inoculation, no natural infection occurs in this host (Verma and Giri 1998). Nagendran et al. (2015) also reported mechanical transmission of the virus by inoculating Nicotiana

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glutinosa plants with crude sap extracts from symptomatic leaves of snake gourd. They first documented serological and molecular evidence for the occurrence of CGMMV in snake gourd in India. The virus is also capable to infect Datura stramonium (Singh 1987). Other tobamovirus infecting cucurbits are Cucumber fruit mottle mosaic virus (CFMMV), Kyuri green mottle mosaic virus (KGMMV), Zucchini green mottle mosaic virus (ZGMMV), which were reported by the scientists from different parts of the world (Antignus et al. 2001; Francki et al. 1986; Yoon et al. 2001; Ryu et al. 2000; Yoon et al. 2002).

5.4

Watermelon Mosaic Virus (WMV) (Potyviruses)

Watermelon Mosaic Virus (WMV) is among the top ten economically significant filamentous viruses of the Indian subcontinent (Varma 1988; Verma and Giri 1998). The virus has wide host range and reported to cause severe damage to the crops. Symptoms Watermelon mosaic virus and Watermelon mosaic virus-2 produce mosaic symptoms on host. Primarily, the symptoms appear on younger leaves showing alternate green and yellow patches, which are of irregular in shape and enlarge rapidly, ultimately covering the entire leaf. Besides, diseased leaves are deformed severely, growth of the leaves becomes restricted and sometimes curled downward. Often they are filiform. Except the tissues adjacent to veins and veinlets, remaining lamina surface may be destroyed. The vein and veinlets frequently protrude beyond the leaf margin and leaves become spindle shaped. The veins in the leaves originate from the base of the leafstalks. Poor flowering and defoliation are the other defects. This virus is the most dangerous among the entire cucurbit virus (Singh 1987; Verma and Giri 1998). The Pathogen Watermelon Mosaic Virus (WMV) is differently known as Papaya Ring Spot Virus (PRSV-W), Watermelon Mosaic Virus-2 (WMV-2), Melon Mosaic Virus, Muskmelon Mosaic Virus, Cucumis Virus 3 (Singh 1987). Earlier, they were considered as strains of the watermelon mosaic virus. But, now they appeared to be distinct on the basis of host range study and antigenicity test (Verma and Giri 1998). In India, the earliest record of this virus seems to be that of Vasudeva and Lal (1943), who described it as bottle gourd mosaic virus causing mosaic disease. It was difficult to distinctively identify the virus, because the studies of Vasudeva and Lal (1943) were limited only on host range and physical properties. Later investigations revealed that PRSV-W and WMV-2 are anisometric filamentous viruses with particle length of 720–760 nm (Raychaudhuri and Varma 1975a). Slight variations in the length of particles were found in different isolates of the virus (Bhargava 1977). The viruses, PRSV-W and WMV-2 are easily transmitted by sap inoculation, but no evidence of seed transmission was recorded in India (Raychaudhuri and Varma

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1975a). These viruses are efficiently transmitted by different species of aphids in a non-persistent manner (Shankar et al. 1969; Raychaudhuri and Varma 1975b; Darekar and Sawant 1989). Although, the aphids viz. Aphis gossypii, A. craccivora, A. fabae, Macrosiphum sonchi L., Rhopalosiphum maidis Fitch and Myzus persicae transmit PRSV-W in India (Bhargava et al. 1975), while WMV-2 is transmitted efficiently through A. gossypii and Myzus persicae (Raychaudhuri and Varma 1975a, b). Aphis gossypii is the most important vector for transmission of these viruses (Bhargava et al. 1975; Verma and Giri 1998). A. gossypii can acquire the virus after 1 min of feeding. No incubation period is required and the vector becomes viruliferous immediately. Ten aphids can cause 100% infection (Singh 1987). In expressed sap of infected Cucurbita pepo the virus loses infectivity after 10 min at 58–65  C and after 20–50 days at 20  C. The thermal inactivation point of Indian isolates is reported to be 55–60  C (Raychaudhuri 1977). The dilution end point of C. pepo isolate is 1:10000 to 1:100000 and that of watermelon isolate 1:100 to 1:10000. In vitro longevity is only 8 h (Singh 1987). Isolates of Papaya Ring Spot Virus (PRSV) from cucurbits resemble the type W strain of the virus (Purchifull et al. 1984). The host range of all the isolates of PSRVW is restricted within the family cucurbitaceae. The virus causes mosaic diseases in Cucurbita maxima Duch. (Singh 1981), C. moschata Duch. ex Poir. (Ghosh and Mukhopadhyay 1979a, b), C. pepo (Reddy and Nariani 1963) and vegetable marrow (Raychaudhuri and Varma 1975a). The important reservoirs of PRSV-W are vegetatively propagated Trichosanthes dioica, Lagenaria vulgaris, Momordica dioica and Coccinia grandis (Bhargava et al. 1975). Watermelon Mosaic Virus (WMV-2) has a wide host range, causes severe disease in C. pepo and other cucurbits (Raychaudhuri and Varma 1975a, b). Bottle gourd, chow-chow, pointed gourd, watermelon and ash gourd were reported to be infected with Watermelon Mosaic Virus (WMV) from different parts of India. The virus produces mosaic disease and sometimes causes severe damage to the crops (Shankar et al. 1972; Bhargava and Bhargava 1977; Singh 1981; Vani 1987). The disease is more severe in bottle gourd when the plants are infected with both Cucumber Green Mottle Mosaic Virus (CGMMV) and WMV. Mahmood et al. (1974) reported that the disease in bottle gourd is more severe when the plants also infected with powdery mildew disease (c. o.: Sphaerotheca fuliginea). Susceptibility of the plants to root knot nematode (Meloidogyne incognita) may be increased due to the infection of WMV (Mahmood et al. 1974; Nayar and More 1988). WMV is a serious problem of chow-chow in Karnataka (Singh 1981). The virus is efficiently transmitted by aphids and through seeds. In watermelon, mosaic disease starts appearing about 40 days after sowing and reaches about 80% incidence by the end of the season in Delhi condition (Vani 1987). Bhargava and Bhargava (1977) reported the WMV causing mosaic disease of ash gourd and pointed gourd from Uttar Pradesh, which is sap transmissible and also transmitted by Myzus persicae and Aphis gossypii in a non-persistent manner. In case of ash gourd, the host range of the virus is restricted to cucurbits and Vigna sinensis whereas, in pointed gourd, the host range is restricted to cucurbits, Vigna sinensis and Zinnia elegans.

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Aphids and in some cases leaf miners can transmit the watermelon mosaic virus. The virus spreads by farm machinery and pickers, as well as by insects. The disease is severe during the warm growing season (Gour et al. 2008). Roy and Mukhopadhyay (1980) studied the epidemiology of watermelon virus-1 (WMV-1) in pumpkin and detected the virus in root, leaf debris and seeds. They not only recorded 86% transmission by Aphis gossypii but also observed transmission of the virus through contact between the above ground parts of the plants. Manual handling is another method of transmission of the virus recorded by them (Mukhopadhyay and Nath 1998).

5.5

Pumpkin Yellow Vein Mosaic Virus (Geminiviruses)

Geminiviruses were found to be associated with bitter gourd, muskmelon, pumpkin, sponge gourd and cucumber from different parts of India, and incidence of the disease in bitter gourd was recorded nearly 80% (Varma 1955; Ghosh and Mukhopadhyay 1979a, b; Giri et al. 1981). In India, yellow vein of cucumber was first reported from Pune (Varma 1955) and later from West Bengal (Ghosh and Mukhopadhyay 1979a). In 1989, the disease of cucumber and pumpkin appeared in epidemic form in Delhi (Verma and Giri 1998). Yellow vein disease of pumpkin was reported from Maharashtra (Capoor and Ahmad 1975), Uttar Pradesh (Bhargava and Bhargava 1977) and West Bengal (Ghosh and Mukhopadhyay 1979a). The disease has also been reported to be common in South India (Capoor and Ahmad 1975; Singh 1981). Symptoms Vein clearing of the finer veins and appearance of scattered chlorotic blotches all over the surface of leaf lamina are common characteristic symptoms of the disease. Vein clearing is increasing in trend in case of infected young leaves. Leaves of older plants show a mixed pattern of vein yellowing in smaller areas and chlorotic patches over larger areas of the lamina (Singh 1981). The virus causes leaf distortion in bitter gourd, yellow vein in cucumber and pumpkin (Giri et al. 1981; Varma 1955; Ghosh and Mukhopadhyay 1979a, b). Leaf distortion in bitter gourd is very common in northern and eastern India during rainy season. Besides, the diseased plants develop veinal chlorosis and chlorotic spots. The internodes of infected plants are shortened and axillary buds proliferate. Fruiting is reduced. Fruits are deformed and contain shrivelled seeds. Infection results in about 18% reduction in viability of pollen. The symptoms are very prominent in the susceptible variety, Faizabadi (Giri et al. 1981; Verma and Giri 1998). The disease also appears on tinda (Citrullus vulgaris var. fistulosus), sponge gourd (Luffa spp.), aster plant (Callistephus chinensis) and tobacco (Singh 1981). The Pathogen The viruses of this group have geminate particles measuring 30  19 nm formed by the joining of two icosahedral particles. The concentration of the particles is greater

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in fully expanded young leaves than in the very young and old leaves. These viruses are efficiently trapped by the antiserum to squash leaf curl virus in immune-electron microscopy tests. Various geminiviruses can be distinguished by their reactions to panels of monoclonal antibodies to African and Indian cassava mosaic viruses (Verma and Giri 1998). The Virus infecting pumpkin is neither seed nor sap transmitted. Even one whitefly can transmit the virus but maximum transmission occurs with 20–50 viruliferous vectors. Though the vector can pick up the virus by feeding on a diseased leaf for only 30 s, optimum feeding period is 5 min. An incubation period of 2 h is required after feeding. Transmission feeding period is 2 min. The virus is semi-persistent in the vector (Singh 1981). The virus is transmitted by whitefly, Bemisia tabaci, but not by aphids Myzus persicae or Cerosipha gossypii (Singh 1981). The geminivirus infecting bitter gourd is easily graft-transmissible. The virus is not transmitted by sap inoculation, whereas it is efficiently transmitted by the insect vector, whitefly (Bemisia tabaci), in a persistent manner. The virus is also seed borne in bitter gourd (Mishra et al. 1983). The viruses of this group are gradually becoming more prevalent and they may become a serious problem for cucurbit cultivation. The ecological conditions that favour cucurbit cultivation also favour these viruses (Verma and Giri 1998).

5.6

Tobacco Ring Spot Virus (Nepovirus)

Nepovirus was found associated with muskmelon (Cucumis melo) and long melon (Cucumis melo cv. utilissimus) with different types of symptoms viz. mosaic, ring spot, etc. Ring spot type symptoms of muskmelon were reported by Vishwanath et al. (1980) from Delhi. In ring spot, the leaves of diseased plants develop mosaic or mottling with chlorotic areas that subsequently form a ring spot pattern. Occasionally, young leaves develop small yellowish brown dots surrounded by bright yellow halo or margin (Vishwanath et al. 1980). The causal virus disease is transmitted mechanically, but not by aphids. It also infects Nicotiana tabacum, N. glutinosa and Petunia hybrid, producing systemic symptoms, and induces local lesions on inoculated leaves of Cucumis amaranticolor. The virus has been tentatively identified as tobacco ring spot virus (nepovirus) (Verma and Giri 1998). Mosaic type symptoms of long melon were reported and described by Rani et al. (1971) and Raychaudhuri (1973) from Delhi. They recorded 70% disease incidence. The leaves of the diseased plants show fine vein clearing followed by mottling and well defined mosaic. The mottling usually starts on the margins of leaves and gradually progresses towards the petiole. Leaf size is reduced without any apparent blistering or puckering. The virus is not transmitted by aphids and seeds, and it infects mostly cucurbit hosts. Chenopodium amaranticolor is a good assay host and Datura stramonium is a diagnostic host (in which the virus produces severe symptoms). On the basis of serology, Rani et al. (1971) identified the Lucknow

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isolate to be tobacco ring spot virus. However, this needs further confirmation as various properties of the causal virus suggest that it may belong to comovirus group (Verma and Giri 1998).

5.7

Cucumber Latent Virus (CLV)

A latent virus disease of muskmelon was reported from West Bengal with 25–40% incidence (Bandyopadhyay and Mukhopadhyay 1977). The causal virus was tentatively identified as a strain of cucumber latent virus (Webb and Bohn 1961; Webb 1963). The virus is transmitted by sap inoculation, and by the aphids, Aphis gossypii, A. craccivora and Myzus persicae in a non-persistent manner. The virus is transmissible to Cucumis sativus, Cucurbita moschata, Luffa acutangula, Vigna sinensis and Cucumis amaranticolor. The virus is not transmissible to Nicotiana tabacum cv. White Burley and Datura stramonium. It is revealed from the properties of the virus that it may be a strain of CMV (Verma and Giri 1998).

5.8

Zucchini Yellow Mosaic Virus (ZYMV)

Zucchini yellow mosaic virus (family Potyviridae, genus Potyvirus) causes severe damaging to the cucurbitaceous crops. The virus is destructive especially in tropical and subtropical regions of the world (Desbiez and Lecoq 1997; Coutts et al. 2011; Lecoq and Katis 2014). It has 680–730 nm flexuous filamentous virions (Desbiez and Lecoq 1997), and a positive sense, single stranded RNA genome consisting of 9951 nucleotides (nts) (Lecoq and Katis 2014). The leaf symptoms of ZYMV infection are severe vein banding, yellowing, severe mosaic, deformation, leaf malformation, blistering and reduced size. Infected plants are stunted. Fruit symptoms of pumpkin, zucchini, squash, watermelon and cucumber include mottled skin, uneven colouring and knobbly areas that cause prominent deformations. Infected rock melon fruit often have poorly formed surface ‘netting’. Infected fruit has reduced shelf life. Symptoms are similar to those caused by infection with papaya ringspot virus and watermelon mosaic virus (Nasr-Eldin et al. 2016; Anonymous 2018). The severity of symptoms and magnitude of yield and quality losses depend on the time of infection, strain of the virus and the variety grown. As much as 100% yield losses occur if the cucurbit plants are infected early i.e. before flowering. Qualitatively defective and unmarketable fruits can be produced by the plants when infection occurs before or at fruit setting stage. When plants are infected after fruit set, lower yield with inferior quality fruits is frequent. The virus is unable to survive in soil or dead plant material. The spreading of ZYMV occurs from infected cucurbit crops or volunteer cucurbit plants. Aphid vectors (Aphis gossypii, A. craccivora and Myzus persicae) acquire the virus particles from infected alternative hosts and spread it to healthy cucurbitaceous crops growing nearby in a non-persistent manner. Aphid picks up the virus within 1–2 s while probing an infected plant and then transmits the virus within 1–2 s to healthy plants. After that the aphid loses its infectivity (Desbiez

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Table 8 Viral diseases of cucumber in Eastern India Particle characteristics and physical properties of viruses Cucumber mosaic virus (CMV) is the isometric Cucumovirus, 30 nm in diameter, (+)ssRNA, DEP 1:10000, TIP 60–70  C, LIV 3–4 days Potato virus Y (PVY) is the unenveloped filamentous Potyvirus with a modal length of 750 nm  12 nm, (+) ssRNA, DEP 1:100–1:1000, TIP 52–55  C, LIV 24–48 h

Transmission and interseasonal carryover of viruses Transmit mechanically and by aphid vector i.e. Myzus persicae, Aphis fabae and Macrosiphum euphorbiae in non-persistent manner. Interseasonal carryover of the virus occurs through infected crops, weeds and contaminated seeds

Symptoms produced by the virus Mixed infection of CMV and PVY: Lamina shows mosaic with irregularly distributed chlorotic tissues with or without sharp margins

and Lecoq 1997; Lecoq and Katis 2014; Anonymous 2018). ZYMV is readily spread between plants when footwear, cutting implements or machinery damage infected leaves and the infective sap then brushes or rubs onto healthy plants. The virus can survive on surfaces, including metal, plastic, rubber and cotton for several hours. Such virus spread can be reduced by using footbaths or cleaning cutting implements and machinery with a 1:4 dilution of household bleach or a 20% solution of skim milk powder (Anonymous 2018). Plumb et al. (2000) recorded different viruses of crops and weeds in Eastern India. They presented a clear picture about the following viral diseases of cucurbitaceous vegetables. The details of cucurbits infecting viruses, their particle characteristics and physical properties (Bawden and Pirie 1937; Ross 1948; Anderson 1954; Weintraub and Ragetli 1966; Smith 1972; Narayanasamy 2001) are presented in tabular form below (Tables 8, 9, 10, 11, 12, and 13).

5.9

Management of Viral Diseases

Continuous cultivation of cucurbits, monocropping and their intercropping provide ideal condition for the perpetuation, inoculum build-up and spread of the virus diseases. The most important cucurbit virus in India is PRSV-W. It is efficiently transmitted by aphids in a non-persistent manner and infects almost all the cucurbits grown in India. Separation of PRSV-W and WMV-2 is rather difficult. Therefore, for management purposes they may be considered as one virus. Another important cucurbit virus is CGMMV, which again infects all the cucurbits. It is transmitted easily by contact. The epidemics of whitefly-transmitted geminiviruses in recent years are a pointer to the possibility of increase in diseases caused by geminiviruses necessitating great attention to their management. Management of the viral diseases are very much difficult. Some important techniques that can be adopted to reduce the

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Table 9 Viral diseases of ivy gourd in Eastern India Particle characteristics and physical properties of viruses Watermelon mosaic virus 1 (WMV 1) is the unenveloped filamentous to flexuous Potyvirus, (+)ssRNA, DEP 1:10000–1:30000, TIP 55–60  C, LIV 9–10 days

Zucchini yellow mosaic virus (ZYMV) is the unenveloped filamentous to flexuous Potyvirus, (+)ssRNA

Cucumber green mottle mosaic virus (CGMMV) is the unenveloped rod shaped Tobamovirus with a modal length of 364 nm  18 nm, (+)ssRNA, TIP 80–90  C, LIV 1 year

Transmission and interseasonal carryover of viruses Transmit mechanically and by aphid vector i.e. Myzus persicae, Aphis craccivora and Macrosiphum euphorbiae in non-persistent manner. Interseasonal carryover occurs through infected crops where they harbour and transmitted to susceptible crops by the insect vectors/mechanical contact Transmit mechanically and by aphid vector i.e. Aphis gossypii, Aphis craccivora, Lipaphis erysimi, and Myzus persicae in non-persistent manner. Interseasonal carryover of the virus through infected crops and weeds. Interseasonal carryover occurs through infected crops where they harbour and transmitted to susceptible crops by the insect vectors/ mechanical contact Transmit mechanically, no vector known. Interseasonal carryover occurs through infected crops, and acts as reservoir host of the virus for other cucurbits

Symptoms produced by the virus Mixed infection of WMV 1 and ZYMV: Lamina shows diffuse mottling, mild deep green blisters; marginal lobes become deep CGMMV: Lamina shows irregularly distributed sharply marginal yellowish chlorotic spots

spread and severity of these diseases in field as well as greenhouse condition are discussed below:

5.9.1 Disease Free Seeds/Planting Materials In India, seed transmission has been found only for the CMV in different cucurbits. Whereas, in Japan CGMMV has been shown to be transmitted through seeds (Komuro et al. 1971). Seed transmission of a geminivirus causing leaf distortion in bitter gourd has also been reported. So, disease free seeds from healthy plants are essential to avoid seed borne inoculum. Use of disease free healthy transplants can also minimize the problem. To eliminate CMV infection in Cucurbita pepo, the virus can be inactivated by treatments with hot air (70  C for 2 days) or hot water (55  C for 60 min) (Sharma and Chohan 1973).

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Table 10 Viral diseases of bitter gourd in Eastern India Particle characteristics and physical properties of viruses Zucchini yellow mosaic virus (ZYMV) is the unenveloped filamentous to flexuous Potyvirus, (+)ssRNA

Potato virus Y (PVY) is the unenveloped filamentous to flexuous Potyvirus, (+) ssRNA, DEP 1:100–1:1000, TIP 52–55  C, LIV 24–48 h

Transmission and interseasonal carryover of viruses Transmit mechanically and by aphid vector i.e. Aphis gossypii, Aphis craccivora, Lipaphis erysimi, and Myzus persicae in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by aphid vector i.e. Myzus persicae, Aphis fabae and Macrosiphum euphorbiae in non-persistent manner. Interseasonal carryover occurs through weeds and infected potato tuber

Symptoms produced by the virus Mixed infection of ZYMV and PVY: Irregular yellowish chlorotic spots, gradually coalesce together to form more or less sharp yellowish areas particularly around the tips of the lamina which becomes rough, thick and leathery with upward cupping; deep green blisters are found around the vein

Table 11 Viral diseases of ridge gourd in Eastern India Particle characteristics and physical properties of viruses Watermelon mosaic virus 1 (WMV 1) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 760–800 nm  12 nm, (+) ssRNA, DEP 1:10000–1:30000, TIP 55–60  C, LIV 9–10 days Zucchini yellow mosaic virus (ZYMV) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 750 nm  11 nm, (+) ssRNA Cucumber green mottle mosaic virus (CGMMV) is the unenveloped rod shaped Tobamovirus with a modal length of 364 nm  18 nm, (+)ssRNA, TIP 80–90  C, LIV 1 year

Transmission and interseasonal carryover of viruses Transmit mechanically and by aphid vector i.e. Myzus persicae and Aphis craccivora, etc. in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by aphid vector i.e. Myzus persicae and Aphis fabae in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by contact; no vector known. Interseasonal carryover occurs through infected crops, weeds and contaminated seeds

Symptoms produced by the viruses WMV 1: In general, the lamina shows slight distortion, pale yellowing and irregularly distributed deep green blister. While in some cases of infection lamina becomes pale yellowish, with irregularly distributed deep green spots; vein and veinlets prominent ZYMV: Mosaic mottle, yellowish chlorotic spots on the surface of the lamina; veins and veinlets prominent and greenish CGMMV: Diffused yellowish chlorotic patches in the interveinal regions

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Table 12 Viral diseases of pointed gourd in Eastern India Particle characteristics and physical properties of viruses Cucumber mosaic virus (CMV) is the isometric Cucumovirus, 30 nm in diameter, (+)ssRNA, DEP 1:10000, TIP 60–70  C, LIV 3–4 days

Cucumber green mottle mosaic virus (CGMMV) is the unenveloped rod shaped Tobamovirus with a modal length of 364 nm  18 nm, (+)ssRNA, TIP 80–90  C, LIV 1 year

Transmission and interseasonal carryover of viruses Transmit mechanically and by aphid vector i.e. Myzus persicae and Aphis gossypii in non-persistent manner. Interseasonal carryover occurs through infected crops, weeds and contaminated seeds Transmit mechanically and by contact; no vector known. Interseasonal carryover occurs through infected crops, weeds and contaminated seeds

Symptoms produced by the viruses CMV: Lamina shows mosaic mottling, irregularly distributed yellowish patches and green vein banding CGMMV: Lamina shows irregularly distributed chlorotic spots

5.9.2 Cultural Practices Field should be kept weed free. CGMMV can be transmitted through water (Vani and Varma 1988). It is, therefore, essential to use uncontaminated water for irrigation. CGMMV can also spread by contact and contaminated tools. Proper hygiene can be maintained to minimize spread of the virus. Avoidance of overlapped cropping will help reduce the incidence of viruses transmitted by aphids or white flies. It may also be possible to devise protection methods which minimize aphid transmission of the virus during the early period of growth (Thomas 1980). Use of mulches (Vani et al. 1989) can reduce viral disease incidence and helps in improving the yields. Silver reflective mulches may reduce aphids’ infestation (Kennelly 2012). The light reflected from the mulch surfaces (aluminium foil or ‘Panda’ film) can prevent winged aphids from landing on the plants. If infection could be prevented or reduced until the plants started to crop, the loss in production could be minimized, as shown for WMV-2 on pumpkin and cucumber crops in New Zealand by Thomas (1971). Rogueing and destruction of infected plants from the field are important to manage the disease. All the infected plants should be eradicated from the field. The field and its surroundings should be kept free from the hosts including weeds, wild hosts and self-sown cucurbits to reduce any potential virus and aphid sources. Control of WMV-1 and CGMMV is difficult since the presence of wild pumpkin, balsam apple and many other wild cucurbits and non-cucurbits facilitates a carryover of the virus from one season to the next. Incidence of the virus can be reduced by destroying these weed hosts (Thomas 1980; Lecoq and Katis 2014). New planting near older cucurbits fields should be avoided. Proper sanitary measures should be maintained i.e. disease inoculum should be destroyed by ploughing down of old cucurbit crops. Removal and proper destruction of old cucurbit crops have to be performed immediately after the final harvest to minimize virus spread to new crops.

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Table 13 Viral diseases of pumpkin in Eastern India Particle characteristics and physical properties of viruses Watermelon mosaic virus 1 (WMV 1) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 760–800 nm  12 nm, (+) ssRNA, DEP 1:10000–1:30000, TIP 55–60  C, LIV 9–10 days Watermelon mosaic virus 2 (WMV 2) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 750 nm  12 nm, (+)ssRNA, DEP 1:10000–1:30000, TIP 55–60  C, LIV 9–10 days Zucchini yellow mosaic virus (ZYMV) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 750 nm  11 nm, (+) ssRNA, TIP: 55–60  C, LIV: 3–5 days. Virus first reported in Cucurbita pepo from Italy (Lisa et al. 1981) Bean yellow mosaic virus (BYMV) is the unenveloped filamentous to flexuous Potyvirus with a modal length of 750 nm  12 nm, (+) ssRNA, DEP 1:800–1:1000, TIP 56–60  C, LIV 24–32 h

Transmission and interseasonal carryover viruses Transmit mechanically and by aphid vector i.e. Myzus persicae, Aphis craccivora and Macrosiphum euphorbiae in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by aphid vector i.e. Myzus persicae and Aphis craccivora in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by aphid vector i.e. Aphis gossypii, A. craccivora, Lipaphis erysimi and Myzus persicae in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds Transmit mechanically and by aphid vector i.e. Myzus persicae and Aphis fabae in non-persistent manner. Interseasonal carryover occurs through infected crops and weeds

Symptoms produced by the viruses WMV 1: Mosaic mottle, starting from the base of the lamina; irregularly distributed chlorotic yellowish patches on the surface of the lamina; laminar tissues rugose. In acute infection lamina becomes crumpled, blistered, yellowish, leaving isolated green tissues around the veins and veinlets Mixed infection of WMV 2, ZYMV and BYMV: Greenish yellow mosaic mottling on the upper surface of the lamina; chlorotic tissues mostly located near the margin of the lamina and internal areas; infected leaves become slightly deformed. Most characteristic symptom is thickening of vein and veinlets on the under surface of the lamina and formation of cup shaped enations; petioles become stiff and slightly curved

Some other important options of cultural practices that can be employed to manage the viral diseases of cucurbits are use of physical barrier surrounding the field, use of trap crops, adjustment of planting time, etc.

5.9.3 Prevention of Vector Transmission The insect vector can be managed by the use of insecticides. Application of systemic insecticides to crops is unlikely to reduce the incidence of WMV-l because aphids may not be destroyed quickly enough to prevent their transmitting the virus in the non-persistent manner when migrating from infected weeds (Thomas 1980). Use of nylon net or shed net for culturing the cucurbits helps reduce the disease incidence by making barrier of crops from vectors. Planting of tall non-host border crops (like Cajanus cajan, Vigna negundo, etc.) around the cucurbit crop about 4 weeks before

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planting can hinder the direct entry of the insect vector. A non-host border crop acts as a cleansing barrier for insect vectors especially aphids. Infective aphids that feed on it will lose the virus and will no longer be infective when they land on the cucurbit crops (Anonymous 2018). Target specific and eco-friendly insecticide should be used, as the insecticides are one of the main causes of pollution. It discourages pollinators and natural enemies in crop fields, and also disturbed soil microbiota. Application of oils (Krishi oil @ 2%) can be advantageous in reducing virus transmission by aphids. This was reported by Raychaudhuri and Varma (1983) in case of WMV-2 in Cucurbita pepo. Poison bait (composition for preparation of 2 L poison bait: Malathion 50% EC 20 mL + molasses 200 g + water 2 L) can also be used to prevent insect vector effectively (Bhattacharya et al. 2006). The disease can be controlled by spraying of Phosphamidon 40% SL @ 0.15% that effectively lowers down the insect vector populations in field (Gour et al. 2008). Spraying of systemic insecticides (Acetamiprid 20% SP at 0.05%, Imidacloprid 17.8% SL at 0.05%, Thiamethoxam 25% WG at 0.03% at 10 days’ interval) or Neem based insecticides (Azadirachtin 1% EC at 0.1% or Azadirachtin 5% EC at 0.05%) can help to reduce aphid infestation in cucurbits.

5.9.4 Inactivation of Viral Particle The bottle gourd isolate of the CMV is completely inactivated by crystal violet, sodium lauryl sulphate and thiouracil, when mixed with the inoculum. Treatment of systemic hosts with sodium lauryl sulphate and thiouracil delays appearance of symptoms and the treated plants and calli contain less virus than the untreated control (Rao et al. 1976; Verma and Giri 1998).

5.9.5 Host Resistance Use of resistant plant is one of the most vital key components for successful Integrated Pest Management system. Use of host plant resistance is obviously a prophylactic measure. It has even greater potentiality than any other single tactic or strategy for pest suppression. The majority of cucurbits possess huge genetic diversity. However, very limited efforts have been made to identify sources of resistance and development of resistant varieties. There is an urgent need to improve germplasm collection of various cucurbits so that resistant varieties are developed by traditional breeding (Verma and Giri 1998). Development of plant resistance involves active participation of specialists from different concerned disciplines. The programme requires input from Plant Geneticists, Plant Breeders, Entomologists, Plant Pathologists and Plant Virologists. Various methods have been used to confer resistance to cucurbit viruses including conventional breeding, transgenic techniques, and cross protection with mild strains (Lecoq and Katis 2014). Resistant cultivars of cucurbitaceous crops to many cucurbit viruses including CMV, ZYMV, WMV, are available commercially with many dominant and recessive resistance genes as well as quantitative trait loci (QTLs) (Lecoq and Desbiez 2012; Lecoq and Katis 2014).

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Angiospermic Parasite

217

5.9.6 Use of Biological Agents Biological suppression of plant pathogens including viruses is much interesting and has several advantages over chemical control. When this method is applied in association with others methods of control measures, then it performed best. Different workers are trying to develop best management practices to control viruses infecting cucurbitaceous vegetables throughout the world. Montasser et al. (2017) tried to control CMV biological by using a mild strain of CMV associated with satRNA combined with a mixture of plant growth promoting Rhizobacteria (Pseudomonas aeruginosa and Stenotrophomonas rhizophila). They indicated that the presence of PGPRs significantly improved the plant growth, yield, fruit number, and fruit set rate in chilli pepper compared to using satRNA alone. They recorded reduced rate of viral infection. El-Dougdoug et al. (2012) also expressed similar views when inoculated culture filtrate of Streptomyces species and CMV mechanically to the leaves of Chenopodium amaranticolor. CMV is unable to produce any symptoms on inoculated leaves. They observed that Streptomyces species were able to produce a non-phytotoxic antiviral component in the culture filtrate, which is effective to control of CMV infection. Use of cross protection with mild strains, transformation of plants with coat protein gene of the virus or use of certain of the mild satellite RNAs, either in an inoculum applied to the field-grown plants or as transgene, can reduce the severity of the disease (Agrios 2000). The vectors of viruses can also be managed biologically by applying Verticillium lecanii 1.15% WP at 28–75 gai/ha (Anonymous 2010, 2016b). 5.9.7 Use of Grafting of Technology Grafting a susceptible scion onto a resistant rootstock can provide a resistant cultivar without the prolonged screening and selection required to breed resistance into a cultivar (Davis et al. 2008). It was reported that grafted seedless watermelons increased tolerance to viral complexes (CMV, WMV-II, PRSV and ZYMV) and also showed improved tolerance to Melon necrotic spot virus (MNSV) (Wang et al. 2002). It is apparent that the increased tolerance is due to increases in vigour, photosynthesis, chlorophyll content, and/or peroxidase activity associated with the grafted plants (Davis et al. 2008).

6

Angiospermic Parasite

6.1

Broomrape

Broomrape (Orobanche, Orobanche ramosa and O. aegyptiaca) is one of the most important angiospermic, herbaceous, root holoparasitic plants under the family Orobanchaceae. It causes serious damage (5–100% yield losses) to several economically important crops like cucurbits, tobacco, potato and tomato, etc. especially in the drier and warmer areas of Europe, the Mediterranean region, Central Asia, the Arabian Peninsula and some African countries (Klein and Kroschel 2002; Habimana et al. 2014). It is native to North Africa, but it is known in many other places as an

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introduced species. Broomrape consists of two types—hemp broomrape and branching broomrape. Cucumber cultivation in the Middle East and Mediterranean region is susceptible to infestation of Egyptian broomrape (O. aegyptiaca) (Ashrafi et al. 2009). From a thick root system, the plant produces many slender and erect stems. The yellowish stems grow 10–60 cm tall and are provided with glandular hairs. The broomrape is an annual and sometimes perennial plant and is parasitic on other plants, draining nutrients from their roots. It lacks leaves and chlorophyll. The inflorescence bears several flowers, each in a yellowish calyx of sepals and with a tubular white and blue to purple corolla. Branched broomrape blooms from October to November. Flowers resemble small snapdragons; colour varies from white to blue or violet. Twenty or more flowers cluster together to form a spike-shaped flower head. Upper flowers are stalkless and lower flowers are with short stalk. Stems and flower heads are covered with very short glandular hairs. Seeds of the broomrapes may easily spread from infected to non-infected fields through activities of human, agricultural tools, crop seeds, propagules and animal excreta. The seeds can persist in soil up to 20 years. A single broomrape plant can release more than 5 lakh seeds (Habimana et al. 2014). Broomrape spend most part of their life cycle underground, where they undergo processes of germination, haustorial differentiation from the radicle, haustorial penetration of the host, formation of vascular connection with the host, acquisition of host nutrients and storage of resources in a parasite organ called the tubercle or nodule. Haustoria penetrate the host tissues until they reach the vascular system for uptake of water, nutrients, assimilates and grow at the expense of the host plant’s resources (Joel et al. 2007). Because the infection and pathogenesis processes occur underground, damage to the crops takes place prior to the emergence of the parasite and diagnosis of infection (Habimana et al. 2014). Management The life cycle of most parasites occurs belowground connected to the host plant, and therefore, it is very difficult to control by either agronomic practices or herbicides (Goldwasser et al. 2003). Many management strategies have been tried against Orobanche ramosa and other broomrapes, but few of them have proved reliable and these are only economical in high value agriculture (Ashrafi et al. 2009). • The strength of branched broomrape lies in its ability to form a bank of seeds in the soil. A management or eradication program must aim at reducing this seed bank, while minimizing the production of new seeds and their dispersal to new sites. • Quarantine is therefore an essential element in control or eradication programs. • A simulation model (Kebreab and Murdoch 2001) predicted that sustainable control of Orobanche spp. requires a permanent reduction of the seed bank to below 2000 seeds per square metre. Cultural control techniques, applied individually in their model, needed to be highly effective to achieve this reduction; integrated control using several techniques including those aimed at reducing seed recruitment was therefore recommended.

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Diseases Caused by Nematodes

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• In-crop control of Orobanche also requires an integrated strategy. Linke and Saxena (1991) recommended a combination of solarization, herbicides and hand weeding with careful choice of cultivars and sowing times to manage Orobanche in legume crops; none of these methods gave complete control when used separately. Soil solarization which precludes chemical contamination is the most appropriate technology to control Egyptian broomrape on cucumber (Ashrafi et al. 2009). • The late post-emergence application of glyphosate was effective (Lolas 1986) on O. ramosa in tobacco. Two treatments of 50 g/ha glyphosate reduced the number of O. ramosa and increased celery yield (Americanos 1991). Control strategies can only be developed when enough is known of the biology of a weed to recognize its own life strategy, and the vulnerable points in this strategy.

7

Diseases Caused by Nematodes

Plant parasitic nematodes (PPNs), ‘the hidden enemy of crops’ is one of the harmful organisms that cause substantial economic damage to many agricultural and horticultural crops (Khan et al. 2015). Approximately 12% yield loss in vegetables due to infestation of PPNs has been recorded in India (Sehgal and Gaur 1999). Nematodes not only cause direct damage to the plants but also act as predisposing agents to increase susceptibility for developing disease complexes caused by different fungi, bacteria and viruses. Extensive cultivation of susceptible crops particularly in irrigated system significantly increases nematode problems in various crops (Khan et al. 2015). The plant parasitic nematodes have very broad host range. More than 700 hosts have so far been detected, which include most cultivated crops and ornamentals. The nematode is more important in warm temperate, tropical and sub-tropical regions of the world (Brodie et al. 1993; Dasgupta 1998). The cosmopolitan distribution of some species is the result of the movement of rooted plants in commerce and at the local level through movement of water, soil and equipment and rooted seedlings of crop plants and ornamentals (Table 14). Table 14 Diseases caused by the parasitic nematodes

Common name Dagger, American Lesion Pin Reniform Ring Root-knot Spiral Sting Stubby-root Stunt

Scientific name Xiphinema americanum Pratylenchus spp. Paratylenchus spp. Rotylenchulus reniformis Criconemella spp. Meloidogyne spp. Helicotylenchus spp. Belonolaimus longicaudatus Paratrichodorus minor Tylenchorhynchus claytoni

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Deaseas of Cucurbits and Their Management

Root-Knot of Cucurbits

Root-knot of vegetable crops was first reported by Berkeley (1855) in England and Chattopadhyay and Sengupta (1955) in India (Dasgupta 1998). The disease on pointed gourd was also reported for the first time in West Bengal, India, by Mukherjee and Sharma (1973). Later, the disease has been reported in Bihar (Nath et al. 1976a, b). Root-knot nematode population of 1–2 juveniles per gram soil reduced 43.8–44.0% yield of pointed gourd (Dasgupta 1998). The infested plant produces less number and underweight fruits (Verma and Anwar 1999). Other cucurbit vegetables, i.e., cucumber, squash, bottle gourd, sponge gourd, muskmelon and pumpkin are also infested by the pathogen (Dasgupta 1998). The nematode species has cosmopolitan distribution and recorded in warm temperate, tropical and sub-tropical regions of the world. The root-knot nematodes cause root galls at the initial stages of the crop growth. The larvae feed on the roots, which show typical galls, and later the entire root system shows heavy galling. The foliage becomes light yellowish; the plants become stunted and result in flower and fruit drop. In spite of irrigation, the plants appear sick and drooping during daytime in case of heavy infestation. Because of the extensive growth of cucurbitaceous plants, the visible effects of root-knot nematodes are not very clear but there is unthrifty development of the plant, and susceptibility of the roots to other root pathogens is increased. The Pathogen The disease is caused by root-knot nematode (RKN), Meloidogyne spp. The common species are M. incognita, M. javanica, M. arenaria and M. hapla. It has reported that the cucurbits like cucumber, squash and pumpkin are mainly infested by three different species of RKN, M. incognita, M. javanica and M. arenaria, sponge gourd by two different species of RKN, M. incognita and M. javanica, whereas bottle gourd is only infested by M. javanica (Dasgupta 1998). M. incognita has four races (1, 2, 3 and 4), and M. arenaria has two (1 and 2) races. M. incognita race 1 is the only known race in West Bengal, Andhra Pradesh, Kerala and Madhya Pradesh, while other states surveyed show two to four races (Dasgupta 1998). Muller (1883) was the first to be given credit to describe the life cycle of Meloidogyne spp. However, thereafter, a number of research papers have been published regarding the morphology of different developmental stages and duration of life cycle of the nematode species under different environmental situations and with several host plants in relation to their age and nutritional status. The phytonematode is sedentary endoparasite, parthenogenetic. After hatching from eggs, the larvae become infective juveniles during second stage and invade roots in the region of elongation near the root cap. They migrate between and through cells and position themselves with the head in the vascular tissues. Cell damage occurs as a result of the migration. If several juveniles enter the root tip, cell division may stop which resulted in retardation of no root elongation. As feeding continues, several cells near the head begin to enlarge and become multinucleate. These are called giant cells and there are usually 3–6 associated with each nematode. The formation of

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Diseases Caused by Nematodes

221

giant cells and galls is the result of cell enlargement as well as increased numbers of cells. These changes are induced by substances (salivary secretions) introduced into cells and surrounding tissues during the feeding of the nematode. During this process, the xylem vessels become disrupted and the roots cannot function normally with respect to water and nutrients. During the process of gall formation, the nematodes undergo the second, third and fourth moults to reach the adult stages. Mature females are saccate (pear-shaped) and lay eggs into a gelatinous matrix. This matrix may protrude from the surface of small roots or may be entirely within the gall. Eggs hatch out within a week. The entire life cycle is completed within 20–25 days at 30  C. Males are vermiform and are not needed in reproduction. Symptoms The cucurbits are highly susceptible to nematode infestation especially root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood. The disease occurs at different stages of crop growth. Symptoms associated with the disease in young pointed gourd plants are stunting, occasional chlorosis and reduced stands. Infection on older plants makes the stem thin, weak and pale. Fruit formation is hampered (Mukherjee and Sharma 1973). Root system is reduced. Knots on the top roots are large and confluent. The root swells in such a manner that the diameter of the root comes to 15–20 cm. Such swelling of root is common in ratoon crop. These roots become susceptible to attack by Sclerotium rolfsii Sacc. leading to rotting of root and death of plant. Under low disease pressure, the most characteristic symptom of rootknot is the formation of galls at different size on main and branch roots. The affected plants bear undersized and lesser number of fruits, and sometimes matured plants show wilting in daytime. In addition, galls are formed on vine nodes that touch the soil (Khatua and Saha 2004). The growth of pumpkin, bottle gourd, cucumber, squash and sponge gourd plants infected with root-knot nematodes is reduced with galls found scattered on roots. There is a marked reduction in root and shoot growth and fruit yield. Severe infection causes wilting of the foliage and the plants require more frequent irrigations. Other species of Meloidogyne, especially M. hapla and M. javanica have also been found to infest cucurbits in varying intensity. Ecology Meloidogyne spp. prefer coarse soils. M. javanica juveniles have a diameter of 15–18 μm. It migrates through the fine texture soil is greatly improved when the crumbs are 75–100 μm in diameter and almost nothing in crumbs of 40–75 μm. Biotic factors used to reduce Meloidogyne population in soil are organic amendments like crop residue, cellulose, oilcake, chitin, animal product, refuse, tannery waste, sugarcane pressmud, food preservation waste, forest litter, microbial decomposition products, plant exudates and extracts including oils and other biochemicals as well as host factors, and soil organisms acting as predators and parasites. Meloidogyne have been collected in dust traps 2 m above ground in windblown drifts. Many nematodes including Meloidogyne survive through guts of insects, birds and mammals. Meloidogyne spp. associate with other nematodes and other plant pathogens causing varied aetiological biotic associations. Host

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preference, nematode density, climate or soil environmental factors may influence the nature of interaction (between nematodes, between nematodes and mycorrhiza, between nematodes and Rhizobium, nematode–fungus, nematode–virus, nematode– protozoa, nematode–bacteria, etc.). RKN population varies with sources of nitrogenous fertilizers. NH4–N may reduce and NO3–N may increase RKN population in soil, whereas the ions NH4+, K+, Cl, NO3 may impose barrier between roots and nematodes (Dasgupta 1998). Management • Heat treatment of soil is recommended for glass and polyhouse condition (Dasgupta 1998). • Solar drying of glass or polyhouse soils is important to kill the RKN. Drying with frequent turning of soil is necessary. Summer ploughing also brings down RKN population in soil (Dasgupta 1998). • Seed treatment with bio-pesticide Paecilomyces lilacinus or Pseudomonas fluorescens at 10 g/kg seed can reduce the disease incidence. • Long duration crop rotation with non-host crop, i.e., at least 4–6 years crop rotation can minimize the nematode population in soil. • Incorporation of chopped leaves of Ricinus communis L., Calotropis procera (Aiton) W.T. Aiton, Leucaena leucocephala (Lam.) de Witor Melia azadirach L. in root-knot nematode infested soil at 500, 1000 or 1500 g/m2 increases sprout emergence of pointed gourd and decreases infection by M. incognita (Verma et al. 1998; Verma and Anwar 1997). Soil application with any granular insecticides and pre-plant application of Carbofuran (Furadan 3G at 10 kg/ha) on planting holes control the root-knot nematode and increase the yield. • Apply 2 tons of FYM enriched with Pochonia chlamydosporia and Paecilomyces lilacinus per acre before sowing, along with 100–200 kg of neem or pongamia cake. • Soil solarization and application of FYM at 40 t/ha reduce incidence of M. javanica on cucumber roots (Nasr-Esfahana and Ahmadi 1997). • Green manuring with Tagetes or Xanthium leaf powder followed by application of Verbesina and Artemisia reduces population of M. incognita in cultivation of C. pepo (Sharma et al. 1985). Pointed gourd when grown along with marigold plants reduced gall formation and egg mass development of Meloidogyne incognita in roots. The highest toxic effect on gall formation generally exhibited by marigold variety Saffron Spice and lowest with Yellow Gate (Kaushal 1999). • Resistance to M. incognita has been observed in wild species Cucumis dipsaceus and C. anguria and C. sativus cultivars. • Grafting reduced nematode gall formation in cucumber (Giannakou and Karpouzas 2003), watermelon (Miguel et al. 2005) and melon fields (Siguenza et al. 2005). In some cases, the rootstocks appear to provide tolerance by providing extensive root area and vigour (Giannakou and Karpouzas 2003; Miguel et al. 2005), but some rootstocks have genetic resistance that is exhibited in the grafted plants (Hagitani and Toki 1978; Siguenza et al. 2005; Gu et al. 2006).

Weed and Its Management in Cucurbitaceous Vegetables

1

Introduction

Weed is any wild plant that grows in an unwanted place, especially in a garden or field where it prevents the cultivated plants from growing freely. It competes with the desired crop for moisture, nutrients, light and space and thus can reduce yield of vegetable crops up to 37% (Varshney 2009). Weed removes around two times more N and Ca and 25% more potassium from soil than the cultivated crop (Mallik et al. 1998). The agricultural crops in general are infested with a variety of weeds depending upon soil type, agro-climatic zone, season and particular crop species. Out of over 800 weeds documented in India, 200 are considered as major weeds, out of which only 80 are considered as serious (Singh et al. 2019). Why Weeds Are Our Concern? • Weeds compete with crop plant for nutrients, water and light. Thus, it reduces yield. • Weed increases cost of cultivation through increase in weed control operations and increase in protection costs (weeds harbour other pests). • Decrease land value (due to exhaustion of nutrients) and reduce quality of produce (mixing of weed seed in crop seed). • Some weeds are obnoxious, which may cause allergic problem to human beings and even can cause death to domestic animals (like Larkspur, Locoweeds, Crazyweeds, Digitalis, Parthenium, Calotropis, Datura, etc.). How Weeds Compete with Crop? • Weeds have rapid seedling growth and ability to reproduce even when young. Have quick maturation with shorter vegetative phase. • Have dual mode of reproduction (seed as well as vegetative) • Weeds have environmental plasticity; they are capable of tolerating and growing under a wide range of climatic and edaphic conditions. # Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_4

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• Weed seed can thrive for long periods in dormant condition and can regenerate when environment becomes favourable. • Roots of some weeds are able to penetrate and emerge from deep in soil • Weeds can compete with crop by special means like rosette formation, climbing growth, allelopathy, etc. All vegetable crops including cucurbits are slow growing during the first 3 weeks of their growth. During this period of growth, the crops are very much sensitive and susceptible to any hindrances over their growth. Cucurbits are vine crops, which are sometimes grown over bower or trellis, thus they are less prone to weed growth. They surpass weed growth by the spreading vines and developed crop canopy at later stages of plant growth. But, severe weed infestation in early 20 days can pose serious threat to crop stand. The minimum weed-free period in cucumber, squash and other cucurbit crops has been estimated as the first 4–6 weeks after planting (Noble 2009; Peet 1996; Stall 2009). In watermelons and muskmelons, it has been observed that if weeds such as smooth pigweed emerge 4–5 weeks after the crops, they will not reduce crop yield. If the weeds emerge and compete with the crop in the first 4 weeks, however, yield will be reduced. Two nightshade plants growing within the row and between watermelon plants have been shown to reduce yield by as much as 80–100% (Dittmar and Boyd 2019). So, to have a better crop stand, the crop field has to be kept weed free during the early growth period. Similarly, management of weeds of cucurbits at later part of crop growth is also important for better air circulation for the crop and easy harvesting.

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Some Important Weeds Infesting Cucurbits

Almost all the cucurbits are warm-season crop by nature. But due to development of thermo-insensitive varieties, the crops are grown almost round the year in tropics and in an extended period in temperate regions, thus inviting some more kinds of weeds in the field. Weeds in vegetable fields are in different sizes, forms and behaviours. They belong to many families varying in physiology, morphology and habits of growth. For easy interpretation and management, all the weeds are categorized into three major groups, namely—Broad leaf weed (comprising all dicotyledonous weed species), Sedges and Grasses. Major problems in vegetables are caused by broad-leaf weeds because grass weeds are much better managed in rotation or they can be successfully eliminated with the use of selective foliar-applied herbicides. Some common weeds of cucurbit crop fields are discussed below.

2.1

Broad Leaf Weeds

(a) Amaranthus spinosus L. (Family: Amaranthaceae) Commonly known as Spiny amaranth or kanta note. It is another summer-rainy season obnoxious weed in the tropics and sub-tropics, growing up to a height of

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150 cm. Leaves are alternate and ovate. One plant can produce 2.35 lakh seeds. Small, green coloured male and female flowers are borne on the same plant. Fruit is ovoid and contains compressed, shiny, tiny, dark red to black seeds. Amaranthus viridis Hook. (Family: Amaranthaceae) It is a very common broad leaf weed, known as Pig weed, found in the field of pumpkin, ash gourd, bitter gourd, ridge gourd, sponge gourd, pointed gourd, etc. during summer-rainy season. This annual herb can grow up to a height of 100 cm with glabrous or pubescent stem and leaf. Inflorescence is catkin like cymes of densely packed flowers. Seed 1–1.25 mm, round, slightly compressed, dark brown to black with a paler thick border. This weed is cosmopolitan in all warm regions of the world. Boerhavia diffusa L. (Family: Nyctaginaceae) This is a flowering plant of the ‘four o’clock’ family which is commonly known as punarnava, red spiderling, spreading hogweed or tarvine. This weed appears very commonly during spring to summer season in the vegetable fields. It is a spreading herb, with diffusely branched, pubescent or glabrous stem, often purplish, swollen at the nodes, up to 120 cm long with a stout woody root stock. Leaves are long-petioled, ovate or oblong-cordate, usually rough green coloured. Flowers are red, pink or white, borne in small umbels in axillary and terminal panicles. Chenopodium album L. (Family: Chenopodiaceae) This winter annual is commonly known as Bathu or lambs quarter, predominant in the field of all winter vegetables including cucurbits (mainly cucumber, bottle gourd and melons). This is an erect herb, grows up to 30–300 cm tall with angled stems that are often striped with green, red or purple colour. Leaves are variable in size and shape, upper leaves entire, lower ones toothed or irregularly lobbed, 10–15 cm long, with long petioles. Inflorescence borne in clusters forming a compact or loosely panicled axillary spike. Seeds are minute, round, black and shining. Cirsium arvense (L.) Scop. (Family: Asteraceae) This perennial herb, familiar in the name of Canada Thistle or Creeping Thistle, grows from its horizontal roots every year during late winter and gives rise to aerial shoots of 30–150 cm tall which are slender, green and freely branched. Leaves generally oblong, spiny with entire to deep pinnately segmented margin. Plants are dioecious, with globular shaped male flowers, somewhat smaller than the flask-shaped female heads. Florets of both male and female are tubular, rosepurple to pinkish, 23–26 mm long in female heads and 12–14 mm long in male heads. Seeds are 4–5 mm long with feathery pappus which helps in easy wind dispersal. Convolvulus arvensis Linn. (Family: Convolvulaceae) This is a winter perennial creeper, popularly known as wild morning glory or field bindweed. It produces smooth, slender, glabrous or finely pubescent vine of 100–200 cm long, white or pink coloured funnel or trumpet shaped flowers. Fruits are light brown, two seeded which remain viable in soil for long period. The plant produces deep tap roots with several lateral roots that spread rapidly and

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act as a method of vegetative reproduction. Wild morning glory acts as host plant for aphid in watermelon, pumpkin, ridge gourd, etc. (Hazra and Som 2015). Melilotus alba Medikus (Family: Fabaceae) This is an annual winter legume, commonly known as ban methi or White sweet clover, that extensively appears in vegetable fields including cucurbit cultivation plots. Plants are erect, branching, with up to 3 cm long, 1 cm broad leaf, trifoliolate, appear in alternate phylotaxy. Flowers are small, white, arranged in many-flowered terminal and axillary racemes. Pods are dark brown to black at maturity, ovoid, 2.5–4 mm long, without hairs and cross-ribbed. Seeds are 2–2.5 mm long; 1.5 mm wide; oval, one side plane, the other side rounded; yellowish or greenish yellow and smooth. Phyllanthus niruri L. (Family: Euphorbiaceae) Popularly known as bhuin amla or stone breaker, predominant during summerrainy season. A small, erect, annual herb that grows up to 30–40 cm in height. Quite glabrous, stem often branched at the base, leaf-bearing branchlets are slender, spreading. Leaves are very small, numerous, subsessile. Flowers are small, white to light yellowish. Male flowers are axillary, females in solitary. Fruits are capsule, depressed-globose and smooth. Seeds are trigonous, rounded. Portulaca oleracea Linn. (Family: Portulacaceae) An annual glabrous herb commonly known as purslane. This weed appears round the year excepting chilling winter. Stem is prostrate and succulent with small obovate or spatulate, flattened leaves having entire margin. Yellow coloured complete flowers of 3–10 mm diameter appear terminally. Fruits are ovoid capsule of 4–9 mm diameter. Seeds are black or dark brown, orbiculate or elongate, flattened, 0.6–1.1 mm in size. Solanum nigrum Linn. (Family: Solanaceae) This weed, commonly known as black night shade, grows in dry parts of India and other parts of world (Akilan et al. 2014). It particularly appears in the summer-rainy season. The plant grows up to 1 m height, with erect, glabrous or sparsely pubescent stem and leaves. Leaves are ovate, glabrous and thin, margins toothed, tapering into the petiole. Flowers are small, white, borne in drooping 3–8 flowered cymes that develop yellow or black coloured berry like fruit having minutely pitted seeds. Black night shade acts as alternate host for powdery mildew disease of cucurbits. Sonchus asper (L.) Hill (Family: Asteraceae) An erect annual herb commonly known as prickly sow-thistle or spiny sowthistle which appears during winter with slender, simple or sparingly branched, glabrous stem. Basal leaves form a rosette, upper leaves sessile, slightly rugose, elliptic-oblong and simple dentate. Flowers are solitary, yellow, gland-hairy peduncle, sub-umbellate corymb. Seeds are of 3 mm long and 2 mm wide, fitted with a small parachute of white pappus hairs, that helps in long distance dispersal through wind. Stellaria media (Linn.) Vill (Family Caryophyllaceae) This annual branching herb, commonly known as chick weed or star weed, prefers a cool and moist weather and cannot thrive in hot and dry summer. Plants grow up to 30–40 cm height with prostrate, glabrous stem. Leaves are ovate-

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elliptic to oblong, spatulate, opposite in phyllotaxy. Flowers are small, white, numerous, axillary. Fruits are six valved capsules which contains many tiny greyish brown to reddish brown seeds. Chick weed acts as host plant for melon aphid, which attacks most of the cucurbits (Hazra and Som 2015).

2.2

Sedges

(a) Cyperus rotundus Linn. (Family: Cyperaceae) This is a very common perennial weed, popularly known as mutha or nut grass or purple nutsedge, found in almost all vegetable crop fields. The plant produces narrow linear leaves from its hard, fragrant, globose-ovoid tubers, which are up to 1.2 cm long and 0.3–0.7 cm in diameter. Culm appears either solitary or in cluster, sparsely tufted, erect, 10–75 cm tall, 3-angled at top. Leaves are narrowly linear, shorter or longer than stem, 0.4–0.8 cm wide, dark green above, pale beneath. Inflorescence is a simple or compound umbel with 2–8 rays, each up to 7.5 cm long, bearing short spikes of 3–10 spreading, red-brown spikelets. Fruits are oblong to ovate-oblong nuts, 3–sided, 1.3–1.5 mm long and 0.5–0.7 mm wide, brown at maturity. Yield losses in cucumber were reported up to 43% due to infestation of the sedge weed (William and Warren 1975).

2.3

Grasses

(a) Cynodon dactylon (Linn.) Pers. (Family: Poaceae) This is the most common perennial grass found in almost all vegetable fields. It is commonly known as Durba or Bermuda grass. It prefers moist and warm climate with high light (Holm et al. 1977). The stem/rhizome grows horizontally in the top 10 cm soil and spreads for several metres, with nodes at about 10 cm intervals, each with 2–3 scale leaves and a single axillary bud. It produces fibrous root from the nodes. Leaves are narrowly linear or lanceolate arising from upright stem branches. In dense stands, shoots developing from buds tend to be erect and quite short, up to 25 cm high, which otherwise develop into prostrate runners under less dense conditions. Inflorescence is up to 25 cm height, consists of a single whorl of 3–7 narrow racemes, each 3–8 cm long. Spikelets are 2–2.5 mm long, in two rows. (b) Digitaria sanguinalis L. (Scop.) (Family: Poaceae) Commonly known as large crabgrass or hairy crabgrass, it grows round the year except chilling winter. A prostrate or ascending annual grass having spreading and branched stem with rooting at nodes. Leaves are 3–20 cm long, 3–10 mm wide with hairs on both the surfaces. Sheaths are hairy which may turn dark red with ageing. Inflorescence are 4–6 branched spikes at the top of the stems, each approximately 3–15 cm long. Fruits/grains are shiny, yellowish-brown, 2–3 mm long. (c) Echinochloa colona (L.) Link. (Family: Poaceae) Jungle rice or Deccan grass or Shama grass is a very common annual weed of the rice family (Poaceae) originated in India and prevalent in almost every part

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of the tropics and sub-tropics. It is a fast growing summer grass, naturally found in wetlands and moist soils, though can’t tolerate flooding. It cannot withstand frost and is killed at temperature below 9  C (Ecocrop 2011). Culms are glabrous, cylindrical, 30–100 cm tall, erect to decumbent, often branching from the base. Leaves are flat glabrous, elongated, 10–25 cm long, 5–15 mm wide, light green, sometimes with red tinge at their base. Panicles are erect or nodding, green to purple, 6–12 cm long and bear 4–8 racemes on the main axis. Fruits/grains are caryopsis ovate, usually 2.5–3.5 mm long. Seeds are white to hyaline with longitudinal ridges on the convex surface. (d) Eleusine indica (L.) Gaertner. (Family: Poaceae) Indian crowfoot grass or Indian goosegrass or wire grass is an annual tufted grass, which is clump forming, flattened, radiating outwards from a central distinctive white centre, branching from the base, erect, slender 40–95 cm tall. Leaf blades are flat or sometimes folded, 15–30 cm long, 3–8 mm wide, without hairs or only sparsely hairy. Sheaths are flattened, whitish at the base and sparsely hairy in the collar region. Seed heads composed of 2–13 spikes each 1.5–6 in. long, 3–7 mm wide, in clusters at the top of stems. Two rows of flattened spikelets occur along each spike. Light brown to black, 1–2 mm long. (e) Phalaris minor Retz. (Family: Poaceae) In addition to wheat, this annual or biannual weed, i.e., Canary grass or little seed canary grass, is a very common nuisance to all winter vegetables including cucurbits like cucumber, melons and few gourds. It is prevalent in tropical as well as temperate regions of the world and can tolerate soil salinity. Mature plants can grow up to 180 cm in height, branching at the base with erect or decumbent stem. Leaves are long, linear and acuminate with subcoriaceous to pubescent leaf sheath. The inflorescence at the top of a peduncle is a dense oblong panicle, more or less protruding or entirely protruding from the uppermost swollen leaf sheath, ovate to oblong, 5–8 cm long and green. Spikelets are green, broadly lanceolate on short pedicels, shining, 4–6 mm long, strongly laterally compressed. Seeds, when separated from bracts are hairy, flattened, oblong, translucent and greyish green to straw coloured. (f) Polypogon monspeliensis (L.) Desf. (Family: Poaceae) Commonly known as annual rabbit’s foot grass or annual beard grass, it appears in vegetable field during winter and flowers in spring. Culms are branched to unbranched, 15–100 cm long, weak, erect to geniculate, decumbent at base. Leaves are hairless but slightly rough, flat, up to 20 cm long and 8 mm wide. Inflorescence is a terminal panicle, very dense, soft, cigar-shaped, occasionally with short branches, 2–15 cm long and 1–3.5 cm wide, pale yellow-green with a silvery tinge to yellowish-brown with maturity. Grains are elliptical, terete, 0.9–1.2 mm long, 0.5–0.6 mm wide glabrous, amber coloured.

2.4

Weed Management

All vegetables including cucurbits are grown in good soil having sufficient supply of all critical inputs like plant nutrients, water and light. This growing condition also

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favours weed seed to grow vigorously in the vegetable crop fields. Due to diversity of weed species, their growth habit, season of appearance, root system, reproduction behaviour, etc., a single method of weed control is not enough to make a vegetable field weed free. Judicious management of weed needs long-term strategy and integration of different sustainable methods (Verma et al. 2015). Weeds are managed in three different ways: avoidance, control and eradication. Avoidance or prevention means stopping a given species from contaminating an area. Prevention is often the most practical means of controlling weeds. This is best accomplished by making sure that new weed seeds are not carried onto the crop field through contaminated crop seeds, transplants, manures, irrigation water or from soil on machinery. Preventing existing weeds on the farm from flowering and going to seed and preventing the spread of perennial weeds which reproduce vegetatively are excellent approaches to avoiding weed problems. Control or curative measures are the processes of limiting weed infestations in the crop field, so that there is minimum weed population to compete with the main crop. The term ‘control’ should be a balance between the costs involved in control and the amount of possible negative effect on the crop. Eradication is complete elimination of all living weed plants, plant parts and seeds from an area. Problems involved with eradication are eliminating the living weed plants as well as weed seeds from the cultivable soil. Eradicating the living plants is somewhat easier than the seeds in the soil. Practically, from agricultural point of view, this method is very difficult and not economical. Hence, from a practical perspective, we should discuss different preventive and curative methods of weed management.

2.4.1 Preventive Measures • Clean farm implements: Many weed seeds stick to the implements used in tillage or other operations. So, before using any implement, used earlier in other crop field, should be thoroughly cleaned. • Clean seed: There is always every possibility of getting crop seed mixed with the weed seed, which may have been happened during harvesting or threshing operation of the said crop seed. To minimize weed load in the crop field, the weed seeds should minutely be separated and removed from the crop seed lot, before sowing of the crop. • Well-decomposed organic manure: Many weed seeds remain present in the organic waste or in the cattle dung, when it is left for manuring (Table 1). If the manure is used in the fields under-decomposed, then these weed seeds may germinate in the crop field and create nuisance. • Clean irrigation channel and water: Always keep irrigation channels weed free before irrigating a crop and use weed seed screen filter in the irrigation water to avoid weed seeds or vegetative propagule dispersal through irrigation water. • Prevent reproduction of weeds by removing them in the vegetative stage. • Restrict livestock movement to non-weed infested area. Many weed seeds or propagules get stuck to livestock foot or body, which create new weed flora in a non-weed infested area.

230 Table 1 Viable weed seeds in manure sample

Weed and Its Management in Cucurbitaceous Vegetables

Weed species Amaranthus spinosus L. Echinochloa crus-galli L. Stellaria media L. Setaria viridis L. S. glauca L. Polygonum aviculare Chenopodium album Dactylis glomerata Amaranthus retroflexus Plantago major Circium arvensis Panicum capillare Brassica kaber

No. of seeds/tones 2700 1900 3500 1600 4500 2700 42,000 4700 5200 5100 2700 2100 4700

Source: Pleasant and Schlather (1994)

• Avoid use or transportation of soil from weed infested area. Many times soil is transported to a low-lying crop field to make it elevated. Weed present in this transported soil will make the crop field weed infested.

2.4.2 Curative Measures It is removal of weeds from the crop fields before the critical crop weed competition period to avoid yield losses. There are four ways of controlling weeds in a crop field, i.e., cultural, mechanical, biological and chemical.

2.4.3 Cultural Practices Stale Seedbeds Stale (or false) seedbed technique is very effective for weed management in cucurbitaceous vegetable crops. Here, seedbeds are prepared 2–3 weeks before planting of main crop and irrigated to achieve maximum weedseed germinated. The crop seeds are sown with minimum soil disturbance to avoid exposing new weed seed to favourable germination condition. Finally, all germinated weeds are killed in the field with a non-residual herbicide just before or after sowing, but before crop emergence (William et al. 2000). Success depends on controlling the first flush of emerged weeds before crop emergence, and on minimal soil disturbance, which reduces subsequent weed flushes. Soil Solarization It is a method of killing weed seeds using solar heating of soil and therefore reduce weed emergence. High soil temperature through solarization during the warmest period of the year is a broad-spectrum, simple, cost-effective and environment friendly method of controlling simultaneously pests, diseases and weeds. It does not affect soil properties and usually produces higher yields (Campiglia et al. 2000).

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To increase the effectiveness of solarization, the land should be well levelled and must contain enough water to favour heat transfer down the profile and to make reproductive structure of pests, diseases and weeds more sensitive to heat damage. The steps of soil solarization involve lightly irrigating the soil (if it is dry) and covering it with a transparent white coloured plastic mulch film ensuring all sides properly sealed with earth. It increases soil heat through heat trapping with no heat dissipation to the atmosphere. The success of soil solarization as a weed control method does not depend on the actual value of peak temperature reached in the soil but rather on temperature duration above a certain threshold (45  C) on a daily basis (Horowitz et al. 1983). Significant reduction in weed emergence was observed for a period of 12 months after 1-month solarization in a tunnel glasshouse used for vegetable production in Central Italy (Temperini et al. 1998). To achieve higher weed control efficiency through solarization, the soil subsequently should not be exposed to deep tillage, otherwise weed seeds present in deeper soil layers (less affected by heating) are brought up to the soil surface and can create nuisance. Mulching Mulching is the method of covering the soil surface of a crop field with organic or plastic materials to retain soil moisture, suppress weed growth, maintain soil temperature and to achieve crop protection against some biotic hazards (like insects, birds, etc.). Mulching is one of the possible ways to control weeds without using herbicides (Verma and Singh 2008; Awasthy et al. 2014). Mulch reduces weed growth by depriving it from light and moisture. This is better achieved by using thick and non-transparent plastic. It cuts the transmission of photosynthetic radiation to the weeds thus development of weeds is arrested. Some perennial weeds (like Cyperus rotundus, viny weeds that creep to the edge of a mulch and emerge) are difficult to control, where thick, wide mulches are required. In such cases, inter-row cultivation or treatments may prove effective. After the crop is over, the plastic residues should have to be removed from the field very carefully either for reuse or in the form of waste. Organic materials (straw, sawdust, tree bark, plant residues) can be used, if cheaper source is available nearby. Advantages are similar to plastic, or even better, but weeds can easily reach the surface if the layer is not thick enough. Also, the organic mulch material can fetch other problems like increase in population of crop enemies (insects, rodents, snails, etc.). Black polythene mulch recorded significantly lower density and dry biomass of weeds over water hyacinth, paddy straw and wheat straw mulch (Goswami and Saha 2006). Mixed Cropping Growing two or more crops at the same time and adjacent to one another is called mixed cropping. The advantages are better use of space, light and other resources, a physical protection, better plant defence against some pests and fewer weed problems because the soil is better covered. Disadvantages are intercrop competition, difficulty in crop management and mechanization, higher need for manual labour, incomplete control of weeds and finally the results are less productive than sole crop cultivation. Mixed cultivation of short duration potato and long duration crop pointed gourd ensures better crop management for pointed gourd as well as keeps the field weed free for the initial 70–80 days (Roy et al. 2014).

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Crop Rotation Since long back, crop rotation has been considered as basic practice for obtaining healthy crops and good yields. It is an important component of integrated weed management. The choice and sequence of crops affect long-term weed population dynamics. Rotating crops with different life cycles can disrupt the development of weed–crop associations, through different planting and harvest dates preventing weed establishment and therefore weed seed production (Das et al. 2012), mainly by smothering and allelopathic effect (Dwivedi et al. 2012). Introducing a fallow in the rotation is essential for controlling difficult weeds (mainly perennials), cleaning the field with appropriate tillage or using a broad-spectrum herbicide. Irrigation Method of irrigation has great impact on weed emergence in vegetable field. Weed population is always higher when irrigation water is applied in conventional flood method or in ridge and furrow method. Drip irrigation is the most efficient method with minimum weed emergence and maximum yield realization. Effectiveness of drip method is considerably higher in cucurbitaceous vegetables, as these crops are sown at wide spacing, sometimes in broad beds. Thermal Weed Control It includes use of fire, flaming, hot water, steam and freezing (Ascard et al. 2007), which provide rapid weed control without leaving chemical residues in the soil and water. Selective towards the weeds, they do not disturb the soil (Zimdahl 2007), but its effectiveness depends on the temperature, exposure time and energy input (Ascard et al. 2007). Thermal weed control methods kills aboveground plant parts, they may regenerate and repeated treatment may be required. Flaming uses the heat generated from one or more propane burners to kill weeds. Intense heat sears the leaves of the weeds, causing the cell sap to expand, damaging cell walls (Singh 2014). This causes leaves to wilt and prevents water from moving from the roots to the leaves. In a short period of time, the plant withers and dies (Cohen 2006). In situations when seed production has already occurred, some of the weed seeds can be destroyed by flame burning. The effectiveness of burning depends on the duration and intensity of heat produced and the maturity and location of the weed seeds. Mature and dry seeds are more heat resistant than green seeds, which have high moisture content. Flame burning kills only a small number of seeds on or below the soil surface, which can be destroyed by burning surface trash. But, burning weeds over an extended area destroys valuable surface trash that would normally be returned to the soil through organic manuring (Sharma 2014). Allelopathy Allelopathy is any direct or indirect effect by one plant, including microorganisms, on another through production of chemical compounds that escapes into the environment to influence the growth and development of neighbouring plants (Rice 1974). The allelopathic interactions among various biotic components have a great potential in improving crop production, maintaining ecosystem stability, nutrient conservation and above all in management of weeds and pests (Kong et al. 2004). Plant releases chemicals that show allelopathic potentiality are called allelochemicals or allochemicals. Different plant parts like leaves, flowers, fruits, stems, roots, rhizomes, seeds and pollens are the main sources of allelochemicals of one plant to compete over neighbouring plants, which released

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through crop-environmental ecological process. The exploitation of crop allelopathy against weeds may be useful to reduce issues related to the use of herbicides because in recent years, allelopathic suppression of weeds is receiving greater attention (Inderjit et al. 2005). Allelochemicals or natural compounds have more benefits over synthetic compounds as they have novel structure and short half-life, therefore considered environmentally safe (Duke et al. 2002). Hence, allelopathy mechanism can be applicable as a component of sustainable weed management. There are many plant species having allelopathic potential over other weeds. Weed plant having allelopathic effect Parthenium hysterophorus Mikania micrantha Imperata cylindrica

Weed species, controlled by allelopathy Cyperus rotundus Echinochloa colonum, Phalaris minor Portulaca oleracea

Source: Bahadur et al. (2015)

Plant species Ageratum conyzoides L. Azadirachta indica L. Bidens pilosa L. Euphorbia hirta L. Eupatorium canabium L. Heliantus tuberosus L. Leucaena glauca L. Medicago sativa L. Morus alba L. Herbicide (5 L/ha) Hand weeding

Weed reduction potential (%) 80.8 91.0 81.8 87.9 75.8 70.1 85.9 80.0 72.7 77.8 71.7

Source: Xuan et al. (2005)

2.4.4 Mechanical Control Mechanical weed control is one of the oldest weed management techniques. It includes field preparation by ploughing or disking, inter-culture, mowing, hoeing and hand pulling of weeds. Seedbed preparation by ploughing or disking exposes many weed seeds to variations in light, temperature and moisture. For some weeds, this process breaks weed-seed dormancy, leading to early season control with herbicides or additional cultivation. Land Preparation and Tillage Suitable land preparation depends on a good knowledge of the weed species prevalent in the field (Labrada 1996). When annual weeds are predominant (Crucifers, Solanum, grass weeds), the objectives are unearthing and fragmentation. This must be achieved through shallow cultivation. If weeds have no dormant seeds (Bromus spp.), deep ploughing to bury the seeds will be advisable. If the seeds produced are dormant, this is not a good practice, because they will be viable again when they return to the soil surface after further cultivation.

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In case of perennial weeds, selection of tillage tools depends on the types of rooting. Pivot roots (Rumex spp.) or bourgeon roots (Cirsium spp.) require fragmentation which can be achieved by using a rotavator or cultivator. Fragile rhizomes (Sorghum halepense) require dragging and exposure at the soil surface for their depletion, but flexible rhizomes (Cynodon dactylon) require dragging and removal from the field. This can be done with a harrow or cultivator. Tubers (Cyperus rotundus) or bulbs (Oxalis spp.) require cutting when rhizomes are present and need to be dug up for exposure to adverse conditions (frost or drought). This can be done with mouldboard or disk plough. Chisel ploughing is useful for draining wet fields and reducing the infestation of deep-rooted hygrophilous perennials (Phragmites, Equisetum, Juncus). Thus, a good weed information is always necessary to manage the weed problem in a cultivating crop. Inter-Culture To adequately control the weeds, cultivate only as deep as needed. Deep cultivation may prune crop roots, bring weed seeds to the surface and disturb soil previously treated with an herbicide. Watermelon roots at the stem nodes which may extend as far as the tips of the vines. Turning the vines and deep cultivation in the vine area may destroy a large number of roots and reduce water and nutrient uptake. Timely cultivation is also very important. Small weeds are more easily killed by inter-cultivation than large weeds, and weeds should be removed before or during early flowering to prevent seed production. Hand Weeding It is one of the oldest, modest and simplest method of weed control which is very much practicable and efficient for cucurbitaceous vegetable crops. This operation is done by small hand tools like Nirani, Khurpi, Sickle, Spade, etc. It is better applicable over annual weeds than perennials capable of vegetative reproduction, because root remains reproduce a new shoot. Persistent perennials can be controlled by hand pulling, if it is done frequently and with good care to remove the underground root clump/rhizome. Despite its wide acceptability and efficient use, hand weeding takes a lot of time and human energy. Another disadvantage is that the job is not always performed, when it is most needed. Key Points Related to Mechanical Weed Control • Crop spacing must be proportionate with the weeding tool working width. • The soil moisture should be in right tilth condition to operate the weeding tool. • Adequate knowledge regarding tilling depth, speed and angle of the tool to work is necessary. • Judging the right stage of crop and weed to operate the weeding tool is important. There should be no delay in operation. The action must be taken against annual weeds before seed dispersion takes place. • Care is needed in erosion prone soil. In terrain cultivation, avoid any tillage parallel to the slope direction. • Follow weather forecast and plan accordingly. Avoid tillage if rainfall is expected. • All mechanical weeding tools must be cleaned properly after use so that no weed seed or propagule may remain adhered to it and dispersed through it.

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2.4.5 Biological Weed Control Biological weed control is the method of controlling weeds using biotic agents like insects, mites, nematodes, plant pathogens, animals, fish, birds and their toxic products which is harmless to desired crop plants, but affects the health of the weed. Among these, insects are one of the important groups (Tiwari et al. 2013; Kumar 2014). When a biological control agent is purposefully introduced, it is an attempt to restore or enhance nature’s systems (Tiwari et al. 2013). The leaf beetle Zygogramma bicolorata has been proven as a potential biocontrol agent against Parthenium hysterophorus (Kumar and Ray 2011). Advantages of Biological Weed Control • No harmful side effect. Unlike chemical method it is completely pollution free. • Cost involvement is low compared to mechanical or chemical methods • Self-perpetuating, hence no additional input is required, once the agent is successfully established. • High benefit: cost ratio for successful programmes. • Self-dispersing—spread to suitable host habitats. Disadvantages of Biological Weed Control • Success is not guaranteed. The process may fail for many reasons. Control is low • Not work well in short-term cropping cycles. • Control is often dependent on host density. • Risk of damaging the main crop, if there is any minor mistake in selecting the agent. • Number of potential available biocontrol agent is low.

2.4.6 Chemical Weed Control The use of chemicals for weed control in crop field is the most talked about chapter nowadays. Chemicals used for weed control are called herbicides. The chemical method to control weeds is easier, less time-consuming and less costly in comparison with mechanical method. However, the objective of chemical weed control is not to replace hand weeding rather minimizing it for more effective control of weeds. The specific advantage of chemical weed control is minimum destruction of soil structure by decreasing the need for tillage. It also reduces requirements of fertilizers and irrigation by eliminating competing weeds. The first organic herbicide, Dinitro ortho cresol (DNOC), was introduced in agriculture in the 1930s. However, it did not fetch much success. The real breakthrough came after the invention of 2,4-dichlorophenoxyacetic acid (2,4-D), the first widely used synthetic herbicide (Choudhury et al. 2016). Sherwin-Williams Paint Company was the first to commercialize it in the late 1940s. Since then, around 2000 different herbicide molecules of 15 different modes of action have been introduced in the global market (Anonymous 2015). The chemicals used to kill weeds are either selective or non-selective. Non-selective herbicide kills all the plants, wherever it is applied. The selective herbicide kills only the targeted weeds but not the crops. Most of the herbicides used in vegetable cultivation are selective. However, before use, one must know the mode of action and

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Weed and Its Management in Cucurbitaceous Vegetables

nature of tolerance of a particular herbicide. The tolerance level of a crop towards the amount of a particular herbicide varies with season, climate and soil type. Cucurbits, being wide spaced crop, have great scope of using both selective and non-selective herbicides. Properly selected herbicides are effective tools for weed management in cucurbits. Care must be exercised to use herbicides at the proper rate and correct time to avoid crop damage. Cucurbits have very limited tolerances to most herbicides. During the early 20–30 days, when vining of the crop yet not started, non-selective herbicides can be used in-between the rows. In such case, a proper spray-guard should have to be fixed upon the nozzle to protect the main crop from wind dispersal of the herbicide. Crop specific herbicide application fixture along with time and stages of application has been given in Table 2 as per Dittmar and Boyd (2019). Depending upon the application process, herbicides may be pre-emergent and post-emergent. Pre-Emergence • The treatment is made prior to the emergence of specific weeds. Mostly contact herbicides are used in this method. • The weedicides are applied after the weeds have emerged, but before the crop emergence. Here, efficient herbicide is used that does not persist in toxic form in the soil. • Pre-emergent herbicides provide early season weed control when competition results in the greatest yield reduction and when other methods are less efficient. • Pre-emergent herbicides can be categorized as surface-applied or incorporated herbicides. • Surface-applied herbicides require rainfall or irrigation shortly after application for best results. Lack of moisture often results in poor weed control; however, they are relatively easy to apply. • Incorporated herbicides are not dependent on rainfall or irrigation and have generally given more consistent and wider-spectrum control. They do, however, require more time and equipment for incorporation. • Herbicides labelled for surface application may cause phytotoxicity to melons if incorporated. • Soil sterilants, i.e., non-selective or selective pre-emergent herbicides, are used at high rates for the elimination of all plant growth. There are two categories of soil sterilants, persistent and non-persistent. Non-persistent sterilants such as sodium methyl dithiocarbamate and methyl bromide dissipate readily from the soil can be used in the cucurbit cultivation plot prior to the sowing of the crop. Soil sterilant treatments are often used on small areas for serious perennial weeds to prevent their spread. Post-Emergence • The treatment is given after the emergence of specific crop or weed, especially post-emergence of the crop. Here, only selective herbicides are used.

2

Some Important Weeds Infesting Cucurbits

237

Table 2 Crop specific herbicide application fixture along with time and stages of application Herbicide (Common name)

Dose (Kg a.i. / ha)

Timing and application location to the crop

Before seeding

After seeding before emerge nce

Before transpl anting

Postemerg ence

Postemerge ncebetween rows only



Bensulide

Timing Weed according to Controlled/ Weed growth Suppressed stage Preemerg ence

Postemerg ence



Annual grasses

Broad leaves





type Recom mended for crops Pere nnial Sedg es

All cucurbit s All cucurbit s All cucurbit s All melons and cucumb er All cucurbit s

5.70



Carfentrazone











0.04

Clethodim



0.08 – 0.14



Clomazone































0.17 – 0.57

Ethalfluralin + Clomazone

0.460.68 + 0.150.22

DCPA

5.13 – 12

Ethalfluralin





 

1.25 – 1.71



Flumioxazin









0.14

Glyphosate

Halosulfuron

0.34 – 1.14







0.03 – 0.04

Imazosulfuron





























0.0

S-metolachlor

Paraquat

Pendimethalin Sethoxydim

Terbacil



1.08 – 1.44 0.57 – 1.14











1.14





0.22 – 0.32 0.11 – 0.23





Trifluralin

Source: Dittmar and Boyd (2019)













 













Only melons All cucurbit s All cucurbit s All cucurbit s All cucurbit s All cucurbit s Only pumpki n All cucurbit s Only melons All cucurbit s Waterm elon only All cucurbit s

Abiotic Stresses: Nutritional and Physiological Disorders

1

Introduction

Abiotic stress or abiotic disease is differently known as non-parasitic, non-infectious or inanimate disease. It is a major source of crop failure due to unfavourable climatic and edaphic conditions, which include nutritional and physiological disorders, environmental pollution and radiation from nuclear weapons, etc. Different industrial and chemical pollutants can also responsible for the disease. Defective agricultural practices like the excess application of fertilizers and pesticides produce symptoms of chemical injury on hosts. Abiotic stresses lowered the production in terms of both quality and quantity of cucurbits as well as it may aggravate the severity of some biotic diseases. Some important abiotic stresses of cucurbitaceous crops have presented in Table 1. The soil contains nutrients for the plant absorption. Many of these nutrients must be required for a plant to complete its life cycle. Their role in plant growth is specific and direct, and they are not replaceable by other elements. Requirements of such elements are general among plants. More or less 16 elements (C. H, O, N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Mo, B and Cl) are known to be essential for plant growth. Availability of micronutrient to the plant is related to different soil characteristics. Availability of some micronutrients (like B, Cu, Fe, Mn and Zn) generally decreases with the increase of soil pH, while availability of Mo increases with increase of soil pH. Soil containing substantial organic matter supplies adequate amount of micronutrient to the plants. But, in highly organic soils such as peat and mucks, availability of some micronutrient (especially Cu and Mn) will reduce and become unavailable to plants. Generally, manganese, boron and iron deficiency occurs above the soil pH 7.4. Soil pH below 5.5 is not suitable for vegetable production. Acid soils restrict the uptake of some nutrients like phosphorus, potassium. This type of soils also allows the uptake of aluminium and manganese that become toxic to the plants. In acidic soils, physiological disorders like blossom end rot, poor seedling emergence, etc. are common. A range of both external and internal symptoms appear on host surface due the deficiency of nutrients. The symptoms may appear on any # Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_5

239

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Abiotic Stresses: Nutritional and Physiological Disorders

Table 1 Important abiotic diseases and disorders of cucurbits Name Nutritional disorder Air pollution injury Bitter fruit Blossom end rot Bottle neck of fruit/ misshapen fruits Measles/salt injury Sandburn Sunscald (fruit) Windburn Fertilizers injury Pesticides injury Chilling injury Solar injury Soil moisture injury Premature senescence Vein tract browning

Cause Deficiency of N, P, K, Ca, Mg, Mn, Fe, Zn, B, Mo Ozone, Sulphur dioxide and others Sunburn injury, physiologic stress Physiological disorder, calcium deficiency, moisture imbalance Incomplete pollination Physiological disorder, salt toxicity Physiological disorder Excessive or intense direct heat/solar injury Physiological disorder Fertilizers toxicity Pesticides toxicity Low temperature injury UV radiation and heat injury Poor root absorption due to excess soil moisture Presence of ethylene Ageing, accelerated by exposure to the sun during maturation and high temperature

part of a plant, but foliage symptoms are generally the most suitable for visual diagnosis. It is very much helpful in determining the cause of a nutrient deficiency through recording the location of the symptoms on a plant: symptoms of nitrogen, phosphorus and magnesium deficiency appear first on the lower leaves and progress upward; symptoms of boron and calcium deficiency begin at the apex of the plant and progress downward. Deficiency of nutrients can be confirmed by soil testing, plant tissue analysis and petiole sap analysis. Plant tissue analysis is done in laboratory based on dried plant parts and newly developed plant sap testing procedures. In case of cucurbits especially muskmelon, watermelon and cucumber fifth leaf from tip at flowering to fruit set stage is used for plant tissue analysis. Petiole sap analysis is a rapid diagnostic method commonly used for monitoring nitrogen and potassium levels. Now, diagnostic kit for analysis of some micronutrients is also available (De et al. 2003). Micronutrient disorders (deficiency or toxicity) are most common and a major problem in soil for vegetable cultivation and its sustainable production. The ‘adequate range’ of micronutrient is neither a deficiency (when the micronutrient is in deficit) nor toxic (when the micronutrient is in excess), which is an important aid to diagnose the deficiency and toxicity limit of vegetables (Table 2). Very low analytical values below the ‘adequate range’ means acute deficiency with visual symptoms, while very high of that indicate uneconomic nutrition (luxury consumption) or toxicity symptoms. Toxicity symptoms are difficult to recognize visually and are usually mistaken by deficiency symptoms. The ‘adequate range’ may vary with stages of crop growth and variety. Deficiency can be due to absent of the nutrient in

Macro nutrient (%) Micro nutrient (ppm) N P K Ca Mg B Watermelon (fully developed young leaves at middle of growth period) 2–3 0.2–0.45 2.5–3.5 0.15–0.35 0.4–0.8 30–80 Cucumber (fully developed middle leaves during blossoming and fruit development) 2.8–5 0.3–0.6 2.5–5.4 0.5–0.9 0.5–1.0 40–80 Muskmelon (fully developed young leaves at middle of growth period) 2–5 0.3–0.8 2.5–4.5 0.5–1.0 0.5–1.5 25–60

Table 2 Adequate ranges of mineral nutrient contents in dry matter of some cucurbits Cu 5–10 7–15 7–15

Mo 0.20–1.0 0.8–2.0 0.2–1.0

30–100

60–120

30–100

Mn

30–80

35–80

20–70

Zn

50–100

50–300

50–300

Fe

1 Introduction 241

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Abiotic Stresses: Nutritional and Physiological Disorders

Table 3 Availability of micronutrients affected by antagonism in soil and its critical foliar levels for vegetable crops

Micronutrient Boron (B) Manganese (Mn) Copper (Cu) Iron (Fe) Molybdenum (Mo) Zinc (Zn)

Availability reduced by Organic nitrogenous fertilizers and high levels of phosphorus High levels of potassium, phosphorus, iron, copper and zinc High level of zinc, nitrogen and phosphorus High level of copper, manganese, zinc and phosphorus High level of manganese and nitrate-nitrogen fertilizer High levels of copper and phosphorus

Critical foliar levels Minimum Maximum (ppm) (ppm) 25 100–300 30

500

5 50

20–100 5000

0.5

15

20

100–200

the soil system or the unavailability of the nutrient to the plant in spite of its presence in the soil. Soil pH and concentration of different micronutrients also play an important role for availability of micronutrients in soil. The concentration of one micronutrient in soil-plant system may affect the level of other micronutrients through antagonism (Table 3). Small variations of micronutrients from the optimum level required for plant growth can be damaging. So, it is very much essential for growers to have a clear understanding regarding micronutrient management.

2

Nitrogen Deficiency

Nitrogen is one of the most important nutrients required for overall plant health. It is a constituent of proteins, amino acids, enzymes, hormones, chlorophyll and vitamins (Mehrotra 1980). Symptoms Plants deficient in nitrogen are stunted. General yellowing of plants occurs due to the deficiency of nitrogen. The symptoms appear first on lower leaves and gradually progress to the upper leaves (Mehrotra 1980; Anonymous 2009a, b). Thereafter, the affected older leaves turn yellow and dry up. The younger leaves stop growing. Fruit may be misshapen and few in number (Anonymous 2009a, b). Cucumber fruits become slenderer and pinched at the blossom end (Gour et al. 2008). Carmona et al. (2015) recorded initial uniform chlorosis in the leaf blade of intermediary leaves in nitrogen deficient cucumber plants that advances to all leaves. Nitrogen deficiency is one of the strong constraints on the growth of cucumber plants (Carmona et al. 2015). Cantaloupe fruit is small, light-coloured and thin-skinned with small seeds. The ratio of root tissue to the shoot tissue in nitrogen deficient plants is high. Nitrogen deficiency affects respiration and accumulation of sugar occurs in such plants (Mehrotra 1980).

4

Potassium Deficiency

243

Management • Application of huge amount of organic manure during final land preparation can minimize the disease. • There are some nitrogen fixing free living bacteria (such as Azotobacter, Azospirillum, etc.) that can be used to minimize the problem. • Inorganic fertilizers like N, P, K, etc. should be applied as per soil testing report. • Correction of soil pH is necessary as it hampered the nutrient uptake efficiency of the plant.

3

Phosphorus Deficiency

Phosphorus is an important element for plant health and a constituent of phospholipids, nucleic acids and many proteins. It is essential in carbohydrate transformation and respiration. Phosphorus is involved in high energy bonding (Mehrotra 1980). Symptoms Growth of the phosphorus deficient plants becomes slow. Internodes are shortened and stunted in such plants. Deficient plants become bluish-green with purplish tints. Phosphorous deficient cucurbits produce poor quality flowers and fruit, and seed-set is reduced (Mehrotra 1980; Anonymous 2020). Carmona et al. (2015) observed that the symptoms initiate with the loss of the characteristic green colour of cucumber plants in the blade of intermediary leaves in phosphorus deficient condition. With the advancement of the disease, chlorotic areas developed randomly both in intermediary and in old leaves, which ultimately cause tissue necrosis. Management • Application of huge amount of organic manure during final land preparation can minimize the disease. • There are some phosphate solubilizing microorganisms (such as Pantoea agglomerans, Microbacterium laevaniformans, Pseudomonas putida, Bacillus megaterium, Glomus fasciculatum, etc.) that can be used to minimize the problem. • Inorganic fertilizers like N, P, K, etc. should be applied as per soil testing report. • Correction of soil pH is necessary as it hampered the nutrient uptake efficiency of the plant.

4

Potassium Deficiency

Potassium is the third most important plant nutrient required for maintaining overall plant health. It is considered as an essential nutrient and a major constituent within the living cells. Naturally, soil contains potassium in larger amounts than any other nutrients; however, most of the potassium is unavailable for plant uptake. Plants

244

Abiotic Stresses: Nutritional and Physiological Disorders

require potassium ions for protein synthesis, opening and closing of stomata. It improves water use efficiency through regulation of photosynthesis and transpiration. Potassium also functions for activation of some enzymes, phloem solute transport of photoassimilates into source organs, and maintain cation-anion balance in the cytosol and vacuole. Prominent diagnostic symptoms of potash deficiency mainly appear on foliage of cucurbit plants (Gour et al. 2008; Mehrotra 1980; Anonymous 2020). Symptoms Generally, at mid-stages of growth, the deficient plants show scorching and curling of leaf tips along with yellowing of leaves. Prolonged deficiency can cause necrosis from the tip and start drying towards the base. Because of fast mobility of potassium within the plant, deficiency symptoms primarily develop on older (lower) leaves, as plant allocate potassium to younger leaves in deficient situation. Plant growth, root and fruit development are usually reduced in potassium deficient plants. It also induces early flowering. Younger leaves become yellow, necrotic and cup shaped. Cucumber fruits turn brown and/or spotted and may develop a club shape. Development of abnormal flesh texture and off flavour of melons are frequent (Anonymous 2009a). Deficient plants are more prone to the attack of different insect pests and pathogens (Gour et al. 2008; Mehrotra 1980; Anonymous 2009a, 2020). Carmona et al. (2015) recorded the chlorotic symptoms in intermediary leaves of cucumber plant in potassium deficient condition, which advances to marginal necrosis. Conditions Favourable for Potash Deficiency Deficiency of potash is most common in light, sandy soils, because potassium ions (K+) are highly soluble and will easily leach from soils without colloids. Chalky or peaty soils with low clay content are deficient of potassium. It is also found in heavy clays with poor structure. Besides, the crop grown continuously only by applying nitrogen and phosphorus without application of potassium is another cause for potassium deficiency (Gour et al. 2008; Mehrotra 1980; Anonymous 2020). Management • Application of huge amount of organic manure during final land preparation can minimize the disease. • There are some potash solubilizing bacteria (like Frateuria aurantia, Acidithiobacillus ferrooxidans, Paenibacillus spp., Bacillus mucilaginosus, B. edaphicus, B. circulans, Bacillus megaterium) that can be used to minimize the problem. • Inorganic fertilizers like N, P, K, etc. should be applied as per soil testing report. • Correction of soil pH is necessary as it hampered the nutrient uptake efficiency of the plant. • K deficiency may also be corrected with foliar application of KNO3 or K2SO4 @ 0.5–1.0% twice at weekly interval. • Farmers are also using their traditional knowledge to minimize this abiotic disease through application of rice straw ash after irrigating the onion field.

5

5

Iron Deficiency

245

Iron Deficiency

Iron is one of the important element for protein, lipid and porphyrin synthesis. It has functions on different metabolic processes like photosynthesis, respiration, SO2 and SO3 reduction, the TCA cycle and nitrogen fixation. Besides, iron activates a number of enzymes, such as aminolevulinic acid synthetase, copper-phyrinogen oxidase and plays a significant role in the synthesis of RNA (De et al. 2003). Symptoms Deficiency symptoms occur primarily on newly developed leaf tissue. Younger leaves become chlorotic. The larger veins remain green in the early stages of the deficiency while the entire leaf becomes uniformly chlorotic and necrotic spots develop in the leaves at later stages. Interveinal chlorosis of young leaves commences at the leaf base and progress to the tip. Ultimately, the youngest leaves become pale green to yellow or even white as the deficiency progress (De et al. 2003; Gour et al. 2008; Anonymous 2020). Iron toxicity is rare because plants can tolerate a wide range of iron concentrations. Stem and root development of the affected plant are also hampered (De et al. 2003). Conditions Favourable for Iron Deficiency Iron deficiency is common in calcareous, poorly drained compacted soils. Availability of iron to the plants decreases with increase of soil pH. Presence of high levels of copper, manganese, zinc and phosphorus in soil reduces the availability of iron (De et al. 2003; Gour et al. 2008). Management Early correction of iron chlorosis is essential to prevent yield losses. It is difficult to correct iron chlorosis through soil application of iron fertilizers, as applied iron reverts rapidly to unavailable form for plants. Foliar spray is better to minimize the problem. • The problem can be corrected through improving drainage and aeration of soils. • High soil temperatures can reduce the incidences of iron chlorosis. • Soil application of ferrous sulphate—20% Fe (FeSO4, 7H2O) at 5 kg/ha can minimize the iron deficiency (De et al. 2003). • Ferrous sulphate at 0.2% foliar spray can reduce the iron chlorosis (Gour et al. 2008). De et al. (2003) reported that one spray of ferrous sulphate at 25–100 ppm will correct the mild iron chlorosis. While, in case of more severe chlorosis ferrous sulphate can be applied at 15 days interval. Surfactant can be mixed with tank mixture for foliar spray to improve leaf adherence and iron absorption.

246

6

Abiotic Stresses: Nutritional and Physiological Disorders

Manganese Deficiency

Manganese plays a key role in oxidation-reduction processes, such as electron transport in photosynthesis and detoxification of oxygen-free radicals, and acts as activator of many enzymes. Concentrations of chloroplast membrane constituents, glycolipids and polyunsaturated fatty acids are reduced up to 50% in manganesedeficient leaves. It acts as a cofactor for a number of important enzymatic reactions involved in the biosynthesis of plant secondary metabolites. In manganese-deficient plants, different metabolites (aromatic amino acids, phenolics, coumarins, lignins, flavonoids, IAA) associated with shikimic acid pathway are lower. Disease resistance capability of such plants is decreased. Growth of Mn-deficient plants is retarded due to inhibited synthesis of gibberellic acid, sterols, quinones, etc. It is also important for production of chlorophyll, metabolism of carbohydrates and nitrogen (De et al. 2003). Symptoms Symptoms of manganese deficiency generally appear on the new growth, and the symptoms closely resemble iron deficiency. The interveinal area of younger leaves becomes chlorotic while veins remain green. As the deficiency continues, older leaves become chlorotic. In severe cases, chlorotic areas may become grey, turn brown, and finally the affected leaves may die. Curling of leaves and slow growth are also associated with the Mn-deficiency (Gour et al. 2008; Anonymous 2009a, b, 2020). Cucurbitaceous crops are sensitive to excess manganese. Different kinds of symptoms like stunting of plants, severe chlorosis followed by necrosis of leaves, leaf spot and crinkling of leaves appear on plants due to Mn-toxicity (De et al. 2003). Conditions Favourable for Iron Deficiency Manganese deficiency is commonly found in the coastal areas and linked with very high soil pH. Availability of manganese to the plants decreases with increase of soil pH by holding manganese in an insoluble form. Different soil factors like pH, organic matter content and degree of aeration have great role in availability of manganese in soil. Manganese may have leached from root zone of plants in light soil. Presence of high levels of potassium, phosphorus, iron, copper and zinc in soil reduces the availability of manganese (De et al. 2003; Gour et al. 2008; Anonymous 2009a). Management • Application of well rotten organic matter is efficacious to prevent leaching of manganese from root zone of plants. It also acts as buffering agents for soil Ph. • Over-liming should be avoided. It is better to apply lime or dolomite according to soil testing report (De et al. 2003; Anonymous 2020). • Deficiency of manganese can be controlled either by soil application or foliar spray usually at first bloom (De et al. 2003). It can be corrected by soil application of manganous sulphate—28% Mn (MnSO4.H2O) at 10 kg/ha or by 0.2% foliar

7

Molybdenum Deficiency

247

spray (Gour et al. 2008). De et al. (2003) also reported that the problem can be reduced through soil application of manganous sulphate at 5–10 kg/ha.

7

Molybdenum Deficiency

Molybdenum plays an important role in enzymatic activities of plants. A close relationship exists among Mo supply, NO3 reductase activity and growth. NO3 reductase activity is low in Mo deficient plants. Role of Mo in protein synthesis is well known. It has pronounced effects on chlorophyll concentration, chloroplast structure and growth. Molybdenum also has a striking effect on pollen formation. A number of metabolic changes occur in Mo deficient plants. Symptoms Molybdenum deficiency results in interveinal chlorosis in older leaves. Afterwards leaf margins turn brown and the plants remain stunted (Gour et al. 2008; De et al. 2003; Anonymous 2009a, 2020). Poor and delayed flowering, and reduced viability of pollen grains occurs in Mo deficient muskmelon plants growing on acid soils which results in reduced fruit formation (De et al. 2003). Drying of terminal bud is another important deficiency symptom. Less production of female flower in watermelon occurs due to Mo deficiency (Nayban 2002). Stress resistance is decreased in Mo deficient plants against low temperature or water logging (De et al. 2003). Conditions Favourable for Molybdenum Deficiency Molybdenum deficiency is commonly found in acid soils. Availability of molybdenum to the plants decreases with decreases of soil pH. Presence of high level of manganese and nitrate-nitrogen fertilizer in soil reduces the availability of molybdenum (De et al. 2003; Gour et al. 2008). Management • Application of well rotten organic matter is efficacious. It also acts as buffering agent for maintaining soil pH. • Application of lime or dolomite according to soil testing report is important. • Deficiency of Mo can be controlled either by soil application or foliar spray. It can be corrected by soil application of sodium molybdate (Na2MoO4.2H2O) or ammonium molybdate [(NH4)6Mo7O24.4H2O] at 1.0 kg/ha. Spraying of sodium molybdate or ammonium molybdate at 0.05% is efficacious to manage the problem. Foliar spraying is better than the soil application (Nayban 2002; Anonymous 2016a).

248

8

Abiotic Stresses: Nutritional and Physiological Disorders

Zinc Deficiency

Zinc is indispensable for plant growth. A low zinc supply encourages protein deficiency, dwarfism in plants and poor yields. The infected plants will die in severe cases. Zinc is essential for protein synthesis, auxin production, seed production, rate of maturity and lots of other metabolic activities of plants. It protects the membrane lipids and proteins against oxidation. Zinc deficiency aggravates abnormal metabolic signals in plants leading to appearance of certain visible symptoms on hosts. Symptoms Symptoms of Zn deficiency generally appear on older leaves as characteristics irregular chlorotic mottling. When the symptoms appear on younger leaves first, the mottling is restricted to the intercostal areas, while in some cases it is extended to secondary and primary veins too. The younger leaves malformed, often became thick, brittle, pale green, mottled and very small. In cucumber, the leaves of zinc deficient plants show dead brown area (necrotic) on edges and less of green colour (chlorosis) between the veins. The flowers start drying and no fruits are formed. Retardation of terminal growth, broad indentation at petiole, extreme short internodes with a bushy growth habit of the leaves and restricted root growth are the common symptoms for zinc deficiency (De et al. 2003). Zinc toxicity is not very common. If it happens, it can be reduced by liming the soil. Conditions Favourable for Zinc Deficiency Zinc deficiency is very common in saline alkali soils and calcareous soils. Water logged soils and sandy soils containing low organic matter are also zinc deficient. Availability of zinc to the plants decreases with increase of soil pH. Presence of high level of copper and phosphorus in soil reduces the availability of zinc (De et al. 2003; Gour et al. 2008). Zinc deficiency is aggravated by some human activities like loss of fertile upper surface of soil and indiscriminate use of certain chemical fertilizers especially phosphate. Climatic factors that affecting Zn response are temperature and moisture. Management • Application of well rotten organic matter is efficacious. It also acts as buffering agent for maintaining soil pH. • As the Zn deficiency is favoured by high soil pH, application of lime or dolomite according to soil testing report is important. • Upper surface of soil should not be replaced. Care should be taken during application of chemical fertilizers especially phosphate. • Deficiency of Zn can be controlled either by soil application or foliar spray. Foliar application is better than the soil application. It can be corrected by soil application of zinc sulphate—36% Zn (ZnSO4.7H2O) at 25 kg/ha or chilleted zinc—12% Zn (Zn-EDTA) at 7–10 kg/ha during final land preparation in mixing with organic

9

Boron Deficiency

249

manure. Two spraying of chelated zinc (0.05%) at an interval of 15–20 days can effectively manage the situation (Nayban 2002; Anonymous 2016a).

9

Boron Deficiency

Boron is an important micronutrient involved in cell division, fruit formation, carbohydrate and water metabolism, protein synthesis, lignin formation and seed development. It has prominent role in pollen germination and pollen tube growth. Boron does not translocate readily within the plant system as like as other nutrients. So that a continuous supply of boron must be available through the growing season of the crops. Symptoms Sufficient amount of boron in early growth stages is very much imperative for normal growth of the crops. Symptoms of boron deficiency mainly come up on leaves. Brittleness of the foliage, yellowing of the lower leaf tips and necrosis of the terminal growing point is common (De et al. 2003; Carmona et al. 2015). The younger leaves become smaller. Development of corky areas around the stem end, open locules and uneven ripening are some of the common symptoms appearing on fruits due to deficiency of boron (De et al. 2003; Carmona et al. 2015; Anonymous 2020). In severe deficient condition, cracking of fruits may occur. Poor seed yield of cucurbits is linked with insufficient supply of boron during seed development stage. Conditions Favourable for Zinc Deficiency Boron deficiency is mainly found in coarse textured soils. This micronutrient is easily leached from root zone of crops. Boron deficiency is frequent under drought conditions. Availability of boron to the plants decreases with decrease of soil moisture. Presence of organic nitrogenous fertilizers and high levels of phosphorus in soil reduce the availability of boron (De et al. 2003; Gour et al. 2008). Management • Application of well compost, vermicompost or other organic manures is important to minimize the problem. • Judicious application of fertilizer is essential. Application of fertilizers should be as per the soil testing report. • Deficiency of boron can be controlled either by soil application or foliar spray. Foliar application is better than the soil application. It can be corrected by soil application of Borax-11% B at 2–5 kg/ha. Foliar application of borax or solubor 19% B at 0.2% is effective when applied twice at 25–30 days and 40–45 days after sowing. Boric acid 17% B (H3BO3) at 0.1% can be applied to manage boron deficiency in cucurbits (Nayban 2002; De et al. 2003; Anonymous 2016a).

250

10

Abiotic Stresses: Nutritional and Physiological Disorders

Calcium Deficiency (Blossom End Rot)

It is a nutritional disorder related to the concentration of calcium in developing fruit tissues. Calcium is a limiting factor in cell wall formation and consequently indirectly involved in cell division. The activity of several enzymes is influenced by this element (Mehrotra 1980). Symptoms The main symptom of this disorder is the sunken area at the distal end of the fruit. This develops as the fruits mature during the period when there is high temperature, low humidity and warm dry winds prevailing in the field or in the growing house. About 75% of the crop may be affected at harvest time. Although this deformity does not progress after harvest, it creates a serious market blemish. The first fruits of the season are worse affected. The disorder always initiates at the blossom end, though the rot may enlarge to affect half of the fruit. Mouldy growths on the rotted area are due to secondary fungal and bacterial invasion. Blossom end rot of watermelons was studied in different countries of the world including Iraq, Italy and Brazil (Cirulli and Ciccarese 1981; Carmona et al. 2015). Calcium deficient plants are stunted, having distorted, cupped leaves and typical interveinal chlorosis. Symptoms appear first on new growth (Anonymous 2009a, b). Carmona et al. (2015) recorded some important symptoms on calcium deficient plants. They observed development of chlorotic stains randomly scattered initially over young leaves of vines, which advances to intermediary leaves with tissue necrosis. Tipburn, shrivelling and chlorosis in young leaves of cucumber occur due to the calcium deficiency. Apical rot in fruits occurs finally. Mehrotra (1980) reported that the tips of the leaves of deficient plants curl back with irregular ragged margins. These distorted leaves become brittle due to the accumulation of starch. Growth of calcium deficient plants is retarded and internodes are shortened. Leaf margins stop expanding and leaves cup downward. New root growth is impaired. Blossom end rot of the fruit may occur (Anonymous 2020). Conditions Favourable for Calcium Deficiency Calcium deficiency occurs mostly in alkaline soil or when water containing high residual sodium carbonates is used for irrigation (Gour et al. 2008). It is also common in highly saline soil. Some factors that aggravate the calcium deficiency situation are extreme fluctuations in soil moisture, rapid early-season plant growth followed by extended dry weather and excessive rain that restricts root hairs. Closer spacing may also augment the calcium deficiency. Cylindrical fruited cultivars are especially susceptible to this disorder. Management • Spherical fruited cultivars are not generally susceptible to this disorder. So, such types of cucurbits should be grown (Cirulli and Ciccarese 1981). • Maintenance of uniform soil moisture by mulching and proper watering is effective.

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Fertilizer Injury

251

• It is better to avoid high-ammonia fertilizers and large quantities of fresh manure. Watering should be done regularly during dry periods. • If the soil or water is salty, more water can be provided during irrigation to help leach salts through the soil. • Application of single super phosphate can correct calcium deficiency. • Calcium deficient soils may require amendment with gypsum (calcium sulphate), lime or dolomite. • Frequency of irrigation can be increased to permit efficient uptake of minerals (http://www.backyardgardener.com/wcgp/problems/blossom.html). • Chelated calcium may be used in greenhouse situations as spray solution (Anonymous 2009b).

11

Magnesium Deficiency

Magnesium (Mg) is one of the most important metabolic constituent of chlorophyll. The magnesium deficient plants develop interveinal chlorosis on older leaves that initially appears at leaf margins and progresses inward. Ultimately entire leaves become necrotic. Because magnesium deficiency develops late in the growing season, fruit yield is generally not reduced significantly (Mehrotra 1980; Carmona et al. 2015; Anonymous 2020). Management • The application of magnesium sulphate or magnesium lime stone to the soil is generally recommended for managing the magnesium deficiency (Mehrotra 1980). Apart from nutritional disorders there are some non-infectious factors like adverse water relations (excess water, drought, etc.), adverse physio-chemical conditions (acidity, alkalinity, calcareousness, salinity, etc.), adverse climatic conditions (high or low temperatures) and environmental pollution (toxicity due to Sulphur dioxide, ozone, ethylene, chlorine, pesticides, ionizing radiations, etc.) that greatly influenced the crop growth and production. A sustainable approach is very much important to manage such disorders or stresses.

12

Fertilizer Injury

This condition happens when chemical fertilizers are applied at high concentrations. Even though, all vegetables can be affected by fertilizer burn, cucurbits are particularly very much sensitive because they do not have a thick waxy cuticle on their leaves. Therefore, they do not shed water like as onions or the Brassica species. During transpiration, the soluble salts move with water through the plant and become concentrated in the leaves where moisture is lost rapidly on hot and dry conditions through evaporation, which can quickly desiccate (dry out) the leaves,

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leading to fertilizer burn. Leaf burn or scorch may also result from direct foliar contact with some fertilizers. Seedlings are very tender and are particularly sensitive. Symptoms include a generalized burning appearance or flecking resembling a spray pattern. The severity of injury depends on some factors like soil type, salt levels, irrigation practices, level of soil moisture, growing season, environmental temperature, etc. This problem is more severe in hot and dry weather conditions. Management • It is better to avoid foliar application of fertilizers. If required, care should be taken during foliar feeding about dose, time and environmental condition, etc. • The leaves are capable to taking up only small quantities of fertilizer as compared to roots. When using a water-soluble fertilizer in the greenhouse, growers may like to rinse the fertilizer off the leaves. • Growers should design on providing all the necessary fertilizers for their crops through fertigation or soil applications. Water must be applied just after soil application of fertilizers. • Fertilizer burn can be prevented by applying slow release organic fertilizers. Application of huge amount of organic manure or application of mulching materials can prevent the fertilizer burn through moisture conservation.

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Pesticide Injury

Pesticides are the important tools to protect crops from different kinds of pests and pathogens. The symptoms of pesticide injury appear on different parts of the plants due to misuse or misapplication of pesticides. So that, careful attention must be paid about the selection of field, residual toxicity, pesticidal drift, doses of pesticides, time of application of pesticides, etc. Some pesticides like atrazine, 2,4-D, sulphur, etc. have severe deleterious effect on cucurbitaceous crops. Atrazine is a non-selective herbicide used widely to control broadleaf in grain cultivation, but its residue may persist in soil for several seasons, which limits the growth and production of broadleaf crops planted afterward. Cucurbitaceous plants of affected field appear dwarfed. Leaf scorching is common. Plant vigour and yield are reduced due to toxicity of Atrazine (Anonymous 2009b). 2,4-D is also a widely used non-selective herbicide used against broadleaves generally in grain cultivation. It is volatile and may drift for significant distances from the point of application, affecting sensitive crops including the cucurbits and tomatoes. This drifted herbicide affects the new growth of the crop that become distorted and twisted. In affected cucurbits, fan-shaped leaves with flattened petioles are common (Anonymous 2009b). Applying sulphur containing compounds during periods of extreme heat may damage sensitive varieties that includes marginal necrosis and plant dwarfing. Cool damp weather may increase the chance of injury by copper fungicides. The toxicity of pesticides may also result from incompatible mixing of pesticides.

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Chilling Injury

253

Management • It is very much important to know ‘pesticide history’ and ‘crop history’ of a particular field before sowing of any crop, that can help to avoid planting sensitive crops in fields where persistent chemicals have been applied (Anonymous 2020). • Volatile 2,4-D esters should not be applied within several hundred yards of sensitive crops (Anonymous 2009b). • Sulphur containing compounds should be applied only during moderate temperatures. Before use, it is better to be careful about the label recommendations. Soil application of sulphur during final land preparation can be done instead of foliar spray (Anonymous 2009b). • Registered pesticides should be applied according to label directions.

14

Salt Injury

Superfluous salinity may happen due to application of poor quality water or improper use of fertilizers. As a result the affected plants show stunted growth followed by death. Plants affected by high salt concentrations frequently appear dark green in the early stages, but quickly develop marginal yellowing and necrosis of older leaves (Anonymous 2009a, b). Management • Careful attention has to be paid during fertilizer application and watering mainly in greenhouse and container (tub, sac, etc.) grown crops. In case of container grown plants, watering should be done in such a way that the excess water can runoff that will prevent salt build-up (Anonymous 2009b). • Little can be done in a field situation where water quality is poor; some beneficial effects of planting on the sides of beds (as opposed to the top or centre where the salt tends to build up because of the wicking effect) have been reported (Anonymous 2009a, b). • There are some land development models for saline and coastal areas that can be followed to overcome the situation (Mukherjee 2007).

15

Chilling Injury

Air temperatures at or slightly below freezing can severely damage all cucurbits. Seedling stages may be severely stunted or killed by low, but non-freezing temperatures because they are ‘chilling sensitive’ crops. There is a report that the critical temperature below which chilling injury can occur is between 10  C and 14  C for watermelons. Melons are less susceptible and their cultivars differ substantially. Damage progresses from a water-soaked appearance of affected leaf tissue immediately after exposure, to a greyish-green ‘scorched’ appearance of leaves that eventually turn brown and papery within a day or two (Anonymous 2009b). Due to this disorder, reddish brown patches may appear on the skin of fruits (Pitcha 1986;

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Lipton and Wang 1987). Multiple lesions are developed on the surface of fruits. Ripening may be delayed. Quality of the fruits especially taste and texture is reduced. Chilling injured tissues shows an increased tendency to get decayed. Management • Overhead irrigation applied during the low temperature exposure may provide limited protection against a light frost (Anonymous 2009b). • Sensitivity to chilling injury can be reduced by plastic film wraps of fruits. • Pre-shipment treatment with ethylene or pre-shipment conditioning for a few days at moderate temperature can reduce the chilling injury. Such treatments permit storage of melons at 4–7  C.

16

Solar Injury

The solar injury may result from UV ray or heat or a combination of both (Lipton 1977). Common symptoms due to the injury are bronzing and discolouration on surface of fruits. In ‘wintermelons’ such as Honey Dew, the affected area may be brown or blotched or else greyish as if bleached. Severely injured tissues become sunken or wrinkled. Flesh quality may be reduced. In hot arid growing areas solar injury can be a problem in crops where there is scanty foliage cover to shade the maturing fruits. Harmful exposure to the sun may also occur at harvest time if fruits are not brought under cover promptly. In this situation flesh temperature can rise several degrees above the ambient temperature that sometimes may result into permanent damage. Management • White wash can be applied to the melons so that sun light and heat are reflected (Lipton 1977). The white wash can easily be removed by washing the melons after harvest. • Care should be taken just after harvest. Providing shade after harvest and transporting of harvested melons without delay can reduce the problem.

17

Excess Soil Moisture

Each crop has its specific water requirement. Too much watering can be harmful, especially if the flooding persists for more than 2 or 3 days. Roots require plentiful oxygen to live and grow, and waterlogged soils become anaerobic rapidly. Waterlogged plants are stunted and frequently exhibit nutritional deficiencies because of poor root absorption. Waterlogged plants are also prone to root diseases (Anonymous 2009b). Management • Field should be labelled with good drainage system.

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Vein Tract Browning

255

• Raised bed is preferable to avoid the situation. • Careful monitoring of frequency of irrigation, duration of irrigation, depth of irrigation, etc. is essential particularly during cool weather (Anonymous 2009b).

18

Air Pollution Injury

Air pollution injury occurs on cucurbits mainly due to ozone and sulphur dioxide injury. Ozone injury appears first on older leaves. Affected leaves appear silvery to whitish. Bleaching will finally kill the leaves in most severe cases. Watermelon appears to be fairly sensitive to ozone (Anonymous 2009b). Management • There are no known cultural controls for ozone injury. It is better to avoid growing of susceptible crops away from heavily polluted areas (Anonymous 2009b).

19

Premature Senescence

This disorder arises in presence of ethylene. Watermelons are generally harvested when already ripe or very nearly to ripe, and do not have much capacity for development in flesh quality. On the contrary, once the fruits are harvested it is not long before there is decline in colour, texture and flavour of the ripe flesh. These changes like fading, softening and development of off flavours are hastened by exposure to ethylene (Risse and Hatton 1982). Management • Separation of watermelons from banana, tomato, apples, etc. should be done during shipment and storage. In comparison with watermelons these fruits produce substantial quantities of ethylene.

20

Vein Tract Browning

It is a post-harvest disorder of melons. Ageing is accelerated by exposure to the sun during maturation and high temperature after harvest (Lipton 1977). In this case, darkening of longitudinal grooves occur on the fruits. This condition is the consequence of ageing, accelerated by exposure to the sun during maturation and to high temperature after harvest (Lipton 1977). Management • Storage in high humid condition is helpful for minimizing development of this disorder.

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Abiotic Stresses: Nutritional and Physiological Disorders

Misshapen Fruits or Bottle Neck of Fruit

This disorder can appear in field due to several reasons. Among them, pollination is one of the major cause for misshapen fruits. For fruit development of cucurbits insect or hand mediated pollination is very much important. Due to lack of pollinating agents or faulty pollination, this disorder may happen. The fruits may be crooked or constricted. Management • Release of one bee per plant or 2.5 strong and active hives per hectare is effective. In case of high density planting five hives per hectare need to be introduced. Bees to be put into cucurbit field only after starting of the flowering because cucurbits are not so preferred plant of bees. Insecticides should not be applied near the hives or in the field when the bees visit flowers especially from sunshine to early afternoon. • Proper hand pollination can be done to avoid the problem. It can be recommended for small scale cultivation. But, in case of larger field, it is impracticable mainly because of labour cost. In such case, after collecting pollen grains (male) in water at morning time, can be spread over the field.

Breeding of Cucurbits for Resistance Against Biotic Stresses

The technology of plant breeding for pest and disease resistance is the secondary objective of a total breeding programme in addition to yield and quality. Host plant resistance to insect pests and diseases is an underutilized pest management strategy in vegetable production. Increased pressures to reduce pesticides and changes in technology now increase the economic viability and possible role of host plant resistance in vegetable pest management, which reflected in the relatively recent release of several insect-resistant varieties and breeding lines (Eigenbrode and Trumble et al. 1994). Like other vegetables there is ample opportunity to exploit this technology in managing several biotic stresses in cucurbits. But, care should be to monitor the status of pests for minimizing the threats of resistance breaking biotypes. For development of new resistant varieties and to make it available to the growers dynamic breeding programme is of utmost necessity. Resistance sources are generally present in landraces and wild relatives. Genetic resistance to biotic stresses is may be due to non-preference, antibiosis, tolerance or a combination of these factors. Sources of resistance to downy mildew (Pseudoperonospora cubensis) is reported in snap melon (C. melo var. momordica), sources of resistance to fruit fly is reported in C. callosus, etc. Most of the resistant varieties in cucurbits have been developed by simple selection (Rai et al. 2008). As per the survey of G. F. Sprague and R. G. Dahms in the USA, more than 100 cultivars resistant to more than 25 different insect species had been released to commercial production by 1972 (Pedigo 2002). Recently, many open-pollinated and F1 hybrids resistant to insect pests and diseases in vegetable crops developed by conventional plant breeding methods. In some cases, abiotic stress resistance varieties are also developed for cucurbits. Some important resistant sources and tolerant lines of various cucurbitaceous vegetables against major diseases are mentioned in Table 1. Cucurbits are the largest group of well-known vegetables all over the world. Similar to other vegetable crops, they are attacked by a number of pests and pathogens including weeds and abiotic stresses, which cause a severe damage and loss to these crops. The crops can be protected from these biotic and abiotic stresses by taking suitable management strategies as soon as the symptoms of the attack start # Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5_6

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Table 1 Sources of resistance or tolerant lines for major diseases of cucurbits Crop Watermelon

Biotic stress Fusarium wilt

Anthracnose

Muskmelon

Fusarium wilt and anthracnose Anthracnose, powdery mildew, downy mildew (multiple resistance) Powdery mildew, downy mildew Powdery mildew

Downy mildew

Powdery mildew, downy mildew

Fusarium wilt

Alternaria leaf spot Gummy stem blight CMV WMV ZYMV CGMMV

Bottle gourd

Downy mildew, powdery mildew, Alternaria blight, WMV-1 (multiple resistance) Fusarium wilt CMV, SqMV, WMV Bottle gourd mosaic virus Bottle gourd mosaic and WMV

Resistance source/tolerant lines Summit, Conqueror, Dixilee, Crimson sweet, Citron, Calhoun Gray, Sornkylee, Crimson Sweet, Charleston Gray, Lousiana Queen, Hawkesbury, Klondike R-7, Kleckly Resistant, Leesbury, Miles, Baby Klondike, Ironsides Fair, Charleston gray, Congo, PI 189225, Black Stone, Dunbarton, Garrisonian Calhoun Sweet, Fairfax, Blackstone Arka Manik

Asahi Yamato, Sugar Baby PMR 45, PMR 450, PMR 5, PMR 6, PI 124111, Arka Rajhans, Georgia-47, C-68, Edisto, Campo, RM 43, Pusa Sharbati, Jacumba, Levlita, PM 5, PI 164323, PI 180283 MR-1, PI 414723, DMDR-1, DMDR-2, Edisto, Seminole, Buduma Type-1, 2 and 3, Phoontee, Goomuk, Nakkadosa, Ex-2, Annamalai, Edisto, Harvest Queen, Cucumis callosus, WMR-29, MR-l, Punjab Rasila, Cinco, DMDR-l, DMDR2, EC 163888, Texas Resistant Home garden, Perlita, Planers Jumbo, PMR Cantaloupe-45, PMR-6, PMR-7, PMR-8, Campo, Jacumba Delicious-51, Cucumis melo var. reticulatus, Indorus, Chito, Flexuosus, Golden Gopher, Iroquois, Minnesota Midget, Harvest Queen, Delicious-51 Purdue-44 PI 140471 Freeman PI 414723, B 66-5, Cucumis metuliferus PI 161375. DVRM-1, DVRM-2, DMDR-1, DMDR2, Cucumis africanus, C. ficifolius, C. anguria W1, W3, W4, W5, W6

Taiwan variety Renshi PI 271353 Warte, Midnapore 1 Arka Chandan (continued)

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Breeding of Cucurbits for Resistance Against Biotic Stresses

259

Table 1 (continued) Crop

Cucumber

Biotic stress Bottle gourd mosaic and Cucurbit latent virus Bottle gourd mosaic, Cucurbit latent and WMV Blossom end rot Anthracnose, powdery mildew, downy mildew Anthracnose

Downy mildew Powdery mildew

Powdery mildew and downy mildew Powdery mildew, downy mildew, anthracnose, angular leaf spot CMV

Pumpkin

CGMMV WMV Powdery mildew and viruses Powdery mildew Bacterial wilt Root knot nematode SqMV ZYMV, WMV

Round melon Snap melon Squash

WMV, CMV Downy mildew Downy mildew ZYMV, CMV

Resistance source/tolerant lines EC 121270 (Costa Rica), Brazil Tehuacan Smooth Arka Bahar N. Shishir (NDBG-202) PI 175111, PI 175120, PI 179676, PI 182445, wise 2757 (USA), PI 197087, PI 175111 B-184, B-159, Chinese Long, Palmetto, PR-27, Santee, Palomar Phule Shubhangi, PI 200815, PI 200818, Cucumis hardwickii, PI 197087, Yomaki, Spartan Salad, PI 197088, C. ficifolia, C. anguria, C. dinteria, C. sagittatus, IVT 1801, PI 280231, PI 147065, C. anguria var. anguria, PI 374209, PI 282441, Wise 2757 (USA), SS 717 Cucumis hardiwickii-14 and 15, Cucumis sativus var. sativus, SM 12735, IIHR-27, IIHR-35, IIHR-303, IIHR-64 and 82 Poinsettia Wisc SMR-12, SMR-15, SMR-18, Wise 2757 (USA), TMG-1, Tokyo Long Green, Chinese Long, Wisconsin, Table Green, Shamrok Ilima, Ohio MR-200, Ohio MR-17, Wisconsin, SMR-9 Cucurbita anguria Table Green, Sarinam Cucurbita lundelliana, C. martenezii Cucurbita moschata Cucurbita pepo, C. máxima, C. andreana, C. lundellina Jaipur, Dasna Cucurbita pepo, C. máxima, C. moschata Cucurbita ecuadorensis, C. faetidistima, C. martenezii Cucurbita ecuadorensis, C. foetidissima INGR-99038 (HT-10) INGR-07044 (B-159), SP-l, SP-2, SP-3, KP-2, KP-7, KP-9. ZW20 (transgenic line) (continued)

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Breeding of Cucurbits for Resistance Against Biotic Stresses

Table 1 (continued) Crop Summer squash Ridge gourd Bitter gourd

Biotic stress Powdery mildew, CMV

Resistance source/tolerant lines Punjab Chappan, Kaddu-1

Root knot nematode

Panipat, Meerut special

Downy mildew

Phule Green Gold

Source: Choudhary and Fageria (2002), Rai et al. (2008), Pitchaimuthu et al. (2012), Dasgupta (1998), Mukhopadhyay and Nath (1998), Satpathy et al. (1998), Satyagopal et al. (2014) CMV Cucumber mosaic virus, CGMMV Cucumber green mottle mosaic virus, SqMV Squash mosaic virus, WMV Watermelon mosaic virus, ZYMV Zucchini yellow mosaic virus

appearing. Care should be taken during selection of chemicals as control measures not only ensuring natural enemies and pollinators are saved, but to avoid environmental pollution, residual toxic effect of the chemicals on the crops as the crop is used for consumption only after a certain period. In kitchen garden crops, application of these chemicals should be avoided. Besides, physical and cultural control measures, host resistance, use of herbal and biological weapons along with incorporation of indigenous knowledge will help to protect the cucurbits from the damaging agencies. Measures should be region specific, cost effective and environment friendly.

Some Important Plates Related to Cucurbit Cultivation

Fusarium root rot of bottle gourd

Sclerotium stem rot of cucumber

Fusarium wilt of bitter gourd

Rhizoctonia root rot of bottle gourd (continued)

# Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5

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Some Important Plates Related to Cucurbit Cultivation

Bacterial wilt of bottle gourd

Gummy stem blight of bottle gourd

Pythium fruit rot of pointed gourd

Sclerotinia fruit rot of pointed gourd

Fusarium fruit rot of cucumber

Fruit and vine rot of pointed gourd (continued)

Some Important Plates Related to Cucurbit Cultivation

Pythium fruit rot of ridge gourd

263

Pythium fruit rot of cucumber

Downy mildew of pointed gourd

Downy mildew of ridge gourd

Powdery mildew of ivy gourd

Powdery mildew of bottle gourd (continued)

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Some Important Plates Related to Cucurbit Cultivation

Powdery mildew of pumpkin

Powdery mildew of ridge gourd

Alternaria leaf blight of bottle gourd

Alternaria leaf blight of pumpkin

Alternaria leaf blight of cucumber

Net blight of pointed gourd

Alternaria leaf blight of watermelon

(continued)

Some Important Plates Related to Cucurbit Cultivation

265

Anthracnose of cucumber

Phoma blight of cucumber

Bacterial soft rot of bottle gourd

Bacterial soft rot of cucumber (continued)

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Some Important Plates Related to Cucurbit Cultivation

Angular leaf spot of bottle gourd

Bacterial leaf spot of ivy gourd

Bacterial leaf spot of pumpkin

Root knot of pointed gourd

Cucumber mosaic virus on bottle gourd

Cucumber mosaic virus on pumpkin (continued)

Some Important Plates Related to Cucurbit Cultivation

Cucumber green mottle mosaic virus on bottle gourd

Watermelon mosaic virus on pumpkin

Zucchini yellow mosaic virus on bitter gourd

Cucumber mosaic virus on bitter gourd

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Some Important Plates Related to Cucurbit Cultivation

Sun scorching of pumpkin

Pesticide toxicity on cucumber

Pesticide toxicity on pumpkin

Fertilizer toxicity on pumpkin

Cracking of pumpkin due to ‘B’ deficiency

Severe potassium deficiency on pumpkin

Some Important Plates Related to Cucurbit Cultivation

Water droplet hand pollination using pollen mixture (IFP)a

269

Yellowing and fruit dropping of bitter gourd and pumpkin due to faulty pollination (continued)

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Some Important Plates Related to Cucurbit Cultivation

Deformed bitter gourd and cucumber fruits due to incomplete pollination and poor fertilization

Physiological disorder of cucumber due to splitting of ovary

(continued)

Some Important Plates Related to Cucurbit Cultivation

Superior ovary in pumpkin - male flower turned to hermaphroditic a

271

Flower visitors—Amegilla sp. and Apis cerana indica

IFP indigenous farmers’ practice

Seedling raising of bitter gourd in polythene packet to protect from damping-off (IFP)a

Seedling raising of bitter gourd in pot tray to protect from damping-off

No land cultivation of cucurbits on tree top (IFP)

No land cultivation of cucurbits on hut top (IFP) (continued)

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Some Important Plates Related to Cucurbit Cultivation

Cultivation of cucurbits on roof top. Polythene wrapping to protect bottle gourd from fruit flies and fruit rotting fungi (IFP) a

a

Bitter gourd cultivation in land embankment (IFP)

IFP indigenous farmers’ practice

Bitter gourd and pumpkin cultivation in broad bed-furrow system (IFP)a

Bitter gourd cultivation in land embankment in vertical bower system (IFP)

Ariel cultivation of bottle gourd over pond (IFP)

Multi-tier cropping of bottle gourd in heap methods (IFP)

IFP indigenous farmers’ practice

References

Agarwal JM, Chippa HP, Sobti AK (1980) A note on two post harvest disease of vegetable from Rajasthan. Indian J Mycol Plant Pathol 10:97–98 Agrios GN (2000) Plant pathology, 4th edn. Academic Press, Elsevier, New Delhi, p 635 Aharoni Y, Copel A, Fallik E (1993) Hinokitiol (β-thujaplicin), for postharvest decay control on ‘Galia’ melons. N Z J Crop Hortic Sci 21(2):165–169. https://doi.org/10.1080/01140671.1993. 9513763 Ahlawat YS, Kulshreshtha UK (1977) A new graft transmissible disease of Sechium edule. Indian Phytopathol 30:268–269 AICVIP (1997–1998) Progress report, published by ICAR, New Delhi Ainsworth GC (1935) Mosaic disease of cucumber. Ann Appl Biol 22:55–67 Akilan CA, Srividhya M, Mohana Priya C, Jeba Samuel CS, Sundara Mahalingam MA (2014) Comparative analysis of phytochemicals, antibiogram of selected plants in solanaceae family and its characterization studies. Int J Pharm Pharm Sci 6(2):946–950 Al-Ali AS, Al-Neamy IK, Alwan MS (1982) On the biology and host preference of Aulacophora foveicollis Lucas (Coleoptera, Galerucidae). J Appl Entomol. https://doi.org/10.1111/j.14390418.1982.tb02548.x Alabouvette C, Rouxel F, Louvet J, Bremeersch P, Mention M (1974) Recherche d’un porte-greffe resistant au Phomopsis sclerotioides et au Verticillium dahliae pour la culture du melon et du concombre en serre. PHM 152:19–24 Alonso-Prados JL, Luis-Arteaga M, Alvarez JM, Moriones E, Batlle A, Lavina A, Garcia-Arenal F, Fraile A (2003) Epidemics of aphid-transmitted viruses in melon crops in Spain. Eur J Plant Pathol 109:129–138 Americanos PG (1991) Control of Orobanche in celery. Technical Bulletin – Cyprus Agricultural Research Institute No. 137 Amin KS, Ullasa BA (1981) Effect of thiophanate on epidemic development of anthracnose and yield of watermelon. Phytopathology 71:20–22 Amin KS, Ullasa BA, Sohi HS (1979) Watermelon anthracnose epidemic in relation to fungicidal sprays. Indian J Agric Sci 49:53–57 Amin KS, Ullasa BA, Sohi HS (1982) Quantitative determination of resistance to fungicidal sprayers. Indian J Agric Sci 49:53–57 Anderson CW (1954) Two muskmelon mosaic virus strains from Central Florida. Phytopathology 44:371 Anonymous (1996) Plant protection schedule for important crops of West Bengal. In: Somchaudhury AK, Chowdhury A (eds) The directorate of research. Bidhan Chandra Krishi Viswavidyalaya, West Bengal, p 63

# Springer Nature Singapore Pte Ltd. 2020 B. Mondal et al., Stresses of Cucurbits: Current Status and Management, https://doi.org/10.1007/978-981-15-7891-5

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274

References

Anonymous (2000) Report on plant disease. RPD No. 948. Department of Crop Sciences, University of Illinois at Urbana-Champaign, pp 1–4 Anonymous (2009a) Disease identification guide for cucurbits. Syngenta Crop Protection, Inc, Greensboro, p 74 Anonymous (2009b) Vegetable resources. Aggie Horticulture®. Nutrient Deficiencies: Texas A&M University System, College Station, TX. https://aggie-horticulture.tamu.edu/vegetable/problemsolvers/cucurbit-problem-solver/leaf-disorders/ Anonymous (2010) Plant protection schedule: integrated pest management. Directorate of Agriculture, Government of West Bengal, 200 pp Anonymous (2015) The pesticide manual (BCPC), 1991 and 2012, and pesticide properties database, University of Hertfordshire. http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/1160.htm Anonymous (2016a) Mati pariksha o phasole susamo sar proyog, 10th edn. SATSA Agriculture Booklet-2. SATSA, West Bengal, p 32 Anonymous (2016b) Krishite upokari jibanur babohar, 5th edn. SATSA Agriculture Booklet-5. SATSA, West Bengal, p 20 Anonymous (2017a) Annual report for 2016–2017. ICAR-Indian Institute of Horticultural Research, Bengaluru Anonymous (2017b) Compendium of extant notified varieties registered under PPV&FR Act, 2001 (Volume I: February 2009–March 2017). Protection of Plant Varieties and Farmers’ Rights Authority, Department of Agriculture, Co-operation & Farmers Welfare, Ministry of Agriculture and Farmers Welfare, Government of India, NASC Complex, DPS Marg, New Delhi, www.plantauthority.gov.in Anonymous (2018) Zucchini yellow mosaic virus in cucurbit crops. Agriculture and Food Division, Department of Primary Industries and Regional Development. Government of Western Australia. https://www.agric.wa.gov.au/minor-fruits/zucchini-yellow-mosaic-virus-cucurbitcrops. Retrived on 1 May 2020 Anonymous (2020) Nutrient deficiencies: lack of major or minor nutrient elements. Seminis Vegetable Seeds, 800 North Lindbergh Blvd, St. Louis, Missouri, https://seminis-us.com/ resources/disease-guides/cucurbit/nutrient-deficiencies-2/. Retrived on 6 May 2020 Antignus Y, Wang Y, Pearlsman M, Lachman O, Lavi N, Galon A (2001) Biological and molecular characterization of a new cucurbit infecting tobamovirus. Phytopathology 91:565–571 Ascard J, Hatcher PE, Melander B, Upadhyay MK (2007) Thermal weed control. In: Upadhaya MK, Blackshaw RE (eds) Non-chemical weed management. Principles, concepts and technology. CABI, London Ashrafi ZY, Hassan MA, Mashhadi HR, Sadeghi S (2009) Applied of soil solarisation for control of Egyptian broomrape (Orobanche aegyptiaca) on the cucumber (Cucumis sativus) in two growing seasons (in Iran). J Agric Technol 5(1):201–212 Aulakh KS (1971) Damping off of toria seedling due to Pythium butleri. Indian Phytopathol 24:611–612 Awasthy P, Bhambri MC, Pandey N, Bajpai RK, Dwivedi SK (2014) Effect of water management and mulches on weed dynamics and yield of maize. J Environ Sci 6:473–478 Aycock R (1966) Stem rot and other diseases caused by Sclerotium rolfsii. North Carolina agricultural experiment station Technical Bulletin No. 174 Babadoost M (2005) Phytophthora blight of cucurbits. Plant Health Instruct. https://doi.org/10. 1094/PHI-I-2005-0429-01. Updated 2016. The American Phytopathological Society, St. Paul Babadoost M, Islam SZ (2003) Fungicide seed treatment effects on seedling damping-off of pumpkin caused by Phytophthora capsici. Plant Dis 87:63–68 Backman PA, Brenneman TB (1984) Compendium of peanut diseases. American Phytopathological Society, St. Paul Bag TK (2000) Status of vegetable diseases caused by Sclerotinia sclerotiorum in different land use systems of Arunachal Pradesh. Environ Ecol 18(1):88–91

References

275

Bahadur S, Verma SK, Prasad SK, Madane AJ, Maurya SP, Verma VK, Sihag SK (2015) Eco-friendly weed management for sustainable crop production-a review. J Crop Weed 11 (1):181–189 Bains SS, Jhooty JS (1976a) Overwintering of Pseudoperonospora cubensis causing downy mildew of muskmelon. Indian Phytopathol 29:211–213 Bains SS, Jhooty JS (1976b) Host range and possibility of pathological races in Pseudoperonospora cubensis, cause of downy mildew of muskmelon. Indian Phytopathol 29:214–216 Bains SS, Jhooty JS (1978a) Epidemiological studies on downy mildew of muskmelon caused by Pseudoperonospora cubensis. Indian Phytopathol 31:42–46 Bains SS, Jhooty JS (1978b) Relationship between mineral nutrition of muskmelon and development of downy mildew caused by Pseudoperonospora cubensis. Plant Soil 49:85–90 Bains SS, Jhooty JS (1978c) Mode of efficacy of four fungitoxicants against Pseudoperonospora cubensis on muskmelon. Indian Phytopathol 31:339–342 Bains SS, Prakash V (1985) Susceptibility of different cucurbits to Pseudoperonospora cubensis under natural and artificial epiphytotic conditions. Indian Phytopathol 38:138–139 Bains SS, Sharma NK (1986) Two new races of Pseudoperonospora cubensis on muskmelon in Punjab. Indian J Mycol Plant Pathol 7:86 Bains SS, Vidyaprakash (1985) Susceptibility of different cucurbits to Pseudoperonospora cubensis under natural and artificial epiphytotic conditions. Indian Phytopathol 38:138–139 Bains SS, Sokhi SS, Jhooty JS (1977) Melothria maderaspatana, a new host of Pseudoperonospora cubensis. Indian J Mycol Plant Pathol 7:86 Bandyopadhyay SR, Mukhopadhyay S (1977) Incidence of a new disease of muskmelon (Cucumis melo L. var. reticulatus) in West Bengal. Curr Sci 46:566–567 Barkai-Golan R, Kahan RS, Temkin-Gorodeiski N (1968) Sensitivity of stored melon fruit fungi to gamma irradiation. Int J Appl Radiat Isot 19:579–583 Barnes WC (1961) Multiple disease resistant cucumbers. Proc Am Soc Hortic Sci 77:417–423 Barnes WC (1966) Development of multiple disease resistant hybrid cucumbers. Proc Am Soc Hortic Sci 89:390–393 Batten JS, Scholthof KB, Lovic BR, Miller ME, Martyn RD (2000) Potential for biocontrol of Monosporascus root rot/vine decline under greenhouse conditions using hypovirulent isolates of Monosporascus cannonballus. Eur J Plant Pathol 106:639–649 Bawden F, Pirie N (1937) Liquid crystalline preparations of cucumber viruses 3 and 4. Nature 139:546–547. https://doi.org/10.1038/139546b0 Bem FP, Vassilakos N (2000) Occurrence of the disease “internal deterioration of watermelon fruit” in watermelon cultivation in Greece. Phytopathol Mediterr 39:325 Beraha L, O’Brien MJ (1979) Diaporthe melonis sp. nov., a new soft rot of market cantaloupes. Phytopathol Z 94:199–207 Berkeley MJ (1855) Vibrio forming cysts on the roots of cucumbers. Garden Chron Agric Gaz 14:220 Bharathi LK, Munshi AD, Chandrashekaran S, Behera TK, Das AB, Joseph John K (2011) Cytotaxonomical analysis of Momordica L. (Cucurbitaceae) species of Indian occurrence. J Genet 90(1):21–30 Bharathi LK, Behera TK, Sureja AK, Joseph KJ, Todd CW (2013) Snake gourd and pointed gourd: botany and horticulture. In: Janick J (ed) Horticultural reviews, vol 41, 1st edn. Wiley Bhargava B (1977) Some properties of two strains of watermelon mosaic virus. J Phytopathol 88:199–202 Bhargava B, Bhargava KS (1977) Cucurbit mosaic viruses in Gorakhpur. Indian J Agric Sci 47:1–5 Bhargava AK, Singh RD (1985) Comparative study of Alternaria blight, losses and causal organisms of cucurbits in Rajasthan. Indian J Mycol Plant Pathol 15:150–154 Bhargava B, Bhargava KS, Joshi RD (1975) Perpetuation of watermelon mosaic virus in eastern Uttar Pradesh, India. Plant Dis Rep 59:634–636 Bhatia SK, Mahto Y (1969) Influence of temperature on the speed of development of melon fly, Dacus cucurbitae Coquillett (Diptera: Tephritidae). Indian J Agric Sci 40:821–828

276

References

Bhattacharya SP, Mondal B, Bardolui S (2006) Crop pests and its management In: Agricultural science, vocational second paper (Class XII). (In bengali language-Shasya satru-o-tar pratikar. In: Krishi Bidya). West Bengal State Council for Vocational Education and Training, Kolkata, pp 1–118 Bilgrami KS, Jamaluddi, Rizwi MA (1979) Fungi of India, Part-I. List and reference. Today and Tomorrow‘s Printers and Publishers, New Delhi, p 467. http://www.threatenedtaxa.org/ ZooPrintJournal/2011/June/0262226vi111872-1874.pdf Bilgrami KS, Jamaluddin, Rizwi MA (1981) Fungi of India, Part II. Host Index and Addenda, Today and Tomorrow’s, New Delhi Bisognin DA (2002) Origin and evolution of cultivated cucurbits. Cienc Rural 32(4). http://www. scielo.br/scielo.php?script¼sci_arttext&pid¼S0103-84782002000400028&lng¼en&tlng¼en Bletsos FA (2005) Use of grafting and calcium cyanamide as alternatives tomethyl bromide soil fumigation and their effects on growth, yield, quality and Fusarium wilt control in melon. J Phytopathol 153:155–161 Blumer S (1967) Echte Mehltaupilze (Erysiphaceae). Ein Bestimmungsbuch fur dic in Europa vorkommenden Arten, Jena, Fisher, p 436 Booth RH, Burden OJ (1983) Post-harvest losses. In: Johnston A, Booth C (eds) Plant pathologist’s pocketbook, 2nd edn. Commonwealth Mycological Institute, Oxford & IBH Publishing Co., Calcutta, 439 p Borodynko N, Hasiow-Jaroszewska B, Rymelska N, Pospieszny H (2009) Watermelon mosaic virus reported for the first time in Poland. Plant Pathol 58:783 Brodie BB, Evans K, Franco J (1993) Nematode parasites of potatoes. In: Evans K, Trudgill DL, Webster JM (eds) Plant parasitic nematodes in temperate agriculture. CAB International, Wallingford Butler EJ (1918a) Fungi and diseases in plants. Bishan Singh Mahendra Pal Singh, Dehradun Butler EJ (1918b) Fungi and diseases in plants. Thacker, Spink and Co., Calcutta, pp 314–315 Butler EJ, Bisby GR (1931) The fungi of India. Science Monograph I. ICAR, New Delhi Buzi A, Chilosi G, Reda R, Magro P (2002) Le principali fitopatie checolpiscono il melone. Colt Prott 9:31–45 Buzi A, Chilosi G, Reda R, Magro P (2004) Il colasso da Monosporascus cannonballus: emergenza fitopatologica su melone e cocomero. Colt Prott 12:85–87 Campbell RN, Lecoq H, Wipf-Schiebel C, Sim ST (1990) Soil-borne viruses of melons and cucumbers in France. In: Proceedings of the First Symposium of the International Working Group on plant viruses with fungal vectors, Braunschweig, Germany, 21–24 August 1990, pp 153–154 Campiglia E, Temperini O, Mancinelli R, Saccardo F, Stoffella P, Cantliffe D, Damato G (2000) Effects of soil solarization on the weed control of vegetable crops and on cauliflower and fennel production in the open air. 8th Int. Symp. on Timing of Field Production in Vegetable Crops. Bari, Italy. Acta Hortic 533:249–255 Cantliffe DJ (1976) Improved fruit set on cucumber by plant growth regulator sprays. Proc Florida State Hort Soc 89:94–96 Capoor SP, Ahmad RJ (1975) Yellow vein mosaic disease of field pumpkin and its relationship with the vector Bemisia tabaci. Indian Phytopathol 28:41 Capoor SP, Verma LM (1948) A mosaic disease of Lagenaria vulgaris Ser. In the Bombay Province. Curr Sci 17:274–275 Cappelli C, Stravato VM, Carannante G, Parisella R (2004) First report of cucumber black root rot caused byPhomopsis sclerotiodesin Italy. Plant Dis 88:425 Carmona VV, Costa LC, Cecílio Filho AB (2015) Symptoms of nutrient deficiencies on cucumbers. Int J Plant Soil Sci 8(6):1–11 Carter WW (1981) Reevaluation of heated water dip as a postharvest treatment for controlling surface and decay fungi of muskmelon fruits. HortScience 16:334–335 Chadha KL (ed) (2001) Handbook of horticulture. Directorate of Information and Publications of Agriculture. ICAR, Krishi Anusandhan Bhavan, Pusa, New Delhi, p 1031

References

277

Chahal DS, Chohan JS, Sidhu GS (1970) Alternaria leaf spot of cucurbits in Punjab. Indian Phytopathol 23:580–581 Chattopadhyay SB, Mustafee TP (1967) Outbreaks and new records, India: occurrence of two new diseases on vegetables. FAO Plant Prot Bull 15:40–41 Chattopadhyay SB, Mustafee TP (2008) Plant diseases and their management. Aditya Books Private Limited, New Delhi, p 627 Chattopadhyay SB, Sengupta SK (1952) Addition to the fungi of West Bengal. Bull Bot Soc Bengal 5:58–61 Chattopadhyay SB, Sengupta SK (1955) Root knot disease of jute in West Bengal. Curr Sci 24:276–277 Chaudhary ZA, Alikhan MA (1990) Effects of temperature and relative humidity on the development and fecundity of red pumpkin beetle Aulacophora foveicollis Lucas (Chrysomelidae: Coleoptera). Indian J Entomol 52:274–278 Chaudhuri S (1975) Fruit rot of Trichosanthes dioica L. caused by Pythium cucurbitacearum Takimoto in West Bengal. Curr Sci 44(2):68 Chaurasia SC (1980) Studies on the foot rot and leaf rot diseases of Pan (Piper betle). IX. The effect of various substances on the oxygen uptake of Phytophthora parasitica var. piperina. J Phytopathol 98(2):163–170 Cheema SS, Kang SS, Bansal RD (1999) Viral diseases of cucurbitaceous crops and their management. In: Verma, Sharma (eds) Diseases of horticultural crops-vegetables, ornamentals and musrooms, Indus Publishing Co., New Delhi, 735 pp Chen HY, Zhao WJ, Gu QS, Chen Q, Lin SM, Zhu SF (2008) Real time TaqMan RT-PCR assay for the detection of cucumber green mottle mosaic virus. J Virol Methods 149:326–329 Chod J, Jokes M (1991) The occurrence of Zucchini yellow mosaic virus in Czechoslovakia. Ochrana Rostlin (Plant Prot) 27:111–115 Chopra BL, Jhooty JS (1974) Biochemical changes in a resistant and susceptible variety of watermelon due to infection by Alternaria cucumerina. Indian Phytopathol 27:502–507 Chou TG, Yang SJ, Huang PY (1976) Mycoplasmalike bodies observed in the plants of bottle gourd, chayote and balsam-pear with witches’-broom in Taiwan. Plant Dis Rep 60:378–380 Choudhary BR, Fageria MS (2002) Breeding for multiple disease resistance in cucurbits (water melon, musk melon, cucumber and squash) – a review. Agnc Rev 23(4):300–304 Choudhury B (1990) Vegetables, 8th edn. National Book Trust, New Delhi, p 195 Choudhury PP, Singh R, Ghosh D, Sharma AR (2016) Herbicide use in Indian agriculture. Information Bulletin No. 22. ICAR- Directorate of Weed Research, Jabalpur, Madhya Pradesh, 110 p Chowdhury AK (1998) Chemical plant protection of vegetable diseases and their environmental impact. In: Sengupta PK, Chowdhury AK (eds) Proceedings of the national seminar on vegetable diseases and their management strategies in West Bengal, Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, pp 17–21 Chowdhury AK, De BK, Raj SK (1998) Present status of vegetable diseases and suggested future lines of research work in West Bengal. In: Sengupta PK, Chowdhury AK (eds) Proceedings of national seminar on vegetable diseases and their management strategies in West Bengal. Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, pp 1–9 Cirulli M, Ciccarese F (1981) Effect of mineral fertilizers on the incidence of blossom-end rot of watermelon. Phytopathology 71:50–53 Clark CA, Moyer JW (1988) Compendium of sweet potato diseases. American Phytopathological Society, St. Paul Clausen CP, Clancy DW, Chock QC (1965) Biological control of the Oriental fruit fly (Dacus dorsalis Hendel.) and other fruit flies in Hawaii. Tech Bull US Depart Agric 1322:1–102 Cohen BB (2006) Flame- weeding: a hot alternative to herbicides. J Pesticide Reforms 26(4):6–7 Cohen R, Pivonia S, Burger Y, Edelstein M, Gamliel A, Katan J (2000) Toward integrated management of Monosporascus wilt of melons in Israel. Plant Dis 84:496–505

278

References

Cohen R, Burger Y, Horev C, Porat A, Edelstein M (2005) Performanceof galia-type melons grafted on to Cucurbita rootstock in Monosporascus cannonballus-infested soils. Ann Appl Biol 146:381–387 Coutts BA, Kehoe MA, Webster CG, Wylie SJ, Jones AL (2011) Zucchini yellow mosaic virus: biological properties, detection procedures and comparison of coat protein gene sequences. Arch Virol 156:2119–2131 Crinò P, Lo Bianco C, Rouphael Y, Colla G, Saccardo F, Paratore A (2007) Evaluation of rootstock resistance to Fusarium wilt and gummystem blight and effect on yield and quality of a grafted ‘inodorus’ melon. HortScience 42:521–525 Cucumber (1988) Vegetable crops production guide for the Atlantic Provinces. Prepared by the Advisory Committee on vegetable crops. Published by authority of the Atlantic Provinces Agriculture Services Co-ordinating Committee, 9 pp. www.nr.gov.nl.ca/nr/agrifoods/crops/ veg_pdfs/cucumbers.pdf Culliney TW (1990) Population performance of Thrips palmi (Thysanoptera: Thripidae) on cucumber infected with a mosaic virus. Proc Hawaiian Entomol Soc 30:85–89 Dalela GG (1956) A species of Rhizopus causing drying of young fruits of Cucurbita maxima L. Indian Phytopathol 9:197 Darekar RN, Sawant DM (1989) Relationship of bottle gourd mosaic virus with its aphid vectors. In: Proceedings of the 41st annals meetings Indian phytopathology society, vol 42, p 340 Das R, Mandal SK, Maity TK (2009) Insect pollinators of pointed gourd and effect of different artificial methods of pollination on fruit setting and subsequent development of fruits. Veg Sci 36(3 Suppl):353–355 Das TK, Tuti MD, Sharma R, Paul T, Mirja PR (2012) Weed management research in India: an overview. Indian J Agron 57:148–156 Dasgupta MK (1998) Meloidogyne – at the acme of nematode parasitism with special reference to vegetables. In: Sengupta PK, Chowdhury AK (eds) Proceedings of national seminar on vegetable diseases and their management strategies in West Bengal. Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India, pp 39–47 Dasgupta MK, Mandal NC (1986) Ecology and Epidemiology of post Harvest disease of perishable: prelude to their control. Rev Trop PI Pathol 2 (1985/1986). Today and Tomorrow’s Printers and Publishers, New Delhi Dasgupta MK, Mandal NC (1988) Post harvest diseases of perishables. Oxford and IBH Publishing Co. Pvt. Ltd., Calcutta Dasgupta MK, Mandal NC (1989) Postharvest pathology of perishables. Oxford and IBH Publishing Co. Ltd, New Delhi, 623 pp Davis AR, Perkins-Veazie P, Sakata Y, López-Galarza S, Maroto JV, Lee SG, Huh YC, Sun Z, Miguel A, King SR, Cohen R, Lee JM (2008) Cucurbit grafting. Crit Rev Plant Sci 27(1):50–74 De N, Singh KP, Rai M (2003) Micronutrient deficiency symptoms in vegetable crops and their management. Technical Bulletin No. 14. Indian Institute of Vegetable Research, Varanasi, 28p Desai BG, Pathak VN (1969) Some studies on a soft rot disease of Luffa cylindrica Roem. Phytopathol Mediterr 8:238–239 Desbiez C, Lecoq H (1997) Zucchini yellow mosaic virus. Plant Pathol 46:809–829 Description of Plant Viruses (2010) Available in: http://www.dpvweb.net/dpv/dpvnameidx.php Deyo A, O’Malley B (2008) Cucurbitaceae; College seminar 235, food for thought: the science, culture, and politics of food spring Dhillon MK, Singh R, Naresh JS, Sharma HC (2005) The melon fruit fly, Bactrocera cucurbitae: a review of its biology and management. J Insect Sci 5:40 Dias R, Picó B, Espinos A, Nuez F (2004) Resistance to melon vine decline derived from Cucumis melo ssp. agrestis: genetic analysis of root structure and root response. Plant Breed 123:66–72 Dittmar PJ, Boyd NS (2019) Weed management in cucurbit crops (muskmelon, cucumber, squash, and watermelon). HS190, Horticultural Sciences Department, University of Florida/FAS (Institute of Food and Agricultural Sciences) Extension Doharey KL (1983) Efficacy of some insecticides against fruit flies. Indian J Entomol 45:465–469

References

279

Duarte V, De Boer SH, Ward LJ, de Oliveira MC (2004) Characterization of atypical Erwinia carotovora strains causing blackleg of potato in Brazil. J Appl Microbiol 96:535–545. https:// doi.org/10.1111/j.1365-2672.2004.02173.x Dubey GS, Nariani TK, Prakash N (1974) Identification of snake gourd mosaic virus. Indian Phytopathol 27:470–474 Duke SO, Dayan FF, Rimando RM, Schrader KK, Aliotta G, Oliva A, Romagni G (2002) Chemicals from nature for weed management. Weed Sci 50:138–151 Dwivedi SK, Shrivastava GK, Singh AP, Lakpale R (2012) Weeds and crop productivity of maize + blackgram intercropping system in Chhattisgarh plains. Indian J Weed Sci 44:26–29 Ecocrop (2011) Ecocrop database. FAO Edelstein M, Cohen R, Burger Y, Shriber S, Pivonia S, Shtienberg D (1999) Integrated management of sudden wilt in melons, caused by Monosporascus cannonballus, using grafting and reduced rates of methyl bromide. Plant Dis 83:1142–1145 Egel D (2017) Phytophthora blight of cucurbits. Vegetable Crops Hotline. A newsletter for commercial vegetable growers prepared by the Purdue University Cooperative Extension Service No. 637 Egel DS, Martyn R, Gunter C (2008) Planting method, plastic mulch, and fumigation influence growth, yield, and root structure of watermelon. HortScience 43:1410–1414 Eigenbrode SD, Trumble JT (1994) Host plant resistance to insects in integrated pest management in vegetable crops. J Agric Entomol 11(3):201–224 Eighenbrode S, Trumble JT (1994) Host plant resistance to insects in Integrated Pest Management in vegetable crops. J Agric Entomol 11(3):201–224 El-Dougdoug KA, Ghaly MF, Taha MA (2012) Biological control of cucumber mosaic virus by certain local streptomyces isolates: inhibitory effects of selected five Egyptian isolates. Int J Virol 8:151–164 Enkerlin W (2003) Economics of area-wide SIT control programs. In: Recent trends on sterile insect technique and area-wide integrated pest management-economic feasibility, control projects, farmer organization and bactrocera dorsalis complex control study. Research Institute for Subtropics, Naha, Japan, pp 1–10 Erwin DC, Ribeiro OK (1996) Phytophthora diseases worldwide. American Phytopathological Society Press, St. Paul Ferreira SA, Boley RA (1992) Colletotrichum lagenarium. Crop Knowledge Master. Department of Plant Pathology, CTAHR. University of Hawaii (Manoa). 2A-COLAG www.extento.hawaii. edu/kbase/crop/type/c_lagen.htm Ferrer F (2003) Cuantificación de ascosporas de Monosporascus cannonballusen campos de melón en la Comunidad Valenciana. In: Trabajo Fin de Carrera. ETSIA, Universidad Politécnica de Valencia Francki RIB, Hu J, Palukaltis P (1986) Taxonomy of cucurbit infecting tobamovirus as determined by serological and molecular hybridization analyses. Intervirology 26:156–163 Franski RIB, Hatta T (1980) Cucumber mosaic virus – variation and problems of identification. Acta Hortic 11:167–174 Fukuda M, Meshi T, Okada Y, Otsuki Y, Takebe I (1981) Correlation between particle multiplicity and location of virion RNA of the assembly initiation site for viruses of the tobacco mosaic virus group. Proc Natl Acad Sci U S A 78:4231–4235 Gangopadhyay S, Kapoor KS (1973) Fruit rot of summer squash and its control. Indian Phytopathol 26:751–753 Gangopadhyay S, Sharma RK (1976) Spongy rot of pumpkin. Indian Phytopathol 29:423–424 Garcia-Jimenez J, Martinez-Ferrer G, Armengol J, Velazquez T, Orts M, Juarez M, Ortega A, Jorda MC, Alfaro A (1993) Agents associated with melon collapse in various areas of Spain. Boletin de Sanidad Vegetal, Plagas 19:401–423 García-Jiménez J, Armengol J, Martínez G (1994) Puntos negros de las raices de melón y sandía (Monosporascus spp.). Enfermedades de las Cucurbitáceas en España. Sociedad Española de Fitopatología. Phytoma-España, pp 38–41

280

References

Garg PK, Gupta MN (1983) Fusarium rot of bottlegourd fruits [Lagenaria vulgaris]. Indian J Mycol Plant Pathol 13:119 Gennari S, Mirotti A, Sportelli M (1999) Riperimento di Monosporascus cannonballus da piante di cocomero. Informatore Fitopatologico 1-2:38–40 Ghosh SK, Mukhopadhyay S (1979a) Some viruses of pumpkin (Cucurbita moschata) in West Bengal. J Phytopathol 94:172–184 Ghosh SK, Mukhopadhyay S (1979b) Incidence of squirting cucumber mosaic virus of cucumber in West Bengal. Curr Sci 48(7):788 Ghosh SK, Senapati SK (2001) Biology and seasonal fluctuation of Henosepilachna vigintioctopunctata Fab. on brinjal under Terai region of West Bengal. Indian J Agric Res 35:149–154 Giannakou IO, Karpouzas DG (2003) Evaluation of chemical and integrated strategies as alternatives to methyl bromide for the control of root-knot nematodes in Greece. Pest Manag Sci 59(8):883–892 Gilbert-Albertini F, Lecoq H (1994) The characterization of a strain of Zucchini yellow fleck virus found in southeastern France. J Phytopathol 140:375–384 Giri BK (1985) Studies on tomato mosaic. PhD thesis, PG School, IARI, New Delhi Giri BK, Chenulu VV, Mishra MD (1981) A new graft-transmissible disease of Momordica chrantia L. Discussion on current problems on virus and virus-like plant diseases, Kalimpong, IARI Reg. Station, Kalimpong, 19–21 October Goldwasser Y, Eizenberg H, Golan S, Kleifeld Y (2003) Control of Orobanchae crenata and Orobanchae aegyptiaca in parsley. Crop Prot 22:295–305 Gopalakrishnan TR (2007) Vegetable crops. In: Peter KV (ed), New India Publishing Agency, New Delhi, pp 104–105 Goswami SB, Saha S (2006) Effect of organic and inorganic mulches on soil-moisture conservation, weed suppression and yield of elephant-foot yam. Indian J Agron 51(2):154–156 Gour TB, Ramesh Babu T, Sriramulu M, Reddy DDR, Chandrasekhara Rao K, Ravindra Babu R, Narayan P (2008) Crucifers, cucurbits – insect pests, diseases, nutritional disorders. Agricultural Information and Communication Centre, ANGRAU, Hyderabad. Information Bulletin No. 12: 90 pp Grabowski M (2013) Common diseases of cucurbit crops in Minnesota, University of Minnesota, http://www.extension.umn.edu/distribution/horticulture/DG1172-1.html. Last update on 13th July 2014 Gupta DK, Chile SK, Vyas KM (1982) A fruit rot disease of Mormordica diocia. Indian Phytopathol 35(2):351 Gupta AK, Sharma RC, Sharma S (2001) Fungal disease of cucurbits. In: Gupta VK, Paul YS (eds) Disease of vegetable crops. Kalyani Publishers, New Delhi, pp 71–86 Habimana S, Nduwumuremyi A, Chinama RJD (2014) Management of Orobanchae in field crops – a review. J Soil Sci Plant Nutr 14(1):43–62 Hall DH, Gubler WD, Sciaroni RH (1981) Fusarium fruit rot of cucurbits. Calif Plant Pathol 54:3 Hasanuzzaman MD, Mian MAK, El-Taj HF, Saiful H, Amin MR (2004) Floral biology of snake gourd. Pak J Biol Sci 7(4):525–528 Hausbeck MK, Lamour KH (2004) Phytophthora capsici on vegetable crops: Progress and challenges. Plant Dis 88:1292–1303 Hazra P, Som MG (2015) Vegetable science. Kalyani Publishers Hirai G, Nakazumi H, Yagi R, Nakano M (2002) Fusarium wilt (race1,2y) -resistant melon (Cucumis melo) rootstock varieties ‘Dodai 1’ and ‘Dodai 2’. Acta Hortic 588:155–160 Hiremath PC, Govindu HC (1973) Studies on market diseases of vegetables in Mysore State. I. [alternaria tenuis, Rhizopus nigricans, Curvularia lunata]. Mysore J Agric Sci 7 (3):428–435 Hoffman MP, Zitter TA (1994) Cucumber beetles, corn rootworms, and bacterial wilt in cucurbits. Fact sheet. Department of Plant Pathology Cornell University, p 781.00

References

281

Hollingsworth R, Vagalo M, Tsatsia F (1997) Biology of melon fly, with special reference to the Solomon Islands. In: Allwood AJ, Drew RAI (eds) Management of fruit flies in the Pacific. Proceeding of the Australian Country Indus Agril Res, vol 76, pp 140–144 Holm LG, Donald P, Pancho JV, Herberger JP (1977) The world’s worst weeds: distribution and biology. The University Press of Hawaii, Honolulu, Hawaii, 609 pp Horowitz M, Regev Y, Herzlinger G (1983) Solarization for weed control. Weed Sci 31:170–179 Hossain MS, Khan AB, Haque MA, Mannan MA, Dash CK (2009) Effect of different host plants on growth and development of epilachna beetle. Bangladesh J Agric Res 34:403–410 Hsieh WH, Goh TK (1990) Cercospora and similar fungi from Taiwan. Maw Chang Book Company, Taipei Huh YC, Om YH, Lee JM (2002) Utilization of Citrullus germplasm with resistance to Fusarium wilt (Fusarium oxysporum f. sp. niveum) for watermelon rootstocks. Acta Hortic 588:127–132 Huitron MV, Ricardez MG, Camacho F (2011) Influence of grafted watermelon plant density on yield and quality in soil infested with Melon necrotic spot virus. Acta Hortic 917:265–268 IARI (2016) Accomplishments. https://www.iari.res.in/index.php?option¼com_content& view¼article&id¼613&Itemid¼1572 Igarashi I, Tsugio K, Takeo K (1987) Disease and pest resistance of wild cucumis species and their compatibility as rootstock for muskmelon, cucumber and watermelon. Bull Natl Res Inst Veg Ornam Plants Tea A1:173–185 Imazu T (1949) On the symbiotic affinity caused by grafting among Cucurbitaceous species. J Jpn Soc Hortic Sci 18:6–42 Inderjit, Weston LA, Duke SO (2005) Challenge, achievements and opportunities in allelopathy research. J Plant Interact 1:69–81 Ioannou N (2001) Integrating soil solarization with grafting on resistant rootstocks for management of soilborne pathogens of eggplant. J Hortic Sci Biotechnol 76:396–401 IPM Scouting Guide for Common Problems of Cucurbit Crops in Kentucky (2009). http://www.ca. uky.edu/agc/pubs/id/id91/id91.pdf Islam SZ, Babadoost M, Lambert K, Ndeme A, Fouly HM (2005) Characterization of Phytophthora capsici isolates from processing pumpkin in Illinois. Plant Dis 89:191–197 Jaczewski AA (1927) Karmannii Opredelitel gribov, Leningrad, p 626 Jarvis WR (1992) Cucumber diseases. Agriculture Canada publication 1684/E. 49 pp Jeffrey D (1990) Appendix: an outline classification of the cucurbitaceae. In: Bates DM, Robinson RW, Jeffrey C (eds) Biology and utilization of the Cucurbitaceae, Cornell University, Ithaca and London, pp 449–463, 485 p Jhooty JS (1967) Identity of powdery mildew of cucurbits in India. Plant Dis Reptr 51:1079–1080 Jhooty JS, Behar DS (1972) Control of powdery mildew of pea and pumpkin by seed treatment with benomyl. J. Agric Sci 42:505–508 Jhooty JS, Grover RK (1971) Rhizoctonia root rot of cucurbits and its control in India. Indian Phytopathol 24:571–574 Jhooty JS, Singh RS (1971) Charcoal rot of melon – a new record for India. Indian Phytopathol 24:578–579 Jhooty JS, Chander S, Bains SS (1978) Factors affecting resistance in muskmelon and wild melon against Pseudoperonospora cubensis. Nat Acad Sci Lett 1(8):278–281 Joel DM, Hershenhorn J, Eizenberg H, Aly R, Ejeta G, Rich PJ, Ransom JK, Sauerborn J, Rubiales D (2007) Biology and management of weedy root parasites. Hortic Rev 33:267–349 Joseph PJ, Ramanathan MM (1978) Studies on the mosaic disease of snake gourd (Trichosanthes anguina L.). Agric Res J Kerala 16:148–154 Joshi RD (1977) Efficacy of Aphis gossypii as vector of turnip mosaic virus and water melon mosaic virus. Indian Phytopathol 30:541–544 Juarez M, Kassem MA, Sempere RN, Truniger V, Moreno IM, Aranda MA (2005) Cucurbit aphidborne yellow virus (CABYV): a new virus found in cucurbit crops in southeastern Spain. Boletin de Sanidad Vegetal, Plagas 31:587–598

282

References

Kannaiyan S, Prasad NN (1975) Saprophytic activity of muskmelon wilt fungus in soil. Indian Phytopathol 28:167–170 Kannayan S, Prasad NN (1975) Effect of certain amendments on the saprophytic activity of muskmelon wilt pathogen in soil. Indian Phytopathol 28:385–386 Kapoor JN (1967) Sphaerotheca fuliginea, Erysiphe cichoracearum: C.M.I. descriptions of pathogenic fungi and bacteria. Set 16:152–159 Kapoor VC, Agarwal ML (1983) Fruit flies and their natural enemies in India In: Drew R (ed) Proceedings of the CEC/IOBC international symposium on fruit flies of economic importance, Athens, Greece. Balkema Publications, Rotterdam, pp 104–105 Kaur J, Jhooty JS (1985) Presence of race 3 of Sphaerotheca fuliginea on muskmelon in Punjab. Indian Phytopathol 39:297–299 Kaur J, Jhooty JS (1986) Pathological specialization in Sphaerotheca fuliginea causing powdery mildew of cucurbits. Indian Phytopathol 38:302–305 Kaushal KK (1999) Proceeding of National symposium on rational approaches in nematode management for sustainable agriculture, Anand, India, pp 16–19 Kebreab E, Murdoch AJ (2001) Simulation of integrated control strategies for Orobanche spp. based on a life cycle model. Exp Agric 37:37–51 Keck CB (1951) Effect of temperature on development and activity of the melon fly. J Econ Entomol 44:1001–1002 Kennelly M (2012) Diseases of cucurbits crops. In: Proceedings of great plains growers conference held on 6th January 2012, at Kansas State University, Department of Plant Pathology, pp 1–20 Kesavan R, Prasad NN (1974) Correlation between crude cucurbitacin content in certain muskmelon varieties and Fusarium wilt incidence. Indian J Exp Biol 12:476–477 Khan MW, Khan AM, Akram M (1972) Perithecial stage of certain powdery mildews including some new records. Indian Phytopathol 25:220–224 Khan AM, Khan MW, Akram M, Khan AH (1976) Studies on the cucurbit powdery mildew. II. Varietal response of some cucurbits to Sphaerotheca fuliginea. Indian Phytopathol 29:306–308 Khan MR, Mukherjee A, Pal S, Sarkar P (2015) Nematode pests of crops in West Bengal: a comprehensive monograph. Directorate of Research, Bidhan Chandra KrishiViswavidyalaya, Kalyani, West Bengal, 128p Khandelwal GL, Prasad R (1979) Nutritional requirements of Alternaria cucumerina causing blight disease of cucurbits. Indian J Mycol Plant Pathol 9:237–241 Khatua DC, Maiti S (1982) Two new leaf blight diseases caused by Rhizoctonia solani. Indian Phytopathol 35:124–125 Khatua DC, Saha G (2004) Diseases of pointed gourd. In: Plant pathology: problems and prospectives. Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, pp 101–109 Khatua DC, Das A, Ghanti P, Sen C (1981) Downy mildew of cucurbits in West Bengal and preliminary field assessment of fungicides against downy mildew of cucumber. Pestology 5 (2):30–31 Khatua DC, Mondal B, Hansda S, Ray SK (2014) Sclerotinia rot of ridge gourd and pointed gourd in lateritic zone of West Bengal. Scholar Acad J Biosci 2(4):251–254 Khosla HK, Dave GS, Nema KG (1973) Identity of powdery mildew on white gourd (Benincasa hispida cogn.) in Madhya Pradesh. JNKVV Res J 7:175–177 Kijima J (1933) Watermelon grafting using bottle gourd rootstock. J Okitsu Hortic Soc 29:111–115 Kiss EF, Kazinezi G, Horvath J, Kobza S, Baranyi T, Varga M, Havasreti B, Feher A (2003) Virus disease problems on field cucumber in Hungary. Bull OILB/SROP 26:219–228 Klein O, Kroschel J (2002) Biological control of Orobanchae spp. with Phytomyza orobanchia. BioControl 47:244–276 Komada H, Ezuka A (1974) Varietal resistance to Fusarium wilt in cucumber.1. Relation between the resistance reaction of adult plants in field and that of seedlings in greenhouse. Bull Veg Ornam Crops Res Stn Japan Ser A 1:233–245

References

283

Komuro Y (1971) Cumber green mottle mosaic virus on cucumber and watermelon and melon necrotic spot virus on muskmelon. Jpn Agric Res Quart 6:41–45 Komuro Y, Tochihara H, Fukatsu R, Nagani Y, Yoneyama S (1968) Cucumber green mottle mosaic virus on watermelon in Chiba and Ibaraki prefectures. Ann Phytopathol Soc Jpn 34:377 Komuro Y, Tochihara H, Fukatsu R, Nagai Y, Yoneyama S (1971) Cucumber green mottle mosaic virus (watermelon strain) in watermelon and its bearing on deterioration of watermelon fruit known as “Konnyaku” disease. Ann Phytopathog Soc Jpn 37:34–42 Kong CH, Liang WJ, Xu XH, Hu F, Wang P, Jiang Y (2004) Release and activity of allelochemicals from allelopathic rice seedlings. J Agric Food Chem 52:2861–2865 Kontaxis DG, Kurupas T (1975) Watermelon rind necrosis in Imperial Valley. Calif Agric 29 (9):14–15 Korbin M, Kaminska M (1998) Characterization of cucumber mosaic cucumovirus isolates. Phytopathol Pol 16:71–84 Kore SS, Kharwade LR (1987) Fruit rot of round gourd caused by Fusarium oxysporum. Indian Phytopathol 40:251 Krishnamurthy V, Goswami BK, Gupta JN (1972) Helminthosporium rostratum causing a leaf spot of cucurbitaceous host muskmelon (Cucumis melo). Indian Phytopathol 25:302–303 Kulkarni SA, Kulkarni S (1994) Biological control of Sclerotium rolfsii a causal agent of stem rot of groundnut. Karnataka J Agric Sci 7:365–367 Kumar S (2014) Biological control of terrestrial weeds. In training manual advance training in weed management, held at DWSR, Jabalpur, on 14–23 January, pp 91–95 Kumar S, Ray P (2011) Evaluation of augmentative release of Zygogramma bicolorata for biological control of Parthenium. Crop Prot 30:587–591 Kumar B, Pandey R, Verma AK (2003) Studies on host range of Sclerotinia sclerotiorum of broccoli. Progress Agric 3(1/2):131–132 Labrada R (1996) Manejo de malezas en hortalizas. In: Labrada R, Caseley JC, Parker C (eds) Manejo de malezas para países en desarrollo. Estudio FAO Producción y Protección Vegetal 120. FAO, Roma, pp 298–308 Lamichhane JR, Varvaro L, Balestra GM (2010) Bacterial leaf spot caused by Xanthomonas cucurbitae newly reported on pumpkin in Nepal. New Dis Rep 22(20). https://doi.org/10. 5197/j.2044-0588.2010.022.020 Lamichhane JR, Balestra GM, Mazzaglia A, Varvaro L, Kshetri MB (2011) An overview on bacterial diseases of the most important agricultural crops in Nepal. Acta Hortic 917:203–210 Lamour KH, Hausbeck MK (2000) Mefenoxam insensitivity and the sexual stage of Phytophthora capsici in Michigan cucurbit fields. Phytopathology 90:396–400 Lange L, Eden U, Olson LW (1989) Zoosporogenesis in Pseudoperonospora cubensis.The causal agent of cucurbit downy mildew. Nord J Bot 8:497–504 Laxminarayana P, Reddy SM (1976) Post-harvest diseases of some cucurbitaceous vegetables from Andhra Pradesh. Indian Phytopathol 29:57–59 Lebada A, Kozelska S, Kristkova E, Novotny R (1996) The occurrence of viruses on Cucurbita spp. In the Czech Republic and resistance of squash cultivars to CMV and WMV-2. Z Pflanzenkrankheiten and Pflanzenschutz 103(5):455–463 Lecoq H (1992) Viruses of melons and courgettes grown in the field (II). PHM Revue Hortic 324:15–25 Lecoq H, Desbiez C (2012) Viruses of cucurbit crops in the mediterranean region: an ever-changing picture. Adv Virus Res 84:67–126 Lecoq H, Katis N (2014) Control of cucurbit viruses. Adv Virus Res 90:255–296 Lecoq H, Bourdin D, Wipf-Scheibel C, Bon M, Lot H, Lemaire O, Herrbach E (1992) A new yellowing disease of cucurbits caused by a luteovirus, cucurbit aphid borne yellows virus. Plant Pathol 41:749–761 Lee KY, Lee BC, Park HC (1990) Occurrence of cucumber green mottle mosaic virus disease of watermelon in Korea. Korean J Plant Pathol 6:250–255

284

References

Lee LWY, Hwang YB, Cheng CC, Chang JC (1992) Population fluctuation of the melon fly, Dacus cucurbitae, in northeastern Taiwan. Chinese J Entomol 12:285–292 Leonian LH (1922) Stem and fruit blight of pepper caused by Phytophthora capsici. Phytopathology 12:401–408 Lin YS, Hwang CH, Soong SC (1998) Resistance of bitter gourdloofah grafts to Fusarium oxysporum f. sp. momordicae and their yield. Plant Protect Bull 40:121–132 Linke KH, Saxena MC (1991) Towards an integrated control of Orobanche spp. in some legume crops. In: Wegmann K, Musselman LJ (eds) Progress in orobanche research. Eberhard Karls University, Tubingen, pp 248–256 Lipton WJ (1977) Ultraviolet radiation as a factor in solar injury and vein tract browning of cantaloupes. J Am Soc Hortic Sci 102:32–36 Lipton WJ, Wang CY (1987) Chilling exposure and ethylene treatment change the level of ACC in honey dew melons. J Am Soc Hortic Sci 112:109–112 Lisa V, Boccardo G, D’Agostino G, Dellavalle G, d’Aquilio M (1981) Characterisation of a potyvirus that causes zucchini yellow mosaic. Phytopathology 71:667–672 Lobo M (1990) Colapso del melón producido por hongos del género Monosporascus. Boletın Sanídad Vegetal. Plagas 16:701–707 Lolas CP (1986) Control of broomrape (Orobanche ramosa) in tobacco (Nicotiana tabacum). Weed Sci 34:427–430 Lovisolo O (1980) Virus and viroid diseases on cucurbits. Acta Hortic 88:33–71 Luis-Arteaga M, Alvarez JM, Alonso-Prados JL, Bernal JJ, Garcia-Arenal F, Lavina A, Batlle A, Moriones E (1998) Occurrence, distribution and relative incidence of mosaic viruses infecting field-grown melon in Spain. Plant Dis 82:979–982 Madan RL, Grover RK (1977) Some pathological studies on anthracnose affecting bottle gourd. Indian Phytopathol 30:392–398 Mahajan V, Mukherjee SC, Shaw SS (1997) Use resistant vegetable varieties: a best alternative to tackle diseases and insect pests. Farm Parliam 33:29–30 Mahato A, Mondal B (2014) Sclerotium rolsfii: its isolates variability, pathogenicity and an eco-friendly management option. J Chem Biol Phys Sci B Biol Sci 4(4):3334–3344 Mahato A, Mondal B, Dhakre DS, Khatua DC (2014) In vitro sensitivity of Sclerotium rolsfii towerds some fungicides and botanicals. Scholars Acad J Biosci 2(7):467–471 Mahmood K, Akram M, Quamar S, Naqvi A, Alam MM (1974) Studies on interaction between bottle gourd mosaic virus and powdery mildew fungus, Sphaerotheca fuliginae. Indian Phytopathol 27:827–829 Mahrishi RP, Siradhana BS (1984) On the occurrence of oospores of Pseudoperonospora cubensis in Rajasthan, India. Indian Phytopathol 37:323–325 Maity B, Sahoo AK, Kaiser SAKM (2004) Studies on pests of fruit crops in West Bengal. In: Raj SK, Pan SK, Chattopadhyay SB (eds) Plant pathology: problems and perspectives (A festschrift volume to Prof MK Dasgupta). Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India, pp 151–165 Majumdar A (1988) Role of plant quarantine in disease management of vegetable crops germplasm. In: Sengupta PK, Chowdhury AK (eds) Proceedings of the national seminar on vegetable diseases and their management strategies in West Bengal. Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, p 82 Mallik RK, Yadav A, Rana MK (1998) Farmers and parliament, December Issue Mandal NC (1981) Post harvest disease of fruits and vegetable in West Bengal. PhD thesis, Visva— Bharathi, Santhiniketan Mandal NC, Dasgupta MK (1980) Postharvest diseases of Perishables in West Bengal, India. III Further addition to some new vegetable diseases in India. Indian J Mycol Plant Pathol 10:31 Mandal NC, Dasgupta MK (1981) Post harvest disease of perishables in West Bengal. II. Losses. Ann Agric Resour 2:73–75 Mandal NC, Dasgupta MK (1982) Post harvest disease of perishables in West Bengal, India. Indian Phytopathol 35:645–649

References

285

Mandal NC, Dasgupta MK (1983) New report on post harvest diseases of perishable fruit and vegetables and their implication. Geohios New Rep 2:119–121 Mandal S, Mandal B, Mohad Q, Haq R, Varma A (2008) Properties, diagnosis and management of cucumber green mottle mosaic virus. Plant Viruses 2(1):25–34 Mandloi SC, Khare MN (1969) Control of powdery mildew of cucurbits (Erysiphe cichoracearum DC.) by fungicidal sprays. Mysore J Agric Sci 3:248–250 Martyn RD (2002) Monosporascus root rot and vine decline of melons. The Plant Health Instructor. https://doi.org/10.1094/PHI-I-2002-0612-01, Updated 2009 Martyn RD (2007) Late-season vine declines of melons: pathological, cultural or both? Acta Hortic 731:345–356 Martyn RD, Miller ME (1996a) Monosporascus root rot/vine decline: an emerging disease of melons worldwide. Plant Dis 80:716–725 Martyn RD, Miller ME (1996b) Monosporascus root rot/vine decline of muskmelon and watermelon. In: Zitter TA, Hopkins DA, Thomas CE (eds) Compendium of cucurbit diseases. APS Press, St. Paul, pp 18–19 Mathew SK, Girija D, Abraham K, Binimol KS (2002) Occurrence of bacterial wilt of bitter gourd and ridge gourd in Kerala. Bacterial Wilt Newslet 17:21 Mathur RL, Mathur BL (1958) Fruit rot of Citrullus vulgaris var. fistulosus L. Indian Phytopathol 11:66–69 Mayee CD, Nandpuri KS, Lal T (1976) A mosaic disease of muskmelon in Punjab. Veg Sci 3:87–90 Maynard DN, Hochmuth GJ (2007) Knott’s handbook for vegetable growers. Wiley, Hoboken McSorley R, Waddill VH (1982) Partitioning yield loss on yellow squash into nematode and insect com-ponents. J Nematol 14:110–118 Mehrotra BS (1954) The ‘cottony leak’ (Pythium aphanidermatum) of Citrullus fistulosus fruits. Sci Cult 19:564–565 Mehrotra RS (1980) Plant pathology. Tata McGrow-Hill Publishing Company Limited, New Delhi, p 771 Meng X, Chai A, Shi Y, Xie X, Ma Z, Li B (2017) Emergence of bacterial soft rot in cucumber caused by Pectobacterium carotovorum subsp. brasiliense in China. Plant Dis 101(2):279–287. https://doi.org/10.1094/PDIS-05-16-0763-RE Messenger PS, Flitters NE (1958) Effect of constant temperature environments on the egg stage of three species of Hawaiian fruit flies. Ann Entomol Soc Am 51:109–119 Midwest Vegetables Production Guide for Commercial Growers (2011) https://web.extension. illinois.edu/smallfarm/downloads/46907.pdf Miguel A, Marsal JI, López-Galarza S, Maroto JV, Tarazona V, Bono M (2005) Comportamiento de portainjertos de sandía frente a nematodos. Phytoma-España (in press) Mishra MD, Lene L, Giri BK (1983) Seed transmission of a white fly transmitted Gemini virus. In: Proceeding of the fourth international congress of plant pathology, Melbourne (Abstract) Misra S, Gupta N (1988) ‘Yellow’ disease of vegetable and oil seed crops in Rajasthan. Indian Phytopathol 41:266. (Abstract) Mital S, Akram M (1985) Cucumis sativus (cucumber): a common host for Erysiphe cichoracearum DC and Sphaerotheca fuliginea (Schlecht.). Poll Acta Bot Ind 13:259–260 Mitra M, Subramanian LS (1928) Fruit rot diseases of cultivated cucurbits caused by Pythium aphanidermatum Fitz. Mem Dept Agric Indian Bot Ser 15:79–84 Mohaned MA, Mohamed M, Elabdeen HZ, Ali SA (2013) Host preference of the melon worm, Diaphania hyalinata L. (Lepidoptera: Pyralidae), on cucurbits in Gezira State, Sudan. Persian Gulf Crop Protec 2:55–63 Mondal B, Khatua DC (2013) Evaluation of Plaster of Paris and some fungicides for management of foot rot of Amorphophallus campanulatus Blume caused by Sclerotium rolfsii Sacc. Int J Agric Environ Biotechnol 6(4):585–589 Mondal CK, Maitra NJ (2011) Parthenocarpic pointed gourd. ICAR News 17(3):9

286

References

Mondal B, Bhattacharya R, Ranjan RK, Khatua DC (2004) Bacterial wilt disease of horticultural plants in West Bengal and its chemical control. Green Technol 6:70–74 Mondal B, Bhattacharya I, Khatua DC (2011) Crop and weed host of Ralstonia solanacearum in West Bengal. J Crop Weed 7(2):195–199 Mondal B, Mahapatra S, Khatua DC (2012) Records of some new diseases of horticultural plants of West Bengal. J Interacad 16(1):36–43 Mondal B, Bhattacharya I, Khatua DC (2014a) Incidence of bacterial wilt disease in West Bengal, India. Acad J Agric Res 2(6):139–146 Mondal B, Das R, Saha G, Khatua DC (2014b) Downy mildew of pointed gourd and its management. Scholars Acad J Biosci 2(6):389–392 Mondal B, Mandal S, Mondal CK, Khatua DC (2016) Occurrence of bacterial wilt of bitter gourd in Sundarban region of West Bengal, India. Eur J Biotechnol Biosci 4(8):01–03 Mondal B, Mondal P, Dasgupta MK (2017) Traditional knowledge in relation to human affairs. In: Sarkar AK, Ghosh PK (eds) Human development and sustainability: challenges and strategies. Atlantic Publishers & Distributors (P) Ltd, New Delhi, pp 234–247. ISBN: 978-81-269-2307-6 Montano HG, Davis RE, Dally EL, Pimentel JP, Brioso PST (2000) Identifcation and phylogenetic analysis of a new phytoplasma from diseased chayote in Brazil. Plant Dis 84:429–436 Montasser MS, Dashti NH, Ali NY, Cherian VM (2017) Biological control of a severe viral strain of cucumber mosaic virus (CMV) using a mild strain of CMV associated with viral satRNA combined with a mixture of plant growth promoting Rhizobacteria (PGPRs). Int J Biotechnol Bioeng 3(5):132–141. https://doi.org/10.25141/2475-3432-2017-5.0126 Moradi Z, Jafarpour B (2011) First report of coat protein sequence of cucumber green mottle mosaic virus in cucumber isolated from Khorasan in Iran. Int J Virol 7:1–12. https://doi.org/10.3923/ijv. 2011.1.12 Motes JE (1977) Pickling cucumbers - production and harvesting. MSU Cooperative Ext Service Bull, E-837, 8 pp Mukherjee N, Khatua DC (1998) Diagnosis and management of vegetable bacterioses. In: Sengupta PK, Chowdhury AK (eds) Proceedings of the seminar on vegetable diseases and their management strategies in West Bengal. Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal, pp 48–63 Mukherjee N (ed) (2007) Aajker Krishi Bhabna. National Book Agency Pvt. Ltd., p 334 Mukherjee SK, Sharma BD (1973) Root-knot disease of Trichosanthes dioica. Indian Phytopathol 26:248–249 Mukhopadhyay S (1988) Final report of the project on Breeding for disease resistance in pumpkin, brinjal and bhendi (ICAR). Bidhan Chandra Krishi Viswavidyalaya, West Bengal Mukhopadhyay S (1990) Final report of the project on Field resistance of pumpkins against some virus diseases (ICAR). Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal Mukhopadhyay S, Nath PS (1998) Current status of virus diseases of vegetables and research in West Bengal. In: Sengupta PK, Chowdhury AK (eds) Proceedings of the National Seminar on Vegetable diseases and their management strategies in West Bengal, Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, p 82 Mukhopadhyay S, Saha K (1968) Transmission of cucumis virus (cucumber mosaic virus) through seeds of Cucurbita maxima L. Sci Cult 34(N210):436–437 Mukhtar I, Mushtaq S, Khokhar I, Hannan A (2013) First record of Cercospora citrullina leaf spot on Lagenaria siceraria in Pakistan. J Anim Plant Sci 23(6):1756–1757 Muller C (1883) New Helminthocecidien und derren erreger. pp 5–50 Muller C, Brother H, Bargen S, Buttner C (2006) Zucchini yellow mosaic virus – incidence and sources of virus infection in field-grown cucumbers and pumpkins in the Spreewald. Germany J Plant Dis Prot 113:252–258 Mundkur BB (1937) Anthracnose of cucurbits in Punjab. Curr Sci 12:647–648 Murata J, Ohara K (1936) Prevention of watermelon Fusarium wilt by grafting Lagenaria. Jpn J Phytopathol 6:183–189

References

287

Mustafee TP (1998) Fungicidal impact on vegetable disease management. In: Sengupta PK, Chowdhury AK (eds) Proceedings of the National Seminar on Vegetable diseases and their management strategies in West Bengal, Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, p 82 Nagaich BB, Singh B (1960) Damping off of cucurbitaceous vegetables and its control. Agra Univ J Res (Sci) 9:125–135 Nagendran K, Aravintharaj R, Mohankumar S, Manoranjitham SK, Naidu RA, Karthikeyan G (2015) First report of cucumber green mottle mosaic virus in Snake gourd (Trichosanthes cucumerina) in India. Plant Dis 99(4):599 p. https://doi.org/10.1094/PDIS-10-14-1071-PDN Narain A, Swain NC, Sahoo KC, Das SK, Shukla VD (1985) A new leaf blight and fruit rot of watermelon. Indian Phytopathol 38:149–151 Narayanasamy P (2001) Plant pathogen detection and disease diagnosis, 2nd edn. CRC Press, Florida, 544 pp Nasr-Eldin MA, Abdelkader HS, Abo-Senna AS, Othman BA (2016) Characterization and phylogenetic analysis of zucchini yellow mosaic virus infecting cucurbita pepo in Egypt. J Am Sci 12 (3):93–104 Nasr-Esfahana M, Ahmadi AR (1997) Studies on the effect of soil solarisation, manure and their integration on root knor and total nematode populations in cucumber fields. Appl Entomol Phytopathol 65:18–20 Nath P (1966) Varietal resistance of gourds to the fruit fly. Indian J Hortic 23:69–78 Nath PS (2004) Disease management in vegetable crops. In: Raj SK, Pan SK, Chattopadhyay SB (eds) Plant pathology: problems and perspectives, p 248 Nath RP, Haidar MG, Akhter SW, Prasad H (1976a) Studies on the nematodes of vegetables in Bihar-I. Effect of the reniform nematode, Rotylenchulus reniformis on Trichosanthes dioica. Indian J Nematol 6(2):175–177 Nath RP, Haider MG, Akhter SW, Prasad H (1976b) Studies on the nematodes of vegetables in Bihar-II: combined effect of Meloidogyne incognita and Ozonium texanum var. parasiticum on germination of eggplant. Indian J Nematol 6:175–177 Nayar NN, More TA (eds) (1988) Cucurbits. Science Publishers, p 340 Nayban G (2002) Sahaj Kathay Bijnanbhittik chashbas, 2nd edn. Ananda Agency, Kolkata, p 206 Nishijima W (1993) Alternaria alternate – fruit spot of papaya. Crop Knowledge Master. 3A-ALALT, http://www.extento.hawaii.edu/kbase/crop/type/a_alter.htm Noble D (2009) Working toward better cucurbits: weed management strategies for the coming season [Online] Ojha NL (1983) Pathological and biochemical studies on fruit rot of legenaria vulgaris. Ph. D. thesis submitted to Bhagalpur University, Bhagalpur Okada Y (1986) Cucumber green mottle mosaic virus. In: Regenmortel VMHV et al (eds) The plant viruses. Plenum Press, New York, pp 267–281 Pal AB, Srinivasan K, Doijode SD (1984) Sources of resistance to melon fruit fly in bitter gourd and possible mechanisms of resistance. SABRAO J 16:57–69 Palodhi PR, Sen B (1979) Role of tylose development in the muskmelon disease caused by Fusarium solani. Plant Dis Rep 63:584–586 Pandey KK, Pandey PK, Satpathy S (2002) Integrated management of diseases and insects of tomato, chilli and cole crops Technical Bulletin No. 9. Indian Institute of Vegetable Research, Varanasi, pp 1–22 Pandey S, Singh B, Singh M (2011) IIVR vegetable varieties: a ready reckoner, IIVR Technical Bulletin No. 41, IIVR, Varanasi, pp 1–108 Paolo MA (1933) A sclerotium seed rot and seedling stem rot of mango. Philippine J Sci 52:237–261 Papavizas GS, Bowers JH, Johnston SA (1981) Selective isolation of Phytophthora capsici from soils. Phytopathology 71:129–133 Paplomatas EJ, Elena K, Tsagkarakou A, Perdikaris A (2002) Control of Verticillium wilt of tomato and cucurbits through grafting of commercial varieties on resistant rootstocks. Acta

288

References

Horticulturae. In: Proceedings of the second balkan symposium on vegetables and potatoes, Thessaloniki, Greece, vol 579, 11–15 October 2000, pp 281–284 Pavlakos JG (1943) The biology and control of Aulacophora foveicollis, Luc. in Greece. Zeitschrift fur Angewandte Entomologie 1:1–78 Pavlou GC, Vakalonnakis DJ, Ligoxigakis EK (2002) Control of rootand stem rot of cucumber, caused by F. oxysporum f. sp radicis cucumerinum, by grafting onto resistant rootstocks. Plant Dis 86:379–382 Pedigo LP (2002) Entomology and pest management. Prentice Hall of India Pvt. Ltd., New Delhi, pp 441–476 Peet M (1996) Sustainable practices for vegetable production in the south. Focus Publishing, R. Pullins Company, Newburyport Peris P (2004) Epidemiología de Monosporascus cannonballus en cultivos desandía injertada y no injertada. Trabajo Fin de Carrera. ETSIA UniversidadPolitècnica de Valencia Pessarakli MD (2016) Handbook of cucurbits: growth, cultural practices, and physiology. CRC Press, Taylor & Francis Group, Boca Raton Pillai MG (1971) A mosaic disease of snake gourd (Trichosanthes anguinal). Sci Cult 37:46–47 Pitcha DH (1986) Post harvest fruit conditioning reduces chilling injury in watermelon. Hortic Sci 21:1407–1409 Pitchaimuthu M, Souravi K, Ganeshan G, Kumar GS, Pushpalatha R (2012) Identification of sources of resistance to powdery and downy mildew diseases in cucumber [Cucumis sativus (L.)]. Pest Manag Horticult Ecosyst 18(1):105–107 Pleasant JM, Schlather KJ (1994) Incidence of weed seed in cow manure and its importance as a weed source for cropland. Weed Technol 8:304–310 Plumb RT, Mukhopadhyay S, Jones P (eds) (2000) Viruses of crops, weeds in Eastern India. IACRRothamsted, Hertfordshire United Kingdom and Bidhan Chandra Krishi Viswavidyalaya, India Polischuk V, Budzanivska I, Shevchenko T, Oliynik S (2007) Evidence for plant viruses in the region of Argentina Island, Antarctica. FEMS Microbiol Ecol 59:409–417 Pollack FG, Uecker FA (1974) Monosporascus cannonballus, an unusual ascomycete in cantaloupe roots. Mycologia 66:346–349 Pospieszny H, Cajza M, Plewa R (2003) First report of Zucchini yellow mosaic virus in cucumber in Poland. Plant Dis 87:1399 Prakash O, Singh SJ (1977) Anthracnose of bitter gourd caused by Colletotrichum lagenarium. Indian Phytopathol 30:290–291 Prakash O, Sohi HS, Sokhi SS (1974) Studies on anthracnose disease of cucurbits caused by Colletotrichum legenarium (Pass.) Ell. & Halst. and its control. Indian J Hortic 31:278–282 Prasad SS, Ambasta KK (1987) Fruit rot of sponge gourd. Indian J Mycol Plant Pathol 17:235 Prasad MM, Poddar KD (1977) Physiological changes in vegetables during pathogenesis. In: Bilgrami KS (ed) Physiology of microorganism. Today and Tomorrow’s Printers Publishers, New Delhi, pp 275–284 Priya A (2017) Healing effects of Cucurbitaceae family. ASANA Int Yoga J. https://www. asanajournal.com/healing-effects-cucurbitaceae-family/ Punja ZK (1985) The biology, ecology, and control of Sclerotium rolfsii. Annu Rev Phytopathol 23:97–127 Punja ZK (1988) Genetic of plant pathogenic fungi. In: Sidhu GS (ed), vol 6. Academic Press, London, pp 523–534 Purchifull D, Edwardson J, Hiebert E, Gonsalves D (1984) Papaya ringspot virus. CMI/AAB description of plant viruses no. 292. CMI, Kew, UK Purohit SD, Arya HC (1980) Phyllody: an alarming problem for sesamum growers. Agric Digest 4 (5):12 Radewald KC, Ferrin DM, Stanghellini ME (2004) Sanitation practices that inhibit reproduction of Monosporascus cannonballus in melon roots left in the field after crop termination. Plant Pathol 53:660–668

References

289

Radhakrishnan P, Sen B (1985) Effect of different methods of inoculation of Fusarium oxysporum and Fusarium solani for inducing wilt of muskmelon. Indian Phytopathol 38:70–73 Rai M, Pandey S, Kumar S (2008) Cucurbitaceae. In: Pitrat M (ed) Proceedings of the IXth EUCARPIA meeting on genetics and breeding of Cucurbitaceae, INRA, Avignon (France), 21–24 May 2008 Raina GL, Chand JN, Suryanarayana D (1968) Control of fruit rot of kakri (Cucumis melo L. var. utilissimus Duthie and Fuller) with chemicals. Indian Phytopathol 21:137 Rajak DC (2000) Studies on population fluctuations of red pumpkin beetle on muskmelon (Cucumis melo L.). Agric Sci Digest 20:54–55 Rajasree RS, Sibi PI, Francis F, William H (2016) Phytochemicals of cucurbitaceae family – a review. Int J Pharmacog Phytochem Res 8(1):113–123 Rajendran V (1965) A note on the occurrence of perfect stage of bottle gourd powdery mildew in Mysore. Indian Phytopathol 18:389–390 Ramakrishnan TS, Ramakrishnan K (1950) Addition to the fungi of Madras – VIII. Proc Indian Acad Sci 32B:97–111 Ramaswamy K, Prasad NN (1975) Effect of potassium nutrition on phenol metabolism of melon wilt. Madras Agric J 62:313–317 Ramsey GB, Smith MA (1961) Market diseases of cabbage, cauliflower, turnips, cucumbers, melons and related crops, vol 184. U.S. Department of Agriculture, Agricultural Handbook, 49 pp Rangaswami G, Mahadevan A (2004) Diseases of crop plants in India, 4th edn. Prentice-Hall of India Pvt. Ltd., New Delhi, p 536 Rangaswamy G, Mahadevan A (2004) Diseases of crop plants in India, 4th edn. Prentice Hall of India Pvt. Ltd., New Delhi, 536 p Rani S, Sharma GS, Verma HN (1971) Epidemiology of virus diseases of cucurbits. Proc Indian Nat Sci Acad 37:345–351 Rao VG (1964) Some new market and storage disease of fruits and vegetables in Bombay (Maharashtra). Mycopath Mycol Appl 23:297–310 Rao VG (1965) Some new records of market and storage diseases of vegetable in bombay (Maharashtra). Mycopath Mycol Appl 27:49–59 Rao VG (1966) An account of the market and storage diseases of fruits and vegetables in Bombay (Maharashtra). Mycopath Mycol Appl 28:165–176 Rao DR (1976) Epidemiology and characterization of viruses naturally occurring on bottle gourd and vegetable marrow. PhD thesis, PG School, IARI, New Delhi Rao VG, Subramaniam V (1975) A new rot of muskmelon. Sci Cult 41:496–497 Rao ALN, Varma A (1984) Transmission studies with cucumber green mottle mosaic virus. J Phytopathol 109:325–331 Rao MHP, Raychaudhuri SP, Varma A (1976) Inhibition of cucumber mosaic virus by some chemicals. Act Phytopathol Acad Sci Hung 11:259–269 Raychaudhuri M (1973) Studies on cucurbit viruses. PhD thesis, PG School, IARI, New Delhi Raychaudhuri SP (1977) Manual of virus diseases of tropical plants. Macmillan, India Raychaudhuri M, Varma A (1975a) Virus diseases of cucurbits in Delhi. In: Proceedings of the 62nd Indian Sci Congr Part III, p 74 Raychaudhuri M, Varma A (1975b) Virus vector relationship of marrow mosaic virus with Myzus persicae Sulz. Indian J Entomol 37:243–250 Raychaudhuri M, Varma A (1978a) Effect of oils on transmission of marrow mosaic virus by Myzus persicae Sulz. J Entom Res 7:107–111 Raychaudhuri M, Varma A (1978b) Mosaic disease of muskmelon caused by minor variant of cucumber mottle mosaic virus. J Phytopathol 93:120–125 Raychaudhuri M, Varma A (1983) Effect of oils on transmission of marrow mosaic virus by Myzus persicae Sulz. J Entom Res 7:107–111 Reddy HR, Nariani TK (1963) Studies on mosaic disease of vegetable marrow (Cucurbita pepo L.). Indian Phytopathol 16:260–267

290

References

Rice EL (1974) Allelopathy. Academic Press, New York Risse LA, Hatton TJ (1982) Sensitivity of water melon to ethylene during storage. Hortic Sci 17:946–948 Ristaino JB, Johnston SA (1999) Ecologically-based approaches to management of Phytophthora blight on bell pepper. Plant Dis 83:1080–1089 Robak J (1995) Epidemiology and control of cucumber downy mildew Pseudoperonospora cubensis. Biuletyn Warzywniczy 43:5–18 Robinson RW, Decker-Walters DS (1997) Cucurbits. Cab International, Wallingford, Oxon, New York Robinson RW, Decker-Walters DS (2004) Cucurbits: crop production science in horticulture, vol 6. CAB Publishing, Wallingford Ross AF (1948) Local lesions with potato virus Y. Phytopathology 38:930–932 Roy AK (1973a) Occurrence and control of powdery mildews on a few plants in Assam. Indian Phytopathol 26:578–581 Roy AK (1973b) Fruit rot of bottle gourd. FAO Plant Protection Bulletin 21(5):116–117 Roy S, Mukhopadhyay S (1980) Epidemiology of a virus disease of pumpkin in West Bengal. Indian Plant Pathol 32(2):207–209 Roy AK, Singh HNP (2003) Appraisal of post-harvest pathology of perishables (fruits and vegetables) in India. In: Sen C, Dasgupta MK, Chaudhuri S (eds) Plant pathology at crossroads. B. C. K. V, Mohanpur, pp 270–283 Roy DK, Garain PK, Mondal CK (2014) Relay cropping boosted cropping intensity. ICAR News 20(2):19 Roychaudhury SP, Verma JP (2000) Diseases of crops. In: Handbook of agriculture. Directorate of Information and Publications of Agriculture. ICAR, Krishi Anusandhan Bhavan, Pusa, New Delhi, p 1303 Ryall AL, Lipton WJ (1972) Handling, transportation and storage of fruits and vegetables, vol 1. AVI Pub. Co., Westport Ryu KH, Min BE, Chol GS, Chol SH, Kown SB, Noh GM, Yoon JY, Chol YM, Jang SH, Lee GP, Cho KH, Park WM (2000) Zucchini green mottle mosaic virus is a new tobamovirus: comparison of its coat protein gene with that of Kyuri green mottle mosaic virus. Arch Virol 145:2325–2333 Saha G (2002) Fruit and vine rot of pointed gourd. PhD thesis, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal, p 147 Saha G, Maity SS, Khatua DC (2002) Techniques for isolation of Pythium aphanidermatum from soil and laboratory evaluation of fungitoxicants against it. J Mycopathol Res 40(2):145–147 Sahu Kritagyan SP, Singh SP (1980) Fruit rot of pointed gourd in Bihar [Trichosanthes dioica, India]. Note. Indian Phytopathol 33:308–309 Sakata Y, Takayoshi O, Mitsuhiro S (2007) The history and present state of the grafting of cucurbitaceous vegetables in Japan. Acta Hortic 731:159–170 Sakthinathan B, Swaminathan V, Balasubramanian P, Sivakumar T (2017) Effect of ethrel on sex expression in pumpkin (Cucurbita moschata L.). Int J Chem Stud 5(6):964–966 Saljoqi AUR, Khan S (2007) Relative abundance of the red pumpkin beetle, Aulacophora foveicophora Lucas, on different cucurbitaceous vegetables. Sarhad J Agric 23:109–114 Samalo AP, Beshra RC, Satpathy CR (1991) Studies on comparative biology of the melon fruit fly, Dacus cucurbitae Coq. Orissa J Agric Res 4:1–2 Sarkar BB, Mukhopadhyay S (1979) Separation of nine anisometric cucurbit viruses by host reactions. Veg Sci 6:142–144 Sarma BK, Singh UP (2002) Variability in Indian isolates of Sclerotium rolfsii. Mycologia 94 (6):1051–1058 Sato N, Takamatsu T (1930) Grafting culture of watermelon. Nogyo Sekai 25:24–28 Satpathy S, Samarjit R, Kapoor KS (1998) Intyegrated management of vegetable pests. In: Kalloo G (ed) National symposium on ‘emerging scenarion in vegetable research and development’,

References

291

Indian Society of Vegetable Science, Project Directorate of Vegetable Research, Varanasi, India, 12–14 December 1998, pp 123–130 Satyagopal K, Sushil SN, Jeyakumar P (2014) AESA based IPM – cucurbitaceous vegetable crops (cucumber, bottle gourd, bitter gourd, sponge gourd, snake gourd, ash gourd, pumpkin, squash). AESA BASED IPM Package No. 21. National Institute of Plant Health Management, Hyderabad, India Seebold K (2010a) Foliar diseases of cucurbits. UK Cooperative Extension Service, University of Kuntucky, College of Agriculture. Plant Pathology Fact Sheet, PPFS-VG-10 Seebold K (2010b) Fruit rots of cucurbits. UK Cooperative Extension Service, University of Kuntucky, College of Agriculture, Plant Pathology Fact Sheet, PPFS-VG-07 Sehgal M, Gaur HS (1999) Important nematode problem of crops in India and their management. National centre for Integrated Pest Management, New Delhi, 16p Sengupta PK, Chowdhury AK (eds) (1998) Synopsis of the proceedings of the National Seminar on Vegetable diseases and their management strategies in West Bengal. Organized by the Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, p 82 Seshadri VS (1986) Cucurbits. In: Bose TK, Som MG (eds) Vegetable crops in India. Naya Prokash, Calcutta, pp 91–164 Shang H, Xie Y, Zhou X, Qian Y, Wu J (2011) Monoclonal antibody-based serological methods for detection of cucumber green mottle mosaic virus. Virol J 8:228. https://doi.org/10.1186/1743422X-8-228 Shankar G, Nariani TK (1974) A mosaic disease of watermelon (Citrullus vulgaris Schrad.). Curr Sci 43:281–282 Shankar G, Nariani TK, Prakash N (1969) Detection and identification of cucurbit viruses by electron microscopy and serology. In: Proceedings of international symposium on electron microscopy in life sciences, pp 27–28 Shankar G, Nariani TK, Prakash N (1971) Purification and serology of bottle gourd (Lagenaria siceraria Standl.) mosaic virus. Indian J Microbiol 11:43–52 Shankar G, Nariani TK, Prakash N (1972) Studies on pumpkin mosaic virus (PMV) with particular reference to purification, electron microscopy and serology. Indian J Microbiol 12:154–165 Sharma PD (2005) Fungi and allied organisms. Narosa Publishing House Pvt. Ltd., New Delhi, p 545 Sharma AR (2014) Weed management in conservation agriculture systems- problems and prospects. In: National training programme on advances in weed management, pp 1–9 Sharma YR, Chohan JS (1973) Transmission of Cucumis viruses-1 and 3 through seeds of cucurbits. Indian Phytopathol 26:596–598 Sharma BB, Wahab S (1970) Efficacy of actidione and aureofungin in the control of post-harvest decay of some cucurbitaceous fruits due to Pythium aphanidermatum. Hindusthan Antibiotic Bull 13:8–13 Sharma BB, Wahab S (1973) Effect of some antibiotics on the post harvest decay of cucurbit fruits caused by Pythium aphanldermaturn. Ghana J Sci 13:140–147 Sharma RB, Monga A, Roy AN, Gupta MN (1981) Pathophysiological studies on three new postharvest fruit rot diseases of Citrus sinensis. Indian J Mycol Plant Pathol 11:309–310 Sharma OP, Khatri HL, Bansal RD, Komal HS (1984) A new strain of cucumber mosaic virus causing mosaic disease of muskmelon. J Phytopathol 109:332–340 Sharma SB, Saka VW, Nene YL (1985) Plant parasitic nematodes in pigeonpea fields of ICRISAT centre. Int Pigeonpea Newslet 4:41–42 Shinde HJ, Desai UT, Masalkar SD, Choudhari SM (1994) Effect of plant growth regulators to control vine length in watermelon. J Maharashtra Agric Univ 19(1):150–151 Shishido M, Yoshida N, Usami T, Shinozaki T (2006) Black root rot of cucurbits caused by Phomopsis sclerotioides in Japan and phylogenetic grouping of the pathogen. J Gen Plant Pathol 72(4):220–227. https://doi.org/10.1007/s10327-006-0273-0

292

References

Shivalingaswami TM, Satpathy S, Banergee MK (2002) Estimation of crops losses due to Insect pests in vegetables Ed. by Babu S, Varaprasad B, Anitha KS, Prasada Rao K, Chakrabarthy DVJ, Chandurkar PS. Resour Manag Plant Protect 1:24–31 Shooker P, Khayrattee F, Permalloo S (2006) Use of maize as a trap crops for the control of melon fly, B. cucurbitae (Diptera:Tephritidae) with GF-120. Bio-control and other control methods. http://www.fcla.edu/FlaEnt/fe87p354.pdf Siddaramaiah AL, Kulkarni S, Hegde RK (1982) A new fruit rot disease of pumpkin from India. Indian Phytopathol 35:705–707 Siguenza C, Schochow M, Turini T, Ploeg A (2005) Use of Cucumis metuliferus as a rootstock for melon to manage Meloidogyne incognita. J Nematol 37:276–280 Sikora EJ (2011) Common diseases of cucurbits. Publication of the Alabama Cooperative Extension System (Alabama A&M University and Auburn University), ANR-0809, pp 1–8 Singh SJ (1973) A stem end rot disease of snake gourd fruits caused by Glornerella cingutata (Stonem.) Spauld. & Shrenk. Curr Sci 42:296 Singh SJ (1974) A fruit rot of snake gourd caused by Alternuria tennuissirna. Indian Phytopathol 27:384–385 Singh SJ (1981) Studies on virus causing mosaic disease of pumpkin (Cucurbita maxima Duch.). Phytopathol Mediterr 20:104 Singh SJ (1985) Witches’broom of bittergourd - a new yellows type disease in India. Indian J Virol 1(2):320–324 Singh RS (1986) A new fruit rot disease of muskmelon from India. PAU J Res 23:265–266 Singh RS (1987) Diseases of vegetable crops, 2nd edn. Oxford & IBH Publishing Co. Pvt. Ltd., New Delhi, p 362 Singh RS (1990) Plant diseases. Oxford & IBH Publishing Company, New Delhi, 619 pp Singh SJ (1992) Electron microscopy observations of bitter gourd witches broom. Indian Phytopathol 45:354–355 Singh G (ed) (2012) Checklist of commercial varieties of vegetables. Compiled and Edited by Dr. Gorakh Singh, Horticulture Commissioner; Published by: Department of Agriculture and Cooperation, Ministry of Agriculture, Government of India, Krishi Bhawan, New Delhi Singh SP (2013) CUCURBITS: biodiversity, breeding, and production in Uttar Pradesh. Published by Uttar Pradesh State Biodiversity Board, East Wing, ‘A’ Block, 3rd Floor, PICUP Bhawan, Vibhuti Khand, Gomti Nagar, Lucknow Singh R (2014) Weed management in major kharif and rabi crops. In: National training on advances in weed management, pp 31–40 Singh RS, Chohan JS (1972) Charcoal rot of ridge gourd - a pycnidial strain of Macrophomina phuseoli (Maubl.) Ashby from India. Indian Phytopathol 25:463–464 Singh RS, Chohan JS (1977) Factors affecting growth and fruit rot (cottony leak) of cucurbits caused by Pythium butleri. Indian Phytopathol 30:379–383 Singh RS, Chohan JS (1979) Control of charcoal rot of muskmelon fruits. Indian J Mycol Plant Pathol 9(1):5–8 Singh RS, Chouhan JS (1980) Fungal fruit rot of bottle gourd in North India. Indian Phytopathol 33:598–599 Singh DV, Seth ML (1974) Collar rot of pumpkin caused by Sclerotium rolfsii. Indian Phytopathol 27:631–632 Singh D, Nandpuri KS, Sharma BR (1976) Inheritance of some economic quantitative characters in an intervarietal cross of muskmelon (Cucumis melo L.). Res Ludhiana 13:172–176 Singh SV, Mishra A, Bisan RS, Malik YP, Mishra A (2000) Host preference of red pumpkin beetle, Aulacophora foveicollis and melon fruit fly, Dacus cucurbitae. Indian J Entomol 62:242–246 Singh R, Singh RK, Rai RK, Sharma R, Tiwari SP (2013) Improvement of Trichoderma spp. strain for integrated control of soil borne plant pathogens. Int J Agric Environ Biotechnol 6 (3):487–496 Singh A, Pan K, Das B, Bhavana P (2014) Improved varieties of fruit and vegetables, developed by ICAR RCER. Compiled and Edited by AK Singh, RS Pan, B Das, P Bhavana Published by BP

References

293

Bhat, Director, ICAR Research Complex for Eastern Region Patna, Bihar. Technical Bulletin No R-42/Ranchi-15, https://icarrcer.in/wp-ontent/uploads/ 2014/01/Vegetable _Var_Eng.pdf Singh M, Kaul A, Pandey V, Bimbraw AS (2019) Weed management in vegetable crops to reduce the yield losses. Int J Curr Microbiol App Sci 8(7):1241–1258 Sinha PP (1990) Significance of chemical control of parwal powdery mildew. Indian Phytopathol 43(2):229–230 Sinha AK (2001) Fundamentals of plant pathology. Kalyani Publishers, New Delhi, p 183 Sitterly WR (1972) Breeding for disease resistance in cucurbits. Annu Rev Phytopathol 10:471–490 Smith KM (1972) A textbook of plant virus diseases, 3rd edn. Longman, Edinburgh, 684 pp Sohi HS (1975) Recent advances in the control of fungal diseases of horticultural crop plants in India. Pesticides Ann No 101–105 Sohi HS (1984) Present status of our knowledge of important fungal diseases of selected vegetables in India and future needs. Indian J Mycol Plant Pathol 14:1–34 Sohi HS, Nayar SK (1969) Some new records of fungi from India. Indian Phytopathol 22:410–421 Sohi HS, Sharma SR (1998) Fungal diseases and their management. In: Nayar NM, More TA (eds) Cucurbits. Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi, pp 211–245 Sohi HS, Sokhi SS (1976) Further studies on the efficacy of different fungicides for control of anthracnose disease of bottle gourd and watermelon. Pesticides 10(4):30–31 Sohi HS, Ullasa BA, Sokhi SS (1976) Blossom end rot of bottle gourd (Lagenaria siceraria (Mol.) Standl.) incited by Pythium butleri. Curr Sci 45:630–631 Sohi HS, Kaur H, Singh G (1981) Occurrence of cleistothecial stage of Erysiphe cichoracearum DC on Coccinia indica W. & A. Curr Sci 50:779–780 Som D, Bandyopadhyay AK (1981) Rhizoctonia bataticola (Taub.) Butlet on Trichosanthes dioica Roxb- a new report. Curr Sci 50:192–193 Spoodee R, Schneider BL, Padovan AC, Gibb KS (1999) Detection and genetic relatedness of phytoplasmas associated with plant diseases in Thailand. J Biochem Mol Biol Biophys 3:133–140 Srinivasan K (1991) Pest management in cucurbits – an overview of work done under AICVIP. In: Group discussion of entomologists working in the coordinated projects of horticultural crops, Central Institute of Horticulture for Northern Plains, Lucknow, Uttar Pradesh, India, 28–29 January 1991, pp. 44–52 Srinivasan K, Viraktamath CA, Gupta M, Tiwari GC (1995) Geographical distribution, host range and parasitoids of serpentine leaf miner, Liriomyza trifolii (Burgess) in South India. Pest Manage Hortic Ecosys 1:93–100 Srinivasulu B, Narayanaswami P (1993) Effect of chemicals and AMPS in leaf extracts on phyllody in Sesamum indicum L. Indian J Plant Prot 21:77–79 Srivastava SL, Suman B (1986) Inhibitory effect of some phylloplane fungi on powdery mildew disease development. Indian Phytopathol 39:83–86 Stall WM (2009) Weed control in cucurbit crops (muskmelon, cucumber, squash and watermelon) [Online] Stamps DJ (1985) Phytophthora capsici. Commonwealth Mycological Institute descriptions of pathogenic fungi and bacteria no. 836 Stone OM (1962) Alternate hosts of cucumber powdery mildews. Ann Appl Biol 50:570–583 Suhag LS, Duhan JC (1980) Collar rot of muskmelon, a new record. Indian Phytopathol 33:94 Suhag LS, Mehta N (1982) Economics, efficacy and assimilation of some antipowdery mildew fungicides in cucurbit crops. Indian Phytopathol 35:104–105 Sukla GS, Upadhyay VB (1985) Effect of certain factors on the physiological competency of Epilachna dodecastigma Weid. (Coleoptera : Coccinellidae) with reference to the digestion of food. G it Ent 2:289–294 Sumbali G, Mehrotra RS (1982) Cucurbitaceous fruits –new hosts for Fusarium equiseti. Nat Acad Sci Lett India 5:121–122 Suryanarayana D, Ramnath, Lal SP (1963) Seed borne infection of stackburn disease of rice its extent and control. Indian Phytopathol 16:232–233

294

References

Svoboda J (2011) Pathogenic viruses on cucurbitaceous vegetables and their spread in the Czech Republic. Acta Hortic 917:309–315 Svoboda J, Leisova-Svobodova L (2011) First report of Cucurbit aphid-borne yellows virus in squash in Czech Republic. Plant Dis 95:220.3–220.3. https://doi.org/10.1094/PDIS-07-10-0527 Swamy KRM, Datta OP, Ullasa BA (1981) Identifying the sources of resistance to downy and powdery mildew diseases in muskmelon In: Proc Nat Sem on Dis Res in Crop Plants, TNAU, Coimbatore, 22–23 December, pp 101–104 Syed RA (1970) Studies on Trypetids and natural enemies in West Pakistan. Dacus species of lesser importance. Pakistan J Zool 2:17–24 Takahashi H, Kawagoe H (1971) Escape from cucumber Phytophthora rot by using rootstock. Agric Hortic 46:1581–1584 Takeda H, Mori H, Yanai K, Shiraishi K (1980) Mineralogical examinat ion of the Allan Hills achondrites and their besring on the parent bodies. Mem Nat Inst Polar Res Spec Issue 17:119–144 Tandon RN, Varma A (1964) Some new storage diseases of fruits and vegetables. Curr Sci 33:625– 627 Tandon MP, Jamaluddin, Bhargava V (1975) Some new fruit rot diseases. Indian Phytopathol 38:571 Tateishi K (1927) Grafting watermelon onto pumpkin. J Jpn Hortic 39:5–8 Temperini O, Bàrberi P, Paolini R, Campiglia E, Marucci A, Saccardo F (1998) Solarizzazione del terreno in serra-tunnel: effetto sulle infestanti in coltivazione sequenziale di lattuga, ravanello, rucola e pomodoro. In: Proceedings of the XI SIRFI biennial congress, Bari, Italy, 12–13 November, pp 213–228 Thakur JC, Khattra AS, Brar KS (1992) Comparative resistance to fruit fly in bitter gourd. Haryana J Hortic Sci 21:285–288 Thakur JC, Khattra AS, Brar KS (1996) Correlation studies between economic traits, fruit fly infestation and yield in bitter gourd. Punjab Veg Growers 31:37–40 Thomas W (1971) The incidence and economic importance of Watermelon mosaic virus. NZ J Agric Res 14:242–247 Thomas W (1980) Watermelon mosaic virus, the cause of a serious disease of cucurbits in the Cook Islands. N Z J Exp Agric 8(3 & 4):309–312. https://doi.org/10.1080/03015521.1980.10426280 Thompson A (1933) Division of mycology. Annual report for 1932. Department of Agriculture, Straits Settlements and Federated Malay States, Kuala Lumpur (reports of the resource economics and agricultural education. Branches for the year 1932). Bull 14, Gen Ser, 53–62. (Abstract in Rev Appl Mycol, 13: 216) Tiwari A, Meena M, Zehra A, Upadhyay RS (2013) Efficacy of Alternaria alternata as bioherbicide against weed species. In: International conference on global scenario of traditional system of medicine, Ayurveda, Agriculture and Education, RGSC, Barkachha BHU, 21–22 January, pp 498–01 Tjamos EC, Antoniou PP, Tjamos SE, Fatouros NP, Giannakou J (2002) Alternatives to Methyl Bromide for vegetable production in Greece. In: Proceedings of the fifth international conference on alternatives to methyl bromide, Lisbon, pp 168–171 Tomassoli L, Meneghini M (2006) Survey of viral diseases in melons in southern Italy. Inform Agrar 62:35–38 Tomassoli L, Siddu G, Carta A, Lernia G, Barba M (1999) Occurrence of Melon necrotic spot virus (MNSV) on melon in Sardinia (Italy). Inform Fitopatol 49:39–41 Tomassoli L, Tiberini A, Meneghini M (2010) Zucchini yellow fleck virus is an emergent virus on melon in Sicily (Italy). J Phytopathol 158:314–316 Trionfetti-Nisini P, Granati E, Belisario A, Luongo L, Temperini O, Crino P (1999) Resistenza in portinneste di melone alla razza 1-2 di Fusarium. Inform Agrar 55:45–47 Trionfetti-Nisini P, Colla G, Granati E, Temperini O, Crino P, Saccardo F (2002) Rootstock resistance to Fusarium wilt and effect on fruit yield and quality of two muskmelon cultivars. Sci Hortic 93:281–288

References

295

Tripathi RS, Choudhary V (2006) Rodent pest managembnt in arid zone crops. In: Sridhara S (ed) Project coordinator, vertebrate pests in agriculture- the Indian scenario. AICNP Rodent Manag, Jodhpur, pp 227–245 Tripathi G, Joshi RD (1985) Water melon mosaic virus in pumpkin (Cucurbita maxima). Indian Phytopathol 38:244–247 Tripathi SR, Misra A (1991) Population dynamics of Epilachna dodecastigma Wied. (Coleoptera: Coccinellidae). Indian J Entomol 2:203–212 Ullasa BA, Amin KS (1986) Epidemiology of bottle gourd anthracnose, estimation of yield loss and fungicidal control. Trop Pest Manag 32:277–282 Upadhyay G, Roy AN (1987) Efficacy of certain chemicals in the control of species of Fusarium in stored ash gourd. Pesticides 21(5):25–27 Uppal BN (1934) The adsorption and elution of cucumber mosaic virus. Indian J Agric Sci 4:656–662 Utikar PG, Mhaske KD, Shinde PA (1986) Occurrence of new marginal leaf blight of bitter gourd incited by Exserohilum rostratum. Indian Phytopathol 39:492 Vakalounakis DJ, Malathrakis NE (1988) A cucumber disease caused by Alternaria alternata and its control. J Phytopathol 121(4):325–336 van der Merwe JJ, Coutinho TA, Korsten L, van der Waals J (2010) Pectobacterium carotovorum subsp. brasiliensis causing blackleg on potatoes in South Africa. Eur J Plant Pathol 126:175–185. https://doi.org/10.1007/s10658-009-9531-2 Van Koot Y, Van Dorst I (1959) Virus diseases of cucumber in the Netherlands. Tijdschrift over Plantenziekten 65(6):257–271 Vani S (1987) Studies on viral diseases of muskmelon and water melon. PhD Thesis. PG School, IARI, New Delhi Vani S, Varma A (1988) Viral disease problem in muskmelon. National Symposium. Pl. Virus Problems in India. IARI, New Delhi (Abstract) Vani S, Varma A, More TA, Srivastava KP (1989) Use of mulches for the management of mosaic disease in muskmelon. Indian Phytopathol 42:227–235 Vanisree K, Rajasekhar P, Rama Subba Rao V, Srinivasa Rao V (2005) Seasonal incidence of pumpkin caterpillar, Diaphania indica (Saunders) on cucumber in Krishna-Godavari Zone. J Plant Protec Env 2:127–129 Vargas RI, Walsh WA, Kanehira D, Jang EB, Armstrong JW (1997) Demography of four Hawaiian fruit flies (Diptera: Tephritidae) reared at five constant temperatures. Ann Entomol Soc Am 90:162–168 Varma PM (1955) Ability of whitefly to carry more than one viruses simultaneously. Curr Sci 24:317–318 Varma A (1988) The economic impact of filamentous plant viruses: the Indian subcontinent. In: Milna RG (ed) The viruses: the plant viruses. Plenum Press, New York, pp 367–378 Varshney JG (2009) Why weed control. Crop Care 35(10):13–25 Varveri C, Vassilakos N, Bem F (2002) Characterization and detection of cucumber green mottle mosaic virus in Greece. Phytoparasitica 30:493–501 Vasudeva RS (1960) The fungi of India (revised). ICAR, New Delhi Vasudeva RS, Lal TB (1943) A mosaic disease of bottle gourd. Indian J Agric Sci 13:182–191 Vasudeva RS, Raychaudhuri SP, Singh J (1949) A new strain of cucumis virus 2. Indian Phytopathol 2:180 Vasudeva RS, Raychaudhuri SP, Singh J (1950) A new strain of Cucumis virus. Indian Phytopathol 2:180–185 Venkatesha MG (2006) Seasonal occurrence of Henosepilachna vigintioctopunctata (F.) (Coleoptera; Coccinellidae) and its parasitoid on ashwagandha in India. J Asia Pacific Entomol 9:265–268 Verma AC, Anwar A (1996) Assessment of yield loss due to Meloidogyne incognita in pointed gourd, Trichosanthes dioica Roxb. Afr Asian J Nematol 6(1):92–93

296

References

Verma AC, Anwar A (1997) Control of Meloidogyne incognita on pointed gourd. Nematol Mediterr 25:31–32 Verma AC, Anwar A (1998) Effect of organic amendments on sprout emergence of pointed gourd, in root-knot nematode, Meloidogyne incognita infested field. Ann Plant Protect Sci 6 (1):102–104 Verma AC, Anwar A (1999) Studies on Meloidogyne incognita on pointed gourd (Trichosanthes dioica Roxb.) in Eastern U.P., India. Indian J Nematol 29:190–191 Verma A, Giri BK (1998) Virus diseases. In: Nayar NM, More TA (eds) Cucurbits. Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi, pp 225–245 Verma SK, Singh SB (2008) Enhancing of wheat production through appropriate agronomic management. Indian Farm 58(5):15–18 Verma VK, Sirohi PS, Choudhury B (1984) Note on the response to chemical seed treatment on sex expression and fruiting in bitter gourd. Indian J Hortic 41(1-2):113–115 Verma AC, Ali A, Anwar A (1998) Effect of organic ammendments on sprout emergence of pointed gourd, in root-knot nematodes, Meloidogyne incognita, infested field. Ann Plant Protect Sci 6:102–104 Verma SK, Singh SB, Meena RN, Prasad SK, Meena RS, Gaurav A (2015) A review of weed management in India: the need of new directions for sustainable agriculture. Bioscan 10 (1):253–263 Viraktamath CA, Tiwari GC, Srinivasan K, Gupta M (1993) American serpentine leaf miner is a new threat to crops. Indian Farm 10:12 Virupaksha Prabhu H, Hiremath PC, Patil MS (1997) Biological control of collar rot of cotton caused by Sclerotium rolfsii Sacc. Karnataka J Agric Sci 10:397–403 Vishwanath SM, Nariani TK, Chenulu VV (1980) Studies on a melon ring spot virus. Curr Sci 49:483 Vyas SC (1981) Diseases of sesamum and Niger in India and their control. Pesticides 15:10–15 Vyas NL, Panwar KS (1976) Some new post-harvest diseases of fruits. Indian Phytopathol 29:94–95 Wade NL, Morris SC (1982) Causes and control of cantaloupe postharvest wastage in Australia. Plant Dis 66:549–552 Wahab S, Sharma BB (1976) Evaluation of fungicides against cottony-leak of cucurbit fruit due to Pythium aphanidermatum. Indian Phytopathol 29:437–439 Walker JC (1952) Diseases of vegetable crops. McGraw Hill Book Company, Inc, New York, p 529 Walker MN, Weber GF (1931) Diseases of watermelon in Florida. Univ Fla Agric Sta Bull. No. 225, USA Wang Y, Gaba V, Yang J, Palukaitis P, Gal-On A (2002) Characterization of synergy between cucumber mosaic virus and potyviruses in cucurbit hosts. Phytopathology 92:51–58 Wang HR, Ru SJ, Wang LP, Feng ZM (2004) Study on the control of Fusarium wilt and Phytophthora blight in cucumber by grafting. Acta Agric Zhejiangensis 16:336–339 Waraitch KS, Munshi GD, Jhooty JS (1975) Fungicidal control of powdery mildew of bottlegourd. Indian Phytopathol 28:556–557 Waraitch KS, Munshi GD, Chohan JS (1976) A new wilt disease of muskmelon in India. Curr Sci 45:628–629 Waraitch KS, Munshi GD, Nandpuri KD, Lal T (1977) Screening of muskmelon, wild melon and snap melon for resistance to powdery mildew (Sphaerotheca fuliginea). Phytopathol Mediterr 16:37–39 Watson A, Napier T (2009) Diseases of Cucurbits vegetables. New South Wales Department of Primary Industries. Primefacts No. 832. p 6. www.dpi.nsw.gov.au/primefacts Waugh MM, Ferrin DM, Stanghellini ME (2005) Colonization of cantaloupe roots by Monosporascus cannonballus. Mycol Res 109:1297–1301 Weaver JE, Bruner WE (1927) Root development of vegetable crops. McGraw, New York Webb RE (1963) Local-lesion hosts for some isolates of watermelon mosaic virus. Plant Dis Rep 47:1036–1038

References

297

Webb RE, Bohn GW (1961) A virus latent in some cucurbits. Plant Dis Rep 45:677–679 Weintraub M, Ragetli HWB (1966) Fine structure of inclusions and organelles in Vicia faba infected with bean yellow mosaic virus. Virology 28:290–302 Welter SC, Rosenheim JA, Johnson MW, Mau RFL, Gusukuma-Minuto LR (1990) Effects of Thrips palmi and western flower thrips (Thysanoptera: Thripidae) on the yield, growth, and carbon allocation pattern in cucumbers. J Econ Entomol 83:2092–2101 Wien HC (1997) The cucurbits: cucumber, melon, squash and pumpkin. In: Wien HC (ed) The physiology of vegetable crops. CAB International, New York, pp 345–386 Wiggel P, Simpson CJ (1969) Observations on the control of Phomopsis rot of cucumber. Plant Pathol 18(2):71–77 William RD, Warren GF (1975) Competition between purple nutsedge and vegetables. Weed Sci 23:317–323 William RD, Ball D, Miller TL, Parker R, Yenish JP, Miller TW, Morishita DW, Hutchinson P (2000) Weed management in vegetable crops. Pacific Northwest Weed Control Handbook. Extension Services of Oregon St. University, Washington State University and University of Idaho, USA, pp 244–274 Win NKK, Kim Y-H, Jung H-Y (2014) Bitter gourd little leaf disease associated to ‘Candidatus Phytoplasma asteris’. Entomology 39(1):82–88 Wyenandt A, Nitzsche P (2006) Diagnosing and managing important cucurbit diseases in the home garden. Bulletin No. E310. Rutgers Cooperative Research and Extension, N. J. Agricultural Experiment Station Rutgers, The State University of New Jersey, New Brunswick, pp 7. www. rcre.rutgers.edu Xu SL, Chen QY, Chen XQ, Gao JS, Li SH (2005) Effect of graftingon ‘Jiashi’ muskmelon yield and its resistance to melon Fusarium wilt. Acta Hortic Sinica 32:521–523 Xuan TD, Tawata S, Khanh TD, Chung IM (2005) J Agron Crop Sci 191:162–171 Yamaguchi M (1983) World vegetables. Dept. of Vegetable Crop, Univ. of California, 415 p Yoon JY, Min BE, Chol SH, Ryu KH (2001) Completion of nucleotide sequence and generation of highly infectious transcripts to cucurbits from full length cDNA clone of Kyuri green mottle mosaic virus. Arch Virol 146:2085–2096 Yoon JY, Min BE, Chol SH, Ryu KH (2002) Genome structure and production of biologically active in vitro transcript of cucurbits infecting zucchini green mottle mosaic virus. Phytopathology 92:156–163 Yoon JY, Choi GS, Choi SK, Hong JS, Choi JK, Kim W, Lee GP, Ryu KH (2008) Molecular and biological diversities of cucumber green mottle mosaic virus from cucurbitaceous crops in Korea. J Phytopathol 156:408–412 Zaracovits C (1965) Attempts to identify powdery mildew fungi by conidial characters. Trans Br Mycol Soc 48(4):553–558 Zehnder G (2011) Biology and management of pickleworm and melonworm in organic curcurbitproductionsystems. Electronic. http://www.extension.org/pages/60954/biology-andanagement-of-picklewormand-melonworm-in-organic-curcurbit-production-systems#. VNmbv3uH6yc Zimdahl RL (2007) Fundamental of weed science. Academic Press, Burlington Zitter TA (1987) Anthracnose of cucurbits. In: Vegetable crops. Fact Sheet. Department of Plant Pathology, Cornell University, p 732.60 Zitter TA (1992) Fruit rots of squash and pumpkins. Cooperative Extension, New York State, Cornell University, Fact Sheet Page 732.10 Zitter TA, Hopkins DL, Thomas CE (1996) Compendium of cucurbit diseases. American Phytopathological Society Press, St. Paul