MANAGEMENT OF CHARCOAL ROT OF SESAME (Sesamum indicum L.); INCITED BY Macrophomina phaseolina (Tassi.) Goid

Name of the Author : M. DURAI Title of the thesis : MANAGEMENT OF CHARCOAL ROT OF SESAME (Sesamum indicum L.) INCITED BY Macrophomina phaseolina (Tassi.) Goid. Submitted for the award : Master of Science of degree Faculty : Agriculture Department : Plant Pathology Major Advisor : Dr. T.V. CHALAM University : Acharya N.G. Ranga Agricultural University. Year of submission : 2004 Charcoal rot of sesamum caused by Macrophomina phaseolina (Tassi.) Goid is an important seed (externally as well as internally) and soil borne disease. A detailed study on isolation of native mycoflora and bacteria from the rhizosphere of sesamum, in vitro antagonism of native mycoflora and bacterial isolates against M. phaseolina, in vitro efficacy of systemic and nonsystemic fungicides against the pathogen and in vitro compatibility of fungicides with bioagents and integrated management of the disease with biological and chemical methods under glass house condition was carried out during the present investigation. The pathogen was isolated from infected root and stem bits of sesamum, purified and identified as M. phaseolina (Tassi.) Goid, and the pathogenicity was confirmed by soil infestation method under glass house conditions. The characteristic disease symptoms like poor germination, stunted growth of plants, followed by wilting and drying of leaves were observed. Roots of the infected plants exhibited blackening of tap root and formation of numerous sclerotia on roots. Among eleven antagonistic rhizosphere mycoflora of seamum, Trichoderma viride (T6) inhibited mycelial growth of M. phaseolina to maximum 74.70 per cent in dual culture technique. Among the three bacterial isolates isolated from the rhizosphere of sesamum, Pseudomonas fluorescens (B1) was found to be effective which inhibited 71.76 per cent of mycelial growth of the pathogen under in vitro conditions. Efficacy of five fungicides were tested in vitro against M. phaseolina of which, hexaconazole (50 ppm) and thiophanate methyl (50 ppm) were found highly effective in inhibiting the mycelial growth of the pathogen, followed by mancozeb (100 ppm), captan (500 ppm) and thiram (500 ppm). Out of two systemic and three non-systemic fungicides tested in vitro for compatibility with bioagents, mancozeb at 100 ppm was found compatible with native bioagents T. viride and P. fluorescens. An integrated disease management strategy was developed for charcoal rot of sesamum under green house conditions. Out of 15 treatment combinations, maximum disease reduction was achieved by integrated use of seed treatment with mancozeb (100 ppm) + soil application of native T. viride (10 g/kg of soil) and P. fluorescens (20 ml / kg of soil) as this treatment recorded PDI of only 10.67. This treatment not only reduced the disease incidence to a maximum extent, but also recorded maximum plant height (22.29 cm), shoot length (5.41 cm) and root length (4.27 cm), maximum dry weight of shoot (76.28 mg) and root (52.31 mg) of sesamum when compared to all other treatments. ACKNOWLEDGEMENTS It is by the unfathomable grace and blessings of the Almighty and profuse love of my parents and grand parents, I have been able to complete my studies successfully hitherto and present this piece of work uninterruptedly, for which I am eternally indebted for them. It give me immense pleasure in expressing my profound sense of gratitude and indebtedness to my esteemed and beloved chairman Dr.T.V.Chalam Professor and Head, Department of Plant Pathology, S.V. Agricultural College, Tirupati for his inspiring, affectionate and competent guidance, constant encouragement, unflagging help and constructive criticism in planning and presentation of the investigation reported in the thesis. I am greatly beholden beyond words to express my sense of gratitude to Dr. N.P. Eswara Reddy, Associate Professor, Department of Plant Pathology, S.V. Agricultural College, Tirupati, member of my advisory committee, for his affection, keen interest, valuable suggestions and for sparing his precious time to improve the thesis. I wish to convey my heartful thanks to the member of Advisory Committee, Dr. S.V. Ramakrishna Rao, Principal Scientist & Head, AICRP on Citrus, Tirupati for his untiring help and valuable guidance throughout the period of my study. My deep sense of gratitude is due to Dr. N. Ramavatharam, Professor & Head, Department of Soil Science and Agricultural Chemistry, S.V. Agricultural College, Tirupati for his judicious guidance, constructive criticism, generous help rendered during my research work. I wish to convey my heartful thanks to Dr. K. Chandrasekhara Rao, Professor and University Head, Department of Plant Pathology, for his untiring help and valuable guidance throughout the period of my study. I take this opportunity to express my immense gratitude and sincere thanks to Dr.K. Seetharama Reddy, Professor & Head (Retd.), Dr. M. Reddi Kumar, Assistant Professor, Department of Plant Pathology, S.V. Agricultural College, Tirupati for their kind help, valuable suggestions and encouragement during my research work. I am highly indebted to Dr. J. Surya Prakash Rao, Professor and Head, Dr. K. Balakrishna Reddy, Associate Professor, Department of Plant Physiology, S.V. Agricultural College, Tirupati for allowing me to do part of my research work in their glass house. I would be great previlege to express my sincere thanks to Dr.N. Venugopal Rao, Professor and Head, Department of Entomology, S.V. Agricultural College, Tirupati for his constant inspiration, encouragement, valuable suggestions and kind help rendered during my PG programme and research work. I am very glad to express my sincere heartful thanks to my beloved teachers Dr. V.Praksam, Dr. Angappan, Dr. Nakkeeran, Dr. Alice, Professors, Department of Plant Pathology and Dr. N. Natarajan and Dr. N.Raghumurthy Professor, Department of Agricultural Entomology, TNAU, Coimbatore for their blessings, encouragement and their guidance which will go a long way throughout my life. My warmest thanks to my colleagues Rajani and Poornima for their co-operation and company during my course of my work. I am also thankful to my seniors Arunasri, Haritha, Rama, Visu and Madhu and my junior friends Sampath and Sailaja. I consider it my good fortune to express my unbounable gratitude and love to my beloved parents Smt. Palaniyammal Mari and Late Sri P.G. Mari Gounder, Grandpa Late Sri. Govinda Gounder and lovable brother Chinnadurai their dedicated efforts to educate me to this level and whose unparallel affection and persistant encouragement in snaping my career go a long way throughout my life. I am in dearth of words to express my sincere thanks to my dear most amidable friends Om, Babu, Chella, Balu, Govind, Prem, Guna, Vasagam Guru, Muthu, Yuva, Koty, Kaleel, Sunil, Gayathri's, Deivanai, Ratna, Mythili, Sendhil and Suresh and other friends in TNAU 98, for their affection, untiring help extended in memorable ways and for the delightful companionship during my college life. My special hearty thanks to my dear friends Eswar, Amar, Balaji, Sriram, Sudha, Santhi, Sasi, Chaitanya, Kiran's, Halder, Seetha, Sumathi, Anoop, Venkatesh, Sangeetha, Kailai, Kanal, Srividya, Jaya, Sai, Surekha, Gnanesh, Biju, Pari, Vijay, Murali, Manju, Ravi, Rajaji, Siva, Kalyan, Kumaresan and all other UG and PG friends for giving a homely environment during my stay in the hostels of TNAU and ANGRAU. I am thankful to supporting staff Chenchaiah, Eswaraiah and Sreenivasulu for their help during my research work. I am thankful to the authorities of ICAR for providing me financial assistance in the form of Junior Research Fellowship during my period of PG studies. I also thankful to Acharya N.G. Ranga Agricultural University, Hyderabad for the facilities provided during my study. My heatful thanks to K. Visweswara rao, Department of Arts and Photography and Mr. Hemanth, Hemanth Computer Centre for their excellent work, patiently carried out in getting thesis its present shape.