KHAYUM AHAMMED, SNOOR AHMED, SHAIK2020-02-242020-02-242019http://krishikosh.egranth.ac.in/handle/1/5810143463D5870The present investigation was carried out to study the collar rot of chickpea caused by Sclerotium rolfsii Sacc. Chickpea is an important cool season food crop grown mainly in dry land which is a rich source of protein and enriches soil fertility by biological nitrogen fixation. The collar rot disease of chickpea is soil borne and fast spreading pathogen accounts for 55-95% mortality of the seedlings of the crop during favourable environment. During Rabi 2017, diseased samples were collected from major chickpea growing mandals of Kurnool and YSR Kadapa districts and nineteen S. rolfsii isolates were isolated, which were designated as CSR 1 to CSR 19. Pathogenicity test of S. rolfsii isolates on chickpea susceptible variety, L 550 revealed that, S. rolfsii isolate CSR 10 was identified as most virulent isolate. During Rabi 2018-19, a roving survey was conducted to assess the occurrence of chickpea collar rot disease incidence in Kurnool district of Andhra Pradesh recorded that the disease incidence was highest in Alluru village (18.0%) and lowest incidence of 3.6% was recorded in Bandiatmakur village. The incidence ranged from 3.60 to 18.00 per cent due to monocropping and time of sowing in high moist conditions during the last week of october to second week of november. Among sixteen advanced breeding lines screened in screening block, two lines showed resistant reaction, six lines showed moderately resistant reaction, four lines showed moderately susceptible reaction, four lines showed susceptible reaction and none was highly susceptible. Among 17 genotypes from IIPR, Kanpur screened under pot culture, one genotype showed resistant reaction, four genotypes showed moderately resistant reactions, six genotypes showed moderately susceptible reaction, six genotypes showed susceptible reaction and none was highly susceptible. The influence of three different dates of sowing employing three chickpea varieties was studied on growth, occurrence of collar rot, soil moisture, inoculum load and other yield parameters of chickpea. NBeG 49 sown at 19th november showed highest germination and significantly lowest germination was observed in JG 62 sown at 19th november. NBeG-49 sown at 15th october showed highest disease incidence and lowest disease incidence in variety JG-62 when sown at 30th october. Highest soil moisture was recorded with NBeG-49 sown at 15th october and lowest soil moisture with JG-62 sown at 30th october. However, highest inoculum load was observed with NBeG-49 sown at 15th october and lowest in JG-62 sown at 30th october. JG-62 sown at 30th october showed highest shoot length, root length and dry weight of plant and lowest shoot length, root length and dry weight of plant in NBeG-49 sown at 15th october. Highest yield was recorded with JG-62 sown at 30th october and lowest yield in NBeG49 sown at 15th october. The antagonistic effect of ten Trichoderma isolates and ten Pseudomonas fluorescens isolates were assessed against S. rolfsii by dual culture technique. Among the Trichoderma isolates highest inhibition was observed with CRT 8 and among P. fluorescens isolates highest inhibition was observed with CPF 3. Among the eight fungicides tested against S. rolfsii under in vitro conditions, combination of strobilurin and triazole fungicides, tebuconazole 60 FS and carboxin 37.5% + thiram 37.5% WS were highly effective and completely inhibited the mycelial growth of the pathogen at all four concentrations. Lowest inhibition percentage (53.33%) was recorded with carbendazim 12% + mancozeb 63% WP at 500ppm. Compatibility among effective fungicides on the effective Trichoderma isolates (CRT-8) has revealed that carboxin 37.5% + thiram 37.5% WS showed its compatibility with effective Trichoderma isolates and did not affect the mycelial growth of Trichoderma isolates, and this fungicide was used for pot culture study. Efficacy of effective fungicide and bioagent was tested against S. rolfsii through pot culture under greenhouse conditions. Among different treatments T8 (Seed treatment with carboxin 37.5% + thiram 37.5% WS @ 1.5gm/kg seed, Seed treatment with CRT-8 @ 10gm/kg seed, Soil drenching with carboxin 37.5% + thiram 37.5% WS @ 1.5gm/kg soil and Soil application with CRT8+FYM @ 8gm/kg FYM) showed lowest per cent disease incidence (16.67%) with highest germination percentage (100.00%), root length (8.19cm), shoot length (30.77cm) and dry weight (1.15gm). From the study it was clear that integrated treatment T8 is highly effective with highest chickpea seed germination, root length, shoot length, dry weight of the plant and least disease incidence.en-USnullThesis