SARADA JAYALAKSHMI DEVI, RARUNODHAYAM, K2018-08-142018-08-142017http://krishikosh.egranth.ac.in/handle/1/5810064298D5528Pigeonpea [Cajanus cajan (L.) Millspaugh] is the prominent drought tolerant pulse crop with multiple benefits viz., source of dietary protein, protects soil from erosion and enriches it, medicinal properties, stover and fuel wood etc. Pigeonpea wilt caused by Fusarium udum is the most important soil borne disease. F. udum isolates from the same site or diverse geographical origins have been shown to exhibit high variability in cultural and pathogenic characteristics. Information on the variability of the pathogen among isolates collected from different agro-ecological zones of Andhra Pradesh is lacking. Hence variability among 25 isolates of F. udum from Andhra Pradesh and Telangana were studied. The laboratory experiments pertaining to the research work were conducted during the year 2013-2016 in the Department of Plant Pathology, S.V. Agricultural College and Institute of Frontier Technology, RARS, Tirupati, Chittoor district, Andhra Pradesh. Field experiments were conducted during kharif 2013 and kharif 2014 at Agricultural Research Station, Tandur, Rangareddy district, Telangana. Glass house experiments were conducted during 2014-15 in the Department of Legumes Pathology at International Crops Research Institute for the Semi Arid Tropics (ICRISAT), Patancheru, Medak district, Telangana. xvi A total of 25 diseased specimens were collected from different pigeonpea growing areas of Andhra Pradesh and Telangana viz., Chittoor, Kadapa, Anantapur, Warangal, Khammam, Kurnool, Guntur, Prakasam, Rangareddy, Medak and Mahaboobnagar during kharif, 2013. The pathogenic isolates were isolated and designated as FU-1 to FU-25. Pathogenicity test was conducted using root dip inoculation method. Cultural and morphological variability was studied and categorized 25 isolates into various groups based on radial growth, growth pattern, mycelial characters, mycelial colour, pigmentation, dry mycelial weight, septation of macro and micro conidia and size of micro and macro conidia. Molecular characterization was done using RAPD and found polymorphism with K1 primer at 450 bp in FU-25, with K2 primer at 620bp in FU-3, with K3 primer at 320 bp in FU-10, with K4 primer at 550 bp in FU-3 and with K5 primer at 750 bp in Fu-11. The polymorphic bands were used in developing SCAR markers for rapid detection of F. udum isolates. Based on wilt incidence and reaction on selected host differentials (ICP 2376, C 11, ICP 8863 and ICP 9174), 25 F. udum isolates were categorized into six races/variants viz., Variant 0, Variant I, Variant II, Variant III, Variant VIII and Variant IX. SCAR was developed successfully for FU-25 isolate with 450 bp band and for FU-3 with 620 bp. Screening of pigeonpea germplasm was done under sick plot conditions at Tandur and found TRG-59 as best genotype with lower wilt incidence of 17.42% and highest yield of 214.1 g per plant. Potential fungal antagonist T1, potential bacterial antagonist B2 and effective fungicide carbendazim were imposed as treatments in Integrated Disease Management program. Among seven treatments imposed in IDM T5 (Asha-red seed coat resistant check) was found best followed by T2 (Seed treatment with bacterial biocontrol agent).en-USnullThesis