KULKARNI, SRIKANTSHAMRAO PAUL, VASANT2019-10-102019-10-102001-08-04Th-5891http://krishikosh.egranth.ac.in/handle/1/5810130641The leaf blight of wheat caused by Exserohilum hawaiiensis is one of import£int diseases of wheat. The survey revealed maximum disease incidence in Raibag, Gokak, Athani and Dharwad taluks in Kamataka and Mahabaleshwar, Pune, Karad, Niphad taluks in Maharashtra. The loss assessment study indicated reduction in thousand grain weight (18.12%), grain yield (31.30%), height of plants (7.05%) and biomass (19.17%). Crop loss model using input variable PDI was of the farm y = -32.33+1.16 (PDl). The pathogen survived only for few weeks in soil, as it was highly aerobic. The pathogen survived under laboratory conditions for 21 months, 15 months under natural conditions, 27 months under refrigerated conditions and remained viable in seed for 28 months. The pathogen could infect Chloris barbata, Dectyloctenium aegypticum, Eleusine coracana, Oryza sativa. Sorghum bicolor and Zea mays. The perfect state of the pathogen could not be detected. The spore load of E. hawaiiensis showed fluctuations over time fr-om 2.38 to 8.08 per microscopic field per day. Eight isolates obtained from field of different localities. The variability among hyphal tip isolates was assessed on the basis of morphological, cultural, physiological, nutritional and pathogenicity characters. The isolates were classified into four groups such as Group-!: E, F, G, Group-Il: B and C, Group-Ill: D and H, Group-IV: A based on their cultural characters. On the basis of pathogenicity, isolates were classified into three group as highly virulent (Mahabaleshwar and Ugar Khurd), Moderately virulent (Arabhavi, Dharwad and Sangankeri) and least virulent (Kannur, Digraj ^d Pune). Seed treatment with captan or mancozeb or combination of either of them with Trichoderma viride recorded cent per cent control of primary seed home inoculum. Among the fungicides, propiconazole was found effective. The plant extracts viz.. Eucalyptus globus, Lantana camara, Flacourtia ramontchi, Acacia concina, Memecylon edule and Magnifera indica were found effective against E. hawaiiensis.ennullThesis