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ThesisItem Open Access EPIDEMIOLOGY AND MANAGEMENT OF ALTERNARIA LEAF BLIGHT AND RUST OF SUNFLOWER (Helianthus annuus L.)(University of Agricultural Science, Dharwad, 2000) Amaresh, Y S; Nargund, V B"Alternaria leaf blight caused by Alternaria helianthi and rust caused by Puccinia helianthi are two major foliar diseases of sunflower. The yield loss due to Alternaria leaf blight and rust was estimated to be 43.90 and 32.65 per cent during 1998-99 and 1999-2000 respectively. AUDPC value was found to be a better parameter for yield loss assessment and epidemiological model was developed. Autoregressive method of seventh order was used for estimating both uredospore and condial load interms of previous successive seven days. The disease development was predicted by first order autoregressive model and logistic model. The toxin produced by A.helianthi was purified and identified as 3 propyl 4 hydroxy -2oxy -2-3 dihydro furone. The toxin produced typical brown necrotic spots without yellow halo on susceptible sunflower cv. Morden. PAC-36, PAC-304 and DSH-34 were identified as slow blighters and PAC-36, PAC-304 GK-2002 and GAUSUF-15 as slow rusters. Sugars and phenols were more in diseased leaves than healthy leaves. The isozyme studies on catalase, peroxidase and polyphenol oxidase revealed their role in disease development. The higher incidence of Alternaria leaf blight and rust was noticed in kharif and rabi sown crop respectively. Among 30 plants screened, Allium sativum, A.cepa, Amamthus viridis, Ocimum sanctum, Tridax procumbens, and Melia azedarach were found effective against both pathogens. Chlorothalonil, mancozeb, propiconazole and hexaconazole were most effective against both the pathogens. Pseudomonas fluorescens was found to be a better bioagent in the management of both diseases. Among 140 sunflower genotype ACC.No.405, 1583, PAC-36 and PAC-336 were found resistant to both Alternaria leaf blight and rust. In integrated disease management of Alternaria leaf blight the treatment fungicide followed by Pongamia and P. fluorescenss was found to be effective in reducing the disease."