EPIDEMIOLOGY AND MANAGEMENT OF ALTERNARIA LEAF BLIGHT AND RUST OF SUNFLOWER (Helianthus annuus L.)
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Date
2001-08-04
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK BANGALORE
Abstract
Alternaria leaf blight caused by Altemaria 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 hydroj^ -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
AGO.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.
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