DISTRIBUTION OF Alternaria species IN SUNFLOWER, THEIR HOST RANGE AND MANAGEMENT
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Date
2022-12-12
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Abstract
Sunflower an important oilseed crop of India is affected by diverse species of Alternaria causing leaf blight and with significant yield loss. Isolates of Alternaria (23 nos.) from Chitradurga, Chikkaballapur, Chamarajnagar and Bengalore Urban were studied morphologically and grouped to different species, that was re-confirmed by sequence analysis of ITS, Alt 1 a, SSU, GAPDH, endoPG, OPA10-2 and species specific genes (AA, AHN1and QPHEL). It revealed the prevalence of species with distribution frequency as A. alternata (91.65 %), A. tenuissima (66.6 %) A. helianthi (55.33 %) and, A. solani, A. burnsii and A. gossypina had similar frequency (33 %). A. alternata had highest distribution frequency in Chikkaballapur, Bangalore Urban, Chamarajnagar whereas A. tenuissima and A. alternata in Chitradurga only. A. helianthi was second highest in Bangalore Urban. Host range studies revealed that, A. alternata, A. tenuissima and A. helianthi are not host specific and can infect other members of asteraceae family (African marigold, China aster, Safflower and Parthenium). While – A. burnsii, A.solani and A. gossypina infected sunflower only not other host species. In vitro assays of new fungicide molecules revealed that Fluopyram 17.7 % + Tebuconazole 17.7 % 400 SC at 100, 250, 500, 750, and 1000 ppm completely inhibited the mycelial growth of the pathogen. Under field lowest disease severity (7.36% PDI) and best
seed yield (2153 Kg/ha) were obtained in seed treatment with Fluxapyroxad FS @ 1.5 g/kg
seed followed by foliar spray with Fluopyram 17.7 % + Tebuconazole 17.7 % 400 SC @ 1
ml/L on disease appearance.
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