Efficacy of Fungicides and Phyto-extracts for Suppression on Leaf Spot of Cotton Caused by alternaria Spp

The principal part affected is the leaf on which small, dull to dark brown, circular or irregularly shaped spots appear, the spots varying in diameter from 0.5 to 10 mm. When these spots mature they have dry, grey centres which may crack and even drop. The spots may coalesce and occupy large area of the leaf. Fungal pathogens were isolated, purified and identified asAlternaria alternata, Alternaria macrospora and Alternaria gossypina and pathogencity was confirmed on Bt and non Bt cotton in potted plants. In potted plants, minimum disease severity were obtained in Mancozeb and Hexaconazole followed by Copper oxychloride and Tilt. All fungicides as foliar sprays were able to reduce disease severity over untreated control at 0.2% followed by 0.1% concentration. Mancozeb and Hexaconazole were found most effective in management of Alternaria leaf spot of cotton.