Disease management in cotton

摘要

Diseases known to attack cotton are bacterial blight, seedling mortality, fusarial wilt, boll rot, root rot and fungal leaf spots. For cotton disease management, future planning and knowledge of symptomatology of these diseases is must. Cotton is attacked by about 30 diseases. During kharif 2002 field survey, serious outbreak of cotton leaf curl disease was observed at farmers' field. Besides this some other diseases known to attack cotton are bacterial blight, seedling mortality, fusarial wilt, boll rot, root rot and fungal leaf spots. For cotton diseases management, future planning and knowledge of symptomatology of these diseases is must. Main symptoms of cotton leaf curl is thickening of veins, upward cupping and curling of leaves and formation of enations (green leafy structures) on the under side of leaves. In severe cases stunting of plants and twisting of main stem is common. Bacterial blight is known to appear as water soaked spots on all aerial plant parts which later may cause different types of symptoms such as angular leaf spot, vein blight, black arm and boll rot. Fusarial wilt symptoms appear as drooping, yellowing of leaves and drying of plants with roots intact but if split open stem and branches vascular browning is observed. Alternaria spots are characterized by concentric rings having small sclerotia. Myrothecium leaf spots are with dark grey center and broad violet brown margins. Cercospora leaf spots are small, circular having white center with purple margins.