Disease Stage of Occurrence Symtpoms Factors Favouring infection Wilt(Fusarium vasinfectum) All stages of crop growth Yellow to brown coloured cotyledons leaf turn brown and drop off. Browning and blackening of vascular tissue Excessive soil moisture, soil temperature range 24-28° C Root – Rot (Rhizoctonia bataticola) All stages Sudden and complete wilting of the plant High soil temperature Anthracnose(collectotricum gossypium) All stages Small reddish coloured spots and cotyledons. Water soaked small reddish brown deprssions spots and bolls Warm and humid weather (29-33° C) Bacterial blight All stages Angular leaf spots on leaf blackarm leisons on stem and leaf - leison on young leaves. Seed borne bacteria – Secondary infection through natural openings or insect caused wounds. Alternaria leaf spot All stages Brown rouned or irregular spots on leaf with cracked centres – cause canker on stem High humidity – intermittent rains moderate temperature are congeniar. Areolate or Greymildew (Ramularia areola) Maturity stage Irregular translucent spots on leaf – leaves become yellowish brown and finally fall off. Low lying moist localitites – 25-30° C is favourable temperature for conidia germination. Cercospora leaf spot (cercospora gossypiana) Older leaves at maturity stage Purple dark brown or blakish borders and white centres Favourable conditions crop environment Heliminthosporium leaf spot (Heliminthosporium spiciforum) Vegetative (seedling stage) Numerous light brown circular spots on leaves Reported from Dharwar district of Karnataka. Root knot nematode Early stages of crop growth Lack of vigour- stunted plants – galls on tap and lateral roots Reported from Punjab.

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