ABSTRACT
Kolte and Tewari observed that mid-September planting of sunflower escapes the attack of sunflower diseases, including that of Sclerotium wilt, in the Nainital Tarai area of Uttar Pradesh in India. Seed treatment with mancozeb has been found to control seed rot and seedling blight diseases more effectively than captafol or thiram. Although varieties resistant to the disease are obtainable, a fungicide seed treatment which could protect seedlings against infection by soil-borne inoculum would be extremely useful, especially if a new pathogenic race occurs. Changes in ultra-structure of the host cell organelles in rust-infection sunflower tissue have been studied. The invading fungus forms an allantoid primary infection vesicle in the penetrated epidermal cell. The cell organelles show a marked tendency to aggregate around fungal haustoria, and there is an accumulation of starch in plastids. The necrotic lesions with sporulation of the fungus may be seen on hypocotyls and roots without the appearance of typical symptoms.
