Management of powdery mildew disease in grape
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13/03/2008
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Hindu
Grape vine are often prone to fungal infestations often and among them powdery mildew is an economically important one. Powdery mildew results in reduced vine growth, yield, fruit quality, and winter hardiness. Severe infestation can depress vine vigour because damage to leaves and shoots limits photosynthesis and inhibits berry sugar development. Initially it appears as small white powdery growth of the fungus on the leaves, tender veins, and in severe case on tendrils also. wilted appearance. These spots later enlarge and entire leaf gets covered with dusty white fungal growth. Infested stem turns brown and vines exhibit wilted appearance. The advancement of infestation leads to curling and drying up of the leaves. Severely affected leaves drop early. Young inflorescence also gets infestated.The flowers may wither and drop without setting fruit. Berries are most susceptible to infection during the first three to four weeks after bloom. Infected berries may develop a netlike pattern of russet. Affected berries may have spots on the surface similar to those on the leaves, or the entire berry may be covered with the white, powdery growth, which leads to irregular shape, cracking and finally rotting of the berries due to invasion of other saprophytic organisms. Such fruits become unfit for marketing. Pest management Effective control can be done by timely dusting withDinocap (0.2 per cent) or Carbendazim (0.1 per cent) or Folicur (0.05 per cent) for better control of the disease. The dusting should be done early in the morning when leaves and bunches are slightly wet Use of excessive nitrogen fertilizers should be avoided.