Disease management
Downy Mildew : Caused by Plasmopara viticola
Symptoms
• Humid cool weather with frequent intermittent rain/dew favours the development of this disease and it is most common during July-December. The typical symptom is white growth in patches on the lower surface of the leaf and corresponding upper surface has yellow patches.
• The yellow patch dries up and the leaves drop.
• In severe cases, flowers, young canes and fruits are also affected. Flowers wither and drop. Young fruits turn water soaked, dull green, leathery and drop.
control measures
spraying 1% Bordeaux mixture immediately after both the pruning, 0.4% Copper oxychloride or 0.2% Mancozeb or Chlorothalonil at 6 to 7 days interval during July-August and 3 to 4 days intervals during November-December is suggested.
Systemic fungicides like Metalaxyls, fosetyl and dimithomorph at 10-15 days intervals is also recommended. It is suggested to use different fungicides in combination rather than using same chemicals to avoid development of fungicide resistance in downy mildew causing pathogens