Influence of Sowing Dates in Relation to Meteorological Weather Parameters to Development of Powdery Mildew of Green Gram

Adjustment of sowing dates is an obviously good strategy to minimize the disease. Four dates (July 21, 31 and August 10, 20) under natural epiphytotics during kharif, 2012 to study the effect of sowing dates and weather parameters on powdery mildew incidence. The results indicated that average mildew severity was significantly lower (48.29% and 51.46%) in early 21st July to mid 31st July sown (D₁ & D₂) crop whereas, it was significantly higher (63.01% and 72.38%) in late (D₃) 10th August and (D₄) 20th August sown crop. In almost all the sowings peak of mildew was noted with increased temperature (30Úc to 34.4Úc) and decreased humidity during morning (94.8 to 60.3%), whereas disease was significantly negatively correlated with morning relative humidity (RH₁) and evening relative humidity (RH₂) as well as temperature (max.) was significantly positively correlated with disease development. Wind speed did not exhibit a perfect trend with mildew development which was significantly negatively correlated with disease development.