Influence of weather parameters on powdery mildew (Erysiphe polygoni) in greengram

Experiment was conducted in vitro and in vivo to see the effect of weather factors on diseased development and conidial germination of Erysiphe polygoni DC in greengram. Conidial germination was maximum at 250C (32.04%) and minimum (5.14%) at 100C. Per cent conidial germination was maximum at 80 to 90% relative humidity (33.15 and 40.52%), respectively, and 24 h light (16.38%) was found to be favourable as evident by the maximum conidial germination. First initiation of the disease appeared in 31st meteorological week under natural field condition. Among weather factors, maximum temperature (22.6° to 240C), minimum temperature (22.6° to 240C), morning velocity (4.1 to 4.3 km/h), rainfall of 27.6 mm and sunshine hours (4.3 to 5.0) were found favourable for the disease development.