Impact of weather variables on severity and progression of powdery mildew on rapeseed-mustard in Haryana

Powdery mildew is a major devastating disease rapeseed-mustard causing significant reduction in yield as well as quality. Present investigation was under taken to study the impact of weather variables on disease severity and progression of powdery mildew. The maximum disease intensity was in variety Varuna (51.3%) followed by RH-30 (46.0%). The minimum disease intensity was in varieties HC-9002 and YSPb-24 (17.3%). Powdery mildew intensity on pods was also maximum on Varuna (36.7%) and minimum was on GSH-1. The minimum speck size was in the variety GSH-I (2.87mm) whereas maximum in RH-9304 (5.20mm) whereas in all other varieties, speck size ranged between 3.40 to 4.67 mm. The progression was maximum up to the mid of March and there after progression was slowed down. At the end of Marchm progression was static in all the varieties. Temperature (maximum) and relative humidity (morning) played pivotal role on the severity and progression of powdery mildew disease on leaves. The R² values were observed in the range of 0.70 to 0.92 indicating that most of theweather variables contributed significantly in powdery mildew progression.