Association of Agrometeorologists

Effect of weather parameters on the development of Alternaria leaf spot and grey mildew in cotton

S. L. BHATTIPROLU and D. MONGA

The effect of weather factors on the development of alternaria leaf spot and grey mildew in Bt Cotton hybrid Jaadoo BG II was investigated at Regional Agricultural Research Station, Lam, Guntur during kharif 2013-2017. Maximum, minimum temperatures, evening relative humidity, rain fall, number of rainy days and wind speed were negatively correlated and significantly influenced the progress of alternaria leaf spot while number of sunshine hours showed positive significant influence. In case of grey mildew, minimum temperature, evening relative humidity, rain fall, number of rainy days, evaporation and wind speed were negatively correlated and significantly influenced the progress of disease. Multiple regression analysis of pooled data (2013-2016) showed that maximum, minimum temperatures, number of rainy days and wind speed significantly influenced the development of alternaria leaf spot (R2=0.984) where as minimum temperature and evaporation significantly influenced the development of grey mildew (R2=0.976). Validation of these regression equations during 2017-18 indicated the usefulness of these models for prediction of alternaia leaf spot and grey mildew in cotton under given environmental conditions.

Alternaria leaf spot, cotton, grey mildew, weather parameters