Factors influencing dynamics of powdery mildew severity in tomato

Abstract

Levels of powdery mildew (Leveillula taurcica) severity in tomato varied during kharif seasons (2012-2016). Seasonal mean severity during 2012 (48.3%), 2013 (43.4%) and 2016 (47.2%) was at par and significantly higher over 2014 (34.1%) and 2015 (24.8%). Progression of powdery mildew severity was steeper beyond 10 weeks after planting. Cultivars (NC 501 and Shivam) and planting periods between mid-May and June end did not impact the disease severity. Positive and negative influences of maximum and minimum temperature, respectively of the concurrent week were noted. Maximum and minimum temperature congenial for disease progression under field conditions was found to be 28.4 to 30.1°C and 19.1-20.8°C, respectively. With only 3% variation of powdery mildew severity explained by temperature the way forward would be to understand the effect of agronomic practices on crop canopy and phenology of tomato production to effectively manage the disease.