Epidemiological studies on early blight disease (Alternaria solani) of tomato

Abstract

Early blight of tomato caused by Alternaria solani during the winter/spring season is a severe constraint in tomato production. Studies were conducted to understand the development of early blight on tomato cv. pusa ruby with respect to weather conditions. Early blight symptoms were first observed on leaves at 18 days after planting in 2011-12 and 20 days after planting in 2012-13. Increase in disease severity was comparatively higher in the temperature range from 25.6-28.30C (maximum) and 13.6-16.40C (minimum) and average relative humidity of 65 percent in the month of January in 2011-12 and also in 2012-13. In the present investigation carried out at IGKV Raipur, maximum temperature (r= -0.801 in 2011-12 and -0.564 in 2012-13), minimum temperature (r=-0.755 in 2011-12 and -0.682 in 2012- 13), relative humidity during morning (r=-0.550 in 2011-12 and -0.541 in 2012-13), relative humidity during evening (r=- 0.593 in 2012-13) and rainfall (r=-0.531 in 2012-13) had strong negative and significant correlation with disease severity index (DSI) while relative humidity during evening (r=0.342 in 2011-12) and rainfall (r=0.409 in 2011-12) had positive correlation with DSI.