Effect Of Epidemiological Factors On The Severity Of Stripe Rust Of Wheat Caused By Puccinia Striiformis

The effect of epidemiological factors on the severity of stripe rust in cv. PBW 343, under early sowing conditions were studied during 2013-14 and 2014-15, rabi seasons. The disease was first appeared in 1st standard meteorological week (SMW) when the crop stage was at 73 days after sowing. Sharp increase in disease severity was observed during 6th to 8th SMW due to the conducive weather conditions which prevailed during the previous fortnight. The meteorological parameters like maximum temperature, minimum temperature, morning vapour pressure; evening vapour pressure and micro meteorological parameters (canopy temperature and soil temperature) had significantly positive correlation with the disease severity in the tested wheat variety, whereas, maximum relative humidity had significant negative correlation. Rainfall had moderately positive correlation with the disease severity. The models generated through stepwise multiple regression analysis revealed that thermic, and hydric variables contributed significantly for the variance in disease severity. Among the three principal components, Pc-1 that was contributed by various epidemiological factors (thermic and biological) accounted for maximum variance in disease severity followed by Pc-2 (light variables) and Pc-3 (hydric variables).