Correlation coefficient between early blight severity, infection rates and meteorological factors in potato under different fungicidal spray

Early blight caused by Alternaria solaniis a severe constraint in potato production. The severity of this disease has been increasing day by day for last few years in India due to changes in weather. Disease severity and area under disease progress curve (AUDPC) was recorded in each treatment plot. The early blight disease had significant negative correlation with maximum relative humidity during 2012-13 and in year 2013-14 minimum temperature was significantly correlated. The severity of early blight showed significant positive correlation with maximum temperature and highly significant positive correlations with sun shine hours in year 2013-14 in all tested treatments. The study showed that minimum temperature and rainfall revealed negative but non-significant correlation in all treatments except untreated control in year 2012-13. The maximum tuber yield 223.70 and 222.00 q/ha in first and second years, respectively, were recorded with spray of ndFenamidone @ 0.2% at disease initiation and 2spray of Mancozeb @ 0.25% followed by Mancozeb @ 0.25% at 15 days intervals in both respective years