CHARACTERIZATION AND MANAGEMENT OF EARLY BLIGHT OF TOMATO
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Date
2022-12-16
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Early blight caused by Alternaria solani is a predominantly occurring disease of Tomato. Roving survey results of Rabi 2018-19 and 2019-20 in major tomato rowing areas of southern Karnataka revealed that the maximum mean disease severity was recorded in Kolar district (38.63%) followed by Chikkaballapur 38.36%) district during fruiting stage. Among the 23 isolates, isolates AMaNaL and AMaNaS recorded maximum radial growth on six solid media out of the ine media. The isolate AHaBeL showed highest number of horizontal septation (5-7) on oatmeal agar medium and the highest number of vertical septation of -3 were observed in AKoMaL (host leaf extract) and AMyNjL (oatmeal agar). Sporulation was observed only in five isolates viz., AHaBel, AHaCrl, AHaHaL, KoMaL and AMyNjL. The PCR amplification of 23 isolates using universal primer pair revealed that, ITS region of the isolates showed highest nucleotide dentity varying from 91.2 to 94.2 per cent to the Alternaria solani infecting Tomato. The epidemiological studies revealed that per cent disease index (PDI) progressed in linear rate as the age of the plant advances and weather parameters like minimum temperature, evening relative humidity, morning relative umidity rainfall, number of rainy days were found significant and in negative correlation with disease development. Among the three contact fungicides valuated, the highest per cent inhibition (78.61) was recorded in mancozeb 75% WP. Among the different antagonists evaluated maximum mycelial inhibition was noticed in Trichoderma asperellum (69.69%). Hexaconazole 5% EC @0.1% was found effective both under laboratory and field condition against A. solani. Among the 50 commercial varieties/hybrids evaluated, three varieties/ hybrids viz., (ArkaSurabh, Arka Samrat and Arka Vikas) showed moderately resistant (MR) reaction