STUDIES ON EARLY BLIGHT OF TOMATO CAUSED BY Alternaria solani (ELLIS AND MARTIN) JONES AND GROUT
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Date
2022-12-20
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University of Agricultural Sciences, Bangalore
Abstract
Early blight of tomato caused by Alternaria solani is an important disease causing considerable yield loss. The leaves showing typical target board spot with yellow hallow
were used to isolate the pathogen by using standard tissue isolation method. A. solani
produced muriform conidia that were born singly and had a long beak and Koch’s
postulate was proved. The pathogen was further confirmed as A. solani by molecular
characterization using ITS primers. The highest colony growth of 82.10 mm was found
on V8 juice agar medium and the colony colour varied from light brown to dark brown
with completely serrated to smooth margin. The temperature (25oC) and pH (7.00) were
found best for growth of the pathogen. Three different solanaceous vegetables viz., potato, brinjal and chilli were found to be collateral host for the early blight of tomato. Among different fungicides, bioagents and botanicals tested under laboratory conditions, two contact fungicides viz., captan and copper oxy chloride, two systemic fungicides viz., propiconazole and tebuconazole, two combi fungicides, viz., azoxystrobin + tebuconazole and zineb + hexaconazole were found best. Among fungal and bacterial bioagents, T. viride (Tv-B2) and B. subtilis (Bs-O) and among botanicals, touch me not plant and neem leaf extract were found effective against the pathogen. Under field conditions, two foliar sprays of azoxystrobin + tebuconazole @ 0.1% at 15 days interval was found effective with least mean disease severity (16.78 %) and highest yield (37.23 t/ha) and BC ratio (2.49).