Mitigation of early blight of tomato by the intervention of fungal and bacterial bioagents

Bellishree, K. Girija Ganeshan, Ramachandra, Y.L. Archana, S Rao and Chethana, B.S

Tomato is one of the most important vegetable crop and it is affected by number of diseases, major one is early blight of tomato caused by Alternaria solani (Ell. and Mart) Jones and Grout, triggering substantial loss in yield up to 79%. To mitigate early blight of tomato four bioagents, Trichoderma harzianum, Chaetomium sp., Bacillus subtilis and Pseudomonas fluorescence were evaluated for their efficacy against Alternaria solani. These bioagents were screened for their antagonistic activity by dual culture assay, in this method B.subtilis recorded 92.85% inhibition of the pathogen growth and Cheatomium sp showed lowest inhibition of 62.79%. In volatile compound assay, Cheatomium sp inhibited the pathogen growth by 81.6% and least inhibition of 56.86% recorded by T.harzianum B.subtilis treated leaves recorded maximum inhibition of lesion by 94.90% followed by T.harzianum with 77.18% and T.harzianum recorded least inhabition of 54.7%. Under field studies Cheatomium sp recorded lowest PDI of 21.00, with 26.91% decrease over control, and in the second season disease incidence decreased upto 22.46% with PDI of 9.13. In both the seasons Cheatomium sp recorded highest marketable yield of 74.08 tonnes/ha and 75.62 tonnes/ha respectively. Subsequently B.subtilis and T. harzianum reduced the disease severity of early blight significantly when compared with control. These results suggest that the fungal and bacterial isolates studied have a good potential to be used as biocontrol agents against A. solani in tomato.

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