In vitro evaluation of bioagents againstAlternaria tenuissima - An incitant of pigeonpea [Cajanus cajan (L.) Millsp.] leaf blight

Pigeonpea leaf blight caused by Alternaria tenuissima is one of the most important foliar disease causing heavy losses under South Gujarat region. The present investigation was carried out to evaluate the inhibitory activity of different bioagents against A. tenuissima and to find out the efficient bioagent at preliminary level. The experiment conducted in the P. G. Research Laboratory, Department of Plant Pathology, N.M.C.A., Navsari Agricultural University, Navsari. Different bioagents viz., Trichoderma viride Pers, ex. Grey, NAU isolate, T. harzianumRifai, NAU isolate, T. fasciculatum, Pseudomonas fluorescensNAU isolate and Bacillus subtilis EII NAU isolate were evaluated against the growth of A. tenuissima by using standard dual culture technique. The investigation revealed that, maximum per cent growth inhibition (PGI) of A. tenuissima found against T. viride which was followed by T. harzianum and T. fasciculatum. B. subtilis was found least effective against A. tenuissima. The results indicated that among all bioagents, T. viride found most efficient bioagent against A. tenuissima as it gave highest PGI because it may contain viridian like antibiotics or may be the presence of some secondary metabolites or enzymes. Therefore, the T. viride can be explored for the management of pigeonpea leaf blight disease under field condition.