Vol. 11, Issue 11 (2022)

Cowpea [Vigna unguiculata (L) Walp.] is a pulse crop utilised as vegetable source and fodder. Ascochyta leaf blight caused by Ascochyta phaseolorum under humid conditions is often devastating, causing extensive defoliation of cowpea. In this study, plant extracts and bio-control agents were evaluated in vitro against the growth of the pathogen. Among the plant extracts, Solanum torvum at 15% (82.33%), 10% (80.37%) and 5% (77.65%) were found effective against growth of A. phaseolorum. The Azadirachta indica extract at 15% (64.78%) and 10% (51.22%), Curcuma longa at 15% (51.37%), Acorus calamus 15% (48.77%) and Aloe vera at 15% (45.30%) were moderately effective. Extract of W. somnifera at 5% with16.51% percent inhibition recorded the least efficacy. Among the bio-control agents (BCAs), maximum percent inhibition was observed in Trichoderma harzianum (65.93%) which was significantly superior to the rest of BCAs tested and the next best antagonist was T. viride (60.86%). Bacterial antagonists Pseudomonas fluorescens showed moderate percent inhibition (45.31%) followed by Bacillus subtilis strain BS217 (38.64%) and least efficacy was observed in B. subtilis strain BC07 (25.56%). The findings provide the promising efficacy of readily available botanicals viz. S. torvum and A. indica on management of A. phaseolorum on cowpea. Further studies on in-vivo and field efficacy of the plant extracts are required.