Evaluation of biocontrol agents and chemical fungicides against Sclerotium rolfsii causing stem rot and foliar blight of cowpea

Sclerotium rolfsii is a serious pathogen which causes stem rot and foliar blight diseases in cowpea. Infected cowpea plant samples were collected from different locations of Kasargod district in Kerala. Six isolates of pathogen obtained could produce infection in cowpea during pathogenicity test and identified as Sclerotium rolfsii by morphological, cultural and molecular characterization. Among the biocontrol agents tested, highest inhibition of 84.44% was recorded with Trichoderma harzianum followed by Trichoderma viride (71.11). Pseudomonas fluorescens showed zero per cent mycelial inhibition whereas Bacillus subtilis inhibited the growth of pathogen by 38.89 per cent. Among the fungicides, mancozeb (75 WP) and propiconazole (25EC) were recorded with 100 per cent inhibition of pathogen at all the three concentrations (0.1%, 0.2% and 0.3%) tested followed by thiram (75WS) with 99.63 per cent inhibition at 0.3% concentration. Chlorothalonil (75 WP) and azoxistrobin 23SC were also found effective at all the tested concentrations (0.1%, 0.2% & 0.3%). Copper oxychloride (50WP) and carbendazim (50WP) were less effective against the pathogen with inhibition of 5.18 and 12.8 per cent at 0.1% and 0.05% concentrations, respectively.