Management of collar rot and web blight of cowpea with composts and compost teas

Abstract

The study entitled “Management of collar rot and web blight of cowpea using composts and compost teas” was undertaken at the Department of Plant Pathology, College of Agriculture, Vellayani with the objective of developing an eco-friendly management strategy. The pathogen causing the disease was isolated from the collar rot and web blight affected parts and identified as Rhizoctonia solani Kuhn. Pathogenicity was proved following Koch’s postulates and the virulent isolates were identified. Collar rot and web blight isolates of R. solani were found to be cross infective. Neem leaf was found to significantly suppress the collar rot and web blight isolates of the pathogen and was selected for the preparation of leaf compost. Studies on the effect of dilution and brewing time of compost tea indicated that 1:5 dilution brewed for a period of 24 h showed maximum fungal population and was adopted for the preparation of compost teas. The dual culture technique to study the antagonistic potential of the saprophytic fungi isolated from composts against R. solani revealed that Trichoderma sp. exhibited the maximum inhibition. Based on the cultural and morphological studies, the antagonist was identified as Trichoderma virens and was selected for enrichment of composts by inoculating @ 100 ml/ kg compost. Enriched compost teas were prepared from the enriched composts. The effectiveness of composts, compost teas and their enriched forms on the incidence of collar rot and intensity of web blight were assessed in a pot culture experiment. The incidence of collar rot was lowest in soil incorporated with neem leaf compost and Trichoderma enriched neem leaf compost tea. Similarly, the percentage suppression of web blight disease was higher in soil sprayed and drenched with Trichoderma enriched neem leaf compost tea. The application of Trichoderma enriched neem leaf compost tea recorded a higher value for biometric parameters. The present study indicated that the composts and compost teas offer eco-friendly management of collar rot and web blight along with crop growth promotion. The effect can be further augmented by enriching with Trichoderma.