EFFICACY OF Trichoderma virens SOLID FORMULATION FOR MANAGING COWPEA CROWN ROT CAUSED BY Athelia rolfsii

Abstract

This study evaluated the efficacy of Trichoderma virens solid formulation against Athelia rolfsii and assessed biocontrol ability, viability, plant growth promotion and yield enhancement ability. Symptomatic cowpea plants were collected from the faculty field, Faculty of Agriculture, Anuradhapura for pathogen isolation. Along with pathogenicity test and dual plate assay, pot and field experiments were conducted under controlled environment and open field conditions respectively. A. rolfsii was applied to the crown area of seedlings (6 × 105 CFU) using agar disc method. Trichoderma virens was applied with spore suspension at a concentration of 7 ×108 spore mL-1 at seeding and 3 ×106 spore mL-1 in 3-week intervals. The efficacy of T. virens was tested in a pot trial with eight treatments: T1: only soil, T2: A. rolfsii and only soil, T3: A. rolfsii and T. virens only, T4: A. rolfsii and full DOA recommendation, T5: A. rolfsii with full DOA and T. virens, T6: A. rolfsii and half DOA, T7: A. rolfsii, T. virens with half DOA, and T8: A. rolfsii and carbendazim. Plant growth parameters and yield components were meticulously recorded. Additionally, CFU and disease incidence were monitored. Data analysis was conducted using repeated mixed effect model, three-way and four-way ANOVA models in SAS studio version 9.0 software. The pathogen was confirmed morphologically and molecularly as A. rolfsii. Pathogenicity was confirmed via Koch’s postulate. T. virens demonstrated 86.02% inhibition of A. rolfsii in a dual plate assay. The application of T. virens exhibited zero disease incidence. Treatments with T. virens have a significant effect (p<0.05) on pod number, root length and seed weight. Results indicated that T. virens remained viable in soil throughout the experimental period, ensuring sustained benefits. In conclusion, T. virens demonstrates significant potential as a biological alternative to chemical fungicides for managing Athelia rolfsii, effectively promoting growth and suppressing disease in cowpea plants.