ASSESSMENT OF Trichoderma ISOLATES FOR VIRULENCE EFFICACY ON Fusarium oxysporum F. sp. Phaseoli

Trichoderma has been widely studied for their \nbiocontrol ability, but their use as biocontrol agents in \nagriculture is limited due to the unpredictable \nefficiency which is affected by biotic and abiotic \nfactors in soil. Isolates of Trichoderma from Embu \nsoils were evaluated for their ability to control \nFusarium oxysporum f. sp. phaseoli., in vitro and \npromote seedling growth in the greenhouse. Bioassays \nwere run using dual cultures and diffusible compound \nproduction analysis. The Trichoderma isolates \nsignificantly (p < 0.01) reduced the mycelial growth of \nthe pathogen. The principle mechanisms of niche \ncompetition, mycoparasitism, and antibiosis were \nobserved in growth of the pathogen mycelium in the \npresence of Trichoderma spp., through development of \ninhibition zones. There was coiling of hyphae around \nthe pathogen mycelium coupled by lysising of cell \nwall Trichoderma spp., where T. reesei and T. koningii \nwere the most effective isolates. Studies were \nindicative of the synergistic ability of Trichoderma \nspp., being an effective biocontrol of bean seedlings \nagainst Fusarium wilt while also promoting plant \ngrowth.