In vitro antagonistic potential of Trichoderma species against phytopathogenic fungi isolated from selected vegetable crops

Trichoderma species are capable of causing significant changes in the metabolic activities of host plants, thereby triggering plant growth and increasing plant defense mechanisms against a diverse variety of fungal infections. This species has been reported as potential bio-control agents of many phytopathogenic fungi. Therefore, this study aimed to assess the in vitro antagonistic activity of indigenous Trichoderma spp. isolated from selected locations across Kano State, Nigeria, against phytopathogens affecting selected vegetables, in a dual-plate assay. Molecular characterization revealed three Trichoderma isolates: T. koningii (accession number KY886143.1; 99.63% BLAST similarity), T. harzianum (KJ807357.1; 98.94%), and T. viride (OP546802.1; 98.12%). The results revealed that Trichoderma spp. inhibited the radial growth of isolated phytopathogenic fungi compared to the control. The percentage growth inhibition for T. harzianum was higher in the tested species. Specifically, the inhibition percentages of T. harzianum ranged from 10.82 to 72.32%, for T. koningii from 5.49 to 63.15%, and for T. viride from 2.22 to 47.33% in the dual-culture assay. The results for Trichoderma spp. showed a significant decrease in radial growth and a statistical difference ( p < 0.05) in the percentage inhibition of the tested pathogens using a one-way ANOVA. The results of this study reveal valuable knowledge on the mycoparasitic potential of Trichoderma spp. that could be used in the selection of suitable biological control agents. They also provide useful insights into phytopathogen interactions, relevant to developing strategies for the biological control of fungal phytopathogens in crops of agricultural importance.