Biocontrol Potential of Trichoderma spp. Against Fungal Pathogens Associated with Fruit Diseases

Fungal contamination is a major constraint in fruit production and postharvest management, highlighting the need for sustainable alternatives to conventional chemical fungicides. This study evaluated the antagonistic potential and biocontrol mechanisms of different Trichoderma spp. against four fruit-associated fungal pathogens, namely Talaromyces trachyspermus, Paecilomyces variotii, Stemphylium vesicarium, and Alternaria arborescens. The antagonistic activity of Trichoderma strains was assessed using dual-culture assays, while the antifungal activity of culture supernatants and the morphological interactions between Trichoderma and the target pathogens were examined to elucidate possible mechanisms of antagonism. All tested Trichoderma strains exhibited inhibitory activity against the target pathogens, with inhibition rates ranging from 32% to 100%. Among the tested strains, Trichoderma viride and Trichoderma harzianum showed the strongest overall antagonistic activity. In addition, culture supernatants of Trichoderma atroviride and Trichoderma longibrachiatum retained antifungal activity, indicating that extracellular metabolites may contribute to pathogen inhibition. Microscopic observations further revealed several mycoparasitic interactions, including adhesion to pathogen hyphae, hyphal coiling, penetration, morphological deformation, and hyphal lysis. Overall, the results demonstrate that the antagonistic activity of Trichoderma is both strain- and pathogen-specific and involves multiple complementary mechanisms. These findings highlight the potential of selected Trichoderma strains as biological control agents for managing fruit-associated fungal pathogens and as sustainable alternatives to chemical fungicides in fruit production and postharvest disease management.