Biological Control of Southern Blight in Tomato Caused by Sclerotium rolfsii Using Trichoderma spp. under In-vitro and In-vivo Conditions

Tomato (Solanum lycopersicum L.) is a globally important crop often affected by southern blight, caused by the soil-borne fungus Sclerotium rolfsii, leading to significant yield losses. Conventional management using chemical fungicides faces challenges including pathogen resistance and environmental hazards, necessitating sustainable alternatives. This study evaluated the biocontrol potential of three Trichoderma species (T. harzianum, T. viride, and T. asperellum) against S. rolfsii under laboratory and greenhouse conditions. In vitro dual culture assays demonstrated significant inhibition of pathogen mycelial growth, with T. harzianum showing the highest antagonistic effect (64.95% inhibition), followed by T. viride and T. asperellum. Subsequent pot experiments assessed disease incidence and plant growth parameters in tomato plants challenged with S. rolfsii. All Trichoderma treatments significantly reduced disease incidence compared to the inoculated control, with the combined application of all three species achieving the highest disease suppression (85.93%) comparable to the chemical fungicide mancozeb (92.85%). Moreover, Trichoderma treatments enhanced plant growth, reflected in increased shoot and root lengths and biomass. These results highlight the efficacy of Trichoderma spp. as eco-friendly biocontrol agents, capable of suppressing southern blight and promoting tomato growth. Integrating Trichoderma bioagents offers a sustainable approach to managing S. rolfsii, reducing reliance on chemical fungicides and contributing to environmentally safe crop production.