Evaluation of the Biocontrol Efficacy of Trichoderma Harzianum against Soil-Borne Pathogens in Legume-Based Cropping Systems: Implications for Sustainable Disease Management

Soil-borne pathogens, including Fusarium spp., Rhizoctonia solani, and Sclerotium rolfsii, are persistent threats to legume-based cropping systems, causing substantial yield losses and long-term soil health degradation. This study evaluated the biocontrol potential of Trichoderma harzianum through a combination of greenhouse and field experiments over two cropping seasons in diverse agroecological zones. Chickpea (Cicer arietinum), lentil (Lens culinaris) and cowpea (Vigna unguiculata) were selected as representative legumes. Treatments included seed coating with T. harzianum spore suspension, soil application at sowing and untreated controls. Disease incidence and severity were recorded, alongside plant growth indices, yield performance and soil microbial dynamics. Results demonstrated that T. harzianum application reduced disease incidence by 48–72% and disease severity by 40–65% relative to controls. Treated plants exhibited enhanced shoot and root biomass, increased nodulation, and yield gains of 18–25% across crop species. Soil microbial analysis revealed an increase in beneficial rhizosphere microorganisms and suppression of pathogen propagules, indicating a shift toward a more disease-suppressive soil environment. The consistent efficacy of T. harzianum under varying climatic and soil conditions highlights its adaptability and potential for integration into eco-friendly disease management programs. These findings support the adoption of T. harzianum as a viable alternative to synthetic fungicides, contributing to sustainable intensification of legume production while reducing chemical input dependency and enhancing soil resilience.