Native Trichoderma spp. as biocontrol agents against common beans anthracnose

Trichoderma spp. has emerged as a promising biocontrol agent among soil microbiota. This study evaluated the biocontrol potential of 32 native Trichoderma strains recovered from Araucaria Forest soils in southern Brazil against Colletotrichum lindemuthianum (races 475 and 73), the causal agent of anthracnose in common bean (Phaseolus vulgaris L.). Among these isolates, T. hamatum LMA RQ, T. asperellum LMA RS2, and T. atroviride LMA PH exhibited outstanding antagonistic performance both in vitro and in vivo. In dual-culture assays, T. hamatum LMA RQ and T. asperellum LMA RS2 inhibited pathogen growth by 80–88%, while volatile and non-volatile metabolites reduced fungal development by 65–82%. All three strains exhibited high fungicide compatibility (≥ 85%) and maintained robust colony growth under chemical exposure. In the in vivo experiments (detached leaf, pod, and seed germination assays), these Trichoderma strains reduced anthracnose incidence by 60–85% and disease severity (AUDPC) by up to 70%, while sustaining 92–100% seed germination. Their potential modes of action include mycoparasitism, competitive interactions, and the production of secondary metabolites. Notably, the strains were applied as simple conidial suspensions without adjuvants, underscoring their potential for commercial formulation and use as sustainable alternatives to chemical fungicides. Overall, these findings highlight the key role of fungal bioagents in sustainable crop protection and reinforce the biotechnological relevance of Trichoderma spp. from native forest soils.