Abstract BACKGROUND Grapevine trunk diseases (GTD) lead to progressive vine decline and are a major threat to viticulture sustainability worldwide. GTD can involve multiple fungal species, with Phaeomoniella chlamydospora being one of the most prevalent pathogens. Pruning wounds are the primary entry point for wood‐inhabiting fungi. This study assesses the effectiveness of the biological control agent (BCA) Trichoderma atroviride strain SC1 in preventing natural GTD pathogen infections across three vineyard training systems. RESULTS Trichoderma recovery was significantly lowest (48.1%) in the double‐cordon training system (V3) and consistently higher (71.9%) in the head/spur system (V1). The treatment reduced GTD infection by 3.75%, and disease control declined markedly 1 year after application (61.1%) compared with ≤90 days post‐treatment (92.6%). The controlled assay including culture‐dependent and culture‐independent approaches (high‐throughput sequencing and quantitative polymerase chain reaction) revealed distinct detection patterns: culture methods favoured fast‐growing fungi such as Trichoderma , whereas molecular tools enabled the detection of slower‐growing taxa like P . chlamydospora . T . atroviride colonised wood up to 1–2 cm from the application point, whereas P . chlamydospora spread up to 5 cm. Overall, the pathogen had a stronger impact on wood mycobiome than the BCA, supporting the compatibility of Trichoderma with the resident grapevine microbiome. CONCLUSION These findings provide new insights into the integration of BCAs within vineyard GTD management strategies and contribute to the broader transition towards sustainable viticulture and integrated pest management. © 2026 Society of Chemical Industry.
García‐García et al. (Fri,) studied this question.