Integrated evaluation of Trichoderma isolates for the control of strawberry gray mold (Botrytis cinerea) and fruit...

Gray mold, caused by Botrytis cinerea, is a major constraint in strawberry production, particularly at the postharvest levels. The present study was conducted to determine the antagonistic potential of sixteen Trichoderma isolates obtained from strawberry leaves against B. cinerea under in vitro, in vivo and greenhouse conditions. The isolates were identified using ITS rDNA and TEF-α gene sequencing, revealing eight species, including T. crassum, T. virens, T. spirale, T. longibrachiatum, T. saturnisporum, T. lieckfeldtiae, T. asperellum, and T. yunnanense. Dual culture tests showed that all the isolates significantly inhibited mycelium growth of the pathogen, with inhibition rates ranging from 76 to 89%. The most efficient strains (Trc2, TrcF2, Trc3, TrcF3 and Trc4) exhibited strong competitive ability, while volatile organic compounds (VOCs) emitted by T. asperellum (Trc3BB) and T. spirale (TrcF2) reduced mycelia growth by more than 60%. Culture filtrates of T. spirale (TrcF2) and T. crassum (Trc1BB) also showed high antifungal activity. Biochemical assays revealed that the most effective strains exhibited higher hydrolytic enzyme activities including chitinase, β-glucanase, cellulase, and pectinase, as well as siderophore production, phosphate solubilization ability and moderate HCN-release capacity, which are likely involved in the antagonism process. In vivo tests on strawberry fruits demonstrated that VOCs from T. spirale (TrcF2) and T. asperellum (Trc3BB) significantly reduced gray mold incidence (8.3% and 15.6%, respectively) and improved quality parameters such as firmness, total soluble solids and maturation index. FTIR spectroscopy indicated that Trichoderma treatments mitigated oxidative stress and preserved cell wall polysaccharides. Greenhouse assays showed that T. spirale (TrcF2) reduced disease severity to a level similar to a fungicide application. Overall, our findings demonstrate the significant antagonistic and quality-retaining properties of native Trichoderma isolates, especially T. spirale (TrcF2), which is presented as an environmentally friendly alternative to synthetic fungicides for sustainable strawberry production.