In vitro biocontrol mechanism of Trichoderma spp. against crown rot pathogens in banana

Crown rot, caused by various fungal pathogens, is a major post-harvest disease of bananas, leading to significant storage losses. Biocontrol by antagonistic microorganisms is a promising alternative to synthetic fungicide application. Trichoderma spp. are well-known biological control agents due to their strong antagonistic properties. Soil samples were collected from banana-cultivated orchards in the districts of Mayurbhanj, Jagatsinghpur, Jajpur and Ganjam. A total of 4 Trichoderma species were isolated using the serial dilution method: T. asperellum (8 isolates), T. atroviride (4 isolates), T. harzianum (5 isolates) and T. hamatum (6 isolates). Based on their micro-morphological and cultural characteristics, bioagents were identified. Trichoderma isolates were selected for in vitro testing against the Fusarium species by conidia germination assay and dual culture assay. Among the tested isolates, T. asperellum showed the highest inhibition of conidial germination (88.24 %) and mycelial radial growth (91.22 %) of F. equiseti. T. atroviride showed the lowest level of inhibition of conidia germination and mycelial radial growth against the F. equiseti. Solid-phase microextraction (SPME) was applied to trap volatiles emitted by T. asperellum. The GC/MS profiling revealed the presence of antifungal compounds, including azetidine, 1-Methylideneindene, phenylethyl alcohol and fluoro(trinitro)methane, which are involved in antifungal activity and the dominant compound was tentatively identified as phenylethyl alcohol (PEA), making up 21.79 % of the peak area with 96.24 % match in 7.15 retention time. This study indicates that T. asperellum is an effective antagonistic biocontrol agent and can produce volatile antifungal compounds that involve major mechanisms against Fusarium spp. in vitro conditions.