Screening of endophytic fungi biocontrols against sapstain fungus (Lasiodiplodia theobromae) in rubberwood

Rubber trees are often contaminated by sapstain fungus after felling, which seriously affects the appearance of the surface and causes economic losses. In order to combat the discoloration problem that occurs in rubberwood, this study isolated and screened a variety of endophytic fungi from rubberwood against sapstain fungus Lasiodiplodia theobromae, which is widely present in rubberwood. The antagonism experiment initially screened two strains that showed significant inhibitory effects against Lasiodiplodia theobromae on plates. After preparing fungal suspensions of these two strains and applying them to rubber wood, the BH-3 strain was identified as the most effective biocontrol agent based on the rate of mass loss and color difference analysis. This strain was subsequently identified as Trichoderma reesei. FTIR, XRD, TG and SEM analysis were carried out on wood chips before and after treatment and wood chips before and after infection. The results showed that treated wood chips could well resist sapstain fungus infestation and had no significant effect on the thermal stability, MOR and MOE of wood chips. No discoloration was observed in treated wood chips after 4 weeks of coexistence with the sapstain fungus in the presence of Trichoderma reesei suspension. The wood chips did not exhibit any color change, the main chemical components (cellulose, hemicellulose, and lignin) were only slightly degraded, and the microstructure remained intact. Therefore, this study shows that Trichoderma reesei can be widely used as an environmentally friendly, economical and efficient biocontrol agent against sapstain fungus.