Potential of endophytic Trichoderma in controlling Phytophthora leaf fall disease in rubber (Hevea brasiliensis)

Abstract

Fifty-nine endophytic Trichoderma spp., isolated from healthy rubber leaves collected in the eastern and southern parts of Thailand, were evaluated for their antagonistic activity against Phytophthora leaf fall disease, caused by Phytophthora palmivora. Three strains of T. asperellum, three strains of T. harzianum, three strains of T. hamatum, one strain of T. longibrachiatum, and two strains of T. virens were selected based on their potent antagonistic activity against P. palmivora when tested by dual culture. Among the endophytic Trichoderma strains tested, T. harzianum KUFA0436 and KUFA0437 showed potent biocontrol efficacy, suppressing the disease severity by 43 % and 48 %, respectively, under greenhouse conditions. Meanwhile, the other strains showed low to moderate suppression of the disease severity when tested in laboratory and under greenhouse conditions. Trichoderma harzianum KUFA0437 and KUFA0437 were selected to be tested under field conditions and were found to display a significant reduction in defoliation of 30–33 %; while metalaxyl (positive control) showed the best suppression of defoliation of up to 66 %. The antagonistic activities of Trichoderma spp. included fast growth, strong competition for natural resources, and production of antifungal crude extracts. Moreover, all Trichoderma strains showed compatibility with propineb (1,750 ppm), fosetyl-Al (1,600 ppm), and metalaxyl (500 ppm). To the best of our knowledge, this is the first report of endophytic Trichoderma spp. as potential biocontrol agents for controlling rubber diseases. These fungi can serve as alternative fungicides to reduce the use of synthetic fungicides or as part of an integrated pest management scheme in combination with fungicidal treatments.