Abstract

Dragon fruit cultivation encounters significant challenges due to the brown spot disease caused by Neoscytalidium dimidiatum, resulting in reduced yield and quality. In this study, we successfully isolated and identified N. dimidiatum as the causal agent of this disease in Long An, Vietnam. Concerns about the potential adverse effects of fungicide administration on the ecosystem and human well-being have prompted the exploration of alternative approaches. Trichoderma spp., a group of filamentous fungi, have emerged as promising biocontrol agents due to their competitive nature and ability to induce systemic resistance. Fifteen isolates of Trichoderma spp. were evaluated through a dual culture assay and indicated that Trichoderma viride (TDF2), Trichoderma asperellum (TDF5), and Trichoderma harzianum (TC1) exhibited significant antagonistic properties against N. dimidiatum. These isolates effectively inhibited the growth of N. dimidiatum in vitro, with efficacy ranging from 85.05% to 88.35%. Potted experiments further demonstrated that pre-treatment with Trichoderma spp. exhibited the highest level of effectiveness. This approach provided a competitive advantage over the soil-borne pathogen, resulting in a remarkable reduction in disease index by 70.25–75.71%, thus achieving effective disease management. While co-treatment of Trichoderma spp. and N. dimidiatum showed some potential in reducing disease severity, its efficacy was found to be suboptimal compared to pre-treatment. In summary, the Trichoderma spp. isolates investigated in this study have demonstrated their potential in managing brown spot disease, indicating their potential utility as biocontrol agents against N. dimidiatum infection in dragon fruit cultivation.

Key words: Antagonistic activity, Brown spot disease, Dragon fruit, Trichoderma spp, Neoscytalidium dimidiatum