Isolation and Identification of Fusarium proliferatum Associated with Fusarium Wilt of Phalaenopsis and Screening of Endophytic Fungi with Biocontrol Potential

Fusarium wilt of Phalaenopsis spp., caused by Fusarium species, is a major soil-borne disease that severely threatens the yield and ornamental quality of Phalaenopsis. Endophytic fungi can serve as natural biocontrol agents against soil-borne pathogens and have potential applications in biological control. In this study, a pathogenic isolate, HT-1, was obtained from Fusarium-wilted Phalaenopsis plants, and its pathogenicity was confirmed through inoculation assays on detached leaves and intact plants. Morphological observations, together with internal transcribed spacer (ITS) and translation elongation factor 1-α (TEF-1α) sequence analyses, identified HT-1 as Fusarium proliferatum. Seven endophytic fungi with strong antagonism against F. proliferatum were screened using a dual-culture assay. All seven isolates consistently inhibited five representative plant pathogens in vitro, showing broad-spectrum and promising biocontrol potential. Detached leaf inoculation assays showed that both Trichoderma virens and Trichoderma asperellum significantly reduced lesion area and disease severity caused by F. proliferatum, indicating potential application in disease management. In summary, this study identified seven endophytic fungi from Phalaenopsis with broad-spectrum antagonistic potential against multiple plant pathogenic fungi. Meanwhile, the protective effects of T. virens and T. asperellum against F. proliferatum were preliminarily evaluated using detached leaves. These findings provide theoretical reference and fungal resources for screening candidate biocontrol strains against Phalaenopsis Fusarium wilt and related plant diseases, and lay a foundation for future studies on biocontrol mechanisms, whole-plant efficacy verification, and practical application.