First Report of Fusarium acuminatum Causing Wilt Disease on Vincetoxicum stauntonii in China and the Control Strategy of Ethylicin via Membrane Damage and Oxidative Stress.

Vincetoxicum stauntonii is a valuable traditional Chinese medicinal herb widely used in clinical practice for managing various respiratory disorders in China. However, a severe wilt disease recently prevailed in major V. stauntonii cultivation regions in Hubei Province from May to August 2025, resulting in an overall disease incidence exceeding 30%, with the maximum plant mortality rate exceeding 90% in severely affected fields. To clarify the causal agent of this emerging wilt disease and develop effective management strategies, symptomatic V. stauntonii plants were sampled from three representative commercial plantations. Pathogen isolation and purification were performed, followed by pathogenicity validation in accordance with Koch's postulates. The assays confirmed that five isolates could induce typical wilt symptoms on healthy V. stauntonii plants. Based on morphological characterization and multilocus phylogenetic analysis using the concatenated internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (TEF1-α), RNA polymerase II largest subunit (RPB1), and RNA polymerase II second largest subunit (RPB2) sequences, these five isolates were identified as Fusarium acuminatum. Biological characteristic assays showed that the causal agent grew optimally at 25 °C and pH 9.0, with soluble starch and peptone as the most suitable carbon and nitrogen sources, respectively. In vitro antifungal bioassays showed that ethylicin exhibited the strongest inhibitory effect against the pathogen, with a median effective concentration (EC50) value of 3.367 mg/L. Furthermore, greenhouse pot experiments validated that ethylicin exhibited significant protective and curative efficacy against V. stauntonii wilt disease. Mechanistic analyses further revealed that ethylicin disrupted plasma membrane integrity and induced excessive accumulation of intracellular reactive oxygen species (ROS) in F. acuminatum. To our knowledge, this study is the first formal report of F. acuminatum-caused wilt disease on V. stauntonii. Collectively, these findings provide a theoretical basis for the sustainable management of the emerging wilt disease of V. stauntonii.