Objective The objective of this study was to identify the pathogen causing for root rot in Polygonatum cyrtonema Hua in Guizhou Province and to screen for biocontrol bacterias capable of effectively antagonizing this pathogen. Ultimately, this research aims to establish a foundation for environmentally friendly control strategies against P. cyrtonema Hua root rot.

Method Diseased tubers of P. cyrtonema Hua were collected from Taijiang County, Guizhou Province. These samples underwent a sreices of procedures including isolation, purification, pathogenicity verification and identification. Both morphological and molecular biology techniques were employed for the identification process. Strains exhibiting significate inhibitory activity were singled out through dual-culture tests. Based on the analysis of culture shape, morphological traits and phylogenetic tree, its taxonomic status was clarified, and the inhibitory effect of its fermentation broth on the mycelial growth of pathogenic bacterias was determined.

Result Out of 28 fungi isolated from the diseased samples, 12 were found to induce evident symptoms of root rot. Among these, strain 2GF1 exhibited the most severe disease symptoms. Both morphological traits and phylogenetic tree analysis confirmed that the all 12 pathogens belonged to Fusarium oxysporum. In the dual-culture tests, the biocontrol strain WHD01 demonstrated the most potent antagonistic effect with an inhibition rate of 95.21%. Additionally, the bacterial strain WHD04 also displayed a significant antagonistic effect with an inhibition rate of 78.99%. Based on morphological and molecular identification, the strains WHD01, WHD02, WHD03, and WHD04 were identified as Trichoderma virens, Phlebiopsis gigantea, Bacillus amyloliquefaciens, and Bacillus velezensis, respectively. The inhibitory effects on the growth of pathogenic mycelia at a fermentation broth concentration of 200 mL/L were as follows: 32.70% (Trichoderma viridans), 26.72% (Phlebiopsis gigantea), 33.05% (Bacillus amyloliquefaciens) and 33.52% (Bacillus Velez), respectively.

Conclusion This study successfully identified F. oxysporum as the causative pathogen of root rot in P. cyrtonema Hua in Taijiang County, Guizhou Province. Moreover, four biocontrol bacterias with effective antagonistic effects against this pathogen were identified. These findings lay a the groundwork for the development of eco-friendly strategies for managing of root rot in P. cyrtonema Hua.