Identification and Pathogenicity of Fungal Pathogens Associated with Leaf Disease of Fallopia multiflora in China

Fallopia multiflora (Thunb.) Harald is a valuable medicinal plant with substantial economic and therapeutic value, widely cultivated in southern China. In 2025, a leaf disease outbreak occurred in an F. multiflora plantation in Tongnan District, Chongqing, China. Diseased samples were collected for pathogen isolation, and seven representative strains were selected from 50 pure isolates via preliminary pathogenicity tests. Species identification was performed using a combination of morphological characterization and multi-locus phylogenetic analysis, targeting the Internal Transcribed Spacer (ITS), Translation Elongation Factor 1-alpha (TEF1), RNA Polymerase II Second Largest Subunit (RPB2), Beta-tubulin (β-TUB2), Heat Shock Protein 60 (HSP60), and Glyceraldehyde-3-Phosphate Dehydrogenase (G3PDH) gene regions. The isolates were identified as Alternaria alternata, Botrytis cinerea, Botrytis polygoni, Epicoccum mackenziei, and Lasiodiplodia citricola. Pathogenicity assays on living F. multiflora leaves confirmed that all identified species could induce disease symptoms, with distinct interspecific differences. This study verifies that multiple pathogenic fungi can infect F. multiflora, with potential co-infection. It improves our understanding of the pathogenic fungal community associated with this medicinal plant and lays a foundation for subsequent disease management in its cultivation.