Molecular Identification of Stromatinia cepivora Causing White Rot in Allium Species and Evaluation of Fungicide Efficacy

White rot of Allium crops is a soil-borne disease in which sclerotia play a crucial role in pathogen survival and infection. This study aimed to re-identify the causal agent of white rot isolated from garlic and chives and to evaluate the effects of fungicides on mycelial growth, sclerotial formation, and sclerotial germination. Multilocus phylogenetic analysis based on internal transcribed spacer, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase sequences confirmed that all isolates belonged to Stromatinia cepivora. In fungicide sensitivity assays, most fungicides effectively inhibited mycelial growth, whereas pencycuron showed limited activity. Fludioxonil exhibited strong inhibitory effects on both sclerotial formation and germination, regardless of application method, and provided stable disease control in garlic clove dipping assays. These results suggest that fludioxonil is a promising fungicide for suppressing multiple developmental stages of S. cepivora and provide fundamental information for the effective management of white rot in Allium crops.