Citrus sinensis is an important fruit crop valued for its juicy fruit pulp and aromatic rind. Grafted twigs with rot progressing from both ends were observed on C. sinensis trees in 12 orchards in Zigui, China, in June 2017, with only 5 of grafted twigs surviving in some orchards. Severe infection resulted in a rot of the entire twig, with the twig becoming covered by a white mycelium. A fungus frequently recovered from the diseased twigs was identified as Fusarium solani based on cultural and conidial characteristics. Multi-gene phylogenetic analysis including partial gene sequences of the internal transcribed spacer (ITS) region of rDNA, translation-elongation factor 1 alpha (EF-1) and the RNA polymerase second largest subunit (RPB2) indicated that the isolated fungus belonged to the Fusarium solani species complex (FSSC) and was related closely to FSSC22 recovered from Xanthoxylum piperitum in Japan. Pathogenicity tests confirmed that this fungus is the causal agent of grafted twig rot on C. sinensis.
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