First report of anthracnose on Hosta ventricosa caused by Colletotrichum spaethianum in China

Fragrant plantain lily (Hosta ventricosa) is an ornamental plant and widely cultivated in China due to its environmental adaptability and usefulness on landscaping. Leaves of H. ventricosa showing brown necrosis were observed since 2017. Thereafter, anthracnose significantly reduced the ornamental and economic values of H. ventricosa as the garden plants. A fungal species was isolated recurrently from the lesioned leaves of the symptomatic plants. The fungal colony on culture plates was grayish to dark gray with abundant pigmented aerial mycelia and conidia. Based on the cultural and morphological characteristics, the isolated fungus was preliminarily identified as Colletotrichum spaethianum. To confirm the identification, partial sequences of the ITS and the GAPDH and ACT genes of this fungus were amplified and sequenced. Phylogenetic analysis based on these sequences and their orthologs confirmed that this fungus was C. spaethianum. Koch's postulates were confirmed by a pathogenicity test on healthy leaves of H. ventricosa, reisolation and identification. To our knowledge, this is the first report of anthracnose of H. ventricosa caused by C. spaethianum in China. Our study will provide basic references for disease management of this pathogen.