Abstract: To clarify the pathogen causing leaf spots of Hemerocallis fulva in Guizhou Province and its biological characteristic，the pathogen was obtained by using the method of tissue isolation. Its pathogenicity was tested in vitro inoculated leaves，and the pathogen was classified and identified with morphology and ITS gene sequence analyse，the biological characteristic of pathogen were also studied. The results showed that the strain isolated from leaf brown spots of Hemerocallis fulva was numbered as XCS369，its main diagnostic feature were as followed：the mycelia was grayish white and villous，colony center ridge is taupe，back olive green，and the back of colonies were olive green. After 15 days of cultivation，it could produce white sporangium powder. Its smooth and colorless conidia appeared elliptical or oblong. The phylogenetic tree based on ITS gene sequence showed that XCS369 strain was clustered together with Xylaria cubensis，supported by 99%. Together with the morphology characteristics and phylogenetic analysis，it was identified as one member of Xylaria cubensis. The research of biological characteristics showed that the mycelia of XCS369 strain grew faster on potato dextrose medium of pH 7 and had the highest utilization of carbon source maltose and niteogen source yeast extract powder at 25–28 ℃，and it was insensitive to light.

Key words: Hemerocallis fulva, leaf spot disease, pathogens identification, Xylaria cubensi, biological characteristics