Abstract: The leaf-spot disease caused by Mycovellosiella eupotoriio-odorai is the most important disease of Eupatorium adenophorum in Yunnan Province. In the laboratory studies, the optimal temperature for conidia germination of the pathogen was 25°Cand the optimal pH was 5.0. The highest percentage of conidia germination was obtained at the condition of saturated moisture (100%). Conidia germination was accelerated by addition of 1% glucose solution to the medium. Growth of the hyphae was restrained by ultraviolet light, but optimized by fluorescent lamp and diffused light. Maximum formation of conidia was obtained at continuous darkness. Adding fresh leaf of E. adnophorum to the cultural medium enhanced spore production of the pathogen. The fungus could effectively utilize all the carbon sources tested. The hyphae grew best in sucrose as a carbon source and in peptone as a nitrogen source.