【Objective】To confirm the pathogen species that caused brown rot disease on Hylocereus undatus. 【Method】Diseased tissue isolation,indoor pathogenicity test,morphological observation and rDNA sequence analysis were used to confirm the pathogen species. 【Result and conclusion】The colonies of the fungus were dark grey and fluffy on potato dextrose agar( PDA) medium. Two kinds of arthrospore were observed on PDA medium. One was columnar conidium with light-colored,thin-walled and( 5. 00-10. 69) μm ×( 2. 61- 4. ...