Abstract: The major pathogen that causes leaf butt rot of phalaenopsis disease is Fusarium oxsproum. This study aimed to understand the biological characteristics of F.oxsproum and the pathogen's sensitivity to fungicides. It was hoped that some fungicides could be identified for an effective control of the leaf butt rot. The optimum temperature for the bacteria to grow was found to be 26℃, and that for the conidia germination 20℃or 22℃. The pH range for its growth was 6 to 7. For the pathogen's spores to germinate, it required high humidity. High humidity and moisture promoted conidia germination. By alternating light and dark, the spore germination was encouraged. Sportak, sporgon and carbendazim at concentration of 500 mg·L^-1 and 1 000 mg·L^-1 showed strong inhibitive effects on F.oxsproum, with the inhibiting rate of 100% on the mycelium growth. Pot experiment by dipping the leaves infected with phalaenopsis indicated that carbendazim or thiophanate-methyl at the concentrations of 500 mg·L^-1 and 1 000 mg·L^-1 could effectively control the penetration of the pathogen.

Key words: phalaenopsis, leaf butt rot, Fusarium oxysporum schl, biological characteristic, chemical control