Abstract: Collar rot caused the death of Hevea rubber. In order to elucidate the causal agent of Collar rot and its taxonomic status袁the causal bacterium was isolated and characterized with the pathogenicity test袁morphology袁culture feature observation袁and biological characteristics test. The results indicated that the causal agent belonged to Fusarium venfricosum援The pathogenic fungus could grow at temperatures ranging from 10益to 40益, and the most suitable temperature was 30益. When above 40益or below 10益, the growth of mycelium was inhibited. The accumulating water in wet season was the main reason for occurrence of this disease.