云南红河流域木薯褐斑病流行规律初步研究

Epidemic Law of Cassava Brown Leaf Spot Caused by Passalora henningsii in the Red River Basin of Yunnan Province

采用系统观察方法对红河流域木薯主产区木薯褐斑病发生和流行规律进行研究,结果表明：病害在木薯生长前期5月份开始发病,生长中、后期的7月份后病情呈明显上升,9、10月份达到最高峰,危害率达100%,病情指数20.50~30.77;下游区域的病情〉中游〉上游,病情的周年消长和区域性差异主要是降雨量和湿度的影响;高海拔区域（350~400 m）病情高于低海拔区域（250~300 m）,这与高海拔区域气温相对偏低有关。

The occurrence and epidemic law of cassava Brown Leaf Spot were studied through systematic observation. The results indicated that this disease appeared in the early stage of growth in May, and significantly become more seriously in the middle and late growth stage in July, finally to the peak in September and October, with 100% of infection. The disease index ranged in 20.50 to 30.77. It was found that the disease was getting worse from upstream, the middle segment to the downstream of this basin. The rainfall and humidity have greatly effect on the dynamics of the disease in a year. Why there are more serious disease at high altitude o f 350 to 400 m than that of at altitude of 250 to 300 m, just because of the low temperature.