1　前　言定西地区地处甘肃省中部 ,是马铃薯的主产区之一 ,其南部大多属二阴区。这里是定西地区马铃薯的高效种植区和优质生产基地 ,近年马铃薯产业得到了快速发展 ,但严重影响马铃薯产量和品质的晚疫病在各地出现。据 1999年重点调查 ,病田率达 35 % ,病株率达 33% ,田间直接 1 Introduction Dingxi area is located in the middle of Gansu Province, is one of the main producing areas of potatoes, most of its southern two Yin area. Here is the efficient planting area and quality production base of potatoes in Dingxi area. In recent years, the potato industry has been developed rapidly, but the late blight that seriously affects the yield and quality of the potato appears everywhere. According to the key survey in 1999, the disease rate reached 35% and the diseased rate reached 33%