昆明地区玉米灰斑病病斑的扩展规律

Lesion Development of Maize Gray Leaf Spot Disease in Kunming Area

在田间条件下采用喷雾法接种,观测昆明地区玉米灰斑病不同叶层和部位病斑面积与数量,分析其与接种天数和温湿度持续时间的关系。结果表明:玉米灰斑病病斑扩展与温度在20～30℃的时间累计值、10℃以上的有效积温、接种天数、相对湿度90%以上的时间积累值和品种抗性等均极显著相关(P<0.01);抗病品种病斑小而少、产孢少,感病品种则相反;病害主要发生在穗位及以下叶片,病斑主要分布在叶片的中上部,并以纵向扩展为主,横向扩展不明显。

The spore number and lesion area of maize gray leaf spot disease caused by Cercospora zeae-maydis Tehon Daniels in different layers and parts of the leaf were studied by using spray inoculation method under the field condition in Kunming,and the relationship between disease severity and the days after inoculation,time-duration of temperature and relative humidity was analyzed.The result indicated that the correlation between lesion development and time-duration of temperature 20-30 ℃,effective accumulated temperature≥10 ℃,days after inoculation,time of relative humidity≥90% and variety resistance was very significant（P0.01）.Small lesion and few spores appeared on resistant varieties,but big lesion and more spores on the susceptible ones.Lesion occurred largely on the ear leaf and below,in the middle and front of the leaf.The lesion development was mainly longitudinal and altitudinal development was not evident.