玉米粗缩病是由灰飞虱传播的一种病毒性病害，以往年份只是零星发生，病株率一般不超过10％，对玉米产量影响不大。但近年来由于种植结构的调整，套种玉米田面积逐年增多，玉米粗缩病有加重发生的趋势。1998年6月中旬普查，平均病株率25．3％，最高达75％，以其田间显症时间早 Corn sliver is a viral disease transmitted by Laodelphax striatellus, which has only been sporadic in previous years. The rate of diseased plants generally does not exceed 10%, which has little effect on the yield of corn. However, due to the adjustment of planting structure in recent years, the area of ​​interplanted corn fields has increased year by year, and the trend of aggravating corn diseases has been aggravating. In the mid-June 1998 census, the average disease strain rate was 25.3%, up to 75%