玉米粗缩病是病毒病的一种 ,群众叫坐坡。近年来发生呈逐年加重的趋势 ,部分地区发病面积占种植面积的７０ %～９０% ,严重地块减产５０%以上甚至绝收。１症状玉米出苗后即可发病 ,但在５～６片叶时才出现症状。病害首先在心叶基部的中脉两侧出现透明的虚线斑点 ,以后逐渐扩展? Corn is a kind of virus disease, the crowd called the sit slope. In recent years, the trend has been increasing year by year. The disease area in some areas accounts for 70% ~ 90% of the acreage, and the mass production of the block is reduced by more than 50% or even exceeded. Symptoms can be the disease after emergence of corn, but in 5 to 6 leaves before symptoms. Diseases first in the heart of the central veins on both sides of the transparent dotted spots appear, and then gradually expanded?