一、症状表现。玉米粗缩病是危害玉米生产的病毒病，整个生育期玉米均能感染发病，而以苗期被侵染受害最重，早在５－６叶时即可表现症状。开始时心叶侧脉上产生半透明的褪绿虚线条点，后逐步扩散至整个叶片以及上部新抽出叶片。侧脉逐渐肿大，在叶背叶脉上出现蜡泪状突出，形 First, the symptoms. Corn coarse-grained disease is a viral disease that endangers the production of corn. Corn can be infected during the whole growing period, while the most serious damage occurs at the seedling stage. As early as 5-6 leaves, symptoms can be manifested. At the beginning of the leaflet veins to produce semitransparent faded green dotted lines, and then gradually spread to the entire leaves and the upper part of the newly extracted leaves. Lateral veins gradually enlarged, wax tear prominent in the dorsoventral veins, shape