１、玉米圆斑病该病是一种真菌性病害，可侵染叶片，果穗，苞叶和叶鞘，叶片上病斑初为水渍状淡绿至淡黄色小点，以后扩大为圆形或卵圆形斑点，有同心轮纹，中央淡褐色，边缘褐色，具黄绿色晕圈，数个病斑合成长条斑，苞叶上的病斑向内扩展，可侵害玉米籽粒和穗轴，病部变黑凹 1, corn spot disease The disease is a fungal disease that can invade the leaves, ears, husk and leaf sheath, leaf lesions on the early water stains light green to pale yellow dots, later expanded to round or Oval spots, with concentric circular pattern, the central light brown, brown edge, with a yellow-green halo, a few plaques synthesize stripe, lesions on the husk leaves inward expansion, can encroach on corn kernels and cob, Department of dark black concave