玉米斑病主要为害玉米的叶片、叶鞘和苞叶。叶片染病先出现水渍状青灰色斑点,然后沿叶脉向两端扩展,形成边缘暗褐色、中央淡褐色或青灰色的大斑。后期病斑常纵裂。严重时病斑融合,叶片变黄枯死。潮湿时病斑上有大量灰黑色霉层。下部叶片先发病。在单基因的抗病品种上表现为褪绿病斑,病斑较小,与叶脉平行,色泽黄绿或淡褐色,周围暗褐色。有些表现为坏死斑,给种植户造成严重的经济损失。 Corn streak is mainly harmful to corn leaves, leaf sheaths and bracts. Leaves first appear water stains like green-gray spots, and then spread along the veins to both ends to form a dark brown edge, the central light brown or gray-gray spots. Late lesions often longitudinal split. Severe lesions fusion, the leaves turn yellow dead. There are a lot of gray and black mildew on damp spots. Lower leaves first onset. In the single-gene resistant varieties showed chlorotic spots, lesser lesion, parallel with the vein, the color yellow-green or light brown, dark brown around. Some show necrotic spots, causing serious economic losses to growers.