白斑病主要危害十字花科蔬菜,主要危害叶片,为萝卜的一种常见病害,在长江中下游春、秋两季均可发病,尤以多雨的秋季发病重。发病初期叶面上散生灰褐色微小的圆形斑点,后渐扩大成为圆形或不正圆形病斑,中央变成灰白色,直径6～18毫米,有1～2道不明显的轮纹,周缘有苍白色或淡黄绿色的晕圈,但叶背病斑周缘晕圈有时不明显。后期病斑互相合并,形成不规则的大病斑。潮 White spot disease is the main hazard cruciferous vegetables, the main hazard leaves, a common disease of radish in the middle and lower reaches of the Yangtze River can be onset in spring and autumn, especially in heavy rain autumn onset. Early onset foliar Tartan tiny gray brown round spots, gradually expanded into a circular or irregular circular lesions, the center becomes gray, 6 to 18 mm in diameter, there are 1 to 2 obvious wheel pattern, Peripheral pale or yellowish green halo, but the leaves around the halo spot halo sometimes not obvious. Post-lesion merge with each other to form an irregular big spot. tide