一、大葱紫斑病:1、发病症状:主要为害叶和花梗,初呈水渍状白色小点,后变淡褐色圆形斑,继续扩大呈褐色或暗紫色,周围常具黄色晕圈,病部长出深褐色或黑灰色具同心轮纹状排列的霉状物,病部继续扩大,致全叶变黄枯死或折断。种株花梗发病率高,致种子皱缩,不能充分成 First, the green onion purple spot disease: 1, symptom onset: the main damage leaves and peduncles, the beginning was a water-like white dots, pale brown circular spot after the change, continue to expand was brown or dark purple, often with yellow halo around the disease Minister Out of dark brown or dark gray with concentric wheels pattern arranged mildew, the disease continues to expand, causing the whole leaf yellow dead or broken. Strain high incidence of peduncles, resulting in shrinkage of seeds, can not be fully into