白菜黑斑病近年来在北京市有所发展,为了防止其蔓延,我们对该病的症状,发病情况及防治方法进行了研究。 一、症状 黑斑病的症状在白菜叶部产生园形或椭圆形褐色轮纹斑,在叶柄上产生褐色长梭形病斑,严重时在叶脉上也产生园形轮纹斑,并使支脉变细。多数病斑连片后,叶片枯黄脱落。 In recent years, cabbage melasma has been developed in Beijing, in order to prevent its spread, we studied the symptoms, incidence and prevention methods of the disease. Symptoms of black spot disease in the cabbage leaves produce round or oval brown round grain spot in the petiole produce brown long fusiform lesions in severe veins also produce circular pattern spot and make the branch vein Thinning. After the majority of lesion contiguous, the leaves withered off.