霜霉病在南方各菠菜种植区,发生率最高的病害是菠菜霜霉病。该病是由一种叫做菠菜霜霉菌的真菌引起的。田间危害症状表现为:主要危害叶片正面,病斑淡黄色,不规则形,大小不一,直径3～17毫米,边缘不明显。病斑扩大后,互相连接成片,后期变褐枯死。叶片背面病斑上产生灰紫色霉层。病害从外叶逐渐向内叶发展,从植株下部向上扩展。干旱时病叶枯黄,湿度大时多腐 Downy mildew in the southern spinach plantation, the highest incidence of disease is spinach downy mildew. The disease is caused by a fungus called spinach downy mildew. Harmful symptoms in the field are as follows: The main harms are the front of the leaves, pale yellow spots and irregular shapes, and the sizes are 3 to 17 mm in diameter. The edges are not obvious. Lesions expanded, connected to each other into pieces, late brown dead. Leaves on the back of the lesion gray purple moldy layer. Disease gradually from the outer leaves to the inner leaves, growing up from the lower part of the plant. Drought leaves yellowish, when the humidity is more rotten