霜霉病是大棚黄瓜生产中的土要病害之一,俗称“黑色跑马干”。黄瓜自幼苗期便可发病,主要危害叶片。初期,叶片上出现浅绿色至淡黄色水渍状小斑点,扩大后受叶脉限制呈多角形,病斑被面长出灰色霉状物,湿度高时叶片往往腐烂,晴天湿度低时病斑干枯易碎。病重时全株枯死。 Downy mildew is one of the soil diseases in greenhouse cucumber production, commonly known as “black horse race.” Cucumber seedlings can be disease since childhood, the main hazard leaves. Initially, the leaves appear light green to light yellow water spots like small spots, expanded by the limitations of the veins polygonal, lesion was gray mildew growth surface, the leaves are often rotten when the humidity high, dry weather is low when the dry spot fragile. Whole plant wilted when ill.