一、发病症状黄瓜苗期、成株期均可发病,初发病叶呈水浸状黄色小斑点,扩大后一般呈多角形黄褐色病斑,植株自下而上发展蔓延迅速,严重时全株叶片干枯而死;因其病叶背产生白色的似霉状物,故称“霜霉病”;潮湿时白色霉状物很快变成刺毛状物,亦称“黑毛”。二、防治方法1.农业防治 First, the incidence of symptoms of cucumber seedling, adult disease can occur, the initial onset of the leaves were flooded yellow small spots, enlarged generally polygonal brown spots, rapid development of plant spread from bottom to top, severe whole plant leaves dry And died; because of its sick leaves have white like mildew, so called “downy mildew”; damp white mildew quickly become brittle hair, also known as “black hair.” Second, prevention and control methods 1. Agricultural control