保护地黄瓜霜霉病生态防治河北沧州农校李瑞生，韩华梅，马平英黄瓜霜霉病是黄瓜的毁灭性病害，发病时首先在叶片上出现水渍状退绿色小圆点，病斑扩大后受叶脉限制，形成多角形黄褐色大斑，并在叶片背面生长有灰黑色霉。每个病叶由几个病斑发展至无数病斑，使叶片迅速枯萎... Protection cucumber downy mildew ecological control Cangzhou farming school in Hebei Li Ruisheng, Han Huaymei, Ma Pingying cucumber downy mildew is a curative disease of cucumber, the onset of the first water stain on the leaves back green dots, lesions enlarged Restricted by the veins, the formation of polygonal brown big spot, and in the back of the leaves grow gray black mold. Each diseased leaves from the development of several lesions to numerous lesions, so that the rapid wilt leaves ...