蔬菜病害的诊断及防治（续）云南省农科院植保所（６５０２０５）杨家鸾２．２黄瓜病害黄瓜霜霉病危害部位：叶。发病初期叶背有水渍状斑块，叶面症状不明显。随病菌浸染，叶面出现被叶脉限制的多角形黄色斑块。湿度大时病斑上出现黑霉。发病严重时，多块病斑连结成大块黄... Diagnosis and Prevention of Vegetable Diseases (Continued) Plant Protection Institute of Yunnan Academy of Agricultural Sciences (650205) Yang Jiali 2.2 Cucumber Disease Cucumber Downy Mildew Hazardous Sites: Leaves. The early onset leaves with water-like plaque, foliar symptoms were not obvious. With the diphtheria infection, the leaf appears polygonal yellow patches restricted by the veins. Humidity occurs when the stain on the black mold. When the disease is serious, multiple lesions linked into large yellow ...