一、白粉病:主要为害叶片,也侵害花、果、果梗和叶柄。初期在病叶发病中心处产生大小不等的病斑,随后叶背形成白色粉状物。病情严重时,除叶片外,叶柄、花、花梗及果实均能感病,造成叶缘萎缩、枯焦;幼果停止发育,甚至干枯;果实上形成白色粉状物,失去食用价值。严重时全株死亡。防治方法:选用抗病品种或搭配种植抗性较强的品种。实行轮作,以十字花科蔬菜和豆科作物为好,最好 First, powdery mildew: the main damage leaves, but also against flowers, fruit, fruit stems and petioles. Early lesions in the center of diseased lesions of varying sizes, followed by the formation of white powder leaves. Serious illness, in addition to the leaves, petiole, flowers, pedicel and fruit can be susceptible, causing leaf margin shrinkage, Kujiao; young fruit stop development, or even dry; white powder formed on the fruit, loss of food value. Severe whole plant died. Prevention and treatment methods: selection of resistant varieties or varieties with strong resistance to planting. The rotation, to cruciferous vegetables and leguminous crops as well, the best