瓜类白粉病是一种常见病害,每年种植的黄瓜、南瓜、西瓜受害尤为普遍。开始是从下面叶片出现有白色圆形粉状斑点、后扩大成片,似一层白霜,病叶由下而上扩展,严重时白粉呈灰白色、以致叶片枯黄、植株干枯。在气温16～24℃的高温和多露水条件下,病害最容易发生流行。对于瓜类白粉病的防治,经实践使 Melon powdery mildew is a common disease, annual cucumber, pumpkin, watermelon victims are particularly common. Beginning with the leaves appear below the white round powder spots, after the expansion into a film, like a layer of hoarfrost, diseased leaves bottom-up expansion, serious white powder was pale, resulting in the leaves yellow, dry plants. In the temperature of 16 ~ 24 ℃ under the conditions of high temperature and dew, the disease is most likely to occur. For melon powdery mildew prevention and treatment, practice