一、黄瓜霜霉病黄瓜霜霉病是世界性病害,无论保护地、露地都普遍发生,危害严重。病原菌在病叶上越冬或越夏,靠气流传播,高湿利于发病,潜伏期短,再侵染频繁,条件适宜极易造成大流行。药剂防治霜霉病关键要提前预防,正确用药。1、提前预防黄瓜定植15天左右,日光温室春茬一般在4月中下旬,塑料大棚在5月上中旬开始 First, cucumber downy mildew Cucumber downy mildew is a worldwide disease, regardless of the protection of land, are generally exposed, endangering serious. Pathogenic bacteria in the sick leaves wintering or summer, by air flow, high humidity conducive to the incidence, short incubation period, then frequent infections, conditions can easily lead to pandemic. Pharmacy to prevent downy mildew key to prevention in advance, the correct medication. 1, in advance to prevent cucumber planting around 15 days, the spring greenhouse in general in late April, the plastic shed in mid-May start