大葱霜霉病是北方菜区大葱的重要病害之一。1988年7～9月份,我县降雨次数频繁,雨量偏多,造成该病大流行,全县1.5万亩大葱,就有1.08万亩发病,叶片干枯率达65.5％,减产50％以上,产量损失约2160万公斤,经济损失达648万元。为了找出一种对大葱霜霉病防效高、投 Green onions downy mildew is one of the major diseases of green onions in the northern vegetable area. From July to September 1988, there were frequent rainfalls and heavy rainfall in our county, causing the pandemic. The county had 15,000 mu of green onions and had the incidence of 10,800 mu. The leaf dry rate was 65.5% and the yield was reduced by 50% Losses of about 21.6 million kilograms, the economic loss of 6.48 million yuan. In order to find a prevention and control of green onyx mildew, high investment