1985年春季,北京郊区有不少菜农使用塑料大棚生产黄瓜,获得很高的经济效益,是菜农的一条致富之路。多年来,北京郊区春季保护地生产的黄瓜,以长春密刺作为主栽品种,此品种具有早熟、耐枯萎病、较高产等优点。但是,此品种却极不抗霜霉病、白粉病,由于在保护地中多年、多代重茬应用,已有不少单位发现本品种在生产上病害严重,使产量下降, In the spring of 1985, many vegetable farmers in the suburbs of Beijing used cucumbers to produce cucumbers and obtained high economic benefits. This is a way for the vegetable growers to get rich. Over the years, the cucumber produced in the spring protected areas in the suburbs of Beijing has been used as main cultivars under the conditions of early spring, wilt resistance and high yield. However, this variety is extremely resistant to downy mildew and powdery mildew. Many units have found that the plant is seriously damaged in production due to many years of protection in the field,