(一)緒言黄瓜是我國主要蔬菜作物之一。在黄瓜的生產中,霜霉病(Peronoplasmopara cu-bensis)是一個嚴重的問題,全國各地都有發生,成為黃瓜減產的一個重要因子。此病在瓜秧7-8片葉子或採瓜初期開始發生,傅染很快,病情的發展也很快,往往使整個植株在短期内全部枯死,因而造成嚴重減產。由於病情發展很快,所以菜農叫它“跑馬乾”;但北京所稱的“跑馬乾”不只指霜霉病一種,也包括黄瓜的一切葉片枯萎現象。不同的黄瓜品種對此病的抵抗力有所不同:最易感染的是北京刺瓜,抗病力較強的是鞭瓜和截頭瓜,但也仍然每年都要發生或輕或重的病害。目前防治此病的辦法,一般是噴射波爾多液或銅皂液,但並不能得到滿意的效果;此外由於黃瓜容易發生藥害,倘配製藥液 (A) Introduction Cucumber is one of China’s major vegetable crops. Downy mildew (Peronoplasmopara cu-bensis) is a serious problem in the production of cucumbers and occurs throughout the country, making it an important factor in cucumber production. The disease in melon seedlings 7-8 leaves or mining early onset of melon, Fu dye quickly, the rapid development of the disease, often make the entire plant died in the short term, resulting in serious cuts. Because of the rapid development of the disease, the vegetable farmers call it “horse racing.” But what Beijing calls “horse racing” not only refers to a species of downy mildew, but also includes the withering of all the leaves of the cucumber. Different varieties of cucumber resistance to the disease is different: the most susceptible is Beijing Agkistrodon bungei, the disease resistance is strong and melon melon head, but also still occur annually or light or heavy disease . The current prevention and treatment of the disease approach, the general is to spray Bordeaux mixture or copper soap, but can not get satisfactory results; In addition, cucumber prone to injury, if the preparation of liquid