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1984年,在福州大白菜主产区对4000多亩菜田,进行3个月的调查.10月9日在魁岐村始见霜霉病,比1983年提早半个月多.流行期,比常年的11月中旬左右,也提早10天.不但发生早,蔓延快,而且时间长,为害重,损失大,平均亩产10多担,只及1983年的一半,严重的绝收.经调查分析其原因主要有:1.品种因素:从田间调查看出,所有大白菜都受到霜霉病为害;但品种间受害程度不同.城杂5号、75杂—10和发财种发病最重,叶严重度达4～6级.而青杂系统和815等品种病害较轻,一般只在外叶受
In 1984, the main producing area of Chinese cabbage in Fuzhou 4,000 acres of vegetable fields, for 3 months of investigation .9 October in Kuiqi village began to see downy mildew, more than half an hour earlier than in 1983. Pop period, than Around the middle of November, it also took 10 days early, not only occurred early and spread rapidly, but also took a long time to cause serious damage and heavy losses, with an average yield of more than 10 tons per mu, only half of that in 1983. The main reasons are as follows: 1. Variety factors: It is found from field investigation that all Chinese cabbage are affected by downy mildew, but the degree of victimization is different among varieties. The severity of 4 to 6. Green hybrid system and other varieties less prone to disease, generally only in the outer leaves by