1989年9月,京郊部分菜田大白菜出现外叶萎蔫,根部长出大量肿瘤,不久肿根腐烂,菜苗枯死。取样鉴定,证实此病为根肿病菌 Plasmodiophora brassicae 侵染所致。经调查,全市发病面积共1950亩,重病田854亩,毁种397亩。主要发生在顺义木林乡,其次是顺义李各庄、小店、北务、李遂乡、密云城关乡、怀柔西庄乡等7乡13个 In September 1989, some cabbage in the suburbs of the suburbs appeared wilting on the outer leaves, causing a large number of tumors to grow in the roots and swollen roots and rotting vegetables quickly. Sampling and identification confirmed that the disease is due to clubroot bacteria Plasmodiophora brassicae infection. After investigation, the city’s total area of ​​1950 mu of disease, severe disease 854 acres, 397 acres of destroyed species. Mainly occurred in Shunyi Mulin Township, followed by Shunyi Ligezhuang, Xiaodian, Beiwu, Li Sui, Miyun Chengguan, Huairou Xizhuang, etc. 7 townships 13