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我县地处太湖之滨。进入80年代后,耕作制度从原来的一年三熟(麦、稻、稻)演变成一年二熟(麦、稻)。单季稻常年5月20日前后播种,6月20日左右栽插.水稻褐飞虱主要在7月中下旬迁入我地,迁入后直接定居本田繁殖为害2～3个世代。据历史资料统计,我县70年代褐飞虱大发生年频率为30%,80年代上升到80%,为害损失已占水稻各种病虫之首.1990年太湖地区褐飞虱是一个大发生年。根据全县8块单季稻预测圃观察,本地二、三、四各代高峰期百丛虫量分别为104头、4 954头和18 592头。成熟前测查,自然“冒穿”率为
My county is located in the coast of Taihu Lake. After entering the 1980s, the farming system evolved from the three crops (wheat, rice and rice) of the previous year to the second crop (wheat and rice) a year. Single-cropping rice is sowed around May 20, perennial, and planted around June 20. The brown planthopper mainly migrated to China in the middle and late July of the year and directly settled in Honda for 2-3 generations after its migration. According to historical statistics, the annual frequency of brown planthopper occurrence in the 1970s was 30% and increased to 80% in the 1980s. The loss of pests accounted for the first place in rice diseases and pests in 1990. The brown planthopper in the Taihu Lake area in 1990 was a major occurrence year. According to the eight single-cropping rice forecasting bureaus in the whole county, the number of hundred and six insect pests at the peak of two, three and four generations in the local area were 104, 4 954 and 18 592 respectively. Mature before the test, naturally “run through” rate