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近年来 ,由于树种单一 ,气候异常 ,杨树烂皮病(腐烂病 )逐渐严重 ,据沛县森防站调查 :1997的全县发病死亡率 0 .2 % ,1998年死亡率为 0 .7% ,1999年死亡率 1.3% ,2 0 0 0年死亡率 2 .7% ,个别地段农田林网死亡率高达 2 5%以上。发病死亡率呈上升的趋势 ,严重威胁着林业生产的安
In recent years, due to a single tree species, climate anomalies, poplar rot disease (rot disease) is gradually serious, according to Peixian Sen defense station survey: 1997 county incidence of death 0.2%, 1998 mortality was 0.7 The mortality rate in 1999 was 1.3%, and the mortality rate in 2000 was 2.7%. The mortality rate of farmland shelternets in individual areas was as high as 25% or more. The morbidity and mortality rate is on the rise, which seriously threatens the safety of forestry production