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一、危害与分布情况杨吉丁虫(Poccilonota Variolosa Paky)在我县主要分布于第二机械林场上造营林区,全场被害面积占有林地面积的25%。该厂从1972年秋季以来造林12000亩,主要品种有二青杨、小叶杨、美×青、双阳快、小×黑、白城杨。通过林中观察,危害最重的是小叶杨、二青杨,其次是双阳快杨。从1979年发现虫情,起初数量甚少,危害较轻,未能引起重视,到1980年已蔓延成灾。危害最重的是东南退大面积片林,25个林班共39000亩,被害率在90%以上,平均虫口密度7头,最多达40头,大片林木形成小老树。由于此虫是杨树干部害虫,主要危害衰老树木的干部韧皮部,多在中老龄树木上危害。幼虫在韧皮部潜伏危害期较长,给防治上造成一定困难。
I. Hazards and Distribution Poccilonota Variolosa Paky is mainly distributed in Zhaoying Forest Zone in the Second Machinery Forest Farm in our county, accounting for 25% of the total forest area occupied. The plant from the autumn of 1972 afforestation 12000 acres, the main varieties of two Poplar, Populus, United States × Green, Shuangyang fast, small × black, Baicheng Yang. Through the forest observation, the most harmful are Populus, Populus, followed by Shuangyang fast Yang. From 1979, it was found that the number of insects was very small at the beginning, and its harm was negligible. It failed to attract attention and it spread into disasters in 1980. The hardest hit is the southeast area retreat large area of forest, 25 forest classes a total of 39000 acres, the victimization rate of 90% or more, the average density of 7 insects, up to 40, large trees form small trees. As this pest is a poplar cadre pests, the main damage to aging cadavers phloem, mostly in the middle-aged trees on the hazards. Larvae in the phloem latent longer hazard period, to prevent some of the difficulties.