Study on the Selection of Poplar Resistance to Cryptorrhynchus lapathi

In artificial seedling wood of poplar, Cryptorrhynchus lapathi Linne is a serious insect pest. Study was conducted in the plantation,where the damaged plant rate was over 80%. The aim was to select fine trees which were mainly resistant to C. lapathi and combined with the comprehensive target of fast-growing and high-yield. In laboratory, artificial inoculation and natural infection were carried out for the 3-year-old generation of the fine trees. The results showed that the diameter, height and volume of the selected fine tree No.106 was 9%, 7% and 61% bigger or higher than the average of those of the 3 surrounding trees respectivly. As to the artificial inoculation for the 3-year-old generation, the attracted no. of insects and feeding holes in the branches of No.106 were lesser. As to the artificial inoculation in the field, the tree-with-insect rate of No.106 was 40% lower than that of the check, and the damage index 69% lower than that of the check. As to the natural infection, the tree-with-insect rate of No.106 was 54% lower than that of the check, and damage index over 50% lower than that of the check. The volume-growth of No.106 was much more than that of its original species, Populus berolinensis Dipp., but lower than that of P. xiaohei T. S. Hwang, et Liang. According to the analysis of its bark, it's considered that the resistance of the tree was related to the amount of the content of fructose and phenolic acid.