Study on the Disease Resistance of New Poplar Cultivars to Trunk Cancer, Dothiorella gregaria, and Leaf Black Spot, Marssonina brunnea

In 1981~1990, the resistance trials both in the field and lab. in North China demonstrate that poplar cultivars, Zhonglin-115, Zhonglin-319, Zhoiiglin-34 are new ones, which are resistant to poplar trunk cancer, Dothiorella gregaria, and leaf black spot, Marssonina brunnea. They are more resistant than P. bcijingensis and I-214. Their incidence rate of trunk cancer is 80%~100% lower than that of P. 'popularis', and that of black spot is 80% lower than that of P.×canadensis, I-214, Pl5A. They are also rather resistant to other diseases and insect pests, such as, the longhorn beetle etc. They are also fine improved cultivars of fast-growing, high quality, easy propagation, high survival rate and adaptability and they have been extending on a large scale.