Abstract: Poplar canker, mainly caused by Dothiorella gregaria Sacc., a pathogenic fungus, which may cause canker diseases on 132 species and cultivars of poplar tree, is a serious disease in Shanxi Province. Twenty-four species and cultivars of poplar seedings coming from three nurseries were applied to the artificial inducing test of latent infection of poplar canker. The results of the experiment showed that among six induced species of fungi (Dothiorella gregaria, Cytospora chrysosperma, Phoma sp., Fusicoccum sp., Pestalotiopsis sp., Sphaeropsis salicicola) D. gregaria possesed the highest latent infection rate. It was proved that the disease development was closely connected with the relative expanding degree of bark and that the most faverable condition for occurrence of the disease was that when the relative expanding degree of bark decreased to 66-68%.

Key words: Latent infection, Poplar, Canker, Dothiorella gregaria