Ten dominant pathogenic strains were separated from wet-heartwood pathologic tissues of poplar varieties by tissue isolation in this research.Pathogenic strains were inoculated in healthy poplar seedlings by stem injection for pathogenic identification and then the symptom,morbidity and epidemic degree of seedlings were recorded.The results showed that pathogen 2-16 strain caused evident symptom(heartwood discoloration) after injection inoculation.The morphology,physiology,biochemistry of 2-16 pathogen strain were determined.The similarity of 16S rDNA sequence between 2-16 strains and Pectobacterium carotovorum subsp. carotovorum NBRC 14082(AB6850554)was 99%.The 2-16 strain and NBRC 14082 were clustered in the same clade in the phylogenic tree built by Mega5.0.So the 2-16 strain was classified and identified as P. carotovorum subsp. carotovorum.In order to determine the major infection path,pathogen 2-16 strain were inoculated to Zhongshi 7 poplar seedlings by leaf infection,stem carving infection,stem injection and root-irrigation respectively.Both stem carving infection and stem injection with 2-16 strain caused wet-heartwood symptoms in poplar seedlings.The morbidity,length of scab and disease index were higher or longer in stem injected plants than in stem carve infected plants.There were no wet-heartwood symptoms in leaf infection and root-irrigation treatments.The results indicated that the 2-16 strain was mainly invaded by stem wound infection.