Abstract: The etiologic agents of Japanese pagoda-tree (Sophora japonica L.) canker in Nanjing are mainly Dothiorella ribis, and then Fusarium tricirctum. They may cause latent infection in tissues of seemingly healthy green bark all the year round and consequently will cauase disease when the turgidity of the bark decreased to under 85. The disease can be induced by the loss of water at any time throughout the year. There are six other species of fungi inhabiting together with the above two pathogens in tissues of healthy bark. They are parasites in healthy tissues without causing diseases to their hosts.