Bacterial canker of Kiwifruit (Actinidia chinensis) has recently been reported in Japan. The causal pathogen is classified in Pseudomonas syringae on the basis of laboratory tests and is similar to, but not identical with, P. syringae pv. morsprunorum. In inoculated kiwifruit, the pathogen from kiwifruit reproduces the characteristic canker and leaf spot symptoms. P. syringae pv. syringae and P. syringae pv. morsprunorum are only weakly virulent to kiwifruit. The pathogen from kiwifruit is weakly pathogenic to peach and Japanese apricot, but not to 24 other plant species tested. The pathogen is considered to be a pathovar of P. syringae and the name P. syringae pv. actinidiae pv. nov. is proposed. Strain Kw-11 (ICMP 9617) is designated as the pathotype strain.