Outbreak of bacterial canker on Hort16A (Actinidia chinensis Planchon) caused by Pseudomonas syringae pv. actinidiae in Korea

Bacterial canker was first observed on the kiwifruit cv. 'Hort16A (Actinidia chinensis)' in Jeju Province, Korea, in spring 2006. Die back or blight on young canes, often with red-rusty exudation on canes or trunks, and dark brown irregular spots surrounded with yellowish halos on leaves are the typical symptoms. These symptoms closely resemble those caused by Pseudomonas syringae pv. actinidiae on the kiwifruit cv. 'Hayward (Actinidia deliciosa)'. A sudden outbreak and rapid spread of the bacterial canker resulted in the death of severely infected vines and eradication of completely devastated orchards of the kiwifruit cv. 'Hort16A'. Contaminated pruning shears and climatic conditions appear to have been responsible for the sudden outbreak and rapid spread of the epidemics on the kiwifruit cv. 'Hort16A' vines. The causal bacterium was isolated from diseased vines of the kiwifruit cv. 'Hort16A' and identified as P. syringae pv. actinidiae, which is the same bacterial pathogen responsible for cankers on the kiwifruit cv. 'Hayward' by morphological, cultural, physiological and biochemical, molecular and pathogenicity analyses.