First report of bacterial leaf spot caused by Pseudomonas viridiflava on Chinese cabbage in China.
In October 2015 and 2017, outbreaks of a disease of Chinese cabbage caused significant economic losses in many cultivars (yield loss between 60 and 100%) after rain events in Harbin, Heilongjiang province, China. Water-soaked lesions were first observed on lower leaves and later developed into necrotic spots surrounded by yellow haloes and water-soaked rings on the underside of leaves, which were consistent with leaf spots symptoms. The lesions were along the veins in some cultivars, causing the leaves to dry or rot and eventually killing the plant. The causal pathogen was isolated and identified as Pseudomonas viridiflava based on serological, molecular and pathogenicity analyses. This is thought to be the first report of bacterial leaf spot on Chinese cabbage caused by P. viridiflava in China.