First report of bacterial canker of Actinidia deliciosa caused by Pseudomonas syringae pv. actinidiae in Portugal.
Bacterial canker caused by Pseudomonas syringae pv. actinidiae is one of the most harmful diseases affecting kiwifruit plants. It was first isolated and identified in Japan on kiwifruit plants (Actinidia deliciosa) and was subsequently recorded in the most important world kiwifruit production areas, China, Korea and Italy, on the main species (A. deliciosa and A. chinensis) and cultivars of kiwifruit. A new serious outbreak of the disease was observed during the spring (March) of 2010 on 2-year-old plants of A. deliciosa cv. Summer in kiwifruit orchards in Entre Douro and Mińo provinces in Portugal. The symptoms were characterised by dark brown spots surrounded by yellow haloes on leaves, and cankers with copious reddish exudate production on twigs and stem. Disease incidence could be as high as 30%. Based on morphological, biochemical and molecular characteristics, the causal agent was identified as P. syringae pv. actinidiae, which was futher confirmed by PCR amplification with two pairs of pathovar-specific primers. This is thought to be the first report on the occurrence of this bacterial pathogen on A. deliciosa in Portugal.