Effect of bacterial canker caused by Pseudomonas syringae pv. actinidiae on postharvest quality and rots of kiwifruit ‘Hayward’

Kiwifruits produced from plants infected by Pseudomonas syringae pv actinidiae (Psa), the agent of bacterial canker, do not show visible disease symptoms and can be commercialized. Firmness, total soluble solids (TSS), and titratable acidity (TA) of Actinidia deliciosa ‘Hayward’ fruit, infected or not by Psa, were quantified, for two years, at harvest, at 90 days storage, and during shelf life. Analysis of dry matter (DM) and calcium at harvest, and postharvest rots, caused by Botrytis cinerea, during shelf life were also assessed. DM was higher and calcium content was lower in the kiwifruit from orchards infected by bacterial canker. During storage, firmness decreased and TSS increased rapidly in fruit from infected orchards. These parameters, together with the lower TA, favoured the higher susceptibility to grey mould rots. Besides the incidence of bacterial canker, climate conditions throughout the cropping seasons greatly affected the postharvest quality of fruit. Also the storage conditions modified the fruit quality: controlled atmosphere (CA) and 1-MCP treatment delayed fruit softening compared to normal atmosphere. TSS on fruit from healthy orchards was not influenced by the storage conditions. Fruit from Psa diseased orchards showed significantly lower TSS in CA storage and after 1-MCP treatment, compared with normal atmosphere storage. In this work, we showed that the presence of bacterial canker affects postharvest quality, shelf life, and susceptibility to postharvest rots of fruit.