Influence of leaf age on infection of Actinidia species by Pseudomonas syringae pv. Actinidiae

Abstract

The influence of leaf age on infection of Actinidia species by Pseudomonas syringae pv. Actinidiae (Psa) was investigated using two approaches: (a) inoculation of potted 'Hayward' and 'Hort16A' kiwifruit plants and (b) inoculation of whole leaves in a detached leaf assay. Whole plants and detached leaves were spray inoculated with Psa biovar 3 (haplotype NZ-V; Psa-V) and maintained in a saturated environment. Flecking was evident on some of the leaves 8 days after inoculation. Many of the flecks later became necrotic spots with halos similar to the Psa leaf infections that have been observed in the field. With both methods, a higher percentage of leaves that were 1-3 weeks of age at inoculation had flecking and spotting than did leaves of other ages. Leaves that were 7 weeks or older did not show any symptoms of infection by Psa. Overall, leaves of 'Hort16A' showed slightly more flecking and spotting than 'Hayward'.