Preliminary results on susceptibility to bacterial canker of Actinidia spp. accessions

A study was conducted on 14 accessions of Actinidia spp. to evaluate their susceptibility to the bacterial canker. Experimental inoculations were carried out, under controlled conditions, on young leaves of kiwifruit plants grown in pots by spraying a calibrated water suspension of an Italian, virulent strain (isolated in 2013) of Pseudomonas syringae pv. actinidiae. Actinidia chinensis ‘Belen’ was used as positive control, being a known susceptible genotype. Plants inoculated with sterile distilled water and non-inoculated ones were used as negative control. The disease assessments were performed 21 days after inoculation with the pathogen. The disease severity (mean of leaf spots per treatment) allowed to detect one A. chinensis selection showing low susceptibility, comparable to that of selections belonging to A. arguta, A. hemsleyana and A. eriantha species, that showed a very low susceptibility. No selection was found more susceptible than ‘Belen’, but among all selections, one resulted comparable with it. Eight selections were found to be moderately susceptible, and three of them (A. chinensis selections) were less susceptible than A. deliciosa ‘Hayward’, that is known having an intermediate susceptibility.