PSEUDOMONAS-SYRINGAE PV MORSPRUNORUM ON WILD CHERRY FOR TIMBER PRODUCTION - OUTBREAK AND FIELD SUSCEPTIBILITY

In central Italy, Pseudomonas syringae pv. morsprunorum was isolated f rom wild cherries (Prunus avium) that had been planted for timber prod uction. Biochemical tests were consistent with those characterizing th e pathovar. Pathogenicity tests yielded necrotic lesions, shot holes o n the leaves and decoloration of the tissues beneath the twig periderm , but no symptoms on inoculated lilac and pear leaves. In addition, wh ole-cell protein profiles of the isolates and reference strains were r emarkably homogenous when analysed by cluster analysis. All isolates w ere negative in ice-nucleation activity and in antifungal-compound pro duction. The main symptoms observed in the field were cankers on twigs , branches and trunks, as well as withering of the shoots. Evaluation of the field susceptibility of 18 clones indicated that the following selections must be considered susceptible to the pathogen: Montemignai o, Piantata Catenaia, Puzzolo, Raggiolo, Pozzacce 2, Pozzacce 1, Parad ision. Alpe 2 seems to be less susceptible.