Bacterial Blister Bark of Apple Trees in Italy

At the beginning of spring 1996, raised, brown areas along the bark of trunk and twigs were observed on young apple trees in Piedmont (northern Italy). In many cases the epidermis flaked off. Longitudinal cracks accompanied by necrosis of the tissues beneath the bark were also observed. In one orchard the disease caused the death of 2500 trees. Biochemical, nutritional and pathogenicity tests, as well as the comparison of whole-cell protein profiles of the isolates with type-strains, indicated that Pseudomonas syringae pv. syringae was the causal agent of the disease. Bacterial blister bark remains a threat for apple cultivation also in Italy, especially in orchards planted in sandy soils.