Pear blossom blast and dieback caused by Pseudomonas syringae

Pear blossom blast and dieback, caused by Pseudomonas syringae, affects blossoms, shoots, and leaves of pear trees, especially in cold, wet bloom conditions. Susceptible varieties include Xenia, Beurré d'Anjou, Beurré Bosc, and Beurré Alexander Lucas. The bacterium overwinters in buds and activates under favourable weather, leading to yield loss. Management includes avoiding over-crown irrigation, pruning infected parts, and applying copper-based sprays or biological alternatives like Blossom Protect, Bacillus subtilis, or laminarin during spring. Differential diagnosis is essential to distinguish from fireblight (Erwinia amyloae) and Alternaria spp. This 2023 practice abstract from Delphy (Netherlands) is part of the Biofruitnet project, available in English (USA), Dutch, and German (Switzerland), and hosted on Organic Eprints.