Pseudomonas syringae pv. syringae
Bacterial disease causing cankers, dieback, and gummosis in stone fruits and other trees. Often enters through wounds or frost damage.
Sunken, dark cankers on branches and trunk. Gummy ooze from cankers. Dead buds and blossoms. Leaf spots with shot-hole appearance. Branch dieback.
Bacterial pathogen that enters through wounds, leaf scars, and frost-damaged tissue. Overwinters in cankers.
Rain splash, contaminated pruning tools, insects. Spreads during cool, wet weather.
Cool, wet weather (40-65°F). Frost damage. Wounds from pruning, hail, or insects. Stressed trees.
Prune in dry summer weather. Avoid winter pruning. Protect from frost. Maintain tree vigor. Use resistant rootstocks.