Bacterial Canker Devastating Kwanzan Cherry Row: Rapid Spread

Estate entrance lined with Kwanzan cherries in NC foothills. One tree declined in 3 days (gel sap, pale leaves, total defoliation). Four more now showing same. Broad-spectrum sprays failed. Extension agent stumped. Fire blight considered.

Diagnosis

Bacterial canker (Pseudomonas syringae)—also called bacterial blast/gummosis. Prime cherry attacker. Causes leaf yellowing/greening, premature drop, amber gum oozing from bark lesions, limb dieback, fruit lesions. Thrives cool/moist; spreads via rain splash/wind. Summer heat slows it; fall resumes activity.

Management

Extremely difficult to control. Prune cankered branches with alcohol-sterilized tools between cuts. Fall copper fungicide spray helps prevent new infections. Remove/destroy all debris. No growing-season cure.