Bacterial Canker
Pseudomonas syringae pv. syringae, Pseudomonas syringae pv. morsprunorum
Overview
A bacterial disease of stone fruits and other woody plants causing sunken, oozing cankers on branches and trunks, often accompanied by leaf spots and blossom blast.
Symptoms
Sunken, dark, water-soaked cankers on branches and trunks that may ooze amber-colored gum. Dead buds and blossom blast in spring. Small, dark leaf spots with yellow halos. Branch dieback. Sour sap smell from cankers.
Environmental Conditions
Cool
Prevention
Prune during dry weather in summer (not winter). Avoid wounding bark. Paint pruning wounds. Apply copper sprays in fall at leaf drop. Plant on well-drained sites. Use resistant rootstocks.
Management
Prune out cankers well below visible margins during dry weather. Apply copper sprays in fall. Improve tree vigor with proper nutrition. Avoid overhead irrigation. Remove severely infected trees.