Bacterial Canker and Blast
Pseudomonas syringae pv. syringae
36 host plants
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Cankers develop on limbs and shoots wilt suddenly with leaf spots. This bacterial disease causes rapid decline. Prune affected material and improve drainage.
Prune out cankered branches at least six inches below visible symptoms, making cuts into healthy wood. Sterilize your tools between cuts. Canker pathogens typically enter through wounds, so minimize pruning injuries and avoid working on trees when bark is wet. Maintain tree vigor through proper watering and avoid stress from drought or compacted soil, which makes trees more susceptible.
Quick Reference
Management
Fall leaf scar formation through early spring growth. Heading cuts made after spring planting are important infection avenues leading to tree death. Dead bud disease starts in February as buds die on spurs. Cankers develop during winter and early spring dormancy. Girdled limbs may leaf out in spring then die as water demand increases in summer." # Source: PNW Plant Disease Management Handbook (Cherry - Bacterial Canker)
Cool wet weather from fall through early spring. Frost events are critical — P. syringae INA proteins promote frost damage at 28-25°F, creating wounds for bacterial entry. Factors that weaken or injure the tree predispose it to cankers: wounds, frost damage, early dormant season pruning, heading cuts, incorrect soil pH, poor nutrition, ring nematode damage, and infection by Cytospora, Verticillium, or Nectria." # Source: PNW Plant Disease Management Handbook (Cherry - Bacterial Canker)
Cultural Controls
- Sanitation measures have been helpful. Plant resistant cultivars. Prune out all diseased wood as soon as it is noticed and especially before fall rains. Avoid late-summer nitrogen fertilizer applications, that can lead to winter injury Prune susceptible cultivars during dry weather if possible.