Bacterial Canker
Pseudomonas syringae pv. syringae
50 host plants
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
You'll spot sunken, oozing cankers on tree limbs that develop in spring, with small lesions on nearby leaves showing disease progression. This bacterial disease travels readily by rain splash and pruning wounds that provide entry points. Remove affected branches well below the visible canker margin, sterilizing all tools between cuts to prevent further spread. Avoid planting susceptible species in contaminated areas. Proper pruning technique during dry weather and tool sanitation are essential for control.
Sanitation measures have been helpful. Plant resistant cultivars. Prune affected branches well below visible symptoms and sterilize tools between cuts. Avoid pruning during wet weather, which spreads the pathogen through fresh wounds. Maintain plant vigor through proper watering and site management.
Quick Reference
Management
Fall leaf scar formation (October-November) through early spring growth. Natural leaf scars in fall and heading cuts in spring are the primary infection avenues leading to tree death. Dead bud disease starts in February. Cankers develop and expand during winter and early spring. Girdled limbs may leaf out in spring then yellow and die by late summer as water demand increases." # Source: PNW Plant Disease Management Handbook (Cherry - Bacterial Canker)
Cool wet weather from fall through early spring. Frost events are the primary trigger — P. syringae produces ice nucleation proteins promoting frost damage at 28-25°F, creating wounds for bacterial colonization. Factors predisposing trees to cankers include: wounds, frost damage, early dormant season pruning, heading cuts, incorrect soil pH, poor nutrition, ring nematode damage, and co-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.
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