Bacterial twig blight
Pseudomonas syringae (bacterial)
14 host plants
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Young twigs turn dark and die with lesions at branch nodes. This bacterial disease enters through wounds. Prune affected twigs and sterilize tools.
Remove blighted tissue promptly, cutting well below visible symptoms. Improve air circulation by thinning dense growth. Avoid overhead watering, especially during bloom and new growth periods when tissues are most susceptible. For recurring problems, preventive fungicide applications timed to protect new growth can reduce infection, but cultural controls should be your first approach.
Quick Reference
Management
Late winter through spring, when cool wet conditions coincide with frost events and new growth. Young twigs and shoots are most susceptible. Preventive copper applications are most effective in fall after leaf drop. Spring infections cause rapid browning and death of young twigs." # Source: PNW Plant Disease Management Handbook
Cool wet spring weather; frost events followed by rain; overhead irrigation; mechanical wounding; temperatures near freezing. P. syringae produces ice nucleation proteins that promote frost damage, creating entry wounds for bacterial colonization." # Source: PNW Plant Disease Management Handbook
Cultural Controls
- Prune and destroy affected twigs and branches (when practical).
- Maintain proper plant nutrition.
- Healthy plants resist disease better.
- Avoid overhead irrigation.
- Space plants properly and prune to provide good air circulation.