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Bacterial twig blight

Pseudomonas syringae (bacterial)

14 host plants

Last updated

Data Coverage 3 of 6 dimensions
Causal Agent
Host Plants
Symptoms
Management
GDD Threshold
Regional Notes

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

Causal Agent
Pseudomonas syringae (bacterial)
Host Plants
14
Favorable Conditions
Cool wet spring weather; frost events followed by rain; overhead irrigation; ...

Management

Vulnerability Window

For best results, apply in fall after leaves drop.

What Triggers Infection

Cool wet spring weather; frost events followed by rain; overhead irrigation; mechanical wounding; temperatures near freezing

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.

Host Plants (14)