Plum, Prune (Fresh): Bacterial canker

Photo by: R.S. Byther

Use IPM (Integrated Pest Management) for successful plant problem management.

Biology Bacterial canker can infect twigs, branches, fruit, or the trunk. Elongate, dark, purplish cankers develop during early spring, often producing bacterial ooze in wet weather. The infected tissues often produce gum, although gumming is also caused by other factors. The cankers can girdle twigs and branches causing dieback. Leaves on girdled twigs typically yellow and fall by late summer. The bacteria typically infect via wounds caused by disease, insect damage, pruning, or frost injury. Infection can be spread by wind, rain, insects, pruning tools, or by planting or grafting with infected stock. The disease may spread throughout the entire tree (systemic infection) with or without visible symptoms.

Management Options

• Avoid injury. Do not plant where frost damage is likely.
• Avoid overhead watering.
• Burn or cut out cankers on branches or trunks. Cauterizing should be done in the spring prior to bloom. Check cauterized areas for continued bacterial activity 15-20 days later.
• Control weeds, which may serve as a source of bacteria.
• Provide proper culture. Healthy trees are more resistant to disease.
• Prune out and destroy infected tissues during dry weather. Make cuts well below visible canker and sterilize tools between cuts. Do not perform disease removal during regular pruning.
• Pseudomonas infection can be very severe on trees with Prunus tomentosa rootstock.
• Remove severely infected trees.

Revision Date:5/2/2013