How to Manage Pests
Pests in Gardens and Landscapes
Pest identification and confirmation—Bacterial blight
Bark infected with Pseudomonas syringae has infected cankers darker than the surrounding, healthy
bark and the underlying diseased tissue is reddish brown, moist, and may be sour smelling. A gummy, wet
accumulation on the bark adjacent to the canker is characteristic. Cutting into infected bark beyond the
margin of cankers may reveal small, brown flecks in the inner bark tissue, especially in apricots and
plums. Affected limbs may fail to leaf out in the spring or may produce new growth, which dies soon after
temperatures increase in the summer. If trees are killed by bacterial canker, new shoots are frequently
produced from the rootstock.
Trees affected by only leaf blight symptoms may not develop cankers and discolored wood. Confirmation
of the causal organism would need to be done by a plant pathologist in a laboratory.
flecks in wood beneath the main canker