Symptom

• Cankers develop at the base of infected buds on trunk and scaffold limbs. Cankers spread more rapidly above the point of infection than below and only slightly to the sides.
• This results in a long, narrow canker. Cankers develop during the fall and winter but are not visible until late winter and early spring.
• Damaged areas are slightly sunken and somewhat darker in color than surrounding bark. As the trees break dormancy in the spring, gum is formed and flows down the outside of the tree.
• Cankers have a soured smell. The bacterium is a weak pathogen and causes serious damage only when a tree is in a near dormant condition or weakened due to unfavorable growing conditions.

Management

• Avoid using high fertilizer rates in late summer. Succulent, late fall growth is more easily infected. Prune when trees are fully dormant (January and February).
• Trees showing signs of bacterial canker should be left and pruned after all other trees have been completed.