Bacterial Canker symptoms on Plum
Bacterial Canker (bacterium - Pseudomonas syringae): 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. 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.
January, 1995
