Bacterial canker

Bacterial disease common to stone fruits (cherry, plum, peach).

Also known as:
Bacterial blight (Philadelphus)

Also see:
Horse chestnut bleeding canker

Recognize bacterial canker
Bacterial canker, photo: Jerzy Opiola - CC BY-SA 4.0

Bacterial canker (Pseudomonas syringae). Bacterial disease common to stone fruits (cherry, plum, peach): it affects the stems and leaves of Prunus, especially plums and cherries. Also apricots, peaches and Prunus ornamental trees are susceptible. Sometimes found on horse chestnut: Pseudomonas syringae aesculi.
High humidity in spring and fall promote the infection. It starts in the leaf and moves to the bark. The bacteria penetrate the tree through pruning wounds and frost cracks.
Often gummosis occurs as a secondary infestation.

Affected plants


Once infected, the bacterial canker is difficult to to control; sometimes removing the infected parts helps.


Prevent infection by:
– prune during dry weather
– seal pruning wounds
– remove prunings