How to Manage Pests

Bacterial canker—Pseudomonas syringae

Symptoms of bacterial canker are most obvious in spring and include limb dieback with rough cankers and amber-colored gum. There may also be leaf spot and blast of young flowers and shoots. A more severe form of the disease, the sour sap phase, generally occurs in younger trees. This phase may not show gum and cankers, but the inner bark is brown, fermented, and sour smelling. Reddish flecks and pockets of bacterial invasion in bark occur outside canker margins. Trees frequently sucker from near ground level. Cankers do not extend below ground.

Identification | Life cycle

Solutions

Avoid planting on shallow soils. Plant less susceptible rootstocks. Generally, vigorous trees have less trouble with bacterial canker. Practice measures, such as adequate fertilizer and irrigation, that encourage good plant growth. Prune severely cankered or dead scaffold limbs to discourage secondary invasion by wood rot organisms.

Gumming on branch

Bacterial canker infection