Glossary term
What is Canker?
Short answer
A canker is a sunken, dead or swollen patch on bark, branch or trunk, often caused by a fungus or bacteria.
Canker, explained for tree service owners
A canker is an area of dead bark and the tissue under it, shown as a sunken, cracked, swollen or oozing spot on a limb or trunk. Many different fungi and bacteria cause cankers, and so can wounds, frost or sun scald. A small canker on a branch may be harmless, but one that wraps most of the way around a limb can kill the wood beyond it. For a tree service owner, cankers often show up as single dead branches in a green crown. Cutting out a canker-infected limb is a common job. Use clean tools, and tell the owner that the cause can differ, so a plant health expert or local extension office is a good next step.
Related terms
- Crown
Crown is the upper part of a tree made of branches, twigs and leaves, growing from the trunk.
- Defoliation
Defoliation is the loss of leaves from a tree outside the normal fall drop, often caused by insects, disease or weather.
- Dieback
Dieback is the slow death of twigs and branches starting at the tips and moving back toward the trunk.
- Xylem and phloem
Xylem and phloem are the two tissue systems that move water up and sugars through a tree.
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