University of Maryland Extension

Cankers - Trees and Shrubs

large canker on beech tree

Photo: Large canker on beech - R. Mulrooney, University of Delaware

Back to Common Problems - Trees and Shrubs

There are a large number of cankers that cause dieback on trees and shrubs. These are more common on stressed plants due to poor maintenance or site problems. Young cankers are slightly darker in color than adjacent healthy bark and appear slightly sunken. As cankers enlarge they kill the living woody tissue within the branch or trunk.

(click on photos to enlarge)

young canker canker

Cankers are slightly darker in color
than adjacent bark and appear slightly
sunken

Seiridium canker on branch of
Leyland Cypress

canker twig
Canker growth may cause the
bark along the edges to crack and
fall away, exposing the dead
wood underneath

Canker growth may cause the bark along the edges to crack and fall away, exposing the dead wood underneath. After a canker enlarges enough to girdle a branch or trunk, the portion beyond the canker dies. Small twigs are killed more quickly than larger branches. Symptoms may include progressive upper branch dieback, disfigured branch growth, or target-shaped areas on trunks with concentric rings of dead bark. Examples of fungi that cause cankers in the landscape include Nectria, Cytospora, Phomopsis, Monochaetia, Fusarium, and Botryosphaeria.

Canker on rose cane

tree with cytospora canker large trunk canker

Canker on rose

Lower branches dying from Cytospora

Large trunk canker

 Management strategies: There are no chemical controls for cankers and they cannot be stopped once they become extensive. The only control measures available are to remove affected branches and prune back to healthy wood. Drought stressed plants should be watered during dry weather to promote better tree vigor.

Cytospora Canker of Spruce

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2017. Web Accessibility