University of Maryland Extension

Cankers - Trees and Shrubs

 large canker on beech tree

Large canker on the trunk of a beech tree

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.

 young canker
Cytospora canker 

tree with cytospora canker
Lower branches dying from Cytospora

canker on leyland cypress
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
Canker on a rose cane

large canker on trunk
Canker on a tree trunk

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.

Additional Resource

Cytospora Canker of Spruce

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