The Callusing of Tree Wounds Colorado State University Extension Tri River Area Mesa Delta Montrose and Ouray Counties

The Callusing of Wounds in Trees

Narrative and Photographs by
Curtis E. Swift, Ph.D.
Colorado State University Extension
Tri River Area

an improper pruning cut

This pruning cut was improperly made as is seen by the lack of uniform growth of the callus tissue.
The dark stain and ooze is caused by bacterial wetwood

donut-like callus formation around a pruning cut

The donut-like appearance of callus (woundwood) around this wound indicates the pruning cut was made properly.

pruning wound on Honeylocust

The complete `healing' of the pruning wound on this Honeylocust demonstrates the woundwood that forms when the pruning cut is done correctly.

Trees and shrubs are often said to `heal' wounds. They do not, however, heal such damage. Humans and other members of the animal kingdom `heal' wounds by replacing damaged tissue. Trees, shrubs and other woody plants bury their wounds under new tissue. This creates a weak spot in the tree from which frost cracks can originate, insects and disease pathogens enter and disease begin.

Further information on the proper pruning of trees is available.

Placed on the Internet May 21, 1996

WebMaster
Dr. Curtis E. Swift, Area Extension Agent, Horticulture
Colorado State University Extension
2775 US Hwy 50, Grand Junction, CO. 81503
voice: 970-244-1840
fax: 970-244-1700