sooty canker-aspen

Asked November 10, 2013, 2:27 PM EST

Several of my aspens have areas that look like they have been charred. no bark left, just black. I am thinking it is the sooty canker. Will it invade the limbs below the black area? What is the best way to get rid of it? Are there any good reasonable arborists in the Broomfield area?

Broomfield County Colorado

1 Response

Canker diseases commonly affect aspen trees in our area. There are several different canker diseases that may affect aspen. Some spread slowly and affected areas on branches may be pruned off before the canker can cause serious injury. If the infection is widespread or is caused by an organism that spreads too quickly for the tree to compartmentalize the injured tissue, the canker will girdle branches and eventually the trunk, causing the death of the tree.

If pruning out diseased wood, be sure to sterilize pruning tools between cuts to avoid spreading the infection to healthy tissue. Pruning during early spring when the tree is dormant is recommended over pruning during the growing season. Only prune trees during periods of dry weather and properly dispose of pruning debris so as not to infect surrounding trees.

Weak plants and those that are injured are more susceptible to canker-causing disease organisms. To avoid further infection in nearby trees or tissues, maintain plant health by providing adequate water and nutrients and avoid injury to the trunk, branches and roots, which provide entry sites for disease organisms.


This link to the U.S. Forest Service’s Fact Sheet titled “Cankers on Western Quaking Aspen” provides more detailed information: http://www.na.fs.fed.us/spfo/pubs/fidls/q_aspen/q_aspen.htm. This link from the Michigan State Extension Service provides identification information for cankers in aspen: http://plantsciences.montana.edu/horticulture/HighAltitudeLandscapes/Aspencanker.htm.