How to Get Rid of a Colorado Blue Spruce Bark Problem

Identify trees with bark disease. Cytospora canker is the most common and destructive fungal disease of the Colorado blue spruce. The disease begins in the tree's lower branches and spreads upward, killing the bark. The disease can be identified by the white resin covering the infected limb or trunk of the tree. Pinhead-sized fungal fruiting structures can be see in the canker when using a magnifying glass. The disease is more common in trees older than 15 years,especially during the first year or two following a severe drought. Phomopsis occulta canker can be identified by small purplish lesions that form below the bark and break through.

Prune infected branches from the tree with a saw to lessen the chance the canker will spread. Disinfect cutting tools by soaking for two minutes in a 10 percent bleach solution or wiping with rubbing alcohol. Repeating the disinfection process after each branch is removed reduces the possibility of spreading the fungus. Call an arborist for help with badly infected trees, which may need to be removed. Pruned branches should be burned or buried as soon as possible to ensure the fungus does not spread.

Spray a benzamidole fungicide on trees infected with Phomopsis occulta canker to kill the fungus if the disease affects only a small part of the tree. However, no fungicides are effective against Cytospora canker.

Prevent future bark fungal disease by making sure the trees are watered well in dry periods. A three-inch layer of organic mulch can help the soil retain moisture. If Cytospora canker is a problem in the area, consider planting Norway or white spruce instead as they are not affected by this fungus.