Damage, symptoms and biology
The disease kills only small trees. A perennial canker forms on larger trees, but does not kill them. On these trees, the disease is characterized by an area of dead bark surrounded by a ridge of callus tissue. The fruiting bodies of the fungus develop three to five years after the initial infection on the dead bark remaining on the trunk. Cankers provide a point of entry for decay fungi, making the tree more vulnerable to stem breakage and wind throw.
A dead branch stub can often be seen in the middle of the canker. Most cankers form less than 4 meters above the ground.
Canadian Forest Service Publications
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