The cankers enlarge and encircle the cane causing the lateral shoots to wilt and die. On second-year canes, the side branches suddenly wilt and die between blossom time and fruit ripening. Close examination reveals the presence of cankers on the branches or the main cane where insect injury, pruning wound, or other type of wound has occurred. Infected canes become cracked and brittle, and break easily. The same fungus also produces cankers on rose, apple, crabapple, pear, peach, strawberry, Virginia creeper, tree peony, and other many plants.
Infection occurs at almost any time of the growing season.
Conidia formed in pycnidia ooze out during wet periods. These spores are rain splashed, and carried by insects or mites to nearby canes. Under moist conditions these conidia will quickly germinate and penetrate any type of wound, rapidly killing cane tissue. Pycnidia are formed in the dead portions of the older cankers. Dead canes continue to produce conidia and remain a source of infection for at least 4 years.