Drought stress and winter injury have been associated with an increase in infection and canker expansion. Symptoms New infections on twigs and limbs start to become evident by early summer, appearing as small circular spots or blisters. As the lesions expand, the area becomes slightly depressed. By spring small, black pycnidia, the spore-containing structures of the fungus, appear on the smooth surface of new cankers. On older cankers, these may be present throughout the year.
Cankers exhibit a scaly, papery outer bark that is often orange.
Tissues beneath the canker surfaces are watery or slimy and brown. Most cankers are not deep, extending at most to the wood. The fungus causes two fruit rots. Fruit rot infection results in two types of symptoms, depending on the developmental stage of the fruit. One type originates from external infections and the other appears to start internally.