Note The fungus Diplodia sycina var. syconophyla has been reported from Oregon causing canker and dieback symptoms. Nectria cinnabarina has been reported from Oregon and found a few times by the OSU Plant Clinic. Botrytis cinerea, which can cause a stem blight, has been reported from Washington. These fungi do not seem to be a common problem in the PNW. Although Calonectria calhounii is reported from Oregon, it is unclear what disease it might be involved with or if it really has been found or not.
Cold winters with freezing temperatures can also result in a dieback of shoots. Damaged tissue is often colonized by Botrytis.