See:
Raspberry (Rubus spp.) - Ascospora Dieback
Cause Sporocadus lichenicola (sexual: Discostroma corticola), a fungus that can infect blueberry plants suffering from winter injury, sunscald, or damage from other sources. Infection may require a previous low temperature injury of the plant. Has been found sporadically in the Willamette and Hood River Valleys of Oregon. The fungus can also infect red and black raspberry, 'Loganberry', and Himalaya and evergreen blackberry.
Symptoms Twigs have multiple, grey-white cankers with reddish margins associated with nodes and range from 0.25 inch to the entire length of the twig. Dark-brown-to-black fruiting bodies (pycnidia) are found within cankers. Extensive stem cankers can girdle and kill infected twigs.
Cultural control Tactics that minimize winter or other injury to plants is encouraged.
Chemical control None are registered or known for this disease.
Reference Serdani, M., Curtis, M., Castagnoli, S., and Putnam, M.L. 2010. First report of twig canker of blueberry caused by Sporocadus lichenicola (Corda) in Oregon. Online. Plant Health Progress doi:10.1094/PHP-2010-0315-02-BR.