Spur blight (Didymella applanata) fungus infects fruiting laterals of red and black raspberries, and blackberries, especially on the lower portion of canes where conditions are more favorable for disease development.
Individual laterals wilt, and at the base of the lateral is a brown or black lesion.
Infections can occur on primocanes as well, as indicated by lesions that already exist surrounding the dormant buds.
More information:
- Spur Blight of Red Raspberries– (Ohio State)
- Raspberry Spur Blight– (Oregon State)