Stem Canker

Stem canker on blueberry appears as reddish, conical swellings on current-year canes, particularly the principal canes, visible in summer and fall. The cankers develop small pimple-like swellings (pycnidia) on the surface, then enlarge and become fissured and rough in the second year, taking on a blistered appearance. If cankers girdle the cane or extend into the crown, the entire cane or whole plant may die back. The disease hasn't been common in the PNW historically but has appeared in Oregon and should be monitored as a potential threat.

Botryosphaeria corticis enters during warm, wet growing conditions and becomes more severe under plant stress, drought, or poor cultural conditions. The best management is selecting disease-free nursery stock and inspecting any plants arriving from the eastern or southern United States where the disease is established. Prune out and destroy infected branches promptly to reduce spore sources. Maintain plant vigor through proper irrigation, fertilization, and general care; avoid planting in stress sites. Most blueberry cultivars are susceptible, though Northblue shows more resistance than Bluecrop or Duke under controlled conditions.