Phomopsis canker of Blueberries

Phomopsis canker overwinters in infected plant parts. The primary symptom of twig infection is a blighting of one-year-old woody stems that have flower buds. As with other canker diseases, the most conspicuous symptom is “flagging”–during the summer, individual stems wilt and die while leaves turn reddish and remain attached. Under severe disease conditions, several individual canes may be affected on a single bush. The fungus enters the flower buds and eventually moves into the stem. Infected stems will wilt and die, and young twigs will die back from elongated cankers produced by the fungus.
Cankers on one-year-old stems become obvious by early summer and continue to progress downward, eventually encircling the entire shoot. In hot weather, leaves on infected twigs turn brown and remain attached to the stem. As canes mature, they become girdled by the diseased lesions. Fruiting structures of the fungus will form on dead twigs and leaves. These fruiting structures look like small, black dots, which are the spore-containing bodies (pycnidia) of the fungus. These spores are spread primarily by rain splash. Infected fruit are soft and often split and leak juice. To aid control apply lime sulfur at bud-break and in the fall.