Phomopsis Canker
(Phomopsis vaccinii).
Damage: Individual branches turn reddish-brown, called “flagging”, and die, and leaves may fall soon after Large (5-15 cm), reddish brown, oval-shaped lesions can be seen on 1-3 year-old stems.
Disease cycle: This fungus over- winters on cankers on stems. Spores are released from cankers during periods of rainy weather and splash onto adjacent stems mostly in the spring. Lesions may take 1-3 year to fully girdle and kill individual branches.