Cause A phytoplasma that is transmitted only by the blunt-nosed leafhopper. This disease was first detected in Wisconsin, was brought into the Pacific Northwest in infected vines and now can be found in Oregon and Washington. The disease is not spreading actively and is of only minor importance because the insect vector is not in western North America. If the insect vector is introduced, the disease could begin to spread.
Symptoms The lobes of the calyx become enlarged at bloom, and petals are short and streaked with deep pink, red, or green. Flowers usually are sterile (do not produce berries). Branching is stimulated, resulting in a witches' broom. Foliage on infected plants might redden prematurely and fall. Diseased vines grow few if any runners and tend to die out over time.
- Remove infected plants and dead vines when noticed.
Reference Caruso, F.L. and D.C. Ramsdell. 1995. Compendium of Blueberry and Cranberry Diseases. St. Paul, MN: APS Press.