Fruit IPM Factsheet Fruit IPM FactsheetBLUEBERRY PHOMOPSIS IN MICHIGAN
ADAPTED from E-1731
& Compendium of Blueberry and Cranberry Diseases from APS Press
By: Mark Longstroth
This disease is caused by the fungus Phomopsis vaccinii. Phomopsis canker occurs in the southern Lower Peninsula and in Indiana and Illinois. This disease can be devastating to bushes planted in low areas, where winter injury and spring frosts are a problem.
Symptoms and Disease Cycle: The cankers on 1-, 2- and 3 year old stems are not as well-defined as those of Fusicoccum canker. A Phomopsis canker appears as an elongated, flattened canker (Fig. 7). An infected stem feels flattened. Older cankers are covered by small, pimple-like pycnidia (Fig. 8) which contain conidiospores. The conidiospores are spread by splashing rain. In the early stages of canker formation current year stems may have 1 to 2 inch-long reddish-brownish areas. These areas are the beginning symptoms of phomopsis canker.
After the stems have been infected for season, they will wilt during the
summer months (Fig. 9). Under severe disease conditions it is common
to see bushes with a half dozen or more wilting stems. The infectious conidiospores are
spread each time rain occurs during the growing season from bud-break through about August
1. Winter injury and spring frost injury afford an entry point for infection.
Control: Prune out and burn infected cankers. Pruning cuts should be made as deep
into the crown as possible to insure removing the canker. Use season-long fungicidal
sprays. Use Extension
Bulletin E-154 for fungicides, rates and timing.
Figure 7. A stem canker caused by Phomopsis vaccinii..
Figure 8. Pimple-like pycnidia (arrow on a phomompsis canker. These pycnidia contain infectious conidiospores.
Figure 9. Stem wilt caused by Phomopsis canker.
Additional Publications:
