Exotic blueberry viruses found in Michigan

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Michigan Department of Agriculture (MDA) announced Tuesday, July 14, that exotic blueberry viruses have been detected at several locations in west Michigan. The two viruses, known as blueberry shock and blueberry scorch, were found through routine surveys conducted by both MDA and Michigan State University plant pathologists. Both viruses are known to occur in certain West Coast and mid-Atlantic states where they cause significant losses to blueberry producers. These finds are the first detections in Michigan.
Blueberry shock-infected plants will suffer from loss of foliage and blossoms resulting in yield loss the first year of infection. It’s possible that fruit production may resume the next year; however, experts believe this disease could be more severe in this northern climate. The infected plant will serve as a source of infection to other nearby plants since blueberry shock is transmitted mainly through pollinating insects.

Blueberry scorch virus symptoms are similar to shock virus symptoms. In the spring, shoot tips will die back, sometimes on just a few branches. The flowers may blight just as the earliest blossoms open. Scorch infected plants repeat this symptom cycle each spring. The entire bush eventually becomes infected within three years. Fruit production and shoot growth are seriously reduced on scorch infected plants. Scorch is transmitted from plant to plant by aphids. There are no known cures for either of these two diseases.

MDA is working with a team of blueberry experts at MSU to develop a response plan that will protect Michigan’s blueberry industry. The initial action will include eradication of the infected plants and then monitoring of nearby blueberry plantings to assure that the disease has been eliminated. MDA and MSU have partnered to assure adequate outreach information on these exotic viruses is provided to blueberry growers. A meeting with blueberry growers is planned for September to review findings from the surveys; and, to discuss means of safeguarding our industry through a systems approach that incorporates science-based best management practices.

Michigan ranks number one in blueberry production in the United States, with over 17,000 acres reported in production. In 2008, Michigan grew 110 million pounds of blueberries which were valued at $124 million.

More information

Regulatory calls to:
Robin Rosenbaum
Plant Industry Section Manager
Michigan Department of Agriculture

OR Mike Bryan
Nursery Program Manager
Michigan Department of Agriculture
Disease information calls to:
Annemiek Schilder or Jerri Gillett
Department of Plant Pathology
Michigan State University

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