According to Michigan Department of Agriculture (MDA), two viruses — blueberry shock and blueberry scorch — were found through routine surveys conducted by MDA and Michigan State University plant pathologists.
Both viruses have been known to occur in certain West Coast and mid-Atlantic states, causing significant losses. This is the first time they have been discovered in Michigan. According to a news release from MDA, there are no known cures for either disease.
Blueberry shock causes infected plants to suffer from loss of foliage and blossoms, resulting in yield loss the first year of infection. It is possible for fruit production to resume the next year, but experts believe the disease could be more severe in the northern climate. Infected plants serve as sources of infection to nearby plants, as well, since blueberry shock is transmitted primarily through pollinating insects.
Blueberry scorch symptoms are similar to shock. In the spring, shoot tips die back, sometimes on only a few branches. The flowers may blight just as the earliest blossoms open. Infected plants repeat the symptom cycle each spring. The whole bush will become infected within three years, and fruit production and shoot growth are seriously reduced. The virus is transmitted by aphids.
MDA is working with MSU blueberry experts to develop a response plan. The initial action will include eradication of the infected plants and monitoring of nearby blueberry plantings to assure the disease has been eliminated. A meeting with blueberry growers is planned for September to review findings from the surveys, and to discuss means of safeguarding the industry.