LANSING, Mich. - Michigan Department of Agriculture (MDA) Director Don Koivisto today announced two exotic blueberry plant diseases have been identified in Michigan for the first time - blueberry shock and blueberry scorch.  Both viral plant diseases have the potential to cause significant losses to blueberry producers; however, they are not a threat to food safety or human health. MDA and Michigan State University (MSU) officials are aggressively implementing a response plan to eradicate these diseases.
 
Michiganis the nation's number one blueberry producer with more than 19,000 reported acres producing 110 million pounds of blueberries valued at $124 million last year.
 
MDA's Pesticide and Plant Pest Management Division has been diligently watching for these diseases due to their presence in certain West Coast and mid-Atlantic states and taking steps to prevent them from entering the state through issuance of an external quarantine in 2002 and through routine sampling.
 
"Although not totally unexpected, we are very disappointed these two serious diseases have been identified in southwest Michigan - the state's blueberry belt," Koivisto said.  "MDA and its partners are working in concert to quickly eradicate this threat and safeguard this valuable commodity. These viruses do not pose a food safety or health risk, and consumers can select Michigan blueberries with confidence and pride in the product."
 
Annemiek Schilder, MSU associate professor of plant pathology, was part of the team that identified blueberry shock in a research plot at MSU's Trevor Nichols Research Station in Fennville.
 
"Blueberry shock symptoms may look similar to spring frost injury or common plant diseases such as Phomopsis twig blight, but rapid testing confirmed our suspicions," Schilder said.  "Researchers, regulators and growers have learned about blueberry shock and scorch from Web sites and books, but having it here will help us all learn more. We're going to make the best of this situation by researching optimal testing protocols before the plants are destroyed."
 
Blueberry scorch virus was discovered at a private farm in west Michigan. The infected plants have been destroyed and MDA agents are testing adjacent areas to verify blueberry scorch disease has not spread.
 
Blueberry shock-infected plants suffer from loss of foliage and blossoms resulting in yield loss the first year of infection. Fruit production may resume, but MSU researchers believe this disease could be more severe in Michigan's northern climate than in its native region, the Pacific Northwest. The infected plant serves as a source of infection to other nearby plants since blueberry shock is transmitted by pollinating insects.
 
Blueberry scorch disease symptoms are similar to shock 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 until the entire bush becomes infected, typically 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 plant diseases.
 
"We believe that both diseases are restricted to small areas and can be eradicated," Schilder said. "But buying plants from a nursery selling virus-tested plants is the best way to prevent further infection because both plant diseases can be spread via infected cuttings."
 
For more information, visit the MSU blueberry shock Web site http://www.blueberries.msu.edu/shock.htm, the MSU blueberry scorch Web site http://www.blueberries.msu.edu/scorch.htmorcontact Schilder in the MSU Department of Plant Pathology by calling (517) 355-7539.

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