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Published August 31, 2009, 01:17 PM

Blueberry virus equals blueberry blues

DETROIT (AP) — Two destructive viruses have struck the blueberry industry in the state of Michigan, home to a $124 million per year crop that is the largest in the United States.

DETROIT (AP) — Two destructive viruses have struck the blueberry industry in the state of Michigan, home to a $124 million per year crop that is the largest in the United States.

Particularly upsetting to scientists is where one of the outbreaks occurred — Michigan State University's agricultural research station in southwestern Michigan. An outbreak of blueberry shock is forcing scientists to destroy plants that represent two decades and millions of dollars of research.

It will take years for new plants to mature so research can resume, said Annemiek Schilder, an associate professor of plant pathology and blueberry researcher. Still, she said, "We can't risk having that spread its way through Michigan's blueberry industry."

Blueberry shock is believed to have started in the Pacific Northwest and is spread by bees carrying infected pollen. The virus causes sudden death to flowers and leaves, although new ones can grow.

Plants remain infected but sometimes return to full productivity in a few years.

Blueberry scorch — found on two southwestern Michigan farms — is common on both North American coasts. It's spread by aphids and has symptoms similar to blueberry shock. Some infected bushes die, while others appear normal.

Unlike fungus infections, the viruses have no known treatments.

So far, there's no sign of the diseases spread beyond those three spots, but the Michigan Department of Agriculture says the risk to the state's 19,000 acres (7,700 hectares) of blueberries remains.

Michigan harvested 110 million pounds (50 million kilograms) last year. New Jersey was second at 42 million pounds (19 million kilograms). Nationwide, production totaled 407 million pounds (185 million kilograms).

Totals for this year aren't in yet, but industry groups and growers say Michigan had a bumper crop. Nationally, production is expected to be up as well, according to the North American Blueberry Council.

Blueberry shock spreads only in the spring when bees pollinate bushes' blooms. Between now and then, Michigan State scientists are undertaking a crash study of the disease to learn as much as possible before they have to destroy their plants to prevent the virus from spreading.

They will look at the effect of winter dormancy on the infection, monitor the presence of the virus in buds and establish testing protocols, Schilder said. Down the road, their work may help commercial growers struggling with infections.

But the losses are great for the researchers working at the Trevor Nichols Research Complex near Lake Michigan. The 4 acres (1.6 hectares) of blueberries there have been used since the early 1990s for research on diseases and pests affecting the fruit. Scientists at the station have looked at topics ranging from pesticide residue to bee pollination, fruit funguses and insect infestation.

Schilder's own work at Michigan State dates back 11 years. The university could try to lease land from blueberry farmers to continue its research, but once the station's blueberry bushes are destroyed, no work will be done there for four or five years, she said.

It's unclear how the university's plants got the disease. But Schilder said if any good comes from the outbreaks, it will be in raising growers' awareness of the need to obey a quarantine on untested blueberry plants from Oregon, Washington, British Columbia and other infected areas.

The Michigan Department of Agriculture is working to track down the sources and any possible spread of the two diseases, said department spokeswoman Jennifer Holton.

"We're going to figure out how it got into the state and where it spread," she said.

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