DNR Cautions Campers To Avoid Spreading Invasive Tree Diseases in UP
By Paul Gingras

An ash tree infested with emerald ash borers tries to compensate for the death of its canopy by producing new branches at the base. The ash borer usually attacks the top of a tree first. (Photograph courtesy of the Michigan Department of Agriculture)

A ban on transporting any part of the ash tree into the Upper Peninsula remains in effect this year, and the Department of Natural Resources (DNR) is also asking campers not to move American beech logs. Both species can be infected with insects that destroy tree stands, which harms forest aesthetics, development of wood products, recreation areas, and ecosystems. Owing to these and several other wood-borne pests, the Michigan Department of Agriculture (MDA) is encouraging campers to use local wood where they stay, and to consume it completely. Unused wood should be left on site or returned, but not transported.

DNR project leader Robert Heyd, who specializes in pest management, said the ban on transporting firewood across the Mackinac Bridge has been remarkably effective in stopping the spread of emerald ash borers, voracious beetles that destroy ash trees.

"In the past two years, we have confiscated 650 cubic yards of firewood" at the Mackinac Bridge, said John Hill, supervisor for MDA. In the past, the wood was shipped to Gaylord and burned to produce electricity. Now, it is donated to Fort Michilimackinac in Mackinaw City, where it is burned as part of historical reenactments, said Jim Bowles, also of the MDA.

A survey conducted on the bridge during deer hunting season last November revealed that 91 percent of people crossing were aware of the state's effort to eradicate the emerald ash borer, which Mr. Hill calls "a great improvement." Protecting the U.P. has become one of the department's top priorities.

The flow of firewood over the bridge has steadily decreased, highlighting a change in Michigan tradition. Prior to the onset of the ash borer, transporting wood from downstate to northern camps was a common practice, Mr. Hill explained, but the campaign against them has highlighted dangers to trees, and the public is changing its habits.

Jereme Huss inspects wood at St. Ignace Welcome Center for the MDA, which keeps an inspector on site 24 hours a day, seven days a week. Logging trucks and travelers with campfire wood are referred to him by bridge staff, said Mr. Huss, who has been involved the MDA's effort to eradicate the ash borer since 2003. Most wood is confiscated on site, he explained. If it slips through, the MDA, in association with local courts, can fine anyone who ignores the quarantine. Fines range from $100 to $10,000, depending on specific charges, according to the Michigan State Police.

Mr. Huss agreed that transporting ash wood has dropped significantly since the state imposed a quarantine in 2002. The quarantine now covers the entire Lower Peninsula. Ash borers are especially prevalent in southeast Michigan, with smaller pockets of ash borers found elsewhere in the Lower Peninsula, particularly at state parks and campgrounds. Most likely, these were caused by imported campfire wood, he said.

Over the years, the details of the quarantine have changed, Mr. Huss said. Not only is it illegal to transport ash north over the Mackinac bridge, all other species of hardwood are restricted from the U.P., unless they have been stripped of their bark and half an inch of inner wood. Kiln dried or fumigated hardwood is allowed, but few campers use this, Mr. Huss said.

Moving firewood from one location to another is a bad policy for forests in general. Insects that attack ash and beech wood are only two dangers that can be spread by campers. Fungal infections like oak wilt, a disease that rapidly kills oak trees, is also a problem. In the U.P., this disease is found in Menominee and Dickinson counties.

There are new problems on the horizon, also, such as the European sirex wood wasp, which appeared on the east coast in 2004. The wasp is moving through New York, Pennsylvania, and southern Ontario, carrying a fungus that kills conifers like the native red pine.

As the weather warms and campers make their way into the Upper Peninsula, foresters are asking them to think about these dangers, especially the emerald ash borer, which has destroyed millions of trees throughout the Midwest, and beech scale, a tiny European insect that kills beech trees.

The DNR estimates that the ash borer has killed between 20 and 25 million trees, Mr. Heyd said. The only known infestation in the U.P. was found near Brimley two years ago. The area was quarantined and 430 ash trees were destroyed, and there have been no problems since. The quarantine will probably be lifted there next year, Mr. Heyd said.

Residents who remain unaware of the problem, or continue to transport firewood, are an ongoing challenge for the effort, he added.

It can be impossible to tell if an ash tree is infected. Adult beetles attack the top of a tree first and lay their eggs in the bark. Logs from lower portions of infected trees, which appear healthy, have been cut and transported.

Sometimes, the bark of a severely infected tree will split, and larva, called a gallery, can be seen beneath, Mr. Heyd said. The trees generally die from the top down.

The loss of ash trees is primarily an urban phenomenon in the Lower Peninsula, but beech bark disease is moving eastward across the Upper Peninsula. It is prevalent throughout Luce County, and it is also found in western Chippewa, Mackinac, and Schoolcraft counties.

State quarantines on beech wood not been effective, and there are no quarantines in place now, Mr. Heyd said. The disease spreads by moving firewood, wildlife, and wind, and can be slowed by leaving infected wood where it is.

"Be responsible," Mr. Heyd said. "If a [beech] tree dies, don't just cut it down and move the logs to camp."

The minute insects that cause beech bark disease are called scale. They enable Nectria fungus to enter, weaken, and eventually kill the trees. Scale infestations look like cotton on the tree's bark, and heavily infected stands appear whitewashed. Beech scale is active in the midsummer months, Mr. Heyd said.

Scale weakens beech trees, causing them to snap and fall.

Beach bark disease has nearly eliminated the American beech from eastern forests, and Mr. Heyd said the species will become scarce in Michigan, however, foresters have discovered resistant strains and hope to reestablish the species. Between one and three of each 100 trees in infected areas are resistant to scale.

"The resistance is very real," Mr. Heyd said. The DNR is protecting such trees and learning about their resistance.

"It's a long-term project, but a good one," he said.

Resistant strains of American beech are being studied at a laboratory in Delaware, Ohio, operated by the federal Forest Service. There, researchers produce seeds, graft resistant trees, and test them against scale, Mr. Heyd said.