To halt beetle, Md. felling 17,000 trees

Bringing down the ash borer

March 24, 2007|By Tom Pelton | Tom Pelton,Sun reporter

In an escalating war against a voracious Chinese beetle, the Maryland Department of Agriculture is cutting down 17,000 ash trees in a 21-square-mile swath of suburban Prince George's County.

The aggressive tactics are intended to halt the advance of the emerald ash borer - a metallic-green insect the size of a breath mint that has killed more than 20 million trees in the Midwest.

The beetles hitched a ride on saplings shipped from Michigan to a nursery in the Clinton area of Prince George's four years ago. It was the first place the pest has surfaced in the East, and Maryland officials are trying to deprive the bugs of food so they won't spread to destroy all the ash trees in the region, said Dick Bean, coordinator of Maryland's efforts.

"If we can contain it here, we can save the entire East Coast," Bean said. "There will be tens of millions of dead trees if we don't stop the ash borer."

State workers felled 1,100 ash trees within a half-mile circle of the nursery in 2004. They discovered last August that wasn't enough when the flying beetle was spotted in three trees outside the circle, Bean said.

More intensive testing found hundreds of infected trees in a wider area of southern Prince George's County. So this month, teams with chain saws are mowing down trees in the 21-square-mile area, including a wider 1.5-mile circle around each infected tree. The state has also imposed a quarantine, banning shipment of logs or firewood out of the county.

Cutting down healthy ash trees on people's front lawns sometimes provokes anger and shouting.

"It really hurts doing this because we are taking down some beautiful, beautiful trees," Bean said as his workers chain-sawed and then chipped a 20-foot ash in front of a brick ranch house in Clinton. "But it's like fighting cancer - sometimes we have to cut out some good to save the rest."

Many residents are supportive of the efforts, saying they understand the need to starve the beetles of fuel. "I'm glad they're doing it," said Mark McCloud, owner of the home, which now has a stump in front. "I really don't want any infested trees."

Ash trees are among the most treasured shade trees in America, and for decades they have been chosen to ornament front lawns in suburbia. The tree is also regarded as a valuable hardwood, its iron-like durability prized for baseball bats, flooring and furniture.

But now, some arborists worry that the invasive species of Asian beetle could wipe them all out, just as Dutch elm disease decimated the American elm last century, despite aggressive efforts by the government to use pesticides to halt the progress of the fungus, which came from Europe and was carried by a different insect, the elm bark beetle.

The strategy Maryland is using to fight the ash borer - at a cost of $4 million to $6 million - has failed to halt the march of the beetle across Michigan and Ohio. And a few people have grown irritated at all of the tree cutting in Prince George's.

One family in Clinton hammered a warning poster onto their tree in an unsuccessful attempt to ward off the chain saws. "DO NOT DESTROY OUR TREE," read the sign, which Bean kept for his office wall. "ATTORNEY HAS BEEN CONTACTED."

The tree came down, anyway. And like thousands of others over the last month, it was ground into mulch, then pulverized again, to squash the beetle's white larvae, which burrow under bark.

Heavenly Warrick, a nurse in Clinton, stood on the porch of her white Cape Cod and looked at the neon orange stripe that state workers had spray-painted around a handsome, double-trunked, 50-foot ash that shades her front yard.

The bright mark can be seen girdling trees up and down the streets of her town. "Why can't they take down one branch and check that for the beetle?" Warrick asked. "Why do they have to take down the whole tree?"

The difficulty, Bean explained, is that arborists can't really tell whether a tree is infested with the beetle's larvae until after they've cut it down and stripped off the bark to reveal twisting, maze-like burrows. There are some telltale signs, however - such as D-shaped holes in the bark of the trees, cracks in the bark, and lots of woodpeckers attracted by the white larvae.

The emerald ash borer was discovered in America in June 2002, in the Detroit suburb of Canton, said Angela Riess, a planner for the Michigan Department of Agriculture. The beetle likely came from China on a shipping crate.

Trees in Asia, such as the Manchurian ash, have evolved to survive with borers nibbling under their bark. But the varieties of ash native to America, such as the white ash, die within about three years of infestation. This is because they can't survive the reduction in their sap flow when the larvae eat tunnels through the thin layer of cambium under the bark, which is the trees' circulatory system.

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