Emerald Ash Borer Threatens D.C. Region’s Ash Trees
For Immediate Release
September 23, 2008
Media Contact:
Vicki Bendure, APR
540-687-3360
The Care of Trees Offers Tips and Information on Preventative Measures
HERNDON, Virginia – “The Washington metropolitan region needs to be vigilant about obeying the current ash tree quarantines and watching their ash trees for this fatal blight,” states Jeremy Baker, an arborist with The Care of Trees. The Virginia Department of Agriculture and Consumer Services (VDACS) has put a quarantine in place on the counties of Arlington, Fairfax, Fauquier, Loudoun, and Prince William and the cities of Alexandria, Fairfax City, Falls Church, Manassas and Manassas Park. The quarantine prohibits the movement of ash tree firewood and nursery stock.
This past July, an infestation of emerald ash borers (EAB) was discovered in Herndon, Virginia. This is the second time that the non-native beetles have been found in the county since a minor outbreak was contained in 2003. The infestation was due to 121 infected trees that were illegally sold by a Michigan Nursery to a nursery in Prince George’s County, Md. That nursery, in turn, sold 16 of the trees to Fairfax County Public Schools causing infestation in both counties.
While the insects only affect ash trees, an infestation is usually fatal. All native species of ash (green, white, blue and black) as well as their horticultural cultivars, are susceptible to attack. EAB has killed more than 40 million ash trees in southeastern Michigan alone. Additionally, tens of millions of trees have been lost in Ohio, Illinois, Indiana, Maryland, Pennsylvania, West Virginia, Missouri, Wisconsin, and Virginia.
Emerald ash borers were first identified in the Detroit metro area in 2002. Scientists determined that the insects most likely arrived as hitchhikers from Asia in lumber used for crating and packing materials. Since its introduction, EAB has spread via infected nursery stock and firewood.
The emerald ash borer is a beetle; a member of the wood boring group of beetles known as metallic wood borers or flatheaded borers. The adult beetle is bronzish or metallic green and between 1/3 to 1/2 inch long with an elongated shape. But, it’s the grub-like larva that cause the damage. They’re cream-colored and flattened and reach slightly over an inch in length when mature. Mature larva spend the winter in a small chamber in the outer sapwood of the ash tree. In early spring, the larvae transform into pupae, still within the chamber. In late May or June, the adult beetle emerges from the pupa and chews its way to the surface, leaving a “D” shaped hole in the tree.
After mating, female beetles lay their eggs in the bark crevices of ash trees. After the eggs hatch, the larvae tunnel into the tree to the area just below the bark where they create serpentine tunnels and extensive damage to the tree. The tunnels disrupt the flow of water and nutrients through the tree’s vascular system. This is fatal to the tree.
The larvae feed through the summer and early autumn, growing as they do and then they bore about an inch deep into the sapwood and create their winter chamber.
“The health of the tree is of no importance to the emerald ash borer,” Baker explains. “Typically, with other insects, they’ll prey on declining or stressed trees. The emerald ash borer will infest any tree – healthy or sick.”
While there are some limited treatments available for infested trees (these should only be applied by a trained arborist), once trees are infected they may be ordered cut down by the state. “In some areas of the country, the jurisdictions had no choice but to clear-cut large regions because the infestation was so widespread and severe,” says Baker.
There are, however, some preventive measures available that can be used proactively on trees that are not infested. These include insecticide treatments that are applied to the soil or trunk, or injected directly into the trunk. The best choice varies depending on situation and no one treatment is suitable for every scenario. For insecticide treatments to be effective, they must be started before the trees fall under attack.
Baker cautions homeowners and landowners from planting ash trees in the Washington, D.C. region. And to be vigilant if they have existing ash trees. “Check them to see if you see any signs of metallic green beetles or D-shaped holes in the tree. Also, look for heavy woodpecker damage to the tree as woodpeckers are drawn to them,” Baker advises.
“Lastly, if you have any concerns or want to set up a proactive treatment, contact a certified arborist,” Baker adds.