Jefferson County will be quarantined for emerald ash borer, after the tree-killing insects were found just on the other side of its border with Walworth County and tell-tale signs of the pest were found inside Jefferson County itself.
“What we have found is enough to tell us that EAB is, in all likelihood, present in Jefferson County,” said Brian Kuhn, Plant Industry Bureau Director with the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP). “The insects will spread naturally at a slow rate, but we’re taking steps to try to prevent humans from speeding up that spread, or allowing EAB to leapfrog to new areas by being carried on firewood or other products.”
In late June, the insects were found in a tree removed from the grounds of the University of Wisconsin-Whitewater and identified by Department of Natural Resources staff. The city of Whitewater and the campus straddle the Walworth-Jefferson county line, and the tree was about 750 yards inside the Walworth County line.
On July 1, a DATCP specialist worked with the UW-Whitewater grounds crew to remove a tree on the Jefferson County side of the campus. They did not find any insects, but the tree did show tunneling, or “galleries,” under the bark and D-shaped holes that are evidence of EAB infestation.
Walworth County is already under quarantine, because EAB has been identified in other municipalities there. However, this is the first time it has been found in the city of Whitewater.
The quarantine will apply to all of Jefferson County. It prohibits wood products from being moved out of the county to areas that are not infested.
For private citizens, this means that they cannot take firewood from Jefferson County to non-quarantine counties. For businesses handling wood products that could carry EAB, it means that they must work with DATCP to assure that their products are pest-free before shipping.
The quarantine will be put in place temporarily by a Wisconsin emergency rule, until the U.S. Department of Agriculture completes the process to put a federal quarantine in place.
Kuhn had these recommendations for property owners with ash trees in quarantine counties:
Keep a close watch on ash trees for signs of possible EAB infestation: Thinning in the canopy, D-shaped holes in the bark, new branches sprouting low on the trunk, cracked bark, and woodpeckers pulling at the bark to get to insect larvae beneath it.
If your property is within 15 miles of a known infestation, consider preventive treatments. Whether to treat depends on several factors: the age of the trees, the size of the trees, and the number of trees. Treatment costs vary depending on size of the tree and whether you do the treatments yourself or hire a professional.
Consider planting different species of trees that are not susceptible to EAB.
Contact a professional arborist for expert advice, and visit emeraldashborer.wi.gov for detailed information.
Emerald ash borer is native to China and entered the United States about 10 years ago on packing material, showing up first in Michigan. It appeared in Wisconsin in 2008 in Washington County. There are now 16 Wisconsin counties under quarantine: Brown, Crawford, Fond du Lac, Jefferson, Kenosha, La Crosse, Milwaukee, Ozaukee, Racine, Rock, Sheboygan, Trempealeau, Vernon, Walworth, Washington and Waukesha counties.
EAB adults lay eggs on the bark of ash trees in mid- to late summer. When the eggs hatch a few weeks later, the larvae burrow under the bark for the winter and eat the wood, destroying the tree’s ability to take up nutrients and water. In summer, the adults emerge through D-shaped holes in the bark. On their own, they may spread about a half mile per year.