Wisconsin, Natural Resources, Dept. of
Slow-moving Killer Oak Disease Found near in State Forest
Weekly News Article release of DNR Central Office, November 19, 2013
Wisconsin DNR
Original Date

Oak Wilt found in Northern Highland American Legion State Forest, near Woodruff.

  • Bookwood Historical Collection, Star Lake

Using Only Locally Produced Firewood One Way to Stop Oak Wilt Spread.

WOODRUFF, Wis. -- A deadly tree disease known as oak wilt was discovered for the first time on the Northern Highland American Legion State Forest near Woodruff in October, prompting state forestry officials to take immediate action to stop its spread in the north.

Brian Schwingle, Department of Natural Resources forest health specialist, says staff cut down the diseased tree and oaks around it, ripping their stumps out of the ground with a bulldozer and burning all diseased wood. The area will be monitored next summer to determine if these efforts were successful in eradicating oak wilt at this isolated site.

“Such drastic action is necessary to prevent oak wilt from spreading from tree to tree through connected roots in the oak-dominated stands on the state forest,” Schwingle said. “Once oak wilt gets established in an oak stand, it’s like a slow moving fire, killing all oaks in its path.”

Schwingle says oak wilt is not native to northern forests and has been moving northwards in recent years with the inadvertent help of people. Spores of the disease are most frequently brought to new areas in firewood from oaks killed the previous summer.

“New oak wilt infestations are frequently found around vacation homes or campgrounds where people bring wood from southern and central Wisconsin where the disease is common.” Schwingle says. “The first step in protecting your oaks is to get your wood locally. The nearer the wood was cut to where you plan to use it, the less likely it is to be carrying pests or diseases new to your area that can emerge to attack your trees, including oak wilt.”

The second step you can take to protect your oaks is to be sure the spores do not have a way into your trees. Oak wilt spores need a fresh wound in spring to summer to infect an oak. “Too often, we provide an entry for the oak wilt spores when we prune oaks, nail ornaments, insert screws or bump our vehicles into oaks when opening up the cabin,” Schwingle says. “This is the other reason new oak wilt infections are so often found in lake shore developments and other vacation areas.”

Also, he says, avoid causing even small wounds to your oaks from April 15 to July 15 when spores commonly infect fresh wounds. If you accidentally damage an oak or have to prune off a branch broken in a storm, paint or spray the wound with a tree dressing or paint to prevent infection.

For more information on recognizing, preventing, and controlling oak wilt, search the DNR website, for keyword “oak wilt.” If you suspect oak wilt is killing oaks north of Highway 64 between Sawyer and Forest counties, contact Brian Schwingle at the Merrill office of the DNR.

FOR MORE INFORMATION CONTACT: Brian Schwingle, DNR forest health specialist, Merrill, 715-536-0889; Joanne M. Haas, DNR public affairs, 608-209-8147.