DNR Northern Region - Rhinelander, WI. -- A deadly tree disease known as oak wilt was discovered for the first time in Oneida County this July and confirmed in the laboratory by Wisconsin Department of Natural ... More... Rhinelander, WI. -- A deadly tree disease known as oak wilt was discovered for the first time in Oneida County this July and confirmed in the laboratory by Wisconsin Department of Natural Resource forestry officials. An infected tree was found about 4 miles southeast of Eagle River and 3 miles west of the Chequamegon-Nicolet National Forest. “Chances are high that a few oaks in the surrounding landscape also are infected with this disease,” said Brian Schwingle, DNR forestry health specialist. He requests that any landowners who saw their red oaks rapidly die this summer report it to the local DNR forest health specialist in Rhinelander. Lakeshore residences near Cranberry L., Perch L., Meta L., Long L. and Catfish L in the Eagle River and Three Lakes areas should also pay particular attention to their oaks. Schwingle said the oak wilt infection in the county likely happened because someone unintentionally brought up infected firewood from central or southern Wisconsin where oak wilt is common. The disease spreads to new areas easily on firewood. The disease is also present in southeastern Langlade County and eastern Florence County. Oak wilt is a severe disease of red oaks, black oaks, and northern pin oaks (i.e. oaks with leaves that have sharp, pointed lobes). The most common symptom is a quick browning and shedding of all leaves within one spring and summer. A common insect pest, the two-lined chestnut borer, is often confused with oak wilt, but borers do not cause rapid death. Schwingle explained that an oak infested by chestnut borers can die in 2 or 3 years, while oak wilt kills within 2 or 3 months. The disease is caused by a fungus that plugs and kills the water conducting vessels in the outermost wood. Sap beetles carry oak wilt spores from infected wood or trees to fresh wounds on trees, typically from April through July. These beetles can likely fly a few miles. Once oak wilt is in an oak, it can spread from oak to oak through root systems. Oak wilt can have a severe economic and ecological impact. A recent study conducted by the U.S. Forest Service and University of Minnesota reported that oak wilt would likely kill 20% of all oaks in Anoka County, MN in 20 years if no management occurred. The cost of tree removal alone was projected to cost $143 million over those 20 years. Schwingle said that there are ways to prevent and manage oak wilt. Citizens should not move oak firewood and avoid wounding oaks in any way from April through July. To learn how to control an oak wilt infection from spreading, citizens should call a certified arborist or a forester. The Wisconsin DNR’s oak wilt web pages can also help: http://dnr.wi.gov/forestry/Fh/oakWilt/ . The University of Wisconsin-Extension produces an oak wilt publication entitled “Oak Wilt Management – What are the Options?”, which can be found at http://learningstore.uwex.edu/ . Anyone in Oneida County or the surrounding area who wants to report oak trees that have died this summer should contact Brian Schwingle, DNR Forest Health Specialist, 715-365-8908.