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Oak Wilt


Preventing and Controlling Oak Wilt in Wisconsin

trees with oak wilt behind houseOak wilt can rapidly kill oaks in the red oak group (including black, northern red, and northern pin oaks) and may also affect oaks in the white oak group (including white and bur oaks). Oak wilt occurs in the central, northeastern, and southwestern United States and is widespread throughout southern and central Wisconsin. Many communities have lost numerous trees to this disease. This website provides information and references to resources on oak wilt, particularly those relevant to oak wilt in Wisconsin.

Minimizing the Spread of Oak Wilt through Prevention

The fungus which initially causes oak wilt is spread by insects which travel overland (above ground). These insects are attracted to fresh wounds on oak trees. As the insects feed upon these wounds, they infect the trees with the fungus. Once the tree is infected, the disease spreads between adjacent trees through underground root grafts. It becomes very difficult to control at this point. For this reason, prevention of the initial infection is of utmost importance. To minimize - and hopefully prevent - the spread of oak wilt in areas where individual trees have significant aesthetic, environmental, or economic value (such as urban areas or residential construction sites) - do not prune or wound oaks during their entire growing season. The growing season begins when the buds swell in early spring and ends in fall when frosts and freeze-up occurs. The beginning and end dates of the growing season vary each year, depending on weather conditions in different areas of the state. Please be aware that avoiding pruning and wounding of oak trees during the entire growing season is a more cautious approach than is recommended in most of the following publications. If an oak tree must be pruned or is wounded during the growing season, immediately cover the wound with a tree wound paint.

Pamphlets and Publications

Oak Wilt in Wisconsin by Jane Cummings Carlson

This 1997 pamphlet from the Wisconsin Department of Natural Resources includes information on the distribution of oak wilt in Wisconsin (including a map), the cause and symptoms of the disease, how to prevent your trees from becoming infected, and what to do if they do become infected.

Lake States Woodlands:

Oak Wilt Managment -- What Are the Options? By Jane Cummings Carlson and A. Jeff Martin

This 1994 University of Wisconsin Extension publication (G3590) contains detailed information on the spread and treatment of oak wilt. It also includes a county-by-county map of the spread of oak wilt in 11 northern states. It is available in PDF format. Paper copies may be obtained from any Wisconson County Extension office or from the Publishing Unit, Room 170, 630 West Mifflin Street, Madison, Wisconsin 53703. The cost, if ordered from Madison, is $1.40 (price) plus $1.50 shipping and handling.

Controlling Oak Wilt Disease in Wisconsin: Leader Training: Leader Training by Lenore Landry

This 1997 document provides an outline and recommendations for a community or club meeting to educate people about oak wilt. It is also available in .pdf format.

Oak Wilt Images

Oak Wilt images from provides several images from the U. S. Forest Service's Oak Wilt Image Library. It also provides information about the Image Library itself, which contains over 180 images.

Communities Fighting Oak Wilt

Local Ordinances:
Many villages, towns, and cities have oak wilt control programs including ordinances which outline and regulate oak management practices in the community. Having such an ordinance can help prevent oak wilt and can also help settle disputes (sometimes through litigation). Sample of Oak Wilt ordinances.

For More Information or Assistance:

Wisconsin Arborist Association, a professional organization for arborists in Wisconsin.
Wisconsin Arborist Association
c/o Dave Scharfenberger
404 Branch St.
Hartford, WI 53027
(414) 251-6900

North Central Research Station, a USDA research station serving the midwest.

Local commercial certified arborists. The International Society of Arboriculture maintains a searchable List of Certified Arborists.

Or, check your yellow pages under "Arborists," "Foresters--Consulting," "Forestry Services," or "Tree Service." You can also checkAmeritech's Internet Yellow Pages. (For Wisconsin, "Tree Service" seems to be the preferred category.)

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Page Contact: Keith Tackett
July 5, 2011