Oak wilt is a fungal disease that kills thousands of oak trees every year and is spread in two ways, through root grafts between similar species, radiating outward from a central infected tree; and over land, carried by oak sap beetles carrying fungal spores from tree to tree.
Oak wilt, caused by the non-native fungus Ceratocystis fagacearum, is responsible for killing large numbers of oaks annually in Minnesota. Oaks are a valuable and abundant shade and forest tree in the state. Oak wilt is most severe in red oak group species such as northern red oak and northern pin oak. Fortunately, this valuable resource can be protected by utilizing effective management techniques.
Where does Oak Wilt Occur?
Oak wilt occurs in 24 states in the eastern United States and is not known to occur elsewhere. In Minnesota, the disease is currently found in an area bounded on the north by Pine County, on the west by Stearns and Nicollet counties, and south to the Iowa border. The greatest concentrations of oak wilt are found in Sherburne, Anoka, Isanti and northwestern Dakota counties.