Oak wilt is the most important disease of oaks in the Eastern United States, where it occurs in both residential and forested areas. Several species of insects known as “picnic” or “sap” beetles carry a fungus (Ceratocystis fagacearum) that enters oak trees through open wounds, such as those caused by storms and pruning. Oak wilt can also spread when the roots of an infected tree contact those of a healthy tree. Oak wilt has killed millions of trees from Pennsylvania to Minnesota and south to Texas and South Carolina since the 1950s. The disease is gaining in importance as people move into oak-dominated woodlands and as high-value forests become infected.
Skip to Main Content