Oak Wilt - Oak Tree Wilt Disease

Charles O. Rexrode1 and Daniel Brown2

1Principal Entomologist, U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station, Delaware, Ohio.
2Forest Pathologist, U.S. Department of Agriculture, Forest Service, Southern Region, State and Private Forestry, Forest Pest Management, Atlanta, Ga.

Oak wilt, caused by the fungus Ceratocystis fagacearum (Bretz) Hunt, kills oak trees. It has been found in 21 States, with considerable damage occurring in the Midwest. It was first recognized as an important disease in 1944 in Wisconsin (fig. 1) where, in localized areas (less than 100 acres (40.4 ha)), over half the oaks have been killed. Surveys in eight Wisconsin counties showed that about 11 percent of the annual growth increase of oak forests was offset by mortality caused by oak wilt.

Forest Insect
& Disease
Leaflet 29
U.S. Department
of Agriculture
Forest Service