According to the USDA Forest Service. In Texas and 20 other states, Oak Wilt is becoming a serious problem. Oak wilt, caused by the fungus Ceratocystis fagacearum (Bretz) Hunt, kills oak trees. There has been serious 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.
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