Oak wilt is one of the most destructive diseases of oaks in Missouri. Symptoms begin to appear in late June and early July. Look for wilting and rapid leaf drop beginning in the upper crown of red oak species like black, northern red, pin, scarlet, and shingle oak. While a single tree may be affected initially, eventually you may see a group of affected trees; perhaps a few died last year and symptoms are present on adjacent trees this year. Oak wilt is easily confused with oak decline, which is very common in Missouri. When oak decline is present, leaves often stay on the tree after turning brown, or the trees may die back over a period of years before death occurs.

Once an oak wilt-infected red oak tree shows symptoms, it cannot be saved. Fortunately, treatments can help protect nearby healthy oaks. Oak wilt confirmation through sample testing can help guide these management decisions. See plantclinic.missouri.edu for more information on sample testing provided by the University of Missouri Plant Diagnostic Clinic. Learn more about oak wilt in our Oak Wilt Forest Health Alert.