Oak leaves with distinct
oak wilt symptoms.
Oak wilt is a fungal infection (Ceratocystis fagacearum)
, which causes death primarily in the red oaks (Quercus rubra
). Oak wilt is spread by many species of sap beetles (Nitidulidae
), but is most often transmitted via root grafting. To avoid the spread of oak wilt by beetles, it is important not to prune or injure oaks between April and October.
The city’s oak wilt management plan is similar to that of Dutch elm disease. City tree inspectors identify infected oaks, which are then ringed with red paint for removal. In Saint Paul, high concentrations of red oaks exist in the Highwood/Battle Creek area in the southeast as well as other small pockets throughout the city. Forestry staff identified these areas of oak wilt which are monitored for progression every growing season. Bur oaks and white oaks can also be affected by oak wilt, but the species have moderate to low susceptibility.