Oak Wilt - Management

Management

Oak wilt is similar to Dutch elm disease but more controllable. Beetles that carry the oak wilt fungus do not have chewing mouth parts -and need some other creature or physical damage to create open wounds - whereas beetles that carry Dutch elm disease do have chewing mouth parts. Prevention is key, as there is no permanent cure. To prevent beetle transmission, oaks should never be pruned in the spring months in the east and Midwest or February through June in Texas. Care should be taken to prevent injury to susceptible trees during this period, particularly from construction. If a tree is injured through a storm or accident in the spring, tree paint to cover the wound is advised. Reducing the source of spores is helpful. When an oak has died from oak wilt, trees should be debarked, split or chipped then burned or covered with plastic sheeting to effect composting. Heat from composting should destroy or severely enervate the fungus. Logs from trees infected with oak wilt should never be moved to unaffected areas, even for firewood.

If infection is discovered in a tree, a trench (or better yet, two generally parallel trenches at different distances from the area of risk) may be dug to a minimum depth of four feet (ca. 1.2 meters) between it and other potentially susceptible species to prevent root graft disease transmission. Such trenching will sever root grafts that may transmit the disease to neighboring trees. An infected tree should not be immediately cut down lest the oak wilt migrate down into the roots and increase the risk of passing via roots to nearby trees.Injections of propiconazole can help prevent transmission as well; as many as a half dozen injections every six months may be required to protect a large red oak near infected trees. Injections every other year may also be used to treat a white oak, if it is not yet greatly affected.

Re-assessments of control protocols in Wisconsin and Minnesota after 2005 shows that landowners and land managers will need to focus on "passive oak wilt control" especially when managing northern pin oaks on entisol soils. Passive oak wilt control means helping mother nature by speeding-up the return to native forest species such as maple, cherry, bur oak, birch, eastern red cedar(juniper), and red, white & jack pines.