Treating Oak Wilt
What is Oak Wilt?
Oak wilt is a devastating disease caused by the fungus Bretziella fagacearum. The fungus infiltrates the water conducting system of infected trees, resulting in wilting and ultimately the death of the tree. Oak wilt is introduced to an area by sap-feeding beetles that carry oak wilt spores to fresh wounds. Spore-bearing fungal mats develop under the bark in the fall or spring following the death of an infected tree.
The symptoms of oak wilt typically begin with wilting and dropping of leaves in the upper canopy. The wilting progresses down the tree rapidly, with leaves wilting and dropping to the ground during the summer months. Symptoms are most commonly observed from June through September, with July and August being the peak period.
How do I Prevent and Treat Oak Wilt?
Prevention is key when it comes to managing oak wilt, especially for species in the red oak group such as northern red, northern pin, and black oaks. Once wilting symptoms appear on a red oak, the infected tree will lose most of its leaves and typically die within about one month. However, trees in the white oak group, including bur and swamp white oaks, demonstrate moderate tolerance to the disease and can survive several years after symptoms first appear. White oaks generally experience slower disease progression and have a higher chance of survival.
While treatment is not possible for red oak trees already infected with oak wilt, it may save trees in the white oak family. Our recommended approach involves the injection of Propiconazole fungicide every two years as an effective preventative measure for healthy trees. Treatment should be conducted from May through September, with earlier application in that timeframe yielding the best results.
