Oak wilt and what you can do to protect your oak trees

Oak wilt is a non-native fungus (Bretziella Fagacearum) that can affect all types of oak trees. Oak wilt attacks the water-conducting vessels in oak trees. Initial symptoms show leaves browning from the point of infection and spreading throughout the leaf canopy. Dead leaves fall to the ground. Oaks in the red oak group (with pointed leaf tips) are the most severely affected, and die within a few months of infection. Oaks in the white oak group (rounded leaf tips) are more resistant and may take years to succumb.

Oak wilt is spread in two ways. The first way is from sap beetles which feed on sap from freshly broken branches or other wounds. Sap beetles are attracted to the fungus and can transmit the disease from a dead infected tree to a healthy one from a fresh wound. The second way oak wilt spreads is through root grafting. When oaks grow in close proximity to one another, their root systems can grow together forming a large, combined root system. Root graft transmission of oak wilt accounts for the the majority of all oak wilt infections in large woodlands.  

Here’s what we can do

Shadywood Tree Experts can help maintain your uninfected oak trees with the use of systemic fungicide trunk injections and removal of infected trees. When you sign up for plant health care from Shadywood, we administer the recommended protocols for disease prevention control to keep your trees healthy. With each visit, our arborists assess trees for overall health.

Oak wilt infected trees tagged by the city forester for removal

Oak wilt spreads from infected oaks to nearby oaks through root grafting, you can see the newly infected tree here and an older dead tree further back into the woodland

Additional things you can do to maintain the health of your oak tree

Only have oak trees pruned when the Oak wilt risk status is safe. At Shadywood Tree Experts, we follow risk status updates from the University of Minnesota. Water trees regularly using a hose or lawn sprinkler for at least an hour every one to two weeks if there has not been adequate rainfall. Mulch root systems when possible, using natural wood chips to protect the trunk, condition and improve the soil, and to conserve soil moisture. If you see anything that doesn’t look right, have your trees inspected by one of Shadywood Tree Experts International Society of Arboriculture Certified Arborists.