Oak wilt is a lethal tree disease caused in oak trees by a fungus, bretziellafagacearum (sometimes known as ceratocystis fagacearum) which is often introduced to the trees by beetles. The beetles carry the spores from infected trees and spread the disease when they feed on the sap from cuts or wounds on the trees. Sap beetles are attracted to these fresh tree wounds, which happen with storm damage or even pruning. The trees respond by cutting off the sap to branches to keep the disease from spreading and that causes the wilt. Red oaks are extremely susceptible and will die within a week, although all oak trees, even white oak varieties will eventually succumb. The fungus can also spread from tree to tree though the roots underground and destroy an entire stand within weeks. Early detection and diagnosis by a certified arborist are critical to the survival of infected trees.
Symptoms: excessive leaf shedding, wilting branches, leaf discoloration, dead trees
More information: Michigan Oak Wilt Coalition and MSU Extension