Oak wilt is a deadly plant disease that affects primarily oak trees. The disease is caused by a fungal pathogen, Bretziella fagacearum. The fungus can infect all types of oaks trees, but red oak trees are more susceptible than white oaks. Oak wilt spreads from infected to healthy trees through sap feeding beetle species or via grafts between tree root systems. Preventive measures are key to avoid or reduce infection and the spread of the disease.