Tree Disease : Oak Wilt Disease

Oak wilt disease now in Ontario

The first confirmed cases of Oak Wilt Disease were found in Ontario in 2023 in the Niagara region and near Barrie. 

What is Oak Wilt Disease?

Oak wilt disease is a vascular disease of oak trees, caused by the fungus Bretziella fagacearum*. The fungus grows on the outer sapwood of oak trees, restricting the flow of water and nutrients through the tree.

It is crucial to avoid pruning or injuring oak trees when the fungus is most likely to be active. Logan Tree Experts will not be pruning oak trees between April and November. If we cannot avoid pruning (due to storm damage, etc) we will use a wound sealer to protect the tree from the disease.

Photo credit: Invasive Species Centre

What can you do?

• Get to know the signs and symptoms of the disease. Click here to learn more.
• DO NOT move firewood.
• Report to cases to the Invading Species Hotline at 1-800-563-7711 or invasive.species@ontario.ca

For more information on pests and diseases that could affect your trees, visit our Learnng Centre.