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Oak Wilt Management



Oak wilt is a disease which threatens Canadian oak trees. Although the disease is not currently known to occur in Canada, it has been found less than ½ km from Ontario’s border making this disease a new invasive threat to Canada, especially to Ontario and Eastern Canada. Oak wilt can kill a healthy tree in as little as 3 weeks and is known to rapidly spread between neighbouring trees. Containing new infestations requires quick management intervention which makes having a network of trained tree care professionals particularly important. 


In August, ISC staff attended an oak wilt control course held by the Arboriculture Society of Michigan. During this workshop arborists from Michigan reviewed the management tools that are commonly used to contain oak wilt infestations. Techniques regularly utilized to contain oak wilt in Michigan include:


1.     Trenching – To break root connections that could enable disease transmission, a piece of heavy equipment is equipped with a 5’ vibrating blade to trench around infested trees.

2.     Tree & Stump Removal – To remove spore-producing dead wood, arborists will fell and remove infected oak trees. Arborists will then grind or pull impacted oak stumps to prevent further oak wilt transmission.

3.     Fungicide – To protect high-value or high-risk trees from oak wilt infection, licensed applicators inject selected trees with a fungicide to avoid disease transmission.

4.     Herbicide – When appropriate herbicides are used to kill oak trees prior to being infected by oak wilt to form a barrier to preventing oak wilt spread through living trees.


Regardless of which management techniques are used, oak wilt infestations are devastating. All management techniques used in Michigan and other areas impacted by oak wilt can be costly in both ecological and economic terms. This makes preventing this disease important in enabling us to protect Ontario’s oak resources.

The Invasive Species Centre has also created an oak wilt factsheet, offers oak wilt training, and sits on an oak wilt technical advisory committee. To learn more about oak wilt and other invasive forest pests and pathogens visit www.forestinvasives.ca.