Oak Wilt was recently detected in Ontario. See resources and information below.
We’ll update this page frequently as more information is released.

In June 2023 Oak Wilt was confirmed in Niagara Falls, Ontario. This is the first confirmed detection of Oak Wilt in Canada. It has also now been detected near Barrie, Ontario and in Niagara-on-the-Lake. Movement restrictions are currently in place on the affected properties.
There are many pests and diseases of concern in the urban forest. It can be terrifying to think of Oak Wilt killing all the oaks in Ontario, but it is helpful to keep in mind that Oak Wilt has been around in Wisconsin and Michigan for decades, and while certainly killing many of their oak trees, it has not decimated them with great speed like we saw with EAB.

For now, here's what you can do:

• Do not prune or wound Oaks between April and November
• Do not move firewood (of any species)
• Report suspected Oak Wilt to the CFIA

Download ISA Ontario’s one page handout on Oak Wilt here.

Feel free to print, email and share to help get the word out.

Oak Wilt is caused by a fungus that is transmitted by bark beetles.  The beetles won’t travel long distances (a few km), and neither will the fungus (either through spores or through root grafts) – unless transported by humans.  
**This is why it’s extremely important to not move wood / firewood.**

Oak Wilt is often characterized by:

• sudden leaf drying and drop during the summer
• leaves wilting, or browning, first on the edges of the leaves (often leaves at the top of the tree show signs of stress first)
• bulges under the bark where the fungus is sporulating – which leads to vertical cracks in the bark – seen in late fall or early spring.

Red oaks (eg. Pin oak, northern red oak) are the most susceptible, although all oaks are affected.

If you suspect your tree has Oak Wilt, you can reach out to CFIA by completing their online submission form.

Crack in bark of infected red oak tree (left) Leaf discolouration on red oak (right) – photos courtesy of Invasive Species Centre

See additional photos from ISC here.

When Oak Wilt is discovered, the infected trees should be removed and disposed of properly to prevent further spread. Burning of the wood, or chipping are recommended. As well, the stump must always be removed or buried. Adjacent oaks that may have root grafted and become infected underground yet not yet showing signs of the fungus may need to be removed as well. Any stored firewood/logs should be de-barked or tarped.

As always, it is smart to take care of your mature trees just like you would any other shrub or plant in your yard. Water your trees during drought and keep other stresses to a minimum (e.g. Spongy moth).

Now that we know the spores are in our region, it is extremely important not to unnecessarily wound your oak trees between April and November when the fungal spores are active. Even small broken branches, or bark damage from tree climbing can be an invitation for the sap-loving beetles to enter the tree and infect it.