The city of Hamilton is asking residents to not prune their oak trees from now until November, to stop the spread of an infectious fungus.
Oak wilt, a fungal disease that impacts oak trees, was first confirmed in Ontario in May 2023, according the the Invasive Species Centre (ISC). The first case was spotted in Niagara Falls and poses a threat to the province's forests.
Oak wilt enters trees through open wounds, meaning freshly pruned trees can attract the fungus.
ISC is also asking Ontario residents to not move cut firewood long distances, which can introduce the fungus to new environments.
If you spot oak wilt, report it to the Canadian Food Inspection Agency.
How to spot oak wilt
Red oaks (pin oak, black oak, northern red oak) are more susceptible than white oaks (white oak, bur oak, swamp white oak).
The city’s website says the first sign of oak wilt browning, wilting leaves. The browning will often begin on the outer edge of the leaf, working its way inward. Within a few weeks, the tree will die.
ISC says some trees may take up to a year to die from the fungus, while others have died within two to six weeks of showing symptoms.
Another symptom of the fungus is vertical cracks in the bark with mat-like fungal spores underneath, which eventually cause the bark to erupt.
The fungus also produces a sweet smell which can attract sap beetles. The sap beetles pick up spores on their bodies and transfer the oak wilt to more trees.
The city says that once a tree is infected with the fungus, there is nothing that can be done to reverse its effects.
You can learn more about the provinces' oak wilt plan here.
