Plan to protect 14,000 oak trees is underway in Mississauga


Published May 9, 2024 at 1:58 pm

Mississauga looks to keep its oak trees healthy.

Mississauga is taking steps to protect the city’s more than 14,000 oak trees from a disease that spreads rapidly and can kill trees within a year.

While there are no known cases of Oak Wilt in Mississauga at this point, the disease has been found in trees in nearby cities including Niagara Falls and Springwater, near Barrie, according to the City of Mississauga.

That has prompted the city to take a proactive approach and have its staff — and Mississauga residents — be on the lookout for signs of the disease.

City officials said in an online update Oak Wilt impacts all species of oak trees, particularly red, pin and black oaks. The disease is caused by a non-native fungus called Bretziella fagacearumwhich restricts the flow of water and nutrients in infected trees, they added.

To prevent a possible Oak Wilt infection, the city said it will not prune oak trees between April 1 and Oct. 31 this year unless “exceptional circumstances such as potential safety hazards occur.”

In those cases, city officials noted, they’ll apply a protective coating to the tree’s wounds to prevent attracting beetles that spread Oak Wilt. The city also plans to use protective coating on all oak trees pruned now through Oct. 31.

Discoloured leaves are one sign of Oak Wilt. (Photo: City of Mississauga)

“Additionally, the city is educating city staff members, residents and partners about Oak Wilt, detecting it early and preventing the spread,” city officials said, noting the important role oak trees play in a healthy, thriving community.

“Mississauga has over 14,000 oak trees that provide important benefits, including slope stabilization and reduced soil erosion and pollution. They also provide habitat and food sources for many wildlife species. The loss of oak trees from Oak Wilt would result in the loss of these benefits.”

Officials said the fungus responsible for the disease is spread by picnic beetles and through root-to-root contact or by people moving around firewood with pests and diseases.

Oak trees infected by Oak Wilt will show:

  • leaf discolouration and wilting
  • early leaf drop
  • change in the colour of leaves near the crown of the tree
  • cracks in the bark
  • fungus in the form of grey or tan mats found under the bark of infected or dying trees

The city says residents can do their part to protect oak trees across Mississauga by:

  • learning how to identify oak trees and Oak Wilt
  • avoiding pruning oak trees between April 1 and Oct. 31. If you must prune your tree during this time, paint the wounds with pruning paint or any latex-based paint
  • not moving firewood around
  • being on the lookout for signs of infection on your oak trees
  • reporting suspected Oak Wilt to the Canadian Food Inspection Agency or by calling the city’s 311 line
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