Landowners urged to be aware after oak wilt discovered in Niagara Falls neighborhood

JUNE 14, 2023 – Oak wilt, a devastating fungal disease that targets oak trees, has been identified in a residential area in Niagara Falls. This is the first confirmed detection of oak wilt in Canada.

With the aim of preserving the long-term health and beauty of the oak population considering the recent detection, experts are emphasizing the importance of avoiding tree pruning until winter, employing pruning sealer or tree paint over any wounds, refraining from moving firewood, and promptly reporting any suspected cases of oak wilt to the Canadian Food Inspection Agency (CFIA).

Oak wilt, caused by the fungus Bretziella fagacearum, poses a significant threat to oak trees. Once infected, these trees can experience rapid decline and mortality. The fungus spreads from infected oak trees to healthy oak trees on the back of sap beetle that like to drink the sap from fresh wounds (like a pruned limb, cut down tree or broken branch). Once a tree is infected it can spread to healthy neighboring oak trees through root system connections. Red oaks are more susceptible to the fungus, while white oak have been showing some tolerance to the fungus, and slower symptoms.

Colleen Cathcart, Forestry and Landowner Services Technician at Kawartha Conservation, warns of the potential consequences of the disease.

"Oak wilt can quickly spread from one tree to another, leading to devastating losses within the oak population if not adequately addressed” she said.

To curb the spread of oak wilt, it is crucial for residents and landowners to adhere to recommended practices. First and foremost, tree pruning should be postponed until the winter months, between November and March. Do not intentionally damage oak trees between April and October. During the cold months, the fungal spores are less likely to be transmitted, reducing the risk of infection. By avoiding pruning when the sap beetles are most active (April – October), the chances of transmission are greatly diminished, safeguarding the health of nearby oak trees.

In all cases of oak tree pruning, it is essential to apply wound paint immediately after making a cut or causing damage, especially if the wound is created during the warm seasons, but also during the winter months too. Wound paint acts as a protective barrier, preventing the entry of fungal spores into the tree. This simple yet effective measure can significantly reduce the risk of infection and subsequent tree mortality.

Recognizing and reporting suspected cases of oak wilt promptly is vital to effectively combat the disease. The CFIA plays a crucial role in monitoring and managing the spread of invasive pests and diseases. If you notice signs of oak wilt, such as wilting, discolored brown “wilting leaved” leaves starting high up in the crown, defoliation in the spring and summer, or fungal mats (pressure pads) on the trunk of oak trees. These pressure pads smell a lot like juicy fruit gum. It is essential to report the findings to the CFIA for further investigation and appropriate action. Take photos and document your findings.  

Cathcart stressed the importance of community involvement in helping to identify and protect against oak wilt.

"We rely on the vigilance of our residents and landowners to detect and report any signs of oak wilt,” she said. “By working together, we can help mitigate the impact of this disease and protect our oak tree population.

“The discovery of oak wilt in Niagara Falls should serve as a wake-up call that it is now in Ontario, and while it may be some time before it reaches the Kawartha watershed area, residents and landowners should remain vigilant and take necessary precautions,” she added. “By adhering to recommended practices, such as postponing pruning only through the winter months, using wound paint, avoiding the movement of firewood, and promptly reporting any suspicious cases, we can collectively preserve the grandeur and ecological value of oak trees for future generations.

Cathcart noted the loss of oak trees will have a big impact on the biodiversity in forests as well as impact food for wildlife because of the importance of the acorn. Oak trees are also important to stabilize slopes and reduce soil erosion.