District of Muskoka continues to battle invasive plants

They are harmful to the local watershed and environment or they pose a risk to public health, and the District of Muskoka is working to manage their spread and, eventually, eradicate them.

They are invasive species and the three deemed most harmful—Invasive Phragmites Australis (European Common Reed), Japanese Knotweed (Fallopia Japonica) and Giant Hogweed (Heracleum Mantegazzianum)—have been targeted by the District in its roadside management strategy. Fred Jahn, Commissioner of Engineering and Public Works, and Jamie Delaney, Manager of Environmental Compliance, at the District of Muskoka presented details about the strategy to Huntsville’s General Committee at its July meeting.

Why are these invasive species a concern?

Two of the three targeted species—Invasive Phragmites and Japanese Knotweed—are “aggressive and hard to manage,” said Delaney.

Invasive Phragmites grow densely, with up to 200 plants per square metre. They can out-compete native plants for nutrients and inhibit drainage. (Note that there are native phragmites that look similar but are not of concern.) Japanese Knotweed is fast-growing and can wreak havoc on infrastructure—it has the ability to grow through concrete and asphalt and can threaten home foundations.

The third targeted species—Giant Hogweed (pictured above)—produces a noxious sap that sensitizes skin to ultraviolet light, resulting in severe and painful burning and blistering, and can cause temporary or permanent blindness if the sap gets in a person’s eye.

(For information on invasive species in Muskoka, how to identify them, and what you can do to stop their spread, visit the District of Muskoka’s Invasive Species page.)

Invasive phragmites (Image: invadingspecies.com)

Japanese knotweed (Image: invadingspecies.com)

What is the District doing to manage them?

“The strategy is to develop procedures and a knowledge base on managing these plants on roadside and on our public properties,” said Delaney, adding that the District’s GIS database can be used to monitor specific locations and how invasive species in those locations change over time.

The District uses Integrated Pest Management (IPM) procedures to manage all pests and is required to use registered IPM contractors, Delaney told the committee. Where an infestation has been discovered, the contractor prepares and submits a report to the Ministry of Natural Resources and Forestry (MNRF) who determine if herbicide use is appropriate based on the location, time of year, and other factors that could impact the ecosystem. For 2018, 230 locations across Muskoka were identified for potential herbicide application.

“The use of chemicals would absolutely be the last choice,” said Jahn, adding that the District is not aware of any adverse long-term impact to the environment with properly applied herbicides. “It’s far better to apply the herbicide than to do nothing if there are really no other effective tools… There are a few people who feel strongly against that and that is respected, but we just don’t have a better answer yet. I want to assure you that if there was a better answer, we wouldn’t be spraying.”

Delaney said that the District continues to look at alternate methodologies for managing invasive plant species—it uses cutting programs, and it uses a solarizing technique before disposing of vegetation “which means putting it in a dark plastic bag, setting it out in the sun for a week or so until it basically rots, and then disposing of it to prevent transfer of the plant from one site to another.”

The District is also working with the Ministry of Transportation (MTO) to coordinate management efforts in areas where District, municipal and provincial roads meet.

Councillors passed a resolution in support of the District’s roadside management strategy, requesting that the MTO support the strategy and provide an action plan to address the provincial corridors and highways in Muskoka.

For additional information on invasive species in Ontario, visit invasivespeciescentre.ca and invadingspecies.com.

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