Perth County council defers Giant Hogweed treatment initiative to 2026

A plan to monitor, control the spread of and ultimately eradicate the invasive weed species, Giant Hogweed, in Perth County has been deferred for consideration in 2026 as Perth County staff make adjustments to bring it more in line with available grant funding from the province.

At the Jan. 23 Perth County council meeting, councillors voted in favour of a recommendation made by the county’s agricultural working group at its meeting in December. Though the working group supports the program in theory as an enhancement to the county’s existing forestry and invasive species program, it suggested refinements are needed to the project plan to better align it with the objectives of available grant funding.

“A concern around treating the invasive species called Giant Hogweed was identified as a need, thereby necessitating an expansion to our existing county weed-control program,” said county resilience and stewardship coordinator Hannah Cann. “Giant Hogweed is a hazardous, invasive plant from central Asia which poses a risk to humans and ecological health. Giant Hogweed spreads quickly and easily through watercourses as its epic number of seeds disperse easily through the air and the plant often infests riverbanks and marginal lands.

“Treatment is challenging due to this threat to human health and safety with chemical treatment being the most effective option for eradication. Long-term treatment strategies are often required for this species, like many other invasives, and therefore demands for adequate treatment of this species are above and beyond our existing budgetary constraints for weed control in the county, making access to grant dollars desirable.”

Cann said there was an opportunity in the fall and winter of 2024 to expand the county’s weed-control program to include Giant Hogweed treatment through the Invasive Species Centre’s Invasive Species Action Fund, which offered one-to-one, matching-dollar funding for invasive-species mapping and eradication projects.

A plan for the mapping and eradication of Giant Hogweed was presented to the agricultural working group at its Dec. 10, 2024, meeting for feedback because it would involve work on both public and private land across the county. As the working group recommended the program be adjusted, staff brought a report to county council Jan. 23 with a recommendation to defer the project to 2026.

The plan, as it was presented to the working group, included the following actions:

• Identifying hotspots for Giant Hogweed in the county through public reports and regular surveys conducted by the county weed inspector in known and potential areas of infestation such as riverbanks, parks and roadsides. County staff would also use historical data and reports from partner agencies to identify areas with repeated Giant Hogweed occurrences to develop patterns and predict future hotspots.

• Mapping current infestations using the county’s geographical information systems and evaluate the potential risks to ecological and public health associated with each infestation area. Staff will also be able to prescribe proper treatment methods based on the severity and location of each infestation.

• Chemically treating each infestation by trained, certified professionals who adhere to local and provincial regulations, and environmental guidelines, especially near water bodies. Treatment would likely occur between April and June.

• Monitoring treated areas and retreating if necessary. This plan would also seek to empower landowners and community groups to help monitor, identify and report new instances of Giant Hogweed.

Had this program gone ahead this year, Cann said the county would have looked to spend an additional $25,000 that could have been matched for a total of $50,000 through the Invasive Species Centre’s Invasive Species Action Fund. The deadline for applying for funding through that program in 2025 has now passed.

“We’ve been dealing with this in West Perth for a number of years,” said Walter McKenzie, county councillor and West Perth mayor. “It’s all along the Thames River. I’m going to say three or four years at least we’ve been dealing with it, and I guess until such time as its control is a little more broader and countywide, what we’re trying to do, I guess, is futile if we’re not going to control it in other areas.

“I don’t know what other municipalities are doing, but I’d assume it must be all along the waterways. Anybody who has had contact with it; it’s not nice.”

According to the staff report to council, Perth County’s weed inspector has been tracking and treating Giant Hogweed since 2007, but there is community knowledge of the plants being in the county for over 40 years. In 2007, the weed inspector petitioned the province to allow Perth County to add Giant Hogweed to the local list of noxious weeds. Following this request, the Province of Ontario added Giant Hogweed to the Schedule of Noxious Weeds under the Weed Control Act of 2009.

Since that time, Perth County has been unofficially tracking hotspots and treating publicly accessible areas with herbicide, as well as supporting and encouraging landowners to watch for infestations and treat them accordingly.   

In recent years, the City of Stratford has undertaken work specifically towards Giant Hogweed, contracting the services of the Upper Thames River Conservation Authority (UTRCA) to track and treat infestation locations to reduce risk to humans and environmental health. The local municipalities in Perth County also have treatment contracts with their relevant conservation authorities for the treatment of Japanese Knotweed, Phragmites Australis, Common Buckthorn and others.

While county staff previously reached out to the UTRCA to determine what capacity it has to support the county’s proposed Giant Hogweed plan, deputy warden Dean Trentowsky asked staff to touch base with the other local conservation authorities – the Ausable Bayfield Conservation Authority, Maitland Valley Conservation Authority and Grand River Conservation Authority – to determine what capacity they have to support this program.

A report on this program will likely be brought back to council as part of 2026 budget deliberations in the fall.