City of Windsor begins herbicide treatment to control wild parsnip along Ganatchio Trail

The City of Windsor has begun spraying herbicide along the Ganatchio Trail system in Windsor, Ont., on Tuesday, Sept. 2, 2025. (Chris Campbell/CTV News Windsor)

The City of Windsor has begun spraying herbicide along the Ganatchio Trail system to control wild parsnip, a noxious weed that officials say poses both environmental and health risks.

“It’s an invasive plant that threatens our biodiversity and threatens our native species,” said Karen Alexander, the city’s naturalist. “It can rapidly outcompete and take over areas. And one of the major problems with this particular invasive plant is its threat to human health.”

Wild parsnip produces a sap that can cause severe burns when exposed to sunlight.

“If you contact wild parsnip sap on your skin and then expose that area of your skin to sunlight, it can create really painful blisters and burns,” Alexander explained. “And we don’t want that.”

The city hired a professional contractor to apply a federally approved pesticide known as Navius Flex along the trail. The work is expected to continue until Sept. 12, weather permitting.

Alexander said the effort is supported by an invasive species control grant from the Invasive Species Centre in Sault Ste. Marie.

“With that pile of money, we were able to bring in a hired professional to treat the entire Ganatchio trail system, and attempt to get rid of this invasive plant,” she said.

But Alexander cautioned the work will take time.

“It not only takes several days, it takes several years because the plant will come back,” Alexander said. “There’s a seed bank here now, so we will have to continue controlling it year after year until we are happy with the results.”

Trail users like Bernie Cameron welcomed the city’s action.

“I appreciate the effort because this forest is really well used,” Cameron said. “The other side of the forest is quite thick with vegetation, and they’re keeping control of the noxious weeds by doing this kind of work. So it’s really awesome.”

Officials say wild parsnip is already established across Windsor, particularly in disturbed areas such as roadsides and construction zones.

Alexander said residents who spot large patches can report them using the iNaturalist app or through the Ontario Invading Species Hotline.

“We’ve started mapping invasive parsnip in some of our larger park systems, and we’re going to keep doing that to get a better idea of how bad the problem might be,” she said.

Alexander said the plant is easy to identify in late summer, when it produces umbrella-shaped clusters of yellow flowers.

For anyone exposed, she advises washing the skin immediately with soap and water and avoiding sunlight.

“I think we can expect it’s here to stay,” Alexander said. “What we do is manage the best we can and keep it under control, so that we can keep people moving around our parks with less concern.”