Committed to conservation, rare Charitable Research Reserve in Cambridge continues to battle against giant hogweed, the invasive species taking over flood plains near the Grand River at an alarming rate.
But as numbers grow and efforts continue to remove the plants, rare planning ecologist, Tom Woodcock, says more assistance is needed to identify and control the invasive and dangerous species.
Giant hogweed can cause serious injury to humans that have contact with its sap and can crowd out native species and spread rapidly via water in floodplain habitats.
In September, Woodcock reached out to the Grand River Conservation Authority (GRCA) hoping for future collaboration on a watershed-wide effort that can bring together municipalities, environmental organizations and landowners to address giant hogweed in the short and long term.
"The continued strain on staff and resources to address giant hogweed infestation on our property cannot continue, particularly when easily observed plants on adjacent properties are left to flower and go to seed, but for the efforts of John Kemp and his generous volunteers," Woodcock writes in a letter to the GRCA.
John Kemp created the Giant Hogweed Mitigation Project, a volunteer run group dedicated to the removal of the invasive species in Waterloo region.
"This sort of sprung out of conversations from Mr. Kemp and his group who work tirelessly to fight giant hogweed," Woodcock said.
"We are really hoping to bring together property owners and managers, and try and get some sort of a collaborative effort. This is a public health problem and a public sustainability problem. It really shouldn't fall to a volunteer organization."
The rare Charitable Research Reserve is an urban land trust and environmental institute formed in 2001 after the acquisition of more than 900 acres of lands from the University of Guelph.
The organization now protects more than 1,250 acres on eight properties across the Region of Waterloo and Wellington County, including several kilometres of shoreline on the Grand, Speed, and Eramosa Rivers.
Giant hogweed began to appear on the rare floodplains in Cambridge and North Dumfries in increasing numbers in 2014 and 2015, which was rare's first years of record keeping.
In 2015, 422 plants were removed from its floodplain areas, and a concerted effort each year gradually reduced those numbers, until only 16 plants were discovered and removed in 2020.
However, Woodcock says, since that time, there have been dramatic year-over-year increases in giant hogweed populations on rare property, with 730 plants removed in 2021, 994 in 2022, and 807 in 2023.
A doubling of this three-year average was seen in 2024, with 1,485 plants removed by rare staff.
"We have seen about 50 to 100 per cent increases despite our efforts, year over year. And Mr. Kemp has noticed in some places, even greater increases."
Giant hogweed is on the noxious weed list an can pose a serious health threat.
It contains sap that sensitizes skin to sunlight. Once the sap comes into contact with skin, exposure to sunlight can cause severe burns and painful blistering, usually within 48 hours. Blisters can develop into purple and black scars, leading to recurring inflammation and dermatitis as well as permanent scarring. Contact between the sap and eyes can lead to temporary or permanent blindness.
Woodcock says Giant Hogweed is usually found in food plain areas, near rivers.
"They flower once when they are a few years old. Maybe two to five years old, depending on how healthy they are and how good a spot they are growing in. But a single plant that flowers, can produce tens of thousands of seeds. So, they have the potential to increase quite quickly," Woodcock said.
"When the giant hogweed drops its seeds, then the river carries the seeds down stream and deposits them in flood plain areas. And that's what we see," Woodcock said.
Woodcock says the plant offers a couple advantages to aid the search for it because it's a distinctive looking plant and it tends to sprout before everything else.
"If you go out in the spring, you can see the little ones sprouting up much more easily. You can take a shovel and pop them out of the ground. Their roots will be exposed and they will die. We do that with hundreds of them every year, as opposed to later in the season, when you might see giant white flowers," he said.
"That's when it's much more difficult. You have to suit up in a bio hazard suit and go out and cut them down. It's a much more intensive and time consuming process."
Woodcock says pubic agencies will often control giant hogweed where people are expected to be, such as trails and canoe launches.
"But they may not be putting the effort in places that are off the beaten path," he said.
"Along the Grand River watershed, Canoers stop at random spots, and fishermen wander all over the place and an come come into contact with hogweed pretty much anywhere."
The GRCA says is it is aware that giant hogweed has spread throughout southern Ontario and that it does recognize the impact it has on human health if someone comes in contact with this plant and appreciate your concerns.
Although it has a limited role in management and mitigation of invasive species, and most legislation falls under the jurisdiction of the provincial and/or municipal governments, GRCA says it will continue to work within its own role to help mitigate the local impact of giant hogweed where possible.
"Municipalities have been pretty good. If there is Hogweed on City of Cambridge land, they are certainly on top of it. They will come out and control it with their staff," Woodcock said.
But Woodcock hopes for more public input.
"I have heard some interest. And we are going to try to host a gathering of parties, a get together and see if we can start the conversation here at rare," he said.
"An active approach is necessary. It's got to be a lot of boots on the ground."
