By Michael DeRuyter Sun Jun 19 20110 Recommend Region losing battle against invasive plant
KITCHENER — It’s big, mean and hairy and it doesn’t belong here, but it may be in the neighbourhood to stay.
The giant hogweed is an invasive plant from Asia that was brought to North America about a century ago and has been making its way across southern Ontario in recent years. In 2008, the Region of Waterloo designated it as a noxious weed.
When the name hogweed is mentioned to John Stewart, the manager of forestry and horticulture for the City of Waterloo, the first thing he does is laugh with regret.
“I have quite a lot to say about that plant,” he says. “It’s becoming a big issue across the entire watershed. We see it cropping up all over.”
A member of the carrot and parsley family, the hogweed grows in moist soil along rivers and in ravines. It suffocates local vegetation and can grow to more than four metres tall. It has wide green leaves with a cluster of white flowers on top, along with a stem that has purple blotches and is extremely hairy.
A single plant can produce about 100,000 seeds, so its spread can be quick and overwhelming. Stewart recalls an area of the city where they were sure the plant had been eradicated, only to find hundreds there the next year. Despite its stubbornness, Stewart still appreciates the plant’s stature.
“It’s a very impressive plant, wow, is it massive,” says Stewart, before quickly adding, “just don’t touch it.”
He doesn’t laugh while giving that warning. The sap of the plant is a caustic substance, and skin which has contacted the sap becomes extremely sensitive to sunlight, leading to burns and blisters that remain for a long time and can scar. If the sap gets into your eye, it can cause serious and possibly permanent damage.
“A friend of mine got burned because of it, and they had to treat it with steroid injections and it took a long time to heal. It was nasty,” says Stewart.
Currently, city staff wear suits with rubber gloves and boots when removing the plants by digging them up, or by removing the flower of the plant to stop the seeds from spreading. While Stewart says they are doing all they can, he admits that hand-digging each plant is “becoming overwhelming.”
According to Stewart, the only effective way to kill them is to inject a pesticide into the plant. However, provincial legislations restricts the use of pesticides unless it is threatening agricultural land, meaning that the city can do little to stem the tide in parks.
“We are between a rock and a hard place,” says Stewart. “We just feel like we have our finger in the dyke right now.”
Exacerbating the problem is that despite the effort of the city and of the Grand River Conservation Authority, which also is fighting to control it, they are at the mercy of landowners when it comes to private land.
“We will be working on one side of the river and get it removed and then look at the other side on private land and see a bunch of them in flower,” he said.
If hogweed is spotted by region residents, they are asked call the local municipal weed inspector at (519) 575-4016.
Eventually, Stewart thinks that the plant will become like a poison ivy, with the city having little to do but inform people of its dangers.
“I don’t know what to do,” he admits. “It’s almost to the point where all we can do is educate the public to please stay away.”