Giant hogweed in Orillia’s north ward
An eight-foot-tall hogweed towered over Bob Bowles in Orillia’s north ward Thursday afternoon.
The poisonous plant was growing along Sundial Creek on a city property off Sundial Drive.
“If we watch for it and eradicate it when we see it, I think we can keep it under control,” Bowles, a local member of the Ontario Invasive Plant Council, said Thursday. Hogweed’s watery, clear sap contains photosensitizing compounds called furanocoumarins. When the compounds come into contact with skin and the individual is exposed to ultraviolet (UV) radiation (the sun), the sap turns to poison. It causes serious burns and blistering rashes. The sap can also cause blindness if it gets in someone’s eyes.
“It can be a painful experience,” Bowles said. “It’s not the juice itself; it’s once the sunlight, the ultraviolet light, hits it, it reacts with the chemical and causes a rash.”
The invasive plant — which comes from Southwest Asia — has a thick, tall stalk with purple blotching, one-metre-wide leaves and large white flower heads. Hogweed can grow 10 to 12 feet tall in one season.
“It was brought over here as a garden oddity,” Bowles said. “People didn’t realize it had this dermatitis property.”
Using eye protection and gloves, Bowles dug up the Sundial Drive hogweed and left it to die in the sun.
“Cutting the heads off before they go to seed is a big thing,” Bowles said. “Once it’s out of the ground, it will die.”
One flower head can produce thousands of plants.
The seeds spread when they are carried by water, on people’s footwear and by pets, Bowles said.
Hogweed has established itself in parts of Ontario and presents a public safety hazard, states the Ministry of Natural Resources (MNR) website.
Generally, landowners are responsible for dealing with giant hogweed on their properties. The MNR recommends consulting a professional exterminator to remove the plant.
If attempting to remove it yourself, the MNR recommends following the instructions at invadingspecies.com.
The first hogweed was found locally in 2000.
“No one really did anything about it,” Bowles said. “If we don’t do anything about it, it just continues to spread.”
In 2010, thousands of plants were found growing in Severn Township along the Uhthoff Trail.
“The Township of Severn has been spraying it,” Bowles said, adding the numbers have decreased.
The MNR, in partnership with the Ontario Federation of Anglers and Hunters, is tracking and monitoring the spread.
The MNR requests people report giant hogweed sightings to the Invading Species Hotline at 1-800-563-7711 or at invadingspecies.com. The MNR will confirm whether it is giant hogweed.
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