Toxic, invasive weed hits southern Ontario

OTTAWA (CBC) - Biologists and health officials in southern Ontario are scrambling to contain an invasive plant that can cause blindness and severe burns.

Heracleum mantegazzianum, or giant hogweed, is a poisonous plant most recently found growing in Renfrew County, west of Ottawa.

"The concern is it's a very poisonous plant, in the sense that if you get any of the sap from this plant on your skin, it can cause severe blistering and very bad burns," said Jeff Muzzi, manager of forestry services for Renfrew County.

"If you should happen to get the sap in your eyes, it can blind you either temporarily or permanently."

He said the burns can cause permanent scarring and any areas affected will be sensitive to sunlight for many years.

"It [exposure] could be inadvertent," Muzzi said.

"You might not even know it's here, [just] walk into it and happen to break a leaf. The next thing you know, you've got these nasty burns."

He said it can take up to 48 hours after exposure for symptoms to appear.

This is the first time giant hogweed has appeared in Renfrew County, Muzzi said, though it has been found in the western provinces and southwestern Ontario.

"It spreads primarily by seeds," he said.

"Seeds can be carried by vehicles, by people, by winds it could be a bird. It could be any reason at all and I think every plant will produce something to the tune of 500,000 seeds, so the spread potential is pretty big."

The plant can grow up to six metres tall, with leaves as big as 1.5 metres across. It is identified by large purple blotches or striping on its stem.

To stop giant hogweed from spreading further, crews in Renfrew County are embarking on a weed-whacking campaign.

Officials also plan to send out brochures warning residents how to spot giant hogweed. Anyone who sees one of the plants is asked to contact their municipality.