University of Guelph student Meghan Grguric researching how to eradicate invasive giant hogweed in Ontario

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Meghan Grguric’s research into ways of dealing with giant hogweed, a towering invasive plant that can inflict serious injuries, has convinced her of one thing.

The plant is here to stay.

“There is no way we can eradicate it. All we can do is control it to the best of our abilities,” said Grguric, a University of Guelph master’s student. “Once an invasive species gets in, you can’t really eradicate it, unless you are tackling it very early at the source.”

Grguric is investigating different control methods for giant hogweed, which has been found along branches of the Thames River near London and across the province.

Originally introduced as an ornamental garden plant in North America in the early 1900s from southwest Asia, giant hogweed is now considered a significant threat to human health.

The sap of the hogweed plant can cause severe burns and blisters that are triggered by sunlight.

Grguric said hogweed’s large seed production and the seeds’ ability to remain viable for years makes it a difficult plant to stop.

She’s found one of the most popular control methods, the herbicide glyphosate, sold as Roundup, has limited value.

“If you go in and spray giant hogweed, it kills all the vegetation around it as well, which you don’t really want,” Grguric said.

Not only does that leave an area open to erosion, but glyphosate has no residual control and giant hogweed starts popping up again a few months later, she said.

Grguric, in her first year of her field research into controlling giant hogweed, is also investigating injecting herbicides directly into flowering plants.

Another method being tried in her research is repeatedly cutting down hogweed plants.

The first time it’s cut off, hogweed will send up another smaller stem from the root system that will flower fairly quickly, she said

“We are looking at cutting it multiple times to see if the seed will persist and if it is viable and will germinate.”

For landowners who find giant hogweed on their property, Grguric recommends caution.

Despite wearing a Tyvek suit during her research, Grguric has scars on her wrist and calf from giant hogweed exposure.

“The one I’m really sad about is the one on my calf,” she said.

Grguric will be continuing her research next summer.

jminer@postmedia.com

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