WATERLOO — The call comes in and immediately the city dispatches someone to check on the potential threat.

Diligent monitoring is crucial in eradication efforts targeting the dangerous species lurking throughout Waterloo Region — giant hogweed.

"We are right on it," said Andrea Bazler, weed inspector for the City of Waterloo. "We take it really seriously."

A team went out to Bechtel Park on Tuesday after a report of a dog suffering with serious wounds on its paws after possibly being exposed to the plant's toxins while walking in the area.

Giant hogweed sap can cause severe burns when it gets on skin and then is exposed to sun. Once the painful blisters heal, purple scars may form that last for years.

No signs of giant hogweed were spotted in the leash-free park. The official trails through the park are regularly monitored as the Waterloo park is an area where giant hogweed is known to grow, and any giant hogweed found is destroyed.

"If people stay on trails, there should be no problem and if they keep their dogs on leash," Bazler said.

However, other paths have been blazed through natural areas in the park and adjoining private property in the City of Kitchener where giant hogweed can flourish.

Bazler pointed out a footpath where someone recently mowed down the greenery, including a patch of giant hogweed. Felled plants were right on the pathway where people or pets would walk, and growing hogweed nearby could easily be brushed against inadvertently.

"You don't want to touch any part of the plant," Bazler said.

Giant hogweed's size — it grows as tall as five metres — gives it away. The thick stems have bristles and purple splotches or completely purple patches.

The large, umbrella-like flower heads can grow as wide as 1.5 metres. Giant hogweed is easy to spot when it flowers, but that's only in June and July.

Far from an innocuous ornamental plant, giant hogweed is a significant hazard to both health and environment — and the imported perennial is prolific.

"It's not a native species," Bazler said. "If you leave it, it will take over large areas."

That's what eradication programs in local municipalities want to avoid, even if it is a difficult task.

A giant hogweed plant can produce 10,000 to 100,000 seeds, and those remain viable for up to 15 years. That means new plants sprout year after year where soil contains seeds, and one plant hiding along a creek can send loads of seeds downstream to grow on banks and areas that flood.

"The seeds get into the water and it just carries it everywhere," Bazler said.

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The plants often grow in spots that are difficult to access, such as wet areas, rocky shores and densely vegetated areas, which adds to the challenge of eradication.

Giant hogweed on the unofficial footpath near Bechtel Park was marked with bright spray paint to be easily spotted by the contractor brought in to spray the plants, causing them to wilt and die. Physically removing the plant is a dangerous endeavour requiring protective gear and it's not always successful.

"Even if you cut them down, they keep coming back until they flower," Bazler said.

Giant hogweed has been found on several Grand River Conservation Authority properties near Cambridge, Kitchener, St. Jacobs, Belwood Lake and Guelph. The conservation authority and local municipalities all have weed inspectors on the lookout for giant hogweed to check its spread, and anyone who spots the plant is encouraged to report it to the local municipal weed inspector.

When giant hogweed is seen growing on private property, bylaw staff will contact the owner and offer advice on removal.

Waterloo has a map of every area where giant hogweed is known to grow, and those areas are inspected annually, Bazler said.

"It's an ongoing effort to eradicate it, so we do it year after year."

jweidner@therecord.com

Twitter: @WeidnerRecord

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