The knotweed problem in Maple Ridge and Pitt Meadows - and regionally - has hit a critical point, according to a local invasive species expert.

Knotweed has been around for a couple of decades, but Jennifer Grenz of the Invasive Species Council of Metro Vancouver (a non-profit group not affiliated with the Metro Vancouver regional government) said the problem is a lot worse than she had previously thought.

She has been in Maple Ridge and Pitt Meadows over the past few weeks trying to get a handle on the problem.

David Boag with the parks and leisure services spoke with Maple Ridge council on Monday about giant hogweed - of which there have been a handful of cases in Maple Ridge - and about knotweed.

While the latter doesn't cause any health issues, it "absolutely" has to be addressed, Boag said.

He suggested to council that next year's budget should include money to hire a consultant to create an inventory and map out where knotweed exists in Maple Ridge. In addition, he suggested funds be allocated to control the invasive species.

Knotweed, because of its ability to burrow through concrete, can damage homes and public infrastructure, Grenz said, noting it has done so in the United Kingdom.

Knotweed can grow four or more centimetres per day, and can take over areas and become a monoculture.

"It's not a normal plant - it's a plant on steroids," Grenz said.

Currently, knotweed is rampant at Alouette River, and Grenz said its impact on fish habitat in the river could be "significant."

Ditches and riparian areas are ideal for knotweed to grow, as it loves wet roots.

"I liken knotweed to an iceberg - what you see is just a small portion," Grenz said.

Last July, the provincial government added knotweed to its invasive species list, which means the owner or occupier of property where knotweed is growing is responsible for controlling the plant.

Councillor Cheryl Ashlie, as the council liaison to the Alouette River Management Society, learned about knotweed at a meeting between the invasive species council and ARMS which she was invited to attend, and she was "mortified" at the size of the problem.

Ashlie said she is concerned that knotweed might turn into the "Lower Mainland's pine beetle" and affect the economy.

"We need to make sure we get on top of it," she said.

She'd like to see a multi-pronged approach, including educating the public and the District's operations staff, so people know how to deal with it without making it spread further.

Ashlie said the knotweed issue highlights how local non-profit groups are "invaluable" in their advocacy.

"You see why these types of groups are so imperative," she said.

Knotweed and giant hogweed have the highest priority among invasive plants in Metro Vancouver parks, according to Alison Evely, Metro natural resource management specialist.

Knotweed is spreading "rapidly" in the region, primarily through soil movement, both through construction and natural erosion, Evely said.

"Cultural practices such as flail mowing also contribute to its spread," she added. "It is becoming very common along roads and ditches in Maple Ridge and Pitt Meadows. Knotweed does not respond to manual removal, and attempts to do so may contribute to its spread."

Grenz said that, as an organic farmer, she doesn't take the issue lightly, but for the "greater good," she recognizes that herbicides are necessary to get rid of knotweed.

In July, the Invasive Species Council of Metro Vancouver requested funding from Metro Vancouver to develop a regional strategy. The staff report will go the environment and parks committee today (Sept. 11).

mrantanen@mrtimes.com