Japanese knotweed is extremely hard to eradicate.

Japanese knotweed is extremely hard to eradicate.

Concrete-busting knotweed menaces Metro landscape

Nearly invincible plant now posing a challenge for one bridge and for crews building the Highway 1 expansion.



It is truly a demon weed.

Japanese knotweed, now running rampant across Metro Vancouver, can drill through asphalt, break house foundations and spring back from virtually any non-chemical attempt to eradicate it.

And it now has transportation ministry officials scrambling after it was discovered splitting concrete in the footings of the Ironworkers Memorial Bridge and infesting a Burnaby section of the $3.3-billion Port Mann/Highway 1 expansion project.

“It’s a monster plant,” said Jennifer Grenz, program manager at the Invasive Species Council of Metro Vancouver. “And it’s a huge issue in terms of infrastructure and safety.”

She said some Highway 1 construction in Burnaby from Boundary Road to Canada Way may be delayed while plants are sprayed and given time to die, adding they would otherwise grow right back up through the pavement.

The council, which manages invasive plants on local highways, is now moving to assess all provincial highway bridge and overpass footings in the region, Grenz said, and she urges local cities to do the same with their roads and bridges.

A transportation ministry spokesperson said the weed won’t delay the completion of the Highway 1 project and said the infestation at the north end of the Ironworkers bridge is not serious but is being treated.

“This plant is capable of growing through three metres of concrete,” Grenz said, adding she fears it could also rupture fuel pipelines where she’s seen it growing.

“It can very easily grow through a pipeline, making it a very serious public safety concern.”

Plenty of land slated for housing is infested, she said, adding home buyers may later find their dream home has a nightmare of knotweed growing under it because developers failed to correctly remove it.

Stem-injected herbicides are the only practical way to kill knotweed, according to Grenz, who is also a farmer in Richmond.

But she said bylaws banning cosmetic pesticide use in many cities have sown confusion over when chemicals can or should be used to kill weeds. Herbicides can be used to control knotweed and certain other species listed under the B.C. Weed Control Act, which trumps local bylaws.

Metro Vancouver lacks a coordinated regional strategy to battle introduced species, unlike the Fraser Valley and most other regions of B.C.

“Everyone is working in isolation and trying different things,” Grenz said.

One park or property may be treated with herbicide, but an adjoining one isn’t, defeating the investment of the responsible owner.

Grenz appeared before Metro Vancouver’s environment and parks committee Wednesday, asking the regional district for a $40,000 one-time grant to help develop a regional strategy for invasive pests.

The issue was referred to Metro staff for a recommendation on whether the region should develop its own strategy or partner with the council.

Vancouver Coun. Heather Deal, the committee chair, said invasive species pose a “huge problem” that threaten native species and local ecosystems.

Japanese knotweed, which is bamboo-like with heart-shaped leaves and small white flowers, originally arrived here via garden centres that sold it as an ornamental plant that would grow easily and survive neglect.

Property owners with knotweed are urged not to try to remove it manually.

Grenz said it’s almost impossible to dig deep enough to get all the roots, the plant doesn’t compost well and it readily spreads – just a 200 gram stem chunk can spawn a new plant.

For more on the invasive species council or combatting knotweed see www.iscmv.ca.

 

Japanese knotweed found under the footings of the Ironworkers Memorial Bridge on the North Shore. It was immediately treated with herbicide.  Jennifer Grenz photo

Urban region highly vulnerable to invasive species

Knotweed isn’t the only invasive pest raising alarms.

Giant hogweed is another problem plant that brings special control challenges because its sap causes serious burns.

The arrival of aggressive European fire ants, garden-destroying chafer beetles and the recent capture of a snakehead fish in a Burnaby pond have all increased awareness of other invading animals.

“Our region is scary-susceptible,” said Jennifer Grenz of the Invasive Species Council of Metro Vancouver.

The Metro Vancouver region is uniquely vulnerable, she argues, because it’s a hub for tourists and part-time residents from around the world who bring foreign species here.

Grenz said some releases of species, likely including the Burnaby snakehead, are the result of religious rites where animals or plants are deliberately released, adding more public education is needed.

Illegal dumping is also a huge cause behind the spread of invasive plants, which one yard owner chops and dumps in a ravine, park or ditch.

Grenz said some stakeholders have suggested challenges like knotweed are so onerous Metro Vancouver should instead be deemed a “sacrifice area” where authorities would give up on weed management.

That’s an untenable idea, she said.

“We have such small amount of green spaces we need to protect them as much as we can.”

But the invaders Grenz worries most about are the ones that have not yet arrived here.

“Any insect really scares me in terms of invasiveness. At least plants don’t move that fast.”

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

The Maple Ridge Community Foundation is hosting a trivia night fundraiser on Hit TV. (Special to The News)
Connie Werzun has taken up photography classes, and tok this picture along the dikes at Jerry Sulina Park one night recently. Using a seven-minute exposure, “a photo taken at night looks like it was taken during the day.” (Special to The News)
SHARE: Night photo of mountain range appears as day

Send us your photo showing how you view Maple Ridge or Pitt Meadows, and it could be featured soon.

Raphael Baruh of Slavic Rolls creates one of his Eastern European desserts at the Maple Ridge food truck festival on Saturday afternoon. (Neil Corbett/The News)
Food Truck Festival in Maple Ridge this weekend

Pick the drive-through lane for the food you like at Albion Fair Grounds

Coyotes walk down a Maple Ridge residential street. (Special to The News)
Security camera shows coyotes walking down Maple Ridge street

A warning to Silver Valley residents to keep their pets indoors, says home owner

Coach Ray Wakeman and the Maple Ridge Lawn Bowling Club are looking for new members. (Neil Corbett/The News)
Maple Ridge club looking for lawn bowlers

Games have been modified for safety during COVID-19

B.C. Health Minister Adrian Dix and Premier John Horgan describe vaccine rollout at the legislature, March 29, 2021. (B.C. government)
1,262 more COVID-19 infections in B.C. Friday, 9,574 active cases

Province’s mass vaccination reaches one million people

Two-year-old Ivy McLeod, seen here on April 9, 2021 with four-year-old sister Elena and mom Vanessa, was born with limb differences. The family, including husband/dad Sean McLeod, is looking for a family puppy that also has a limb difference. (Jenna Hauck/ Chilliwack Progress)
B.C. family looking for puppy with limb difference, just like 2-year-old Ivy

Ivy McLeod born as bilateral amputee, now her family wants to find ‘companion’ puppy for her

Emergency crews on scene after a small plane crashed in a grassy area on the northeast side of Boundary Bay Airport Saturday morning (April 10). A freelancer said the plane caught fire and one person was transported to hospital by BC Emergency Health Services. (Photo: Shane MacKichan)
1 taken to hospital after plane crash at Metro Vancouver airport

Plane appears to have suffered ‘significant’ damage, says freelancer

A vehicle that was driven through the wall of a parkade at Uptown Shopping Centre and into the nearby Walmart on April 9 was removed through another hole in the wall later that night. (Photo via Saanich Police Department and Ayush Kakkar)
Vehicle launched into B.C. Walmart removed following rescue of trapped workers

Crews cut new hole in parkade wall to remove vehicle safely

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Four members with Divers for Cleaner Lakes and Oceans were out at Cultus Lake on March 28 and 29 hauling trash out of the waters. (Henry Wang)
PHOTOS: Out-of-town divers remove 100s of pounds of trash from Cultus Lake

Members of Divers for Cleaner Lakes and Oceans hauled out 470 pounds of trash over two days

As of Saturday, April 10, people born in 1961 are the latest to be eligible for a COVID-19 vaccine. (Black Press files)
B.C. residents age 60+ can now register to get their COVID-19 vaccine

Vaccine registration is now open to people born in 1961 or earlier

A new saline gargle test, made in B.C., will soon be replacing COVID-19 nasal swab tests for kids. (PHSA screenshot)
Take-home COVID-19 tests available for some B.C. students who fall ill at school

BC Children’s Hospital plans to provide 1,200 kits to Vancouver district schools this April

Ruming Jiang and his dog Chiu Chiu are doing fine following a brush with hypothermia that saw several people work together to get them out of the Fraser River near Langley’s Derby Reach Park on March 25, 2021 (Special to the Advance Times)
Man finds men who rescued him from drowning in B.C.’s Fraser River

A grateful Ruming Jiang says he will thank them again, this time in person when the pandemic ends

Most Read