Patches of Japanese Knotweed tackled in Chilliwack

Have you seen this plant? Whatever you do, don’t try to dig, mow, or weed-whack it

Never try to dig, mow, or weed-whack any patches of Japanese Knotweed.

It will just come back with a vengeance.

That’s one tidbit offered by City of Chilliwack officials about the invasive plant, as they prepare for targeted herbicide treatment this spring in specific areas.

Crews will be tackling some new patches for the first time in more populated or well-used areas than in the past, such as at the south end of Lickman Road, in the parking lot leading to the Vedder Rotary Trail.

A sign is going up soon with some key info about the upcoming treatment plans.

City staff has been proactive about identifying and treating patches of the noxious weed for the past four years.

There are 285 known patches growing on public land in Chilliwack, with many more on private land.

“When left to grow unchecked, Japanese knotweed has the potential to impact homes, roads, parking lots and other infrastructure,” reads the warning from city officials this week.

It ranks among the most difficult plants to control.

Japanese knotweed displaces native plants and animals, and can lead to soil erosion. If left to its own devices, the plant chokes out everything around it, creating a monoculture.

City officials say whereas up until now they’ve concentrated on treating patches on public land like the dikes, shoulders and road safety sight lines, where city infrastructure could be compromised.

But starting this year the crews are moving more into the public eye, and they wanted to get some information and details out to the community beforehand.

Some of the culprits who allow the gnarly weed to spread are those engaging in illegal dumping of clippings, or use of contaminated soil or fill.

In sections that have been treated successfully with glysophate, restricted to targeted, low-pressure applications in the past, the knotweed has either been eradicated or reduced dramatically. But it’s taken repeated applications and multiple inspections in some cases. They’ve managed to cut swaths of 50 square metres down to a few stalks.

So crews are ready to tackle new sections.

It’s important for Chilliwack residents to know what to do if they spot Japanese Knotweed, which resembles bamboo, growing around town or on their properties.

Residents that have confirmed patches of Japanese Knotweed on their property can consider the following control options:

• Never dig, mow or weed-eat Japanese Knotweed. This will only make the problem worse as knotweed can regenerate from stem and root fragments as small as 1 cm.

• Manual Control: Mature stems can be repeatedly cut at the base with a single clean cut using a knife, pruning shears, etc. This process may need to continue for up to five years to exhaust the energy stores in the roots.

• Cut material can be bagged and taken to the Parr Road Green Depot for disposal ($7.50 for up to 100kg). Keep invasive plants separate from other yard trimmings and notify the scale attendant; they will handle the material separately.

• Cut material can be bagged and picked up by the FVRD for safe disposal by calling 604.702.5067. Please clearly label the bags and refrain from having them collected on the same day as your Curbside Collection of garbage and recycling.

• Cut material can be laid on an impervious surface (ex: driveway or tarp) to dry in the sun. When crispy and brown the material can be included in curbside Green Cart, backyard compost, or burnt where/when applicable with a permit.

• Chemical Control: Herbicides, when used by a trained professional, are an effective method of controlling knotweed. Special care must be taken when near a watercourse and to avoid non-target vegetation. Herbicides with the active ingredients glyphosate, imazapyr, or triclopyr are known to be effective. Chemical control may require two applications per year for multiple years to control the plant.

To ask a question or report a Japanese Knotweed patch, contact the Environmental Services Department at 604.793.2907 or