Invasive Plant Species

In 2011, Japanese Knotweed was added to the list of noxious weeds in BC and recently it was added to the Untidy and Unsightly Premises Bylaw No. 6982 (PDF) which requires that residents dispose of this and other noxious weeds, when their presence is noted on private property.

Japanese Knotweed is one of over 35 invasive plant species that have been identified in British Columbia. 


Maple Ridge would like to let you know more information about this specific invasive plant, Japanese Knotweed and provide some overall information on what is happening in our community to control this and other invasive plants.

Noxious Weeds Identification

Overview on Invasive Plants and Animals


An invasive species is any plant or animal species that is introduced into an environment where the species is not native. There are numerous examples of plants, insects, birds and animals that have been transplanted from their natural environments, either by accident or intentionally, into areas where they end up having a serious impact on the natural ecosystem. We have all seen stories of giant pythons in the Florida Everglades and in our own community the Easter Grey Squirrel has become the dominant squirrel species, pushing out the native squirrel populations only 100 years after being introduced into Stanley Park.

In some cases, climate change is contributing factor in some plant and animal species creating environmental damage as the plants and animals extend into new areas, or the natural controls against them collapse. The Pine Beetle is often noted as an example of how the warmer and shorter winters contributed to the massive infestations in BC.

Maple Ridge has been working on the issue of non-native plant control and management for a number of years. The Lower Mainland has some of the most favourable growing conditions in Canada, and as people moved to this region from all around the world; they brought plants and trees with them to plant on their properties. BC's Lower Mainland has one of the largest diversity of tree species in the nation.

Here in BC there are native plants that have adapted to the unique soil conditions and, unusual environments and harsh climates. These plants, if taken elsewhere in the world, could be an Invasive weed, if taken out of their ecosystem that has natural predators and controls.

Such is the case with Japanese Knotweed. This plant was introduced into places in the world as a landscaping plant. In the Lower Mainland, and in other areas of the world, Knotweed has thrived in the soil and moisture conditions and is now pushing out native plant species. In 2011, Japanese Knotweed was added to the list of 'Noxious Weed' species, which allows for more aggressive control strategies.

Currently, Maple Ridge has been dealing with 'Giant Hogweed' which is another 'Noxious Weed' that can cause substantial skin irritation, or burns, when you come in contact with it. As we noted earlier, there are over three dozen plants that are on the Invasive/Noxious Plant Species List.

Noxious weeds that are part of the Untidy and Unsightly Premises Bylaw No. 6982 (PDF):
  • Canada Thistle (Cirsium arense)
  • Bindweed or Morning Glory (Convolvulus)
  • Couch Grass (Agropyon repens)
  • Purple Loosestrife (Lythrum salicaria)
  • Giant Hogweed (Heracleum mantegazzianum)
  • Japanese Knotweed (Polygonum cuspidatum)

Why are these plants a problem?


Plants evolve in their natural setting, and there is often natural climatic, insect and animal controls that keep them in check. Taken out of their natural environment, these plants have no 'checks' to their growth and expansion, and they can very quickly crowd out native plant species and upset the balance of a natural ecosystem.

Some of these plants provide no food or shelter benefits to the native insect and animal species, and in fact, some of these plants can result in erosions and habitat destruction that can impact fisheries ecosystems.

In addition to the natural environment impacts, some invasive plants can speed up the deterioration of public and private infrastructure. Just as the tree that you planted 20 years ago in the back yard has now grown to the point that the root system is pushing up your driveway, or the Ivy you planted has completely grown over your retaining wall and rooted into the cracks in the concrete or wood ties, invasive plants can accelerate the destruction of man-made materials.

Finally, as was noted, some of these plants are harmful to human and animal life. We've all heard of Poison Ivy and Poison Oak, but there are native and non-native weeds that can cause serious injury to people.


What can be done to control invasive and noxious weeds?


The BC Weed Control Act was put into place to protect the environment from the negative impacts of foreign weeds. There is a long list of plants that have been designated as noxious weeds, and that list grows each year. In 2012, Giant Hogweed and Japanese Knotweed were added to the list.

This is important, because many communities, including Maple Ridge, have bylaws that limit the use of chemicals to control nuisance weeds. However, when a plant is added to this list, it opens up the use of chemical control methods and moves it outside any Municipal Bylaw.

The BC Weed Control Act imposes a duty of responsibility on the occupier of the land to control designated noxious plants. That has critical implications on private and public land owners.


What is happening in Maple Ridge?


Maple Ridge has been working on the issues of invasive plant management for a number of years. Staff have been trained on the safe removal of Giant Hogweed, and have assisted citizens in removing these plants when they are identified. Our staff has also been working with lands where development is occurring to ensure that invasive plants are controlled in environmental setbacks for periods of up to five years. This is an important part of the overall protection of 'riparian' areas. Riparian areas are the sides of creeks and streams, and the associated natural ecosystem of plants, insects and wildlife.

With the addition of Japanese Knotweed to the Noxious Plants list, and given that it thrives in the very riparian environments that we are working so hard to protect, Maple Ridge, along with ARMS, one of the most important local partners in the protection and enhancement of our local river system, were given a presentation by the Metro Vancouver Invasive Plant Council during the summer of 2012. They outlined their findings around the Japanese Knotweed spread.

The Invasive Species Council of Metro Vancouver (ISCMV), formerly the Greater Vancouver Invasive Plant Council, is a non profit society that is working to improve the way we manage invasive species in the Vancouver region. There are many plant species that are not native to our region and each of these can threaten the environment, economy and public safety. The purpose of their website is to provide you with information about invasive species, specific species of interest in our region, control methods, ISCMV's services and to keep you updated on weed-related activities in the region.

There is another organization, the Invasive Species Council of BC (ISCBC), which has been communicating information regarding Knotweed, and other invasive species. Their website lists their information as;

The ISCBC is a registered charity whose members are involved in all aspects of invasive species management, with the main focus on invasive plants. Members include technical specialists working for government and industry, regional coordinators, Aboriginal Peoples, foresters, biologists, ranchers, horticulturists, recreation enthusiasts, gardeners and other concerned individuals. Membership is free and open to everyone willing to work collaboratively.

Neither organization is an official department of the BC Government, but are valuable partners in identifying invasive species and reaching out to find best management practices to help control the spread of invasive plant, insect and animal species.

On September 10, 2012, Council was provided with a presentation (PDF) by David Boag, Director of Parks & Facilities. Mr. Boag outlined much of the information that we've included on this web page. He indicated that there needs to be two distinct stages to the control program for Japanese Knotweed.

The first step is to talk with the communities that border Maple Ridge to ensure that there is common approach and commitment to the control of Japanese Knotweed. The best methods for control are being explored at this time, and Council will receive a follow-up report on the best way to implement a control program for the short and long term.

The second step is the identification of where Japanese Knotweed is located in the community, and a systematic control program. The funding for that program was approved by Council as part of the 2013 work plan.

How can we control Japanese Knotweed?


The evidence shows that manual removal, digging it up or chopping the stalks, is not a viable long term solution. The species of Knotweed that we are dealing with here does not 'seed' like other invasive weeds, however the combination of the deep root network and the fact that even the smallest amount of the plant, under 5 grams of material, can re-root the plant. Mr. Boag noted that we have received phone calls from citizens concerned that we are clearing Knotweed along some road systems and noted that the risk to citizens due to reduced visibility on roadways and crowding out the shoulders so that pedestrians and cyclists are forced into the vehicle area of roadways creates a necessity to clear some areas. The Operations Centre and our contractors will be part of the team that develops and implements the control program in Maple Ridge. They will be examining how the plant materials cut during a manual removal should be handled to begin to control the spread of Knotweed as part of the over control program.

The other consistent message that we are hearing from experts throughout the region is that organic chemical controls, such as vinegars, are not effective in controlling Japanese Knotweed.

The method that has the best effect is the use of specific chemicals. There are two methods that are currently being used in the region, and as part of the background work leading to the implementation of a control program on District owned lands, the effectiveness of each method, and its residual impact on the environment will be examined closely to ensure that the best, most effective and most responsible method is used to curb and control Japanese Knotweed.

The first method is called 'foliar' applications which means that you spray the chemical solution on the leaves of the plant that you are trying to eradicate. A recent application of a product whose active ingredient is 'glyphosate' (a commercial name for this product is Roundup), was made along sections of the Lougheed Highway. We will monitor the impact of this control method over the next year.

The second method, and one that seems to be the most effective, is the injection of the chemicals into the plant stalks. Japanese Knotweed has stalks that are somewhat like rhubarb, and the injection of the chemical at the right concentration and dosage, carries the biological agent deep into the root system. The correct amount of chemicals and the application equipment is specialized, and needs to be done by people that are properly trained and have their "Pesticide User Licence."

The reason that Maple Ridge is proceeding with caution is that our community enacted bylaws that limit the use of chemicals to control nuisance weeds. The methods that Maple Ridge deploys in dealing with Japanese Knotweed and other noxious weeds is done in ways that ensure that the eradication is targeted and mitigates any impact on native plant species. The most extensive control program will not 'eradicate' Japanese Knotweed in one year. The realistic approach is to develop a well planned and executed control program that systematically and precisely targets this invasive plant over a number of years.

By following a solid science based plan, we will ensure that the eco-system does not become contaminated with residual chemicals and that natural plant species can recolonize areas that are cleared of Japanese Knotweed. With a concerted effort of private land owners and local governments, this plant will be brought under control.

What should I do if I find Japanese Knotweed on my private property?


At this point we are recommending that citizens contact a qualified business whose applicators have the 'Pesticide User Licence' certification. While we know that some folks may be tempted to take the 'DIY' approach, the concern is that the foliar spraying of Japanese Knotweed in the wrong concentrations or under the wrong conditions may end up doing collateral damage to other plants in your garden, or your neighbour's garden. The websites listed earlier for the BCISC and MVIPSC will help you identify the plants, and provide information that will help you make informed choices.

What should I do if I see Japanese Knotweed on public property?


We have already begun keeping an inventory of locations where citizens have spotted Japanese Knotweed. If you do spot Japanese Knotweed, please call our main switchboard at 604-463-5221 and you will be forwarded to a staff member who will record the information. You can also send us a letter, postcard or an email. All of this information is being compiled to prepare for the coordinated control program.

We will be working with other levels of government and local environmental groups to ensure that we develop an inventory in parks, water courses and protected lands.

What else is being done?


This is the first step in the development of a public education program on Invasive species. More work will be done to ensure that we are passing on the best advice from around the Lower Mainland as other local governments begin their control programs.

We will be reviewing our Cosmetic Pesticide Bylaw and the Municipal Noxious Weed Bylaw to ensure that their wording and practices are aligned with the current situation and allow for citizens and staff to work together to control this, and other, invasive species.

We will be looking at the current regulations around the control of noxious weeds on private property and what impact the movement of land fill materials contaminated with noxious weeds has on spreading the problem. Where the regulations need strengthening, we will work with our neighbouring municipalities and the Provincial Government to ensure that there is strong protection to minimize the spread of invasive species.

Doing nothing is NOT an option!


To be clear, Maple Ridge has been dealing with Invasive and noxious plants for a number of years, and the addition of Japanese Knotweed and Giant Hogweed to the list of noxious weeds is going to have an impact on every community in the Lower Mainland.

The long term control plan was presented to Council's as part of the 2013-2018 Business Plan.

Our current recommendation for private land owners is to ensure that the control of Japanese Knotweed and other noxious weeds is done by an individual or company that has a "Pesticide User License."

Please report any patches of Japanese Knotweed or Giant Hogweed by calling our main switchboard at 604-463-5221 and you will be forwarded to a staff member who will record the information. You can also send us a letter, postcard or an email.

Together, we will get this under control, and this serves as an important reminder to avoid planting non-native plant species in your garden without checking to ensure that it won't become the next addition to the Noxious Weed list.