Invasive Species

Invasive Species, in this context, are plants or animals that have been introduced to an area from somewhere else. They lack the natural predators and diseases which keep them in check in their native habitats. Invasive species also often have special traits that allow them to reproduce and spread prolifically, and colonize degraded or disturbed habitats (for invasive plants, this is often places such as roadsides and creek banks). This gives these alien species an edge, allowing them to easily out-compete native plants and animals.

Multiple invasive species have found their way into the Township of Langley that pose a risk to the health and safety of people, animals, property and the environment. Some of them, like Japanese Knotweed, are listed as Noxious Weeds under BC’s Weed Control Act. As per the Weed Control Act, property owners have the responsibility to control these species on their property.

The big six

The Township has identified these plants as the top six invasive species that require control:

Japanese Knotweed – Fallopia japonica, syn. Polygonum cuspidatum, Reynoutria japonica
Giant Hogweed – Heracleum mantegazzianum
English Ivy – Hedera helix
Purple Loosestrife – Lythrum salicaria L.
Himalayan Balsam – Impatiens glandulifera
Tansy Ragwort – Senecio jacobeae

Japanese Knotweed

Japanese Knotweed is an aggressive plant that has the ability to destabilize building foundations and destroy sewage and water main infrastructure with its vigorous root growth. Knotweed can colonize large areas with just a small portion, grow up to three metres (10 feet) high in a single growing season, and can out-compete native vegetation. In addition, Japanese Knotweed is listed as a provincial-wide Noxious Weed under BC’s Weed Control Act and Weed Control Regulation.

Controlling Japanese Knotweed requires a long-term commitment. The only control method considered widely effective is the application of herbicide, such as products that contain glyphosate (ex. Round Up). This method involves spraying Japanese Knotweed several times until the roots are killed.

Note: glyphosate cannot be used within 1 metre of a stream, as listed on the product label’s restrictions. In this case, removing the plant by digging out the roots and runners is the only viable option at this time. However, this often involves excavating the soil under and around the plant to a minimum depth of 2 metres and up to 7 metres around. Appropriate disposal of the excavated soil is important and typically involves extremely deep burial (over 5 metres deep) and often must be done on-site; therefore, this method is not commonly used due to challenges and expense involved.

Mechanical methods such as mowing and digging generally are not recommended because they can further spread portions of the plant and stimulate root growth. Cutting may be effective for small areas only if repeated frequently (i.e. once a month) during the growing season, repeating for several years until the roots are dead.

If you find Knotweed on your property, do not compost it in your backyard as it could spread. If you do not want to remove the weed yourself, contact Langley Environmental Partners Society, which may remove the weed for you for a fee and/or give you other options to consider. Learn more about best management practices for knotweed.

To learn more about Japanese Knotweed, visit the websites below:

Japanese Knotweed control strategy

The Township of Langley is working to eradicate the threat of Japanese Knotweed from our roads and parks. You may see markers along various roads in the Township identifying where Japanese Knotweed is located. Do not mow these areas. Improper removal of the plant, such as mowing, could result in Japanese Knotweed multiplying.

The Roads Department is using a mild herbicide spray containing glyphosate to control Japanese Knotweed on road right of ways. The removal process is slow and tricky because it will take several treatments and inspections over the course of several years to ensure the roots are killed. When the roots are dead, the stock of the plant is cut and left on-site to dry. It is then transported offsite and buried up to 5 metres deep in one of the municipal operations storage pits.

In our parks, several patches of Japanese Knotweed have been identified and sprayed with herbicide. All sites designated for treatment are marked with signs indicating the date and type of treatment used. The Parks Department will continue to monitor and spray those areas until the threat of the invasive plant has been eradicated. Areas deemed to be free of knotweed after a number of successive years of no detection will be planted with native species to reduce the likelihood of the area being recolonized by invasive plants.

Giant Hogweed

Giant Hogweed poses a health and safety concern. Sap from this plant can cause sensitivity to light when it comes in contact with exposed skin, resulting in burns and blisters. As a result, it is listed as a provincial-wide Noxious Weed under BC’s Weed Control Act and Weed Control Regulation. Thankfully, Giant Hogweed is believed to have a low establishment in the Township of Langley.

Herbicides, such as products that contain glyphosate or triclopyr, are an effective option to control Hogweed, although they can’t be used within 1 metre of a stream (always read the product label’s restrictions). Hogweed also responds well to manual removal, but it is crucial that you wear protective clothing, gloves and eye protection while doing so. Use a sharpened shovel to cut into the soil and through the tap root, about 10 to 20 centimetres into the ground. The cut portion of the plant can be pulled out and either removed or left to dry.

Do not try to compost this plant in your backyard and do not put it in your Green Cart, either.

It is not advisable to remove the weed without proper training and equipment. If you do not want to remove the weed yourself, contact Langley Environmental Partners Society, which may remove the weed for you for a fee and/or give you other options to consider.

Learn more about best management practices for hogweed.

English Ivy

English Ivy is a climbing vine that can spread over the ground like a blanket, choking out vegetation, and climbing trees and shrubs. Ivy can be a safety concern when its weight causes trees and branches to break, particularly during windstorms, with the potential to cause injury to people and livestock and damage property. Thankfully, it can be easily controlled through proper maintenance and disposal.

Hand pulling, while labour intensive, is the best method to remove ivy. It allows for selective removal, leaving desirable vegetation unharmed. Remove ivy by pulling the vine from the ground, taking care to remove as much of the root as possible. Repeated maintenance is required to ensure complete removal. To avoid tree breakage, cut the vines at the base of the tree. The cut stems will eventually decay and fall off by themselves.

Do not try to compost this plant; all parts of the plant can produce a new plant and it will spread from your backyard composter.

Learn more about best management practices for English and Irish ivies.

Purple Loosestrife

A pretty plant with ugly consequences, Purple Loosestrife poses a major threat to wetland habitats. Purple Loosestrife reproduces so prolifically: one mature
plant has the capability of dispersing up to 2.7 million seeds! Wetlands are a vital component to our environment; when Purple Loosestrife invades a wetland, biodiversity becomes limited. Purple Loosestrife can also clog drainage canals, causing flow restrictions and impacting proper drainage. As a result, it is listed as a provincial-wide Noxious Weed under BC’s Weed Control Act and Weed Control Regulation. Thankfully this invasive plant has a low establishment in the Township of Langley.

Purple Loosestrife can be pulled out by hand or dug out. Cutting seed heads can help control its spread by preventing this year’s seeds from producing new plants. It is not advisable to use herbicides to control Purple Loosestrife since it grows in wet areas.

If you remove Purple Loosestrife, do not try to compost it in your backyard composter.

Himalayan Balsam

Himalayan Balsam grows quickly and spreads easily, often suffocating native vegetation. Spring-loaded seed pods burst open when brushed against, sending seeds up to 7 metres away!

The good news is its seeds are viable for only two years, making it easy to control. The entire plant can be easily pulled from the ground, roots and all. Large infestations can be controlled using a string weed whacker to shred the balsam when the plant begins flowering (but before it goes to seed in late summer). Repeat the process two or three times more after the initial cutting to ensure the seed bed in the soil is exhausted. It is not advisable to use herbicide as a control method since the plants often grow in/near streams and wetlands.

Once removed, Himalayan Balsam should be cleared from the site because each node can produce roots, allowing the plant to flower again. Do not compost green plants in your backyard composter as it can spread.

Learn more about best management practices for Himalayan Balsam.

Tansy Ragwort

Tansy Ragwort poses a health concern to humans and animals. If digested, toxic chemicals, called alkaloids, in Ragwort can cause liver damage to livestock and horses. These toxins can be transferred to humans through the consumption of meat and dairy products. As well, honey made by bees that forage in areas with high densities of Tansy Ragwort may also contain trace amounts of toxin. For this reason it is listed as a provincial-wide Noxious Weed under BC’s Weed Control Act and Weed Control Regulation.

Livestock should never have access to fields infested with more than 10 percent Tansy Ragwort. Put up fences to block livestock from the weed. Small invasions of Tansy Ragwort can be controlled by hand pulling, ensuring all the root is removed (easier when the soil is damp). Large infestations may be managed through regular mowing before the plant flowers, or heavy cultivation (frequent tilling of the soil such that plant may not become established, and eventually is eliminated).

Do not burn Tansy Ragwort for control or waste management as it can emit dangerous toxins when burned.

Learn more about invasive species on Metro Vancouver's Invasive Species for Practitioners and Residents.