Management

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BC WEED CONTROL ACT

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The B.C. Weed Control Act places a duty on all land occupiers to control noxious plants. The purpose for the Act is to protect our natural resources and industry from the negative impacts of foreign weeds. To read more about the B.C. Weed Control Act, click here. To learn more about the classified noxious weeds within the different regions of British Columbia, as defined by the BC Ministry of Agriculture and Lands, click here.

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INTEGRATED PEST MANAGEMENT ACT

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The Integrated Pest Management Act and Regulation establish conditions for the sale and use of pesticides in British Columbia through a classification system and regulatory provisions for licences, certification, permits, Pest Management Plans and ministry confirmations of receipt of a pesticide use notice. The Regulation also contains public notification, consultation, reporting, and record keeping provisions – as well as standards for use of Integrated Pest Management and for human health and environmental protection

The primary goals of the Integrated Pest Management (IPM) Act and Regulation are to:

• Establish regulatory requirements based on degree of risk to human health and the environment
• Promote environmental stewardship and integrated pest management
• Set clear and enforceable standards for the protection of human health and the environment.

The Act and Regulation require the use of integrated pest management for pesticide use on public land, on private land used for forestry, transportation, public utilities and pipelines; and for pest control service companies.

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INTEGRATED WEED MANAGEMENT

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Integrated Weed Management focuses on the sound management of our resources. Control of undesirable plants without improving management practices is futile.

The following are the basic principles of Integrated Weed Management:

• Education, prevention and early identification of invasive plants
• Identification and knowledge of weed species Inventory, mapping and monitoring of weed populations and impacts
• Choosing a combination of control methods to reduce infestations Evaluating the effectiveness and results of management decisions

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METHODS

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There are a variety of control methods that can be used to manage invasive plants.

prevention

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Prevention, early detection and eradication of weed species is the most economical and effective means of invasive plant management.  It is important to ensure new weed species or vegetative reproductive plant parts are not introduced into a new area.  

Invasive plants can be spread in the following ways: 

• Contaminated seed, feed grain, hay, straw, mulch
• Movement of unclean equipment and vehicles across uncontaminated lands
• Livestock and wildlife
• Spreading gravel, and road fill that contains seed
• Nursery industry
• Recreation
• Water, and wind transportation

Once invasive weeds are identified, it is important to take action to ensure that they do not spread to uninfested areas.  This includes managing activities on grasslands and seeded pastures to maintain healthy plant communities, promoting low growing vegetation, avoid practices that disturb the soil and promote the dispersal of weeds, and reseed disturbed sites as quickly as possible. 

MEASURES TO PREVENT INVASIVE PLANT SPREAD

• natural controls, primarily the establishment of a stable, low-growing plant community
• ensuring  vehicles and equipment are clean of invasive plants and seed
• minimizing soil disturbance in all construction and maintenance activities
• promote the establishment of a health plant community
• limit the movement of weed-infested soil or gravel
• sow certified weed-free seed in disturbed areas to provide competition for new weeds
• compatible uses, such as agricultural crops, golf courses, sound grazing management or industrial uses
• treat new infestations quickly
• working with local invasive plant groups to deal with new infestations.

In an invasive plant prevention program, it is also essential to contain neighbouring infestations and restrict movement of invasive plants from adjacent lands.  Roadways, railways and waterways are often corridors for invasive plant spread and should be monitored for invasive plant establishment.

Protect areas that are not infested. Educate yourself and others about weeds in your area. Prevent soil disturbance whenever possible. Re-seed disturbed soils to prevent weeds from establishing. Keep machinery and vehicles clean. Do not move weed infested soil or gravel.

mechanical control

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Mechanical control usually refers to the mowing of an invasive plant infestation to limit seed production. With mowing, timing is essential. Invasive plants must be mowed before the plants go to seed in order to be an effective method of control.  Plants should be mowed as close to the ground as possible and may have to be treated more than once in a growing season to achieve desired results.

BENEFITS OF MECHANICAL CONTROL

• Works well for areas that have favourable terrain that is accessible.
• Can be used in environmentally sensitive areas.
• Reduces seed production.
• Most effective on annual or biennial plants.

 LIMITATIONS OF MECHANICAL CONTROL

• Plants must be mowed before they produce seed.
• May not be suitable in some riparian areas.
• Mowing invasive plants is not suitable for steep slopes or rocky terrain.
• Mowing activity will not kill plants but only decrease seed production for that year.
• Perennial plants require several cuttings as they flower multiple times through the growing season.
• Plants should be cut as close to the ground as possible.
• Non-target vegetation (natural forbs and shrubs) will be impacted.
• Must be done repeatedly to exhaust seed bank in the soil.

manual control

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Manual invasive plant control usually refers to hand-pulling.  Manual control works well for dealing with single plants or small infestations that can be eradicated with a small amount of labour. It is most effective if invasive plants are shallow rooted and the soil is loose or moist.  One should be aware this type of control may not be suitable for invasive plants that also reproduce by roots and rhizomes.  In these instances, limited hand-pulling, hoeing or may actually increase the size of the infestation. 

BENEFITS OF MANUAL CONTROL

• Can be used in environmentally sensitive areas.
• Can be used to manage small patches or individual plants.
• Works best in moist, loose soils.
• Persistent pulling can even manage some creeping perennials.

 LIMITATIONS OF MANUAL CONTROL

• Labour intensive and often limited to small infestations.
• Many invasive plants reproduce through rhizomes and extensive lateral root systems.
• Plants must be pulled before seeds are set.
• Pulling must be done repeatedly to exhaust seed bank in the soil.
• Mowing and tillage. Ensure weeds are mowed before seeds form. These methods will not kill the weeds in the infested area but will reduce seed production and control spreading.

cultural control and competition

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Cultural control and competition includes seeding, irrigating or fertilizing to encourage the establishment of a healthy ground or crop cover to resist invasive plants.  When natural vegetation or soil is disturbed, cultural control can be a n effective tool in invasive plant management.  Seeded or intensively managed plant communities can offer competition for invasive plants.  In some cases where invasive plant species are found in soils deficient in sulphur, fertilization of these sites can help to create competition of natural plant communities, or cultivated crops to decrease the invasive plant population (i.e. ox-eye daisy infestations).

Where non-selective herbicides are used, control of present invasive plants will leave bare ground.  In these cases, cultural control (i.e. seeding) should be used in combination with chemical control as part of a long-term management strategy.  Re-vegetation can assist in preventing the return of an invasive plant or the introduction of new invasive species in an area.

Some factors for consideration when re-seeding sites include:

• viability of crop seed,
• seeding rate,
• plant species being seeded,
• soil temperature and planting,
• available moisture, and
• physical properties of the soil.

 It is important to plant seed-mixes that are certified to be “weed-free”.

BENEFITS OF CULTURAL CONTROL

• Valuable in encouraging long-term management of invasive plants.
• Can be used in environmentally sensitive sites.
• Can include use of native plant communities

LIMITATIONS OF CULTURAL CONTROL

• Site and soil conditions can be unfavourable.
• Cultural control methods can be labour intensive.

chemical control

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Various herbicides are approved for treatment of invasive plants within British Columbia and are ideal for spot-treatment of rights-of-ways.  The herbicide selected will depend on the target weed species and environmental considerations.     

Large infestations, infestations near water, or infestations on steep slopes may be too costly or too environmentally sensitive to control by chemical means.  In these situations, it is important to look at other management options.  Also, if chemical control leaves a site bare, it is important to look at getting other plants established so that control is achieved over the long-term.

There are various types of herbicides with various modes of action available for use depending on the plant species and the site suitability.  

Factors that can affect the effectiveness of herbicides include:

• Invasive plants with waxy or hairy leaves may not easily adsorb the required amount chemical to kill the plant.
• Invasive plants are usually most susceptible to herbicide during its active growth stage. This is often in the seedling stage or the bud or early flowering stages.
• Cool or extremely hot dry temperatures may decrease translocation of systemic herbicides.
• Soils with high organic matter or clay content may require higher rates of chemical than sandy soils.
• Soil moisture and pH can also affect persistence and effectiveness of some herbicides.

 BENEFITS OF CHEMICAL CONTROL

• Effective tool for new and small infestations of invasive plants.
• Will kill target plants.
• Can have residual control of seed-bank for future years depending on the chemical selected.
• Less labour intensive than mechanical and cultural methods.

 LIMITATIONS OF CHEMICAL CONTROL

• Precautions need to be taken to limit the affect on non-target plants, soils, and animals.
• Limited use in environmentally sensitive areas or steep slopes.
• May have limitations of certain soil conditions or presence of water.
• Some concern from community groups.
• First Nation concerns

Your choice of herbicide should depend on your target weed species, other crops or plants on site, environmental considerations, and your management objectives.

biological control

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Biological control involves using living organisms to reduce seed production and vigor of an invasive plant species.  Many invasive plants came from Europe or Asia without their natural insects or diseases to keep them in check.  The province of British Columbia has partnered with other agencies, provinces and Agriculture and Agri-Food Canada to introduce agents that are natural enemies of the invasive plant into North America.  Before an insect is released, it must undergo extensive testing to ensure that it will not attack any other plants. 

Biological control often works best on large infestations, or infestations that are near water.  It is a long-term approach and often it takes many years for insects to establish and results to be seen.  In some cases, a single biological control agent can adequately control an invasive plant species.  However, in most cases, a variety of agents are needed to achieve control of the weed species population levels.  

Biological control will not eradicate the infestation directly.  Rather, the agents are used to decrease the vigor and seed production of the plants in order to decrease their competitive ability.  Therefore, it is important to use other weed management strategies to ensure that the infestations are contained.  Some insects may already be present on site.  Local weed specialists or Agrologists could assist in identifying insects present and assisting with obtaining insects for biological control.

Biological control agents are not available for all invasive plant species. However, since biological control research is ongoing, this list is constantly changing.  Check with local weed committee or the B.C. Ministry of Agriculture and Lands office for up-to-date information about insect availability.

BENEFITS TO BIOLOGICAL CONTROL

• Uses the plants natural predators for control.
• Can be used on environmentally sensitive areas, areas near water and steep slopes.
• Suited to large infestations.
• Reduces the vigor of invasive plants being attacked and can reduce seed production.
• Used for long-term management of invasive plants.

LIMITATIONS OF BIOLOGICAL CONTROL

• Biological control agents are not available for many invasive plant species.
• Will not “eradicate” an invasive plant species.
• Can take multiple years (sometimes 10-20) before any noticeable difference in invasive plant populations are seen.
• Biological control agents can require specific site conditions for success.

Talk to your local weed coordinator about biological control options.

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PROGRAMS

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A number of management programs and funding opportunities are available for public and private landowners within the Thompson-Nicola Region.

seven steps to weed management
biological control program
education programs
TNRD noxious weed control programs
utilities funding for private landowners
communities pulling together