Invasive Plants in Alberta: Native Rangeland

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 What is the problem? | Species to watch out for | What you can do | General principles and resources

Land owners and occupiers are responsible for controlling noxious weeds and destroying prohibited noxious weeds under the Alberta Weed Control Act. Listed plants in the Act cause problems for the environment, health or economy. Know your responsibilities under the Act. Regardless of where plants are located, prevention is always the most effective approach in dealing with invasive plants.

What is the Problem?
  • Invasive plants can reduce the quality and quantity of forage available for livestock, both by competing with desirable range plants and by making them less accessible or attractive to grazing animals.
  • Some plant species are distasteful or toxic to livestock. Be familiar with stock poisoning plants; see the resources under Learn More.
  • Some plant species with prickles, spines or burrs can cause a physical irritation to livestock.
Species to Watch Out For
  • Problematic plants listed in the Weed Control Act:
  • Canada thistle (Cirsium arvense)
  • leafy spurge (Euphorbia esula)
  • ox-eye daisy (Leucanthemum vulgare)
  • tall buttercup (Ranunculus acris)
  • common tansy (Tanacetum vulgare)
  • knapweeds (Centaurea species)
  • downy brome (Bromus tectorum)
  • scentless chamomile (Tripleurospermum inodorum)
  • baby’s breath (Gypsophila paniculata)
  • yellow and Dalmatian toadflax (Linaria vulgaris and
  • L. dalmatica)
  • hound’s-tongue (Cynoglossum officinale)
  • field scabious (Knautia arvensis)
  • perennial sow-thistle (Sonchus arvensis)
  • hawkweeds (Hieracium species)
What You Can Do
  • Recognize the role of a healthy rangeland in preventing weed invasion and spread.
  • Use weed-free hay when supplemental feeding is required.
  • Scout your rangelands often throughout the season, and treat small populations of invasive plants before they become a large problem.
  • Avoid excess disturbance, including overgrazing, that creates bare ground where invasive plants may first establish. Use rotational grazing to allow rangelands to recover and further suppress weeds via competition.

Leafy spurge (Euphorbia esula)
  • Grazing can directly control some weeds such as leafy spurge (sheep and goats) and Canada thistle (cattle).
  • Biological control insects are available for some species such as leafy spurge, scentless chamomile and hound’s-tongue. Check with Alberta Agriculture and Rural Development for information on how to obtain these insects.
  • Many herbicides are available for weed control in severely infested rangelands covering a range of effectiveness, residual control options and cost. For tall growing weeds such as Canada thistle, consider herbicides that can be applied with a weed wiper to reduce the effect on desirable species.
  • Consider holding livestock in a containment area before moving to new pasture, as most weed
  • seeds are viable even after passing through
  • digestive systems.

    Ox-eye daisy (Leucanthemum vulgare)

Tall buttercup (Ranunculus acris)

Canada thistle (Cirsium arvense)

Common tansy (Tanacetum vulgare)

Knapweeds (Centaurea species)

Downy brome (Bromus tectorum)

Scentless chamomile (Tripleurospermum inodorum)

Baby’s breath (Gypsophila paniculata)

Field scabious (Knautia arvensis)

Hound’s-tongue (Cynoglossum officinale)

Perennial sow-thistle (Sonchus arvensis)
Yellow and Dalmatian toadflax (Linaria vulgaris and
L. dalmatica)
Hawkweeds (Hieracium species)
General Principles and Resources
  • Land owners and occupiers are responsible for controlling noxious weeds and destroying prohibite d noxious weeds. Know your responsibilities under the Alberta Weed Control Act.
  • Learn to identify invasive plants.
  • Be alert for invasive plants and respond early when they are found.
  • Reduce the introduction of invasive plants as well as the reproduction and movement of their seeds and plant parts.
  • Use effective, appropriate methods to control invasive plants. Alberta Agriculture and Rural Development, Environment and Sustainable Resource Development, municipal Agricultural Fieldmen and urban park departments can provide advice on control methods.
  • Always follow label instructions when applying any herbicide; pay particular attention to grazing and feeding restrictions.
  • Alberta Invasive Plant Identification Guide (from Wheatland County)
  • Alberta Invasive Species Council factsheets
  • Alberta Weed Control Act and Regulations
  • Alberta Weed Monitoring Network
Learn More

Find out more on this topic and access these additional resources at the following web page:
  • Invasive Weed Factsheets
  • Stock Poisoning Plants of Western Canada
  • Common Plants of the Western Rangelands
  • Prescription Grazing for Rangeland Weed Management
  • Alberta Forage Manual
  • A Guide to Using Native Plants on
  • Disturbed Lands
Source: Agdex 640-21. February 2014.
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For more information about the content of this document, contact Chris Neeser.
This document is maintained by Jennifer Rutter.
This information published to the web on September 4, 2014.
Last Reviewed/Revised on August 21, 2018.