Weed and Brush Control in Pastures

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Retrieved: June 25, 2022, 1:13 am

Healthy and productive pastures are the foundation of a successful and sustainable beef cattle operation. When weeds and brush spread into hay fields, rangelands and pastures, desirable forage species are replaced, reducing productivity and profitability.

Pastures can be impacted by annual, biennial and perennial weeds, and each region across Canada will have different weeds that are problematic.

Weeds can be introduced through many ways including:

  • purchasing feed such as baled hay, greenfeed, or straw that contains weed seeds
  • seed distribution by wind (e.g., kochia or baby’s breath)
  • flooding that carries seeds onto a pasture (e.g. red bartsia)
  • in contaminated soil or gravel
  • animals returning from weed-infested pastures that bring back weed seeds in their manure.

Lupine, photo credit, Harlan B. Herbert, Bugwood.org

While some weeds reduce pasture yield, others are poisonous and present a health risk to livestock. Providing cattle access to healthy, vigorous pastures reduces risk of poisoning, as cattle will usually avoid poisonous plants if adequate forage is available. Examples of toxic plants found in Canada include lupines, death camas, red maple or oak, larkspur, locoweed, henbane, water hemlock and poison hemlock.

Weed management, which includes cultural, mechanical, chemical, and biological methods, must be applied and evaluated over an extended period of time to be successful. A good weed management plan starts with cultural methods and integrates two or more additional control measures into a complete management system. The system must be applied and evaluated over an extended period of time to be successful.

Example of biological control, leafy spurge beetle.

Classical biological control uses natural enemies of weeds, such as insects or disease organisms. Biological control may also include the use of sheep, cattle, goats, or other large herbivores to manage weeds. While biological control is not intended to eradicate target weeds, it can be an environmentally safe, cost effective way to reduce weed pressures.

Targeted browsing of weeds by goats or sheep has been used with some success in larger areas of infestation where herbicide control is not practical. While cattle tend to avoid leafy spurge and thistle, targeted grazing as part of an integrated management plan can reduce weed density. Goats and sheep will also graze undesirable plants such as thistle, absinthe, buckbrush and aspen suckers. Fencing, herding, and predator control are required to keep goats and sheep grazing targeted areas, and safe from predators such as coyotes.

Bushes, forbs and shrubs provide habitat for wildlife, and can make up over 20% of livestock’s diet on rangelands, as cattle graze the desirable forbs and forage plants. Undesirable or invasive brush can impact wildlife habitat when encroachment alters native ecosystems. Proper identification is important to ensure that desirable plants are not targeted for weed and brush control.

In many areas of Canada, brush encroachment by trees such as trembling aspen, willow, and shrubs such as buffaloberry, hazelnut, and snowberry, reduces forage yields and availability to cattle. When determining methods to control or reduce brush, consider the cost of control relative to the increased forage production gained. Since production improvements will vary greatly from one operation to another a helpful tip is to create a budget to estimate costs of brush removal versus the anticipated gains of increased forage yield and grazing days.

To learn more about weed and brush control on pastures, visit our new webpage.


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5 thoughts on “Weed and Brush Control in Pastures

  1. Around here (Bulkley Valley of B.C.), I’d say that WHEELS–quads, tractors, pickups, trains–are probably second only to wind as a source of invasives. Machinery from a field with hawkweed, for example, can carry plenty seeds to the next field, nearby or far away.

  2. I would like to offer a different solution to weed management in pasture: teaching cows to eat them. In 2004 I developed a method for teaching cows to eat weeds. It relies on animal behavior principles and research by Pavlov, Skinner, and discoveries by Dr. Fred Provenza and his colleagues about how animals chose what to eat. Training takes just 8 hours spread over 7 days and costs only about $2.50 U.S. Animals remember the weeds from one year to the next. After learning to eat one weed, animals add others to their diet on their own, so you don’t have to teach them to eat every weed in the pasture. You don’t have to teach every animal either. Cows teach their offspring and untrained animals learn from each other. In fact, I worked with one rancher to train 50 of his heifers. They went on to teach the other 800 as he mixed them in with his herd over time.

    Weeds are also very nutritious, often the equivalent of alfalfa or better, and the majority do not cause poisoning. Work with an agricultural economist shows that graziers whose animals eat weeds have 43% more forage.

    I would be happy to share this information with your ranchers, researchers and partners. I think it’s an important because it can reduce weed populations and producer inputs, while improving their bottom line. I’ve published a great deal of information on this in OnPasture.com and can provide links and articles for BCRC as well.

  3. Adding to my previous comment, here are some of the plants trained cattle have turned into forage:
    Canada thistle, bull thistle, sow thistle, musk thistle, leafy spurge, all the knapweed, snowberry/buckbrush, sulphur cinquefoil, hoary cress/white top, russian knapweed, yellow and dalmatian toadflax, gambel oak, poison oak, multiflora rose, coyote brush…the list goes on and on.

  4. In this article weeds/invasives have been listed along with native plants, this should be differentiated and explained. Some native plants are poisonous, however are not usually consumed in amounts that are problematic, though it can happen. Managing rotation to use an area of concern after the plants have senesced may be an option. Some of these plants are important to pollinators, so it should be make clear that eliminating them is not always appropriate, especially on crown land.

    • Thank you for your insightful comment. You are correct that many native range plants are poisonous but are an important part of the ecosystem and infrequently cause problems. The article and web page point that proper pasture management is the most effective method of managing plant toxicity, and that cattle typically avoid poisonous plants if they have access to healthy, vigorous forage. Controlling plants simply because they are poisonous is not a recommended practice, however it is important to note that toxic plants do exist. While problems are rare, they can occur, particularly in abnormally dry or wet years, in areas of overgrazing, with young or inexperienced grazing animals (i.e. heifers or young stock), or in cattle grazing an unfamiliar pasture for the first time. Toxicity can be compounded if an animal’s health is otherwise compromised as well. The BCRC also addresses toxic range plants on the Rangeland and Riparian Health page and provides additional identification resources.

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