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Let’s Legalize Canada Thistle!

By   /  April 13, 2015  /  5 Comments

As states start legalizing marijuana for medical and even recreational use, Kathy asks the question, “Should we consider legalizing other weeds as well?” She starts with Canada thistle, her favorite grazeable pasture weed and adds an offer that can get you in the “habit” of weed grazing for free, or almost free.

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Bees on Canada/Creeping thistle by Richard Bartz courtesy of Wikipedia

Bees on Canada/Creeping thistle by Richard Bartz courtesy of Wikipedia

Canada thistle (cirsium arvense, also known as Creeping thistle in Europe and in Australia as California thistle) is one of my favorite pasture plants for a number of reasons:

• It’s alfalfa-like in nutritional value.
• It is very resilient. It spreads via seeds and roots. It can grow in all kinds of climates, soils and precipitation levels, so it’s always there for us when we need some extra forage.
• It’s really easy to teach livestock to eat it. In fact, I think of Canada thistle as the “Gateway Weed.” Once cattle are eating it, they look at everything else in their pasture in a different way and begin to sample and graze a little of everything.
• Its flowers are pretty, they smell good, and they’re great for bees.

But not everyone appreciates Canada thistle they way I do. In fact, we’ve got a long history of hating it. Sir Anthony Fitzherbert, who published the very first farming manual in English in 1573, said that “thistyll was one of the weeds that greue mooste.” Carolus Linnaeus who developed the first weed classification system in 1753 considered it “the greatest pest of our fields.” In fact, people have disliked this plant for so long that before Canada existed, its name was “Cursed thistle.”

Lots of Canada thistle at Theodore Roosevelt National Park in North Dakota.

Lots of Canada thistle at Theodore Roosevelt National Park in North Dakota.

Cursed thistle immigrated to North America in the 1600s with the pilgrims. The list of laws requiring people to control it started with Vermont in 1795. By the 1800s it was so common in Canada that people assumed it was native, and that’s probably how it got the name we call it now. By 1865, the plant had become such a problem to farmers, that Canada enacted the first legislation for eradication of a weed:  The Canada Thistle Eradication Act of 1865.  By 1868 the state of Iowa wrote its own legislation declaring:  “…that if any resident owner of any land in this state after having been notified in writing of the presence of Canada thistles on his or her premises, shall permit them or any part of the root to blossom or mature, he or she shall be liable to a fine of five dollars and cost of collection for each offense.” We’ve tried hard to comply with the laws we’ve made for ourselves, but our “enemy” has resisted mightily.  It has even developed resistance to 2,4-D, the herbicide most commonly used to control it back in the 1960s.

Maybe it’s just because I’m from Colorado, (where as you all know, another kind of weed was recently legalized), but I’m wondering if it’s not time for us to take another look at Canada thistle. Is it time for us to legalize this weed? We made the laws, and we can remake them if we choose. So, just like my 1976 classmates and I did in high school debate class when assigned the topic of “Should we legalize weed?” let’s consider a few of the arguments about “legalizing Canada thistle.”

Canada Thistle is a Gateway Weed

Lewistown, MT heifer eats Canada thistle in pasture.

Lewistown, MT heifer eats Canada thistle in pasture.

I already admitted that yes, it is a gateway weed. I look at this as a good thing, because once livestock are eating this weed, they begin to eat everything else in their pastures. This means more forage for the livestock, and less time and money spent by producers trying to control something that we’ve not had success controlling since it arrived in North America.

On the other hand, there are times when this weed should be controlled. It IS a pest in crops and gardens. Perhaps we need different laws? Maybe like the medical marijuana laws some states have, we could have forage weed laws that provide for their use as forage, but govern how they are managed in and near crop settings.

Canada Thistle Would Increase

And you say this like it’s a bad thing. 😉 All I can say is “More Forage, More Forage!”

I’m not sure that it’s our laws, nearly as much as it is our culture that keeps us battling this plant. I guess we’d have to ask producers, “If we legalized this weed, or any other weed, would you gladly throw up your hands and let weeds have the run of your place?” I’m guessing the answer would be “No,” but it’s always a good idea to use a little bit of science to give us answers to questions before me make big changes.

Here's a list of how to keep ruminants safe when grazing Canada thistle from another On Pasture article. Click on over to read the whole article.

Here’s a list of how to keep ruminants safe when grazing Canada thistle from another On Pasture article. Click on over to read the whole article.

There Are Health Impacts Associated with Livestock Grazing Canada Thistle

Canada thistle is a nitrate accumulator and if livestock have nothing else to eat, or if their rumens have not had the time to adjust to grazing them, the resulting nitrite poisoning can kill ruminants. This means that if we begin to look at these weeds as forage, we also need to understand how to work with our livestock to protect their health.

Eliminate Weeds for 200,000 more cattleLegalization Would Result in Economic Impacts

If Canada thistle were legalized, one of the impacts could be that folks selling herbicides might see a downturn in sales. These are people who have done us the service of providing us weapons in our War on Weeds, and their families and communities rely on their incomes as part of the economic fabric.

On the other hand, if producers have more forage and have to spend less on weed management, perhaps they’d make more money to add to their communities in other ways. Maybe the way they spend that extra money would even create new, different and even better jobs for the people who once sold them herbicides.

Start eating Canada thistle now!

Start eating Canada thistle now!

Maybe You Don’t Have to Legalize It – Just Eat It!

Even though we know that in the United States it’s the people who make the laws, the process we use takes us through all kinds of elected officials, and the process for creating a new law or remaking an old one can be labor intensive and time consuming. Perhaps we can avoid all that effort and just turn to grazing these weeds in pasture. There’s no law against that.

Kathy’s Offer

Here’s a reminder that I didn’t include when we first posted this article: I’m the person that came up with a simple method for teaching livestock to eat weeds.  It takes as little as 8 hours spread over 7 days and once your livestock have been introduced to one weed, they’ll decide on there own to eat other weeds they find in pasture. They’ll teach their offspring and herd mates to do it too, so basically all you have to do is train one bunch of animals, just once, and you’ve created a weed eating herd that will work for you for the rest of your time on the farm.

Since it’s spring, and we’re getting ready for all those weeds to pop up, I’m going to do what weed dealers have done for decades:  I’m going to make it easy and cheap to get you into the habit of your livestock eating weeds. You can choose your entry level: free, $35, or $50. (And some of the proceeds go to support On Pasture!)

Click to find out more.

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About the author

Publisher, Editor and Author

Kathy worked with the Bureau of Land Management for 12 years before founding Livestock for Landscapes in 2004. Her twelve years at the agency allowed her to pursue her goal of helping communities find ways to live profitably AND sustainably in their environment. She has been researching and working with livestock as a land management tool for over a decade. When she's not helping farmers, ranchers and land managers on-site, she writes articles, and books, and edits videos to help others turn their livestock into landscape managers.


  1. Kathy Voth says:

    Oh dear, Rod and Gene. I can see your confusion. In my head I was thinking of those folks who have been reading On pasture for awhile and know that I’m the person that teaches cows to eat weeds. And that’s why Canada thistle is my favorite weed. Cows learn to eat it with no problem at all, so in just 8 hours spread over 7 days, I’ve turned Canada thistle into a delicious nutritious forage. If you click here and scroll to the bottom of the page, you can see all the articles I’ve written for On Pasture that would help you turn your livestock into weed eaters. No, I don’t expect cows to miraculously start eating it. After 10 years of freely telling people how they can turn weeds into really great forage, to me it would be a miracle if farmers and ranchers suddenly decided they would do it.

    I can see why folks would have written laws about making Canada thistle illegal back in the day when we didn’t realize that it was the nutritional equivalent of alfalfa. And I can see, as I mentioned in the article, reasons for laws dictating how we manage it for the benefit of our neighbors. But now we have new information and to me that means that we can think about things in a new way. After all, if the same old solutions aren’t getting us anywhere, maybe it’s time to think of new ones, whether it’s marijuana, or human beings trying to escape lives of poverty and physical danger, or Canada thistle.

    I’m sorry the title of this article got you all riled. It was really meant as kind of a joke. Oh – and Rachel didn’t even realize that she was posting it on Facebook on the “4/20” when folks are focused on the other weed. So I guess the joke’s on us. 🙂

  2. Gene says:

    The fact that Canada Thistle is difficult to manage without herbicides is no reason to remove Canada Thistle from noxious weed lists. It is an invasive weed that lowers the quality of pasture and forage. I don’t see the correlation with legalized marijuana. Having said that, we do need to consider ways to manage this weed with non chemical methods, such as grazing.

  3. Rod Litzel says:

    I hate to get started on a topic like this, talk of legalization makes me cringe whether it is marijuana, border jumpers or now Canada thistle. To me it is more of an excuse to give up than to stand up for what is morally right and fight. I whole heartily support grazing management for the CONTROL of weeds, it is an important tool in our tool box for integrated weed management. However, the thought that cattle everywhere are going to miraculously start grazing C. thistle because it is now legalized is a crazy notion. Canada thistle doesn’t form monotypic stands because it likes to live in peace and harmony with all the other plants, it’s AGGRESSIVE, like any other noxious weed, and will continue to take over more acreage whether it is grazed or not. You also forget the basic principle of weed management in that the more Canada thistle you give up on, the more pressure from it those poor farmers and gardeners you are throwing under the bus are going to get from this weed. The same pressure surrounding states to Colorado feel from “legalized” pot. The “ole pot boils over” concept. You are also incorrect in stating we can’t chemically control it anymore, in fact there are some very effective products available, if you remain diligent, don’t give up and actually manage your property.

  4. Fred Forsburg says:

    As there were only a few Canada Thistle in one field I have never seen cattle eat them despite watching them grow from tiny plants to waist high. One day with time on my hands I got out the 500,000 BTU torch and cooked several large Canada Thistles which spooked the cattle but on going to the next plant about 50′ away I turned and watched the herd gobble up still steaming Thistle! Each one I cooked were in turn eaten down to the nub.

    What do you make of this? Who knew Angus prefer their food barbecued?

    • Kathy Voth says:

      I don’t know, Fred. People have described to me how cows go and eat things that were cut down or “prepared” in some way that they wouldn’t eat when the food was just standing in the field “raw.” Like, Cows will eat Italian thistle or Sow thistle in California if the rancher goes and chops it down and leaves it laying on the ground. I don’t know why this is. I have a growing theory though, just based on my observations with animals that I have trained. They seem to become accustomed to the idea that our job is to feed them. In my case, I use tubs to show them, “This is food. Eat it.” And they eat it. I’m starting to wonder if they think, “Look, the person whose job it is to feed us seems to have prepared us a new meal. To be polite we should go over and give it a try.” Yes, I know this sounds silly. But it’s my theory. 🙂

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