Organic Control of the Musk Thistle

by Chris on May 16, 2011

A couple of years ago, we temporarily housed 13 horses on our five acres of coastal bermuda pasture while my in-laws transitioned to a new piece of property. Despite providing them with a steady and ample supply of round bales, the pasture was severely over-grazed. As we all know, when you over-graze a piece of land, you are opening yourself up for the succession of aggressive species of plants to move in, no matter how well established the original flora may have been.

Musk Thistle – The Beautiful Invasive

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The Beautiful Musk Thistle Flower

That next spring, we were faced with a variety of invasive weeds, but the most troubling for me was the establishment of a large area of Musk Thistles . Musk Thistle (Cardus nutanns for all you botany nerds) is an invasive species that originated in Europe and Asia and was brought over to North America. It has a two year (biennial) life cycle, which doesn’t sound so bad. But it’s ability to mass produce seeds is amazing. Musk Thistle starts out as a rosette made up of thorny leaves that is generally unpalatable to livestock. As the season progresses, the plant grows stalks culminating with beautiful pink flowers. But those beautiful flowers transition to the equivalent of missile launchers as they expel thousands of downy seeds that are carried across your pasture via the breeze. Although it’s considered a biennial, I have noticed that in Texas where it’s a bit warmer, that often the thistle will produce seeds in the first year, which further compounds the problem.

How to Fight Musk Thistles Organically

I made a decision years ago to try and keep our place organic if at all possible. I’ll be honest, the Musk Thistle has severely tempted me to break that promise. But I persevered and I hope that my trial and errors can help you stay organic. For those of you not interested in following an organic path, there are several herbicides that can be used, although they are often times specific to a certain stage of plant development. You should contact your local extension agency for further details about non-organic herbicides.

Initially, we tried mowing the pasture to keep the plants from growing stalks. This turned out to be impractical on two fronts. It meant that we were having to mow almost our entire pasture multiple times (reducing the ability for the grass we were trying to promote to grow) and the Musk Thistle actually adapted and tried to flower at shorter heights.

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Musk Thistle in the Rosette Stage of Growth

The next year, I attempted to dig plants out with a hoe or pick. This was a bit better since I wasn’t disturbing the rest of the pasture, but I found it to be only partly successful. Often times, my chopping wouldn’t be deep enough and part of the root was left, which would regrow and complete the life cycle.

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A Musk Thistle Beginning to Grow a Flower Stalk

Last year, I finally found what worked best for me. I waited till the first plants began to grow stalks at least a foot high, but preferably before they began to create flower buds. I then put on a sturdy pair of gloves and with both hands gripping low at the base of the stalk, I pulled the entire plant out of the ground, root and all. It’s very important if you go this route to wear thick leather gloves and preferably a long sleeve shirt. The Musk Thistle is extremely spiny and the better the gloves, the more protection you will have for your hands. By pulling slowly, I’m able to extract the entire root of the plant, ensuring that it can’t grow back. We live on “blackland prairie” which is a heavy clay based soil, so it’s best to pull the plants after a bit of rain. The Musk Thistle has a tap root, so with a bit of practice, you will find that you can pull it easily.

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A Musk Thistle - Ready to Be Pulled Up

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Always Use Heavy Leather Gloves When Pulling Musk Thistles

It’s imperative to dispose of any flowers or flower buds properly. Never just throw down the flowers that you may have pulled, because they will just end up growing new plants next year. I bag up all the flowers and flower buds and burn them when weather conditions are right. It’s alright to leave the stalks and roots since they will not produce any seed.

Successful Organic Control of the Musk Thistle Requires Vigilance

Last year’s efforts have really payed off. I dealt with literally hundreds of plants in 2010. But this year, I have had to pull about 15 so far. I have scouted out another ten or so in one small corner of the pasture last year that will need to be pulled when they stalk out. This successful organic method has made me very happy. But as we all know weed control is never a one time battle. My neighbors are not always as proactive on their weed control as I am and their seeds may very well blow along the breeze. But now that I have my own pasture in order, I will be able to deal with any minor breakouts in years to come.

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