The most famous thistle patch in MN

[SD51555]

I did it. I saved a big block of Canada thistle just to show how this works. This site was a trench I had dug to bury some brush and then moved some subsoil over to smooth out the transition between expansions in this plot.

I would have left this patch alone whether we were going to talk about it or not. The thistles are the first responders to repairing soil. What will happen here is this patch will go from 6’ tall and solid to gone over two years. I expect it will weaken significantly next year already. I am going to throw a little gypsum in there because it needs it, but that’s probably it. The thistle itself should be plenty of mulch to cover up my fall seeding.

I’m letting the thistles finish up and produce seed to recharge the seed bank. That white pine in back is the marker tree for this spot. Remember that. I’ll bookmark this and come back to it as things happen.

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[Mortenson]

Not worried about the seed? Most states say it's against the law to allow it to grow. I like that you're doing it in the name of science. Watching.

 

[Catscratch]

Same, watching... always watching.

 

[hillrunner]

I'm interested in this experiment. I've had a life long hatred of thistle. As a kid , I spent a good part of my summers chopping thistles in the pasture with a corn knife. The thistles and the blisters grew faster than we could chop.
These days when I spot a thistle, I waste no time getting it sprayed.

 

[Foggy47]

Following.

 

[SD51555]

I wish I'd have documented this long ago. I haven't had a canada thistle patch that has endured. It was a combination of laziness and refusal to spray that led me to this. When it first came up in a big way, I just threw up my hands and said "the hell with this" and moved onto work on something else.

Also, during covid, I read a lot of obscure books about plants and organic acids, and that's when I discovered the concept of auto-toxicity. Thistles and alfalfa are the same in that regard. Once you have them, they cannot grow back where they were until some time passes and then they can re-emerge. If conditions don't improve, they can keep coming back.

We had wicked bull thistle in the pasture growing up. My dad also grazed it to fairway height and never allowed it to come back, so the bull thistle would just move over a few feet and keep coming back, and then a year later, it'd go right back where it was. I focus on letting the conditions continue to improve. If that spot needs thistle, they'll do their job and then leave. There are lots of big roots pushing channels into that clay. I'm counting on my fall seeding following those thistle roots to pay dirt.

 

[Jerry-B-WI]

I'll have to somewhat agree with SD. After I had some of my land logged to meet MFL requirements I had thick thistle growth in places it never grew before. Probably from disturbing the seed bank and opening up the land. Freaked out for a while. Then I read his theory about thistle burnout and watched it happen in a few spots.

Now if he's got some theories about marestail and cattail I'm all ears.

 

[SD51555]

Not worried about the seed? Most states say it's against the law to allow it to grow. I like that you're doing it in the name of science. Watching.

No. If there was ever thistle in the neighborhood, there is thistle seed everywhere. It only takes one good crop to charge the seed bank for 50 years. And one action to recharge it for another 50 years. There's probably 2 million viable thistle seeds in that patch alone. It only germinates when something that shouldn't have happened happened.

 

[Mortenson]

Saw this today.

Galls on Canada Thistle: Biological Management at Work

A common sight this summer on Canada thistle is odd growths (also known as galls) on stems. These galls are a product of thistle stem gall fly attacking Canada thistle plants.

extension.sdstate.edu

 

[Bill]

I'm a believer. Planted 40 acres of switch after a few years of beans. Trying to spot spray thistle became a nightmare. I read your suggestion and said F-it. A couple years later and there is zero thistle in that field.

 

[Telemark]

I have a different thistle problem. I'm getting more and more thistle in a field that is usually pretty wet. More and more of them come back every year. I limed last year, and the thistle population just grew. I have no idea what to do about it except spray. The same field was getting overrun with dock, so I sprayed it twice this summer, and it seems to be good and dead. The pasture mix i sowed where the dock died off looks great and is getting attention from the deer. The thistle has me scratching my head.

 

[Tree Spud]

I'm a believer. Planted 40 acres of switch after a few years of beans. Trying to spot spray thistle became a nightmare. I read your suggestion and said F-it. A couple years later and there is zero thistle in that field.

Bill ...My thistles are thistles are not in clumps either. How did you deal with them spread out?

 

[Bill]

Bill ...My thistles are thistles are not in clumps either. How did you deal with them spread out?

I just ignored them and they went away.

 

[Brian662]

I have some Canada thistle and bull thistle competing in a CP2 mix that is going on it's 3rd growing season. The diverse CRP blend had been holding it's own but I have done some mowing in this area during mid June to set them back. Hopefully they get choked out before I have to intervene with chemical.

 

[Ben.MN/WI]

A neighbor a mile from my place has a thistle choked crp field that has continues to produce trophy thistles after 5 years. They have been mowing off big chunks of the field, but so far the thistle keeps coming back. I would think the CRP grass mix would choke out the thistles eventually, but it hasn't happened yet.

 

[Brian662]

I have been advised to spray them in the fall after the "natives" go Dormant from a frost. I haven't decided if I want to do that or not yet.

 

[Native Hunter]

A neighbor a mile from my place has a thistle choked crp field that has continues to produce trophy thistles after 5 years. They have been mowing off big chunks of the field, but so far the thistle keeps coming back. I would think the CRP grass mix would choke out the thistles eventually, but it hasn't happened yet.

The CRP can't choke them out where I live. We have one called Pasture Thistle, which is an annual. It finds a way to come up even in thick perennials. Partridge Pea is another annual that can do the same thing. Of course, it's a good one, and I'm glad that it can.

I had a few Bull Thistles and Canada Thistles, but I was easily able to find and kill them. They are easy to see, and the flowering time doesn't vary much. They are close to nonexistent now. However, I think the Pasture Thistle is here to stay. I hunt them down the best I can, but they have a flower that is hard to see, and they germinate all through the season. When the CRP starts getting big, it helps to hide them. Because of that, just enough of them survive to keep them going.

 

[SD51555]

I have a different thistle problem. I'm getting more and more thistle in a field that is usually pretty wet. More and more of them come back every year. I limed last year, and the thistle population just grew. I have no idea what to do about it except spray. The same field was getting overrun with dock, so I sprayed it twice this summer, and it seems to be good and dead. The pasture mix i sowed where the dock died off looks great and is getting attention from the deer. The thistle has me scratching my head.

Are they coming in because your soil isn't waterlogged anymore? That may be your disruption, and the first thing to colonize the newly oxygenated soil is thistle.

 

[Telemark]

Are they coming in because your soil isn't waterlogged anymore? That may be your disruption, and the first thing to colonize the newly oxygenated soil is thistle.

No, it's as wet as ever this year. That may be the problem. It could be marsh thistle.

 

[H20fwler]

Would this hypothetical "theory" work on teasel too?