Knapweed: Can we get rid of it without spraying chemicals? : LUSENET : Countryside : One Thread

We went to our property in E. Washington this past weekend to do fall "maintenance" before the cold weather sets in (although it was well below freezing at night so far). We have to cut down any apple trees that start growing because of the risk of coddling moth infestation in an intense apple growing region (we bought land that had previously been an orchard and was cleared; however apples continue to pop up each year.)

In addition to the apple sapling cutting, we are also trying (in vain) to eradicate knapweed, which has taken hold in an area of an old flume (probably about .25-.5 acres really badly covered.) This is nasty stuff! We have tried carefully cutting it out, removing as many seeds as possible, etc., for the past two years. Nothing works. The weed board has told us to use Tordon (not sure if spelled correctly) but the longevity for this is 7 years for replanting anything woody, as I understand it, plus I'm just not a fan of chemicals anyway.

It was also suggested that we plant alfalfa and then irrigate heavily. That means that we would have to set up a sprinkler system, invest in a pump, possibly, and find someone to crop it for us. Sounds like a good deal for someone close by our property, where there are a few growers, but so far nobody seems interested.

My question is whether or not anyone knows of anything else we can do besides the two options mentioned. Have you had experience with this weed? We live >200 miles away, and on the other side of a mountain pass, which will get snowy and harder to travel on in another month. I don't think there's much we can do until spring anyway...


-- sheepish (, October 09, 2000


Hi Sheepish, we live in northern Idaho and have plenty of knapweed around here. I can't understand the crusade against it,in fact, I rather like it, it's pretty, and it grows where other stuff won't. Looks like light purple bachelor's buttons! But, it's illegal to have it-apparently it kills cattle if they eat it- so we try to control it. Goats love the stuff! It doesn't harm them in any way, and they will keep it cleaned up.It's best to pasture them on it before it sets seed, while it's still young and tender, for best results, and repeat grazing as it grows back during the season.I guess you could burn the site in late spring-early summer before it sets seed, since you can't put goats there unless you are there too. Also, I know that the noxious weed fanatics claim that each plant can set hundreds and thousands of seeds, and that at this rate it will take over the world, but if you take apart a few of the seed heads, there is usually a worm in almost every head. That worm eats the seeds! Now id f they are so gung ho on getting rid of it, why don't they spread around more of this insect? IMHO, this noxious weed control nonsense is just a way for the chemical companies to make buku bucks; what other explanation can there be for it, since they've been the main pushers behind the legislation to get these plants considered "noxious"?

-- Rebekah (, October 09, 2000.

Rebekah, yeah, it does sound a bit nuts! Our neighbor, who is a green fanatic, has been working on getting rid of these weeds for a long time. We like him, and of course, would like to not spread our nasty weeds back to his property either. But sheesh! Short of moving over there, there's not much we can do at the moment. So, it doesn't harm goats? Maybe we should take Siegfried and Roy (our Nubian boys) over with us sometime and let them have at it! Seriously, I don't think there's much we can do short of homesteading on it and that's still a ways away. Maybe we can run black plastic along the fenceline and confine the weeds to our side of the fence at least!

How about birds? Do they eat the seeds?? Thanks for your reply!

-- sheepish (, October 09, 2000.

When I lived in Montana, I had three acres of knapweed. Such a beautiful wildflower! Such an itchy pain! All the farmers around me hated that I refused to spray.

As far as I know, the only ways to get rid of it is to overwater, run pigs or goats or pull by hand.

I had good success with hand pulling, twisting them clockwise and getting the full root. After pulling a patch, I would seed with a pasture mix and water it well. There can be several large plants connecting to a single tap root so even though pulling is effective, it can be hard work.

When eradicating knapweed, be sure to wear gloves. There is some evidence that longterm expsure to knapweed can cause skin cancer. I don't know how credible that evidence is, but I do know that it can cause a nasty, itchy rash.

Here's a thought, if you cut lots of bouquets of those beautiful wildflowers, they won't go to seed! Picture a knapweed and tansy bouquet, enough to drive the weed police crazy!

-- Laura (, October 10, 2000.

We battle with it too but it is not as much a problem as Scotch Broom or blackberries. the latter two I can manage somewhat by pushing the out with the tracttor & loader but the berries still come back, I use Crossbow on them. The knapweed is scattered here and there, we pull it and chop, the brushog gets some but it still persists. When live stock eat noxious weeds the seeds go through them and come out all fertilized. I do not ever expect to get rid of all the weeds, if any. Washingtgon state is especially sensitive about weeds but if you read the national noxious weed list you would be surprised at what has broken out of the garden and feild crops to become a problem. If it is a real problem for you I would spay it and the put down a thick, managable crop.

-- Hendo (OR) (, October 10, 2000.

Sheepish, my husband says that another thing that will help get rid of knapweed is to improve the soil fertility, because it grows mainly where nothing else will, and doesn't have much competition.He thought that mowing it several times, in combination with improved fertility and sowing a pasture crop, should get rid of it.

-- Rebekah (, October 10, 2000.

Whatever you do, don't use tordon! If an animal grazes a tordon field and you try to use the manure in your garden, it will kill everything!

Knapweed can be controlled in many ways. Being 200 miles away will make it extra difficult.

Mowing is the best way. The plant saves up a bunch of carbs in its roots and then has a big growth spurt in late June, early July - just before going to seed. If you cut it then, it has to make that big shoot again. Now the plant is pretty stressed. If you cut it again, the plant will most likely die, but a few will survive. One more cutting and you have probably eliminated most of the knapweed.

Knapweed invades fields by releasing toxic levels of niacin from its roots. So it is a very good idea to get rid of it.

It comes from russia and is controlled by several insects over there thave only recently be introduced here. It sounds like some of you have seen these insects at work! An excellent case for not using insecticides!

Watering washes the niacin away. Giving other plants a chance at competing with the knapweed.

I like the alfalfa idea. This is the first I've heard of that one. I wonder what would happen if you just let the alfalfa go hog wild - don't harvest it. I wonder what buckwheat would do.

As for the folks that refuse to remove it, lots of counties are making laws that it must be removed. I wouldn't be suprised if some backward county might spray tordon first and ask questions later. Not good!

Where in Washington state is this property? I just bought some land there and will be moving up in a few months. I'm about 25 minutes north of Spokane.

-- Paul Wheaton (, January 28, 2001.

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