understanding knapweed

Here in montana .... and I know that idaho and eastern washington too ....  one of the most common problem weeds is knapweed.

Knapweed is not a permaculture buddy.  At least, if it is, I do not yet know how.

Knapweed does really well in dry, crappy soil.  And it exudes gick out of its roots which acts as a sort of herbicide for other plants.  Dirty, rotten cheater!

I've beaten it, organically, several times.  There are two main techniques:

1)  The herbicide it exudes washes away pretty easily.  So if you add a little water, the nearby plants enjoy the extra water and then they outcompete the knapweed. 

2)  Repeated mowing when it is trying to flower.  It really hates that.  And grass likes it. 

In another thread, Sharon Sorby says:

This is what I found out about knapweed from this site:  http://4e.plantphys.net/article.php?ch=&id=377: ; Using this approach, the phytotoxin present in spotted knapweed root exudates was identified as a racemic mixture of (±)-catechin (hereafter catechin) (Figure 2). Bioassays with the two enantiomers revealed that they have different effects. (−)-Catechin is a potent phytotoxin, whereas (+)-catechin is a weaker phytotoxin with some antimicrobial activity (Bais et al. 2002, 2003; Veluri et al. 2004). Purified catechin from spotted knapweed root exudates and commercially available catechin acted similarly against a wide variety of plant species in bioassays, suggesting the chemical identification was correct. While catechin was identified as the principle phytotoxin in spotted knapweed root exudates, other chemicals in spotted knapweed root exudates or plant tissue may have similar phytotoxic properties. Further, spotted knapweed may produce other phytotoxic compounds when grown under more realistic field conditions, as opposed to the highly artificial laboratory conditions used in these experiments. In the model plant Arabidopsis thaliana, distinct root exudation profiles are associated with different stages of development (Walker et al. 2003); thus it is possible that spotted knapweed may secrete different phytotoxic compounds at different stages of development.

However, at this site:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2676754/: Our paper strongly supports the view of others that (-)-catechin is not an allelochemical. This very weakly phytotoxic compound is found in exceedingly low concentrations, if at all, in the soil in which producing plants are found. Furthermore, it is very unstable in soil and in water, and its derivatives do not appear to be significantly phytotoxic. We hope that the findings that challenge the view that (-)-catechin is an allelochemical do not discourage others from initiating or continuing research in this intriguing area of chemical ecology.

Knapweed bio-controls… Yes a new topic would be in order.

When I was doing my master gardener training in 1996, knapweed was pretty scary.  Knapweed comes from russia, and apparently it's pretty hard to find there.  This could be tied to how there are some bugs in russia that think that knapweed is the only food worth eating.  So we brought some of those bugs over here.  I once ordered two different knapweed bugs for a knapweed infestation, but never went back to see how everything turned out.

We have patches of it here, luckly the vetch is ballsy enough to deal, or it hasn't had long enough to really become a problem.  When the wild turkeys were around last winter (didn't have a doggie to scare them away then) I'd watch them pick the seeds out of the dried plants, so maybe we have them to thank for its relative containment as well. 

It definitely doesn't like to be cut down as it flowers, that's what we did all last summer.  That's our basic strategy for all plants we'd rather not have growing here.  And every once in a while my man goes around with a mattock and chops out as many tap roots as he can find in a ten or fifteen minute period.  That's pretty effective.  Well, my man's pretty effective with a mattock in general. 

How bout a star thistle thread?  While we're talking noxious stuff?

I think it would be great if a year from now if we had one thread for each plant.  Including plant that some people call "weeds".  So, today is a great day to start a thread about star thistle.

I'm having a huge problem with knapweed. Has anyone tried the bugs and have been able to see any results?

I'm really debating on spraying, although I'd rather not. I have dairy goats and hogs that share the same area as the knapweed, and I'd rather not take the chance, but I'm getting desperate.  Will it eventually die out if I keep mowing it?

Scott

You can kill it by mowing it.  I have experienced this first hand.

I tried the bugs on one property, but left before I could measure the results.

I would also like to hear about bug reports.

There are GOBS of organic things that work great on knapweed, do NOT spray.  We'll get it all cleaned up. 

First, look around your property:  I bet you can see where there are trees that are outcompeting the knapweed.  And tall shrubs.  So it is possible that if you converted your whole property over to trees, that would be one way to beat the knapweed.  I'm sure that this is something you don't want to do, but my point is:  there is now at least one for sure way to beat knapweed.

Now, let's look at more.

Mowing will work.  You want to do it at just the right time.  I think it is in june.  And you want to mow several times.  Knapweed lays low, building energy, and then shoots up a big bunch of growth with flowers.  And you cut that off.  Then it takes what little energy it has left and tries to do that again.  Cut that off too.  That will kill most of the knapweed.  A few will shoot up a third time - cut that.  Well, you get the idea.

What if your land transformed and while there was knapweed there, it wasn't very common.  Less than 1%.  And stayed at less than 1% - would that be okay?  In which case, some bugs, some trees, some mowing, a few other things - and that should keep it under 1%.  But!  Is this within an acceptable space for you?

Next:  bone dry dirt vs. soil with moisture.  I cannot remember ever seeing knapweed in an area where other plants seem to find enough water.  I know that knapweed's wickedness gets washed away with irrigation - but I wonder if knapweed just doesn't like moister soil?  Or maybe when soil is moister, knapweed does not compete as well.  That leads me to thinking about the techniques discussed in this thread.

How about mulch?  As with many noxious weeds, they have a hard time doing anything when covered with a foot of mulch.  And with the right kind of mulch, maybe two or three inches will be plenty.  And if you throw a few seeds on top of the mulch, that might help to seal the deal.

How many acres do you have?  What is the land like?  Can you upload pics?

Thanks Paul! I have 5 acres that's mixed with evergreens and grass.  I like the idea of mowing, and I also have goats. The goats tend to stay close to the barn and don't wander throughout the property like I'd like, but I know they'll eat knapweed with little convincing if given the chance. Maybe I'll have to divide the property into paddocks and rotate them through the different sections as needed.


I also rotate my Berkshire hogs on the same piece of property. I've seen them eat the grass, but from what I've seen, they don't seem interested in the knapweed. However, they will rototill the soil for me if needed.


I like the idea of improving the soil, and I'll start with that immediately by spreading manure. I also think you're onto something when you mentioned the dry land. It seems to grow better towards the back of the property where it's more neglected.

It's raining pretty hard out today, buy I'll try and post pics later.

Thanks for your help Paul!

As for critters, I once read about a guy that would harvest a whole bunch of knapweed and dry it and store it in the barn.  Come early spring, he would start feeding it to his critters.  The critters were so keen on any change of diet, they gobbled it up. 

Well, it seems they developed a taste for it.  So when he turned them loose on the pastures later, they would find it and eat it!

Unfortunately, I don't think it has any nutritional value.

Howdy folks, if you are interested in controlling spotted knapweed, leafy spurge or Dalmatian toadflax I think we can be of help.  My wife and I own a noxious weed biological control business that provides host specific insects that feed on and control several species of noxious weeds.  These insects are the natural predators of these weeds in their native range of Europe and Asia.  If you would like additional information on biological control visit our website at www.weedbustersbiocontrol.com or give us a call at (406) 251-4261.  Yes we do this as a for profit business, capitalism and ecologically sound practices can co-exist.  Look forward to answering any questions folks may have.

So, Bob, any comments about the other techniques?

And how effective are your bugs?  How long until they wipe out, say, 99%?

Hello Bob! I've been all over your site and found it very informative.

I've thought about your bugs and they look like they would be perfect, but I have free ranging poultry, and I'm afraid my birds would eat all of the bugs before they would have a chance to do their job.

Any suggestions?

Scott

A 99% reduction is obtainable and has been documented by Jim Story of the western Montana Ag reseacrh center in Corvallis, MT  a copy of this research is posted on our website under "supporting research"  that took 11 years to happen and his other site in the study had a 77% reduction in knapweed density.  We have seen similar results in the Missoula area.  You generally do not see a decline in knapweed density for about 4 years as the bugs need to build up to a high population before they can impact the plant. 

If you mow when the plant is in the bolt stage or flower bud stage, the plant will flower again at a later time.  You also throw the plant out of synchronization with the seedhead biocontrols and can actually increase viable seed production.  If you mow when the plant is in flower before it sets seed it generally does not flower again.  However different flowers develop at different times on the same plant.  Heavy watering can reduce the plant density, pulling is very labor intensive and does nothing about the extensive seed bank in the soil.  The seed can stay viable for up to seven years.  As for predation by chickens, turkeys etc they may get a few, if you can keep the birds away from the bugs for just a couple weeks after the first release I think they would be well established, really I think they would do OK without doing anything special but to be sure, it would be good to protect them at first after the first year you should have several thousand of them out there. Voles and other rodents are probably the greatest predator according to Jim Story who has worked on this research for over 30 years.  Hope that helps.

Here's a ton of info from Jim Story's research.  http://www.sheepinstitute.montana.edu/articles/eb311.html

That's good info about mowing while flowering. I just went out and mowed part of my pasture. Now I have a good excuse to put it off another week.
I have about 2 acres of knapweed and I can tell you that, after 20 years, pulling and poisioning won't work as long as you keep watering.
Blue flax seems to steal it's fire though. I think the flax competes for the underground bacterium. It probably tastes better than knapweed.
While most livestock avoid knapweed, I have found that Jacob sheep think it's candy. They passed up corn for fresh knapweed. While being a more wild version of the domestic sheep, they taste so much better than your average mutton. More like goat. Turning the knapweed into a BBQ is a fine method of control.

i tell you with the drought that we are having pulling it is getting a bit ridiculous, it tens to break off underground. fun..that just means hurting a rib trying again when it grows back up..

i have a lot of it here but it mostly grows in my lawn paths between my beds..rather than in the beds themselves..so I guess i'm fortunate..it is a common roadside weed in Michigan

Just read something in the Stockman Grass Farmer on-line and just had to put it here.  Seems that maybe the problem isn't an overabundance of knapweed but and underabundance of sheep

Sheep prefer Leafy Spurge and Knapweed to grass http://www.stockmangrassfarmer.net/cgi-bin/page.cgi?id=753

I am just not a fan of introducing another exotic species into the equation. Lots of problem species all over the world have been introduced to try and solve human developed problems. We really can never know for sure that these bugs might spread and become a problem themselves.

My property had lots of knapweed on it when I purchased it (in the sunny areas, not under the trees). The goatie girls and the two jacob sheep don't seem to eat the stems and leaves... but they love the flowers/buds/seedheads. I'm guessing I know have about 20% of what was here when I bought the place. Knapweed can make for some nasty tasting goat milk.....

I had knapweed beetles here when I bought the property. I don't see that they were winning the battle.

Depending on where you live, and how comfortable you are with the idea setting things on fire, a controlled burn regimen every spring will do wonders to restore a knapweed patch back to nice meadow.  I've seen this firsthand, over the course of several years a nasty knapweed/daisy/hawkweed patch became lush tall grass meadow.  A little hand pulling on a casual basis and keeping the neighbors horses out of meadow helped too.  The trick is to burn as much as possible as early in the spring as possible.  The combination of fresh ash, spring rain and sunshine really give a kickstart to the sod making grasses, which will out compete knapweed given a little chance.

http://www.youtube.com/watch?v=ZpzsnG8VFeY

hi Paul,

here in the wet east knapweed isn't a big problem (we have our own).
my question is " on this very dry land, what would normally be growing if knapweed wasn't there?"

New podcast of Paul and friends at the pub:) Towards the end of it, they talk about "good" weeds and "bad" weeds, knapweed being allelopathic. They also talk about the chop n drop method : http://www.richsoil.com/permaculture/308-podcast-036-aquaculture-community-weeds/

was THINKING about the knapweed thread while I was walking today, and observing how the knapweed grows along side the roads in our general area of Michgan.

I observed that it grew best in undisturbed areas in full sun. It was sharing it's growth with alfalfa mostly, but also queen annes lace, clover, chicory, and some clovers as well as some wild grasses.

It seemed to be most healthy in full sun with only alfalfa..but didn't seem to mind the chicory and queen annes lace.

My thought is, if you have a problem with the knapweed you might try growing the cultivated forms of carrots nearby as they seem to get along well with wild ones, and also if you need alflafla you might try that too, and chicory for greens..if you want to diminish the knapweed, possibly shading it out with more aggressive plants might work, I did notice as I got into shadier areas it would dissapear completely while the chicory and queen annes lace did not, and also where there were areas of wild perennial sweet pea it seemed to choke out the knapweed..if this is helopful.

Paul and Toby Hemenway, author of Gaia's Garden, talk about knapweed, as well as other invasives in this podcast: http://www.richsoil.com/permaculture/367-podcast-053-toby-hemenway-native-plants/

Paul talks about knapweed in this podcast: podcast

Knapweed is in the Centaurea genus. Many/most species of the Centaurea genus are both good sources of insect food (think trap crop) as well as good producers of nectar. So control seems to be a better choice than total eradication. Given the allelopathic nature Paul describes I could see using knapweed to control or reduce other less desirables in areas not often visited or easily accessible. I could also see using it to retake areas of other less desirable but harder to control species as the beginning process for clearing or opening land for other uses.

Which is the problem knapweed?

Some knapweeds are medicinal

http://www.henriettesherbal.com/blog/centaurea-flowers.html

http://www.henriettesherbal.com/eclectic/rafinesque/centaurea.html

There are so many good ways to deal with problem plants. I think sepp holzer's method of sheet mulching and planting right on top of undesired plants is the most effective and the by far the quickest method. His grace and respect for the land helps him see that there is no such thing as a noxious weed, just bad land management policies.

When I think of knapweed growing in western montana, i see the state's most valuable medicinal plant being attacked by almost everyone for being non-native or invasive. The "war on weeds" reminds me of the racism that fueled the mass genocide of indigenous people all over the world.

Knapweed has already seen its glory days here in western montana, where now it is slowly disappearing because of the bugs and the massive herbicide campaign. Because we failed to realize the value of these medicinal plants, we have poisoned the earth and ourselves, and must suffer a loss in the fertility of the land and the increased rates of cancer.

There are many farmers who have keep their fields full of the plants they desired, without using any herbicides to do so.

The most common techniques for controlling knapweed organically in western montana are:

-Rotational grazing using sheep or goats

-Annual or semi-annual burning of grasslands/prairie/meadows

-Routine mowing 2-3 times a year

-Releasing biological controls (the releasing of these insects is now really unnecessary since these insects have become well established in Western Montana)

Sheet mulching should be used in urban areas and where there are small patches of undesired plants. For most of the large scale land management areas, rotational grazing and burning will keep pastures and grass lands healthy enough to encourage a diverse plant community. There are many examples of the effectiveness of these techniques as shown above by others who posted here. Alas, knapweed isn't very hard to manage and isn't very scary. Actually it is quite beautiful.

The problem with knapweed is not that its a weed, but that it displaces native vegetation which is beneficial to livestock and wildlife. I don't think we need to worry about making it extinct here, lol. I don't think we will ever wipe it out. I do wonder how many native plants will disappear because of it though.

I worked for years to clear knapweed from my 1 acre field. My goats wouldn't touch it and I would never make them desperate enough where they would eat it, and repeated mowing alone didn't work because after repeated mowing it would flower at the base, right on the ground where the mower can't reach. A few years ago before I was educated, I sprayed it and that killed a lot of it. But those seeds get everywhere. The only way (in my experience) to get rid of it is repeated mowing combined with plenty of irrigation to get the grass growing. If the grass is doing well, the knapweed won't thrive. I also pulled it out by the root whenever I saw it, especially in the spring when the ground is soft. I really hate that plant.

The problem is that after you have controlled it on your field, it is reintroduced from the neighboring field. Its frustrating to work to clear a field of knapweed and then see it thriving right across the fence in the neighboring field because those damn seeds will just blow over onto my field and start the process over again.

Are the bugs really prevalent in the area now?

Okay, So the ones who named it knapweed, back then still believed in the concept of the "weed". I want one of those shirts that says "weeds, because mother nature is not your personal bitch!" I don't believe in the word weed because it is completely unscientific and anthropocentric (meaning people are the center of the universe) which is a common problem in our society. I would like to point out that a whole lot of plants that people plant for wildlife and livestock are not native, yet we still promote them.

The native vs. exotic debate is too huge to discuss here. I recommend Paul's videos with Toby Hemmenway to help people dissolve the myth of what a native plant is, and the notion that just because it was there first, it is better than introduced plants. The native plant agenda is pushed most by chemical companies, for profit-motivated reasons. Same with the idea that "native" species disappear because of non-native plants. IT doesn't make rational sense. The only reason species disappear, is a lost of habitat. Biodiversity, or having more than a couple species, doesn't make certain species disappear. So the idea that knapweed has or will cause the loss of "native species" is an idea that has no foundation whatsoever. The people who promote this lunacy, are usually working for weed boards or directly for pesticide companies. The only reason species disappear from an area, is because the habitat changes, which is usually caused by humans. A good example of this happening naturally, is the changes in flora after an intense forest fire. Why do you think we named fireweed so?

Making any species go extinct is not a laughing matter. And the fact that a person can actually hate a plant, says more about the person than the plant. If you hate something, then you do not understand it. Maybe that is why paul named this "understanding knapweed."

If you want to relieve yourself of unnecessary stress and worry over this plant, try keeping some honeybees. Then you will come to love knapweed (as all beekeepers in western montana do) and all plants. And then all living things and the whole universe come into this loving fold. This is closer to enlightenment than hating knapweed. Maybe you are frustrated with nature, because she refuses to be your personal bitch. This is where the opportunity to learn comes in.

As for the bugs being prevalent, they sure are in the Missoula area. They will slowly spread themselves throughout the land as nature sees fit.

For now if you want to prevent your field from being suitable habitat for knapweed, take better care of it, improve the soil fertility and/or plant trees. It is easily shaded out, and is easily outcompeted by other plants when the soil is more suited for the plants desired.

Want more knapweed? Do what most people do with their land. Overgraze it, compact and degrade the soil, or spray herbicides. This will ensure good weed habitat, and knapweed dispersed via wind, animals, birds or humans, will happily do what nature intended it to do.

I fought Russian Spotted Knapweed during two summers at Big Bay State Park on Madelin Island out in Lake Superior Wisconsin. It's an evil little plant. My only real observation is that is is persistent beyond belief. You could waste a lot of gas all summer long mowing it gain and again, but the issue is that unless you are planning on taking the area it grows in down to bare soil, the knapweed will happily produce a flow and seed at only a inch and a half off the ground! Best case scenario is to get local species to out compete it, but a single plant going to see can still mean you have to fight it for 10 years to come while dwindling down the seeds buried in the soil. I would suggest pulling plants over 6 inches after a good water soaking, and then mulching heavily. It'll give the natives the best chance to get an upper hand, but if you have a major infestation you can be in for a long fight.

Maybe I missed this point, and if I am being redundant I apologize. Isn't knapweed a pioneer plant? I see it growing where there is poor soil and bare land. In my opinion using sound permaculture design should reduce or eliminate knapweed where it is not desired. Does what I'm saying make sense?

Steve Flanagan wrote:...using sound permaculture design should reduce or eliminate knapweed where it is not desired. Does what I'm saying make sense?

Yes I think you are right. My experience with knapweed was before I even knew what permaculture was and at the time I knew very little about how to take care of a pasture.

I admire the hardiness of knapp weed but as I rudely found out last year the Montana state legislature has made it illegal to have what they call invasive species and have published a booklet outlining all the bad plants and the acceptable ways to get rid of them. By far it recommends poisoning them. I hate using poisions but now my property will be watched for the next five years to see if I am complying. Is there anything I can do, on a limited income in approximately .65 of an acre to get rid of knapp weed & Dalmatian toadflax?? I love the idea about watering but that will take an intensive investment in hoses & sprinklers which will substantially limit my purchasing power for anything else. Please help! Thank you for all the excellent ideas!

And as a brief note. My land was bare prior to my house being built. I live in the Helena valley which is a high mountain desert with tons & tons of rocks and nearly zero topsoil.

Violet,

I appreciate your trying to find a way to control these plants naturally, without cancer causing chemicals. The last thing we need is to promote the use of herbicides. We've already seen way too much of that. I am familiar with Montana geology and understand your situation completely. There are many options for you, and if you truly are interested in permaculture, Sepp Holzer's new book it well worth reading. Based on his recommendations, I think there is an easy solution to your problem.

The rocks on your land are very valuable in a permaculture scenario, while the lack of topsoil is your biggest challenge. Your acreage is small enough to easily take care of the situation without chemicals or hand pulling. Lots of people will suggest irrigation, but I would avoid it since you don't have a good layer of humus yet. Sepp Holzer recommends a few plants in his book for green manure crops. These green manure crops are what you need to seed if you want to build topsoil and increase the fertility of your land.

Being a Montanan, and a beekeeper who loves knapweed, I would suggest planting lots of sweet clover, both yellow and white, for their superior abilities to grow quickly, fix nitrogen and add biomass to the soil. Also from Sepp Holzer's list of good green manure plants, I would plant the following: sainfoin, white clover, oilseed rape, turnips, white mustard, rye, buckwheat, sunflowers, jerusalem artichokes and flax. These plants will provide food for you and for birds and pollinator insects that will deposit small amounts of highly nutritious fertilizer. These crops thrive in Montana and will help build what you need most, the humus layer. Also the tall plants will grow higher than the knapweed and toadflax, thus shading them and hide them from the county weed bureaucrats. When they see the tall sunflowers and sweet clover, they will assume there is no knapweed left. For visible plants, you can weed eat them or pull them.

Paul Wheaton adds a valuable suggestion to the long term goal of getting rid of these plants. It will come easily if you plant shade trees. I would plant fast growing deciduous trees that will shade out the knapweed and the toadflax while adding organic matter to the topsoil. My suggestion is planting apple trees from seeds because they grow fast, can provide food and will be hardy. If you have a limited budget, you can find plenty of wild and native plants to start a green manure polyculture. For easily identifiable plants that you can collect seeds from the roadsides and wild areas to use for starting your polyculture, I would suggest: sweet clover, thistle, mullein, dandelion, wild sunflowers, mustard and white clover.

The other options include hauling in topsoil, composted manure, or other organic material to help build a good humus layer. This could be very expensive and energy intensive. If you need to add organic material quickly, old moldy hay bales would be a good option(there are plenty in Montana!), but you need equipment and lots of manual labor to get the job done. I hope this gives you an idea of what can be done. If you are having trouble with the authorities, remember it is your land, and as long as you are doing something to control the unwanted plants they should be satisfied. At the very least you could mow or weed eat the plants before they flower to reduce their height and visibility to the authorities. I have seen many examples where mowing has successfully eliminated knapweed and toadflax, but usually there is a good layer of humus and healthy soil. In your situation, tall perennials, shrubs and trees will be your best defense. If you are looking for a lawn, then you definitely need to haul in topsoil. If you are looking for beauty and permaculture, try sowing the seeds of the plants I listed above, plus other ones you want to see, add organic matter, plant trees. Seems like a lot, but it all be done in one spring with a bucket of seeds and your own two hands.

Good luck!

My grandfather and I go out along our road and dig it out and/or cut the roots. We have it pretty much under controle.

A friend of mine swears by the tong treatment he came up with years ago. He wraps the ends with fabric dipped in an eco-herbacide (not sure which one) and gently squeezes the bud of each plant. Obviously very time-consuming at the beginning but now he only has a few plants each year to deal with as they blow in. I have also heard goats enjoy the flavor, there was talk of Mt. Jumbo becoming a goat experiment but I guess that idea was squashed. Does anyone know if there is any truth to that and if so what the story is?

Eco-herbicide? I think that is an oxymoron. Maybe its called distilled vinegar.

Mt. Jumbo has sheep grazing it to cut back the leafy spurge, but they still use toxic herbicides to spray for other things like knapweed and toadflax. I wonder how much of those chemicals end up in the sheep.

Years ago there were studies done on Mt. Sentinel to see if sheep would eat the knapweed, but they decided that the sheep more readily eat the spurge. So they quickly gave up on grazing knapweed, and they went back to blanket spraying which has decimated the native wildflower population. And these natives-only nazis talk about collateral damage, HAH!!!

But as long as the war on weeds continues and people let the "officials" hose down the mountainside with tordon and the like, there will never be progress. Terracing the mountainsides and planting shade trees is the best solution, but the native plant societies would shit their pants because they do not comprehend permaculture solutions. They believe in the war.

Goats would do better than sheep at eating knapweed, but they may be harder to contain and look after. Plus, who has that many goats? Maybe we should just turn Mt. Jumbo into a dog park, because that is what it is becoming anyway. Maybe all the dog shit will increase the fertility of the soil and the natives will out compete the knapweed. Oh wait, I forgot that the dog shit is toxic. Maybe that is why the knapweed is doing better than the shooting stars and bitterroots.

"Repeated mowings only encourage knapweed to bloom low to the ground, but one well-timed mowing when the plants are in the bud to early flower stage does reduce seed production by 79-99%. " http://www.wildflowers-and-weeds.com/weedsinfo/Centaurea_spp.htm


i've always heard that you have to pick it for five years before it will die.