the trouble with hawkweed

I remember some folks getting pretty freaked out about hawkweed.  Aparently, it is considered a terrible weed.

Could somebody please be so kind as to help me understand why it is so feared?  Does it kill other plants or something?

I wonder if this statement from wiki can give some clues.

"Few genera are more complex and have given botanists such a headache due to the great number of apomictic species. Through speciation by rapid evolution, polyploidy, and possibly also hybridisation, this variable genus has given rise to thousands of small variations and more than 10,000 microspecies, each with their own taxonomic name, have been described"

If the species is able to rapidly evolve, controlling it could be especially difficult because it could adapt in a hurry to accomodate conditions. Just a thought. I had never heard of it before I just googled it because your post piqued my curiosity.

In any large genus, expect that some species will be thought hurtful or weedy; some benign; some desired. So it is with Hieracium. Seattle has the native woodland wildflower White Hawkweed H. albiflorum, that is weak and particular as to its growing conditions. Two yellow-flowered European species are also present. The first, usually called Spotted Hawkweed, H. maculatum, is technically really H. spilophaeum 'Leopard'. It grows in shade, and has handsome purple mottling on its blue-green leaves; bright yellow flowers make it prized by some gardeners for its beauty. The second is Savoy Hawkweed, H. sabaudum, that blooms in late summer or fall, and grows tall. It is lovely, too. Finally, we have Orange Hawkweed, H. aurantiacum (also called Pilosella aurantiaca), with fiery flowers. Its hybrid H. stoloniflorum is rare but here. These two orange-flowered species spread bu strawberry-like runners.

In my garden I have cultivated all of those. They are lovely, and edible, being mildly bitter. But the Weed Police consider them noxious weeds. The major flaw with Washington State noxious weed laws is it fails to distingush between the gigantic differences between, say, an eastern Washington farm, and a Puget Sound garden. Some plants that thrive on one side of the mountains scarcely survive on the other side. In Seattle, hawkweeds are not serious weeds --dozens of others, dandelions included, are more vexing.

Arthur Lee Jacobson

I can understand concern about some weeds, like leafy spurge or knapweed (which poisons the plants around it) or canadian thistle or bindweed.    These are so invasive that once they get started, they can be really hard to find something to outcompete them.  They can dominate an area pretty thoroughly. 

I've only seen yellow hawkweed and orange hawkweed. 

I guess I don't understand the panic.  Will hawkweed dominate an area?  The plant seems so tiny and low to the ground.  It seems to like only the poorest soils, so it seems like a great indicator of where there are poor soils.

Is it toxic in some way?

Like Arthur was saying, the Weed Police may consider it toxic in an Eastern Washington farm. I've heard of this happening if livestock will eat the plant and get sick or die.

But the thing is, a grazing animal won't eat something that makes them sick unless the land management is horrid. This happens when ranchers don't rotationally graze or they have too many animals for their site. Instead of addressing the larger issue, the Dept of Resources or someone, blames the plant that is actually the symptom of the problem.

Hawkweed's presence is just a symptom of disturbed soils.
Just like a lot of other so called 'noxious weeds'.
There's a communication gap between the people who put weeds on the 'bad' list and the native plant enthusiasts in this situation who may assume that it Ruins ecosystems. While there's nothing wrong with being a native plant enthusiast, why put energy fighting the hawkweed when energy can be better spent fixing the whole ecosystem?

This was especially apparent to me when I saw that the native horsetail is on some 'toxic weed' lists. It's a native plant for goodness sake!! And if there's horrid, poorly drained pasturage than it will come in, and I suspect livestock will get sick from it. (I'm guessing all these connections, so anyone feel free to correct me).

It's the 'nature' bad guy, not the humans-as-bad-managers paradigm. Often we Should just say 'oops' and learn to correct our management.

kelda wrote:

But the thing is, a grazing animal won't eat something that makes them sick unless the land management is horrid.

That is not necessarily true. some practice an intense rotational grazing system that stocks animals high and moves them often and gives extended rest to the grazing area. This creates competition in the herd and less selective eating. The advantage of this is that the animals (cows or goats in this situation) eat the less favored items and not just pick out their favorite. Otherwise animals slowly can kill out favored plant species and allow others to flourish (probably how part of how native species can become invasive). If you think about the giant herds of bison that roamed the plains you will remember that they trampled and ate almost everything in their way and then moved on allowing the grasses to recover until they migrated back through. Intensive grazing mimics this. I think if you were attempting that system an invasive and toxic plant would be pretty scary, although I don't know about the toxicity of hawkweed specifically.

I was at Mike Oehler's place a few days ago (northern idaho).  He was VERY concerned about hawkweed.  He had lots of it and, he is certain, that there are some areas where it has outcompeted wild strawberry and bracken fern.  I'm quite surprised.  Especially about the bracken fern.  How does hawkweed stand a chance against bracken fern? 

So, there is the first part:  apparently, the hawkweed is taking over.  Having a little here and there is not such a big deal until the things he wants to be there are no longer there.

And then there is the second part:  If he doesn't get rid of all of it, the county can come down, spray it, and then make him pay for spraying it.

So far, I have not found wikipedia to be of much help.

How does it outcompete bracken fern and wild strawberries?

What might one plant that could outcompete it?  It appears to thrive in deep shade.

As posted above - aparently it isn't a big deal in the puget sound area, but a big deal in Mike's area?

Help!

Ahhhh .... it's allelopathic ...

http://www.juneauempire.com/stories/050908/nei_277407011.shtml

Hmmmm .... 

Studies in British Columbia revealed that most orange hawkweed populations are in sites low or deficient in sulphur. By fertilizing light infestations with ammonium sulphate, grasses and forbs are encouraged to out-compete the hawkweed.

It is such a beautiful flower ... I wonder how it would look on the table as part of a boquet?

I wonder how it would look as a dried flower?  Maybe you could actually sell them at market and the like! 

from http://ublib.buffalo.edu/libraries/e-resources/ebooks/records/efd1051.html

It has also been reported to be allelopathic, producing phytotoxic chemicals in its pollen grains that inhibit seed germination, seedling emergence, or regeneration of other plants (S.D. Murphy 2001).

I can say that about six years ago I had some hawkweed pointed out to me on my land and I was instructed that I should pull it and burn it.  So I did.  I also covered the area with hay.  And I never saw the hawkweed pop up in that area again.

Many years ago I saw some in our lawn..but at one time a very bad company called True Green made a mistake..and they came to our land when we were not at home and began spraying our property with their herbicides.

I got home and they were here spraying and I demanded an explaination..they apologized as they got the wrong address, and they left..

HOWEVER..that was not the end of the story..i proceeded to sue the pants off them when so many of my treasured wildflowers and plants and even most of my lawn died..!!! and I won..got a huge settlement considering the loss was wildflowers..and wild plants and lawn..

They had to give me enough money to BUY more plants and reseed..etc..

go figure they showed up again and wanted to spray again but this time i caught them..they have a bad reputation for going in and spraying then billing you...without permission..killing off everything in your yard !

needless to say after that a whole lot of "weed" that were in my lawn, daisies, clover, hawkweed, etc..never showed up again..

In his book Weeds: Control Without Poisons, Charles Walters says that any land being overrun by a particular weed tends to have some kind of soil imbalance.

What really needs to be done is to study WHERE a so-called weed grows, and test the soils there.  I'll bet there would always be a deficiency or an excess of something else.

I think the answer is always the same: Know Your Enemy.

Commercial farming methods have been of the knee-jerk variety for over half a century.  Farmers used to know their soil, but not now.

Farmers are always whining about weeds taking over their land, and many of them seem to do everything they can to aggravate the problem.  Acres and acres of yellow star thistle going to seed... when they could have mowed it at the right time and ruined the seed crop.

So is it really noxious weed or lazy, ignorant landkeeper?

Sue

Susan Monroe wrote:
any land being overrun by a particular weed tends to have some kind of soil imbalance.

I often think it is just ingnorance. people don't even try and think of a non chemical way to take care of an issue anymore.

here I go picking on authors again.  about the above idea ........the problem with that assumption is that the term 'weed' is a human one not a natural one. different plants flourish in different areas. whether or not we call them 'weeds' tends to simply be dictated by whether we like them or not. I have trouble with terms like 'imbalance'. it doesnt' really mean anything in this context at least in the sense of the negative connotations it is used to imply.  really. who is to say that soil condition that encourage comfrey are not imbalanced and soil conditions that encourage hawkweed are? is it our view of the species of plant growing that determines whether the soil is imbalanced? it is much more useful to simply try to find out what will discourage the unwanted plant (such as your suggestion of timely mowing) than for authors to throw out terms such as imbalanced encouraging the fantasy that humans have that everything will just fall into place and we will have no troubles if only we reach some kind of state of being 'one with nature' and we find some kind of msytical formula for no weeds, no pest and perfect food.  okie dokie. back to my meditation 

I agree that I was tempted to dismiss hawkweed along with most other "weeds".  Now that I've learned a bit more, I feel I would like to know much, much more. 

First, it is now clear that hawkweed is a prolific breeder that enjoys full sun as well as heaps of shade. 

One plant throws off thousands of seeds per year, and will also reproduce with something like strawberry runners. 

Since the plant exudes a poison, it will kill surrounding plants - to make room for more hawkweed. 

I would like to learn more about which poison it exudes and how it does it. 

Also, apparently its seeds will remain viable for many years - waiting for the right conditions to come to life.

Tricky.

A bit of investigation shows:  this plant makes for lousy honey. 

I wonder how it does as a dried flower?  It's probably illegal to sell as a dried flower - so there is probably no point in exploring that.  It sure is a pretty flower. 

I think I would be hard pressed to come up with many plants that I would say are not a good fit for polyculture - but this one ....  I think it is safe to say that a polyculture environment would do better with zero hawkweed.

Hand pulling combined with deep mulch and vigilant monitoring appears to be the solution so far.  I would really like to figure out something that would be a bit easier.

I am getting a bit obsessed with this one. 

I'm pouring through the index of every book I have. 

And ... as dorky as this is ... some of the very best reference books I have on so many things is the thin "booklets" from ortho.  I've picked many of these up from garage sales.  The trick is to completely ignore their advice on what to spray.  The funny thing is they often give advice on an organic approach first!  So, from the ortho book "controlling weeds" (which I cannot find on amazon):

"The presence of hawkweeds is a give-away that the soil is dry, infertile, acid and compacted."

EXCELLENT!

And to control:  "Apply lime and fertilizer as indicated by a soil analysis.  Aerate the soil in compacted areas." ....  "and improving the soil with considerable amount of organic matter."

....  There is still a great deal I would like to know about this plant.  Especially the allelopathy. 

But, from my permaculture perspective, I think that when you encounter a patch of hawkweed, it does seem wise to drop everything and deal with it immediately. 

I think the area is about to experience a heavy, smothering mulch.  Showing that it is wise to always keep a couple of tons of moldy hay on hand.  Mulch heavily and then toss a seed mixture on top of it.  And then move on. 

oh oh , guess I'll be keeping my eye out for it again..don't remember seeing it since our "spray" incident..

That was kinda my response to the sand spurs that were all over parts of my yard, I dumped a garden on them.  Well first I put cardboard down and then dumped the load of mushroom compost and planted the garden in it.  Will see if they re-appear in the fall.  They are supposed to be a sign of poor fertility and boy do they hurt.

"... who is to say that soil condition that encourage comfrey are not imbalanced and soil conditions that encourage hawkweed are? is it our view of the species of plant growing that determines whether the soil is imbalanced?"

Actually, soil imbalances are not an arbitrary opinion.  It has been discovered that minerally balanced soil have levels that are very close to what they are (well, should be) in a healthy human.  And that makes sense to me.

Balanced soil is said to grow practically everything, from those that are associated with acidic soils (blueberries) to those associated with alkaline soils (cucumbers).

I understand what you're saying, that we always want to change things to accommodate the particular things we're wanting to grow, and that isn't taking in the big picture, either, even though sometimes you do the right thing with the soil, almost by accident.

The way I understand it, when a plant will grow in marginal soil, it's only because it has been able to adapt to that kind of soil, tolerating the excesses or deficiencies.  But that isn't the only place it will grow -- it will grow in minerally-balanced soils just fine. 

The difference is that in balanced soil, everything grows well.  When a wide range of plants have their every need met, they all grow well, and the playing field is leveled, so to speak, because a few plants (considered undesirable) don't have that 'edge' of being able to grow better under nutritionally poor conditions, which will cause them to take over a field.  In good soil, they are kept down by competition of a bunch of other healthy plants.

Comfrey will grow very well in balanced soil.  But so will Hawkweed.  And apple trees.  And dandelions. 

The balance in the soil provides a balance in the plant growth.

Sue

(I am going to post this in the Lawn section, but I wanted you guys to see it ...)


Please help me.
I am quite the dummy about yard care.
I live in Western Pa.

I mean well. I will not use anything except organic approaches. If this is a two- or three-year plan, that is OK.

If I did not live in a bit of a "lawn cult" neighborhood, I would probably let the weeds take over.

So ... my problem ...
My yard is being taken over by Yellow Hawkweed
http://www.msuturfweeds.net/details/_/yellow_hawkweed_25/


I had the soil tested. It is acidic. I was advised to add lime to the yard three times this year, and to add fertilizer three times as well.

I went to a local organic gardening specialist with the soil test report and photos of my yard. He gave me some advice.
Some of it I didn't like ... for example, he said organic weed killer will not work.

So, I am confused about the best way to:
1) get rid of the Hawkweed and
2) grow grass after the Hawkweed is out

I have not applied anything to my yard for years -- not fertilizer, no grass seed, nothing.
Currently, the Hawkweed is blooming.
I have cut the grass twice this season.

Here are my questions:

1) Should I spray the Hawkweed with something (Espoma 4in1?) to kill it -- and then dig it up?
2) Or should I just dig it up?
3) Do I use a rototiller to dig it up? Hawkweed spreads by stolons.
4) Once the Hawkweed is dug up, what is the best approach for growing grass on those spots?
5) Do I just buy a few bags of top soil, dump it on the bare spots, and plant the grass seed in it?
6) Should I put fertilizer on the grass seeds? Or lime first, and fertilizer later?

The front yard is my #1 priority. It is visible to the world. The back yard is not as visible.
The front yard is also much smaller. I will guess 50 feet x 60 feet.
The hawkweed patches in the front yard (two of them) are about 10 feet by 10 feet.

Thanks VERY much for any help you can offer!

Mary
AKA "Hawkweed Hater" -- NOT Hawktail hater -- argh! typo.

Mary,

If you click on the "profile" button at the top and then click on "account related settings" you can change your name (it says "This is the displayed name that people will see.") to "Mary".  Or "Mary" and your last name.

My understanding is that hawkweed does not like mowing or watering.  Are you doing these two things?

The lime and organic fertilizer will help. 

My guess is that it will be easy to beat in a lawn.  But if you have any other landscaping, that might be harder:  I would mulch. 

I suspect that you can beat it entirely organically. 

I beat it organically.  Of course, I just laid mulch on it and did nothing after that.  That might not look so good in a lawn.  But I think the mowing and watering will work for you.

Paul,

Thanks for the speedy reply!

I do not water. I do mow the grass. The Hawkweed spreads each year.

What do you mean by put down mulch? Is the idea to smother the Hawkweed?

Then what about planting grass on those spots?

Thanks,

Mary

The hawkweed generates an herbicide that will help it to outcompete the grass.  Water washes the herbicide away.  Then grass easily outcompetes the hawkweed.

The mowing, lime and fertilizer will help too.

And in the end, you will have an amazing lawn. 

If you read my lawn care article, you'll get a lot of other tidbits that will be a big help.

Paul,

As you requested in the other thread, here are photos of the Yellow Hawkweed in my yard. Every year the patches get larger.

Excellent!

A picture of the weeds a little closer would be good too.

Earlier I quoted:  "The presence of hawkweeds is a give-away that the soil is dry, infertile, acid and compacted."

And it looks like this could be very true.  On every point. 

Earth worms can reverse the compacted part.  But they will need food.  Their food should be lawn clippings and maybe some home made compost (not store bought).  A light dusting of lime dust every month or two will help too.

A bit of watering through the summer will help with the "dry" part.

Some ringer fertilizer, plus the lawn clippings and earthworms will help with the infertile part. 

And the lime dusting will help with the acid part.

In attempting to help your grass beat the hawkweed, make sure that you mow your grass no shorter than 3 inches.  You will end up with a thicker, healthier turf that will need less mowing and less watering.  And annual weeds will almost disappear.

In the first pic - look to the left .... that's a fairy ring.  Notice how thick and lush that grass is. 

So .... in summary .... you have created an environment that is perfect for hawkweed.  Make an environment that is perfect for grass and your grass will flourish and your hawkweed will be sad.

I'll post the close-ups in a few minutes.

By "fairy ring," do you mean "dog urine site?"

My friend's doggie was visiting. Wherever she pees, the grass grows thick and green.

Is it the nitrogen causing this?

Here are closeup photos of the Hawkweed:

dog pee does have nitrogen.  And other stuff that the grass will enjoy.

So the dog must pee in a circle.  Wacky!

One really great thing about hawkweed is that is shore is purty. 

But looky thar!  Grass is still eeking by!

Take a look where the dog pee is.  Imagine if the grass grew that thick and lush where the hawkweed is - would the hawkweed have a chance? 

There are things you can do to beat the hawkweed overnight, but it is a lot of work.  If you follow the advice I've given you and wait a couple of months, I think you will notice a significant improvement.  And next year will be much better still.

"But looky thar!  Grass is still eeking by!"

Well I'll be.

[taking off hat, wiping forehead]

To me this was one solid mass of weed. Impenetrable. Incorrigible metallobioform.

Yet! It's a mix of Itself and grass! And dried up things!

You have saved me a lot of wasted time, money and effort. Thank you SO MUCH.

paul wheaton wrote:
Excellent!

Earlier I quoted:  "The presence of hawkweeds is a give-away that the soil is dry, infertile, acid and compacted."

And it looks like this could be very true.  On every point. 

This is incorrect. I have quite a bit of orange hawkweed 'Devil's Paintbrush' AKA Hieracium aurantiacum in both my front and back yards.

The soil is NOT poor in either location, and vegetables planted in either spot will flourish without much need of any fertilizer, organic or otherwise.

The soil MAY be compacted, but there are plenty of earthworms out there doing their thing, judging by the robins that land on the property and make off with a wormy meal.

And the pH?

paul wheaton wrote:
And the pH?

Couldn't tell ye precisely, as I don't have a PH kit anymore. But here in Western PA, the soil is usually quite acidic vs alkaline. My father used to add lime to the garden, whereas out west a lot of folks add peat moss, I've noticed. Course... the pine trees surrounding the property probably contribute to that some too.

I think that if you have fallow soil, then having weeds like hawkweed pop up are expected. 

I think the bit about the soil being infertile and compacted is an analysis of untilled areas.  Because if the soil were rich and not compacted, then other plants would beat out the hawkweed.

True enough. Of course as it stands, the orange and yellow hawkweeds beat out the yucky grass and provide us with a gorgeous display of colors from spring until fall.

Vajk wrote:
True enough. Of course as it stands, the orange and yellow hawkweeds beat out the yucky grass and provide us with a gorgeous display of colors from spring until fall.

The bright side!

They are amazing blooms!  Especially the orange blooms. 

It is a pity that they do not fit well in the permaculture world.

I got a bee in my bonnet. 

With the big rise in traffic at this site, I wanna bump this and fish:  anybody know what the allelopathic thing is with hawkweed?

No, I didn't even realize that it was considered a noxious weed until I read this thread just now!  There was a lot of it on our place in New Hampshire, probably still is.  Glad I don't have to deal with it, LOL!  It is pretty -- we actually skipped mowing a patch of it in the front yard each year until after it was mostly through blooming.  Had the orange kind there.

Kathleen

paul wheaton wrote:
I got a bee in my bonnet. 

With the big rise in traffic at this site, I wanna bump this and fish:  anybody know what the allelopathic thing is with hawkweed?

The short answer is no.  It is suspected, but has yet to be adequately studied and we (the PNW) lost our academic hawkweed expert that would have delved into this question (pending funding) last year.  Hopefully we still have another up and coming hawkweed expert that may choose to take on this study.  Or perhaps there are European studies that have been performed, but my computer administrator has blocked translation sites, so I do not know.

There are anecdotal indications that some of the hawkweed species have toxic properties, this question also remains unstudied in the US. 

First, I would like to disclose that I am one of the wicked weed cops of Washington State, in the NE corner.  We share ecotype commonalities with the Puget Trough -- we're heavily forested, even with some disjunct inland rainforest stands of large cedar and spruce (complete with devil's club!), and heavily glaciated.

I have a lot of respect for the work you do on the ground and feel it is appropriate for the home yard and garden environment.  It's even appropriate for small scale farming -- if only farmers could still own their farms rather than large corporations.  However, your work is anthropocentric (as appropriate), and having your soil balanced to the human body is also appropriate. 

I work with a multitude of landowners, including state and federal agencies.  With these agencies, I have to work from the ecosystem point of view.  The ecosystem here, as with the Puget Trough, is balanced from the substrate rock and the plants and animals that have co-evolved here.  Our soils are naturally acidic, low in nitrogen, and ours here are high in phosphate (I don't know about the west side).

The problem with noxious weeds (which only means they are illegal (in WA) due to being invasive, difficult to control and damaging -- economically, to the environment or a threat to human health) is that they are pre-adapted to our ecosystem and have developed the ability to better harness the available resources.  This process has been studied with knapweed and it occurs within the soil ecosphere.  The same is suspected with hawkweed, but again, remains unstudied.

The reason we pick on gardeners is that the weeds easily escape the garden environment into the larger ecosystem where they upset the delicate balance between our co-evolved native plants and animals.  Noxious weeds have been documented as second only to land development for loss of our native biodiversity.  From an ecosystem perspective, this is disastrous. 

When hawkweed infestations reach a landscape level (which several species have in my corner of the world), the effects start to cascade.  At this time the outcome is unknown, but I have developed some suspicions.  We have had a population explosion of cougar within the last 5 years, I suspect it is from our abundant white-tail deer population grazing on the potentially toxic hawkweeds, becoming ill and an easier target for their principle predator, the cougar.  Older toms travel to the higher country, the principal habitat where the last vestige of the US population of woodland caribou struggles to survive.  They don't need additional predators threatening their existence.

And Mary, from your close up picture, it looks like you have mouse-ear hawkweed, a 3" mowing height would not likely hit much of the plant, which is good as mowing during bloom can actually spread hawkweeds as any flower heads that are cut will continue to produce seeds and the mower will spread any that are seeding.  I would raise the mow height another inch, and the rest of the suggestions sound excellent.  In the end, it is my guess you will have healthy lawn with a few remaining healthy hawkweeds that you could easily dig out as they appear.  Good luck.

To end my diatribe, I'm pasting from the USDA-USFS publication this admonition to gardeners:  Many invasive weeds, including orange hawkweed, have escaped from gardens. Always obtain correct species identification prior to planting something new in your garden. The detrimental impacts of these weeds far outweigh any potential horticultural benefits. Do not buy seeds via the Internet or mail order catalogues unless you can be sure they are free of invasive plants such as orange hawkweed. Take care when traveling to not bring back seeds attached to hiking or camping equipment, and "spread the word not the weed".

Most states do have a noxious weed law.  State noxious weed lists vary, as does the strength of the law and the enforcement level.  It would be great for gardeners to familiarize themselves with their local law and weed list, and then ally with their local weed cop.

Thanks for listening.

Sharon,

That's a lot of good info even though you aren't giving the info I am really fishing for.  At the very least, it sounds like we can attempt to do some power speculation.  And, I would like to ask you a few other questions - taking advantage of your coming by.

I have a lot of respect for the work you do on the ground

Cool!  I'm a known entity in your world.  I feel all celebrity-ish or notorious or something!

(BWA HA HA HA HA)

your work is anthropocentric

True.  Although lately I've been trying on "symbiotic".  I think I like "symbiotic".

I would like to disclose that I am one of the wicked weed cops of Washington State, in the NE corner.

I think you should put that in your signature!

The problem with noxious weeds (which only means they are illegal (in WA) due to being invasive, difficult to control and damaging -- economically, to the environment or a threat to human health) is that they are pre-adapted to our ecosystem and have developed the ability to better harness the available resources.  This process has been studied with knapweed and it occurs within the soil ecosphere.  The same is suspected with hawkweed, but again, remains unstudied.

I'm familiar with knapweed (and I'm tempted to start a new thread to talk about that).  The alleopathy is niacin via the roots, right?  (In the new thread I'll has how the bio control is going)

What does the hawkweed do?  I've seen patches where there is heaps of it.  Yet it still seems like other plants are outcompeting it.  It's leaves are so low to the ground, it seems like it just isn't gonna do well.    Yet there are lots of blooms. 

And then I see areas where the soil is pathetic.  It seems like nothing would grow there, but a few hawkweed plants are making a go of it.  And in these cases, my thinking is I should throw some seed down that will improve the soil.  But in the meantime, at least something is turning the dust into some kind of life. 

I have seen lawns that were quite riddled with the stuff.  I took one of those lawns on last summer and simply by mowing high, that eliminated 95% of it.  The neighbor continued to mow low and clearly had 20 times more hawkweed. 

But I have yet to see a powerful infestation in a pasture or in the wild.  Are there such occurrences?  If so, how common is that?

If the deer are eating it and getting sick, then I guess it is toxic - but is this a case where they are out of other browse, but the hawkweed has managed to still be edible?

And Mary, from your close up picture, it looks like you have mouse-ear hawkweed, a 3" mowing height would not likely hit much of the plant, which is good as mowing during bloom can actually spread hawkweeds as any flower heads that are cut will continue to produce seeds and the mower will spread any that are seeding.

Two things:

1)  how sure are you that the seeds become viable after the flower is cut?  I would think that seeds might still form (unlikely) but they would not be viable.

2)  I think that if mary mows at 3", then the clipping of the flower stalk does only a little damage to the plant, but the real power is that the turf gets much thicker and healthier and is then better able to outcompete the hawkweed.  And if there are seeds being spread, it will matter little since the seedlings won't stand a chance against the turf of awesomeness.

---

Sorry to hear that you lost your hawkweed expert.  I have a powerful appetite for these answers.

So far I have had excellent success in controlling it organically.  But then, I have not yet seen it take over a really big area (other than nearly every lawn in seattle).

Paul's interest has peaked mine, so I searched a wee bit.
Found this; seems the even the pollen in some species is allelopathic (three out of six known species exhibiting pollen allelopathy are hawkweeds!) More a roadside weed here (NE), see it only in the most depleted lawns, but our soils aren't quit as acid as PNW soils I'd guess...

Interesting indeed, Paul...

HG