Sharon Sorby

Hi Paul,
Thanks for not beating me up.  I did have you half answered on Friday when I made the error of a non-blogger and went to post it after my log-in had timed out – lost everything!  So this time I’m writing it up as a document, will have to log-in and then copy and paste.

paul wheaton wrote:

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

I actually had an acquaintance many years ago, his name was David who was involved with permaculture, I think he was also involved with starting the “Tilth” magazine.  So my understanding of the principles go back many years, anyone who is able to implement the principles on the ground is a celebrity in my eyes.

paul wheaton wrote:

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

Symbiotic is a good word.  Trying to live in symbiosis with another organism(s) is a laudable goal.  However, being in symbiosis with another organism (such as a spouse) is difficult enough when you speak the same language, when you don’t, you can only guess you are "there" when things are running smoothly between you.

paul wheaton wrote:

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)

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.

paul wheaton wrote:

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. 

I was less successful at discovering what hawkweed does.  There are studies on some species that indicates allelopathic properties (such as mouse-ear out of New Zealand), but the only other study I found would have required purchasing the $10 article that I just don’t have the funds to do.

There have been studies on what both plants do in the rhizosphere.  How the mycorrhizae associated with the weeds interacts with the mycorrhizae associated with neighboring grasses.  Primarily, the weeds steal carbon from the grasses at this level.  The weeds are pre-adapted to our low nitrogen soils, so throwing nitrogen on them makes no difference to them, but it does to the grasses, helping them to compete.  Again, this can be accomplished at the home owner level, but not at the landscape level. 

paul wheaton wrote:

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. 

On pathetic soils, we have our own “weeds” (such as fireweed) that should be doing the job that the hawkweed is doing, but they can’t compete.  Remove the hawkweed and they will come up.

paul wheaton wrote:

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 you are in Missoula, my guess is to travel north toward Columbia Falls and follow the powerlines up toward Hungry Horse Dam.  When I conducted a survey there, about 15 years ago, orange hawkweed was invading neighboring lawns, my guess is that it has spread throughout the powerline and into the surrounding forests by now. 

If you travel west into Bonner County Idaho in early June, you will see a multitude of orange and yellow blooms through fields and forest meadows.  Continue west then north across Pend Oreille County and west into Stevens County and you will see more of the same.  Ferry County has mounted a valiant effort over the years to stop encroachment, but with pressure from the west, north and east, it may be a losing battle.

paul wheaton wrote:

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?

A big “if” as it is only speculation on my part.  Apparently hawkweed is edible, (you can see where it’s been grazed) but our deer do not recognize it as toxic.

paul wheaton wrote:

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.

This has been studied, although I have nothing to cite on hand.

paul wheaton wrote:

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.

If you have had success mowing at 3”, and that’s what it takes to get a “turf of awesomeness”, then that’s the best bet as you are correct in the healthier the lawn, the less even hawkweed can compete.

The Wicked Weed Cop of NE WA.

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.