[APWG] Mustard invades bare areas, needs native plants to control it

[Wayne Tyson]

Honored Forum:

Much as I tend to agree with much of what Dremann says, some of his remarks 
strike me as overstated.

For example, I have long been a proponent of using a healthy ecosystem 
approach to alien species management. There's much more to this approach 
than allelopathy, for example, about which little is known, less is proven, 
and much based upon conjecture. The sequestration of nutrients by complex 
biological associations, for example, has its conjectural components, 
certainly, but at least has a well-grounded theoretical foundation. This is 
not to say that I "don't believe in" allelopathy, I only suggest that it not 
be the sole consideration when analyzing a highly complex phenomenon.

Like Dremman, I do not advocate the pulling or spraying of this weed (or 
most others) either, but the devil is in the details.

I agree that any eradication program will theoretically have to be repeated 
until the last seed is dead, and I hereby declare that I don't believe for a 
second that that day will ever come--at any expense. I do not even know for 
sure that population reductions that will turn back the cost-curve are 
feasible, but since there seem to be so many individuals and agencies 
concerned with this taxon's management, it seems to me to use that 
inevitable momentum most wisely and see if an effective way of minimizing 
its spread and the cost of a continuing program of reduction if eradication 
is not possible. Again, my judgment, which I hope is quite wrong, is that 
eradication is not likely to be possible. I am not all that confident that a 
cost-effective reduction program is feasible, and it could be that 
considerable money, effort, and the sucking away of resources from programs 
or efforts with more promise or criticality could be the result of 
allocating significant funds and effort to the management of this taxon. The 
possibility, nay, the probability that Sahara mustard (SM) will outrun and 
out-reproduce even a very large and expensive management program looms 
darkly.

Neither do I, however, believe that "The only effective eradication or 
control for this mustard, is to cover bare areas with native annual 
vegetation . . ." even though I agree that the first consideration should be 
working toward a healthy ecosystem; sometimes "toward" is not good 
enough--sometimes (but not always) you have to "swamp" the site with cover. 
(Most of the time, however, "swamping" is a mistake, and should be 
undertaken knowing the risks by experienced hands who understand the 
possible consequences of the alternatives.) In either case, however, the 
elephant in the room, particularly with desert annuals, is the potential for 
damage done to existing stands when seeds are taken to plant elsewhere. Many 
a "seeding" project has wasted many a seed through much promise and little 
performance. I suggest that "we" and the seed industry would be well-advised 
to be prepared to answer questions about adverse effects upon existing 
populations, lest we suffer a clampdown on wild seed collecting of 
ridiculous proportions.

On the "bright" side, the worst of SM invasions seem to be markedly worse, 
at this time, in disturbed areas--a condition to be expected in the case of 
plants that benefit from disturbances like plowing, grading, and 
wheel-spinning. It does appear in areas that are disturbed by erosion, 
advulsion, wind, and other natural forces too, but insofar as my casual 
observations indicate, SM does not "take over" relatively undisturbed areas 
with the same ferocity as disturbed ones. Disturbing, yes, but encouraging 
if good science can establish whether or not this is and will be true for 
the duration, and the worst-case scenario is that SM will become little more 
than an occasional weed in most or some undisturbed areas. We need honest 
studies that can be and are replicated to answer these questions more 
accurately or refute the present conjectures entirely.

As Dremman wisely points out, the simple expedient of refraining from 
creating new bare areas, is probably the single most cost-effective step in 
reducing the spread and increase of SM.

I believe I have mentioned before that I believe that some SM stands 
constitute a potentially serious fire hazard. However, fire officials tend 
to believe that discing and other forms of disturbance is the best 
"solution" to such threats. "We" should take care to politely suggest that 
other methods can be cheaper, more effective, and less damaging.

WT

PS: I should add to my previous post that broken SM stems (with seed pods 
attached) often hang up in desert shrubs like creosote bush (obviating the 
needs for drift fences?), from which they should be collected and disposed 
of in some lethal way.



----- Original Message ----- 
From: "Craig Dremann - Redwood City Seed Company" <Craig at astreet.com>
To: <apwg at lists.plantconservation.org>
Sent: Monday, February 28, 2011 8:27 AM
Subject: [APWG] Mustard invades bare areas, needs native plants to control 
it


> Dear Wayne and All,
>
> The Saharan mustard was still mostly a roadside weed in the California
> Mojave when my wife and I did our 2,000+ mil-by-mile survey in 2005 for
> that devil, that you can read about at
> http://www.ecoseeds.com/mustards.html.
>
> I call that web page:"How do we get ahead of the spread?" or "Dude,
> where's my Desert Ecosystem?" or "Did you want Mustard on that desert
> ecosystem?"
> or "Got Mustard?" or the "No Mustards Left Behind" program.
>
> Pulling or spraying of this weed, will only allow for plants to colonize
> another day or another year.
>
> The only effective eradication or control for this mustard, is to cover
> bare areas with native annual vegetation, like goldfields, amsinckia, Cal.
> poppies, phacelia, for example. Perennials like Indian Ricegrass and
> desert stipa are good also.
>
> These natives give off natural herbicides as they grow, and suppress the
> mustards from colonizing the areas.  We saw that effect very clearly when
> we were doing our survey, driving over 2,000 miles, and inspecting each
> mile.
>
> And we need to stop creating new bare areas, like the highway department
> does by blading along all of the desert roadsides in California.
>
> Plus, the weed is spread by off-road vehicles using BLM off-road vehicle
> areas, and then it gets spread from those vehicles elsewhere, like the
> rest stop 200 miles north in the San Joaquin valley along I-5 in Kings
> County.  If it gets spread in the hills around the San Joaquin valley,
> that will be the permanent end to a whole lot of annual exotic grassland
> grazing from Fresno to Bakersfield.
>
> I am hoping that some botanists or ecologists will go out and confirm that
> planting local desert native seeds will be the best and only successful
> method to stop this mustard?
>
> Sincerely,  Craig Dremann (650) 325-7333
>
>
>
>
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