[APWG] NPS & Military need to offer Prizes to invent methods for Sahara mustard

[Craig Dremann]

Dear All,

Boy, do we need a really huge PRIZE, offered by the NPS, for someone to
invent the successful technologies, to take care of the Sahara mustard
in Lake Mead!

Here's a report from Dr. Elizabeth Ann (Libby) Powell who works at Lake
Mead for the National Park's service, regarding the Sahara mustard and
Sisymbrium mustard.  

This is from an email discussion we've been having for a few weeks now,
between the National Park's Service, a USGS researcher, State DOT
people, California State weed officials, Nevada BLM people, etc.

I'm forwarding Dr. Powell's comments to other Federal and State public
land managers land managers, to consider, that unless we fund the
invention of not only managing weeds like the Sahara mustard in our
National Parks and Military bases---but we must also fund whatever it
takes to convert those weed-infested areas back to local native
ecosystems---then many of the National Parks and Military bases in the
arid west may just become gigantic solid 4-foot-tall flammable,
Endangered-Species-killing mustard-patches.

There needs to be a "Rapid-response for Exotic Invasives" by the NPS and
Military, otherwise all that beautiful land that was thought to be
protected, actually isn't.

I did not attach the pictures that are mentioned at the end of the
message, but you can email Dr. Powell directly for copies at
mailto:Libby_Powell at nps.gov 

My own pictures and surveys of the Californian Mojave and Californian
portion of the Sonoran deserts are at
http://www.ecoseeds.com/mustards.html .

Sincerely,  Craig Dremann, Redwood City, CA (650) 325-7333

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[Dr. Powell writes]

I think we can all agree that we have a very serious problem with these
weeds.  It appears that most of the Sysimbrium we have is S. irio- as
the fruits are longer than the flower tops and there is not the long
hairs on the stems- but we need to aware that we also may be wrong and
have two very similar species mixed together or are likely to get the
other Sysimbrium at any time.  I don't really care what we call it- it
was far too common this year in too many places.  S. irio- was very much
more common at Lake Mead NRA this year than we have ever seen it
before.  It appears to be along roadsides, where water has pooled, but
was in dense stands in those areas.

We did not like what we saw this year with this plant.  We also did not
like seeing so much African Malcolmia-another mustard- that was
everywhere- particularly on gypsum, this year.   It is very possible
that while our attention is focused on Sahara mustard, we will find out
that Sysimbrium or another species has moved in.   We can't put blinders
on - we need to be aware that all these alien species are potential
threats.

There is no need to nit pick details on Sahara mustard- we have a
disaster on our hands that a great deal of manpower will be needed- just
to keep at bay.   Plants disperse by several mechanisms- large plants
act as tumbleweeds and roll across the landscape shedding seeds that pop
forcefully out of the pods.   Plants can float in water for a long time
and still have viable seeds on them- we tested seed that had been under
water in Lake Mead for up to 11 weeks and they still germinated.  
Rodents cache the seed and move seed into open desert, and frequently to
caches under shrubs where their burrows are,  at some distance from
original infestation, almost immediately.    

These seeds are oil rich and tasty and my guess is that they are a
favorite of all seed eating animals.   Seeds have a mucilaginous coat
then swells up and adheres to almost anything within a few seconds of
being in contact with water.   I suspect that plants are moved by
vehicles, earth moving equipment, people, animals, wind, and water. 
Plants can roll down roads,  float across lakes, be cached and recached
by animals that move the seeds up to 100 meters from the last cache.  
Cached seeds can germinate and go to fruit just fine- even in dense
competition with  other seedlings in the same cache.

I suspect that Sahara mustard has gotten started along roads, either by
earthmoving equipment, road grooming equipment,  vehicles, or because
roads are corridors.  Once on the road side- seeds are cached by animals
into open desert under shrubs, or plants tumble into open desert and get
caught in shrubs, or both.  When populations saturate all the rodents in
neighborhood, plants spread out into the open desert.    We have
observed this at Lake Mead NRA.  We found Sahara mustard along the road,
and particularly at corners, on Christmas Tree Pass in the Newberry
Mountains.

We were particularly puzzled by how disjunct the populations were.  
After talking with Maintenance people, we found out that road repairs
were made with fill from a highly infested area and road grading
probably explained the spread along the road and particularly at
corners, where soil tends to be piled up.  Soft soil piles are good
places for rodent caches, as well. We were able to stop the infestation
from further spread by pulling out all the plants along the roadsides
and from infected places before they went to fruit, but we have had to
do this religiously and thoroughly for 2 years in a row, so far.  This
means that there is a seed bank of unknown longevity that may  haunt us
for years to come.

I think Sahara mustard has a preference for sand and gravels- but we
have found it on heavy gypsum- and in very salty soils, like under
established saltcedar stands- It is mistake to think this plant only is
a menace for sandy soils.  - It goes to sand first- but it goes
everywhere else, as well.    Seeds can germinate in water laced with
high concentrations of salt.

On Sandy Cove, a dune system here at Lake Mead NRA that is home to the
largest known population of a rare plant,  we have been removing plants
with ever increasing intensity for 5 years now.   When the water was
high in 2000, there were very few Sahara mustard plants on the dunes. 
When.the water went down we started seeing infestations in the drawdown
zone.  These infestations have now gotten so huge, we can't deal with
them all.  

Plants get huge along the shoreline where there is ample water and these
huge ball-like plants, break off and the plants blow up onto the
dunes.    A great deal of the shoreline is now infested and plants have
moved up out of the drawdown zone into open desert.  We can't stop it. 
On the east side of the dunes, I found NO Sahara mustard plants in 2001,
in 2003, I pulled out less than 50 plants from the dunes while I was
doing my rare plant survey. In 2004, we pulled out over 3,000 plants
from that same area.  This year we pulled out over 10 times that from
the same area, and had to leave large sections that were too steep for
us to get down on to pull out the plants. 

I think this plants can and does explode, maybe we don't know exactly
how, but it does it.   Seed production is huge, viability is very
high,and there may not be as much predation as we would like.  The rate
of growth may be uneven and extremely large in certain years- also the
seedbank itself works against us.

We also are doing roadside surveys for invasive species of plants,
including Sahara mustard- it costs a lot to do these surveys-the labor,
data management, vehicles, etc.   However, I feel that if we waste
valuable time that this plant does not afford us, by studying how bad it
is- we may miss the window we need to actually do something about it
before it is so widespread, there is nothing we can do- but wring our
hands because now we know how bad it is.    

We have sites on Lake Mead that we have been clearing of Sahara mustard
for the last few years, that were so covered with plants this year, and
our manpower priorities so critical, and time so short, that we could
not do anything this year.   We had to watch helplessly while these
areas get reinfested with another huge seed crop that will haunt us for
the next- who know- 6 years?? And spread even further into the desert
and up washes- making control ever more impossible.


It is time to act, not study this menace- in my opinion- or say goodby
to our favorite desert places as we have known them.   It is definitely
easier and more fun to create experiments rather than start pulling
plants- but pull we better start doing- soon- or we can forget finding
an answer otherwise, in my opinion.  When areas get completely
overwhelmed, we will need to basically nuke the whole area with
herbicide and start over- because Sahara mustard it is not going away-
it is spreading rapidly and populations are becoming denser and more
pernicious every year- that is what I am seeing here at Lake Mead, in
any case.

There are miles upon miles of Sahara mustard infestations on Mormon Mesa
, in Logandale, and along the highway to Mesquite, my surveyors tell me-
you don't have to go to California to find huge overwhelming fields of
this stuff.

There are collections of Brassica tournefortii from Lake Mead in the
1970's, we just recently figured out we had a problem when plants showed
up on Sandy Cove  and in other places around the park that are
particularly sensitive habitats.

These pictures were taken on Sandy Cove.

(See attached file: The way dunes should look.jpg)(See attached file:
The way they are starting to look.jpg)(See attached file: The way they
will look in a couple years.jpg)


<><><><><><><><><><><><><><><>
Elizabeth Ann (Libby) Powell, Ph.D.
Botanist
Lake Mead National Recreation Area
601 Nevada Highway
Boulder City, NV 89005
Phone (702) 293-8759
Fax ( 702) 293-8008
Libby_Powell at partner.nps.gov

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