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<P><FONT size=2><FONT size=3 face=Arial><STRONG>One option is to use the straw
application on the worst, and relatively small, patches of invasives, and
use less harmful traditional treatments around the severely treated spots
so that natives can move back in over a five or ten year
period. </STRONG></FONT></FONT></P>
<DIV><FONT size=2><FONT size=3
face=Arial><STRONG></STRONG></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT size=3 face=Arial><STRONG><SPAN
class=703494011-16112012><SPAN class=109371913-03022012><STRONG><FONT
face="Times New Roman">Marc Imlay, PhD,<BR>Conservation biologist, Park Ranger
Office<BR>Non-native Invasive Plant Control coordinator.<BR></FONT></STRONG><A
title=blocked::mailto:ialm@erols.com href="mailto:ialm@erols.com"><FONT
title=blocked::mailto:ialm@erols.com face="Times New Roman"><STRONG
title=blocked::mailto:ialm@erols.com>ialm@erols.com</STRONG></FONT></A><BR><STRONG><FONT
face="Times New Roman">Natural and Historical Resources Division<BR>The
Maryland-National Capital Park and Planning Commission<BR></FONT></STRONG><A
title=blocked::http://www.pgparks.com/ href="http://www.pgparks.com/"><STRONG
title=blocked::http://www.pgparks.com/><FONT
face="Times New Roman">www.pgparks.com</FONT></STRONG></A><BR></SPAN></SPAN></DIV>
<P><BR></STRONG></FONT><BR>-----Original Message-----<BR>From: APWG [<A
href="mailto:apwg-bounces@lists.plantconservation.org">mailto:apwg-bounces@lists.plantconservation.org</A>]
On Behalf Of Wayne Tyson<BR>Sent: Wednesday, November 14, 2012 4:37 PM<BR>To:
apwg@lists.plantconservation.org<BR>Subject: [APWG] Ecosystem dynamics and 100
percent suppression by strawapplication Allelopathic straw keeping weeds out
& moisturein duringdrought<BR><BR>I have never seen 100 percent suppression
of vegetative growth by anything, much less straw. I once concluded
(erroneously) upon seeing a highly disturbed site "full" of the "worst" possible
assemblage of alien weedy species I had ever seen, that it was "100 percent"
devoid of any indigenous species after conducting a very cursory but pointed
point/quadrat survey of the area, I soon discovered how wrong I was. Down
between the weedy species I started finding small stands of "re-invading"
indigenous species, successfully slugging it out with the weeds. Where these
stands occurred, the invasives were clearly suppressed or entirely
absent.<BR><BR>If Dremann cannot or will not cite the specific mechanisms of
action relevant to the particular project he cites, I must continue to suspend
belief until he supplies more evidence. I find his direction to a website
insufficient to support his claims; moreover it is patronizing. I am well aware
of the suppressive action of "shade," "robbing water," and "robbing nutrients,"
but am aware of no chemical action which has been demonstrated to be any percent
effective in suppressing any weed growth, much less 100 percent. I stand ready
to be corrected and educated, based upon evidence and directly relevant
scientific/scholarly/disciplined research. "Many" does not reveal what
mechanisms of action are responsible for the claimed 100 percent suppression of
the species Dremann mentions.<BR><BR>I do agree with Dremann that "straw,"
including that of standing or prostrate alien species, can be protective of
surface evaporation as well as contribute to water infiltration and other
beneficial effects. However, the presence of any straw can have adverse effects
upon emerging vegetation as well. For example Robinson (????) studied this
effect upon Stipa (Nasella) pulchra (dissertation at the University of Oklahoma,
if my memory serves me correctly), and found that Stipa seedling survival was
very low under such conditions. This, combined with our own observations, led us
to develop the technique of planting very small seedlings in small colonies into
the weed-infested areas. The colonies expanded, albeit slowly, in our
experimental plots. We were never able to finish the large-scale project. We
developed a unique planting method that was very cheap (as were the small
seedlings), and, in terms of actual long-lasting results much more effective
than mass-sowing, using far less seed, thus minimizing the depredation of wild
stand seed stocks by over-collecting. As this work was never properly completed,
we never published on it; however, we did mark the plots with buried iron
markers that could probably be located with a metal detector today, some 32
years later, should anyone be interested in a follow-up.<BR><BR>WT<BR><BR>-----
Original Message -----<BR>From: "Craig Dremann - Redwood City Seed Company"
<Craig@astreet.com><BR>To: <apwg@lists.plantconservation.org><BR>Cc:
<craig@street.com><BR>Sent: Tuesday, November 13, 2012 1:10 PM<BR>Subject:
[APWG] Allelopathic straw keeping weeds out & moisture in
duringdrought<BR><BR><BR>> Dear Wayne and All,<BR>><BR>> Thanks for
your email. I will comment below your email:<BR>><BR>> Wayne--The
grass-straw mulch is an interesting idea, and I certainly<BR>> don't doubt
that such a practice might have some utility in<BR>> suppressing weeds, but I
am concerned about suppression of indigenous<BR>> species as
well.<BR>><BR>> Craig--Native grass and wild oats straw are being used on
a site that<BR>> has been 100% devoid of any natives for the last 12
years of<BR>> monitoring, and you can see a painting of the site at <A
href="http://www.ecoseeds.com/art3.html">http://www.ecoseeds.com/art3.html</A>.<BR>>
Since the straw is 100% effective against annual weed grasses like<BR>>
cereal rye, Medusahead or cheatgrass, plus annual thistles like<BR>> Italian
and Yellow Star, I do not recommend straw to be used in areas<BR>> where
native seeds might still be in the soil seedbank.<BR>><BR>> I wonder just
which "allelopathogens" are responsible for the observed<BR>> effects? What
is their mechanism of action?<BR>><BR>> There are many Journal of
Chemical Ecology articles an<BR>> allelochemicals, that you can access
through <A
href="http://scholar.google.com">http://scholar.google.com</A><BR>> and Dr.
Liu and his team have been important authors since the early<BR>> 1990s
studying the allelochemicals involved. His work was the first<BR>> to
sort out the allelochemical effects from the other plant<BR>> suppression
effects, like roots robbing water, or stealing nutrients,<BR>> or shading of
one plant by another, etc.<BR>><BR>> Since most of the USA is in severe
drought mode again, that you can<BR>> see at <A
href="http://droughtmonitor.unl.edu/">http://droughtmonitor.unl.edu/</A> the
straw mulch is keeping the<BR>> soil surface moisture in place for much
longer, perhaps twice as much<BR>> moisture today--while we have a dry 40%
relative humidity, barometer<BR>> reading 30.20 inches (no rain for a
while), and no dewfall at<BR>> night--than in areas that do not have
any mulch.<BR>><BR>> Sincerely, Craig Dremann (650)
325-7333<BR>><BR>><BR>><BR>><BR>><BR>>
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11/14/12<BR>><BR><BR><BR><BR>_______________________________________________<BR>PCA's
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