[APWG] Ecosystem management Alien species Phytoxins and or complex interactions? Re: Microstegium disease

Fri Sep 4 17:46:07 CDT 2009

APWG: (Please note: In an attempt to prevent multiple emails, I have shorn 
the odd-looking "code" from the end of the previous post. I hope this cures 
the problem of multiple emails, but if it does not, please advise. Thanks to 
all for your patience.)

While it may make apparent "practical" sense to "pull" fewer bigger weeds 
than a lot of small ones, the pulling of a bigger weed also can rip up a 
bigger proportion of the mycorrhizal net too, as well as cause a bump in the 
available nutrients and create optimal conditions for seed capture and 
germination (not to mention the "Hydra" effect sometimes involved in the 
case of asexual propagules), including those lying dormant in the seed 
"bank." Quite so that even standing-crop reduction "might not change 
invasion dynamics very much." While pulling all weeds large and/or small 
might provide visceral satisfaction and leave a "clean" feeling, such a 
Herculean effort may not be necessary. The counterintuitive "action" of 
leaving it up to ecosystem dynamics, including the development of the 
mycorrhizal net, letting second-growth vegetation sequester nutrients, and 
even perform ecosystem services that all the "King's" researcher men and all 
the King's researcher men haven't even guessed at yet, just might get 
farther eventually. This is not to say, however, that less traditional 
measures might not be taken to accelerate those dynamics, including 
resistance to invasion (Ewel, 1987, and St. John, 1992 
http://www.rngr.net/Publications/proceedings/1992/stjohn.pdf/file ).

When intuition and evidence butt heads, the former often drives and 
"validates" the paradigm, but an intuition driven by a bit of new or 
challenging evidence and theory might just lead toward a "paradigmless" 
future.

WT

Ewel, J. J. 1987. Restoration is the ultimate test of ecological theory. pp. 
31-33 in: W. R. Jordan, M. E. Gilpin, and J. D. Aber (eds.). Restoration 
Ecology: a synthetic approach to ecological research. Cambridge University 
Press, Cambridge.

----- Original Message ----- 
From: <ialm at erols.com>
To: <sflory at indiana.edu>; <forestruss at aol.com>; 
<apwg at lists.plantconservation.org>
Sent: Friday, September 04, 2009 10:41 AM
Subject: Re: [APWG] Microstegium disease

Regarding: "Everyone who works on Mv knows that it is not limited by seed
availability so even a 50 or 75% reduction in seed production might not
actually change invasion
dynamics much." for spraying this may be true because we have fewer plants
but thery are bigger because of lack of competition with each other. For
hand pulling, however, it is much easier to pull after the seed bank has
been exhausted for 3 years. It takes no more time to pull a tall big plant
as it does to pull a small plant and there are about 1/5th as many plants.

Marc Imlay, PhD

Conservation biologist, Anacostia Watershed Society
(301-699-6204, 301-283-0808 301-442-5657 cell)
Board member of the Mid-Atlantic Exotic Pest Plant Council,
Hui o Laka at Kokee State Park, Hawaii
Vice president of the Maryland Native Plant Society,
Chair of the Biodiversity and Habitat Stewardship Committee
for the Maryland Chapter of the Sierra Club.

Original Message:
-----------------
From: S. Luke Flory sflory at indiana.edu
Date: Thu, 03 Sep 2009 22:13:40 -0400
To: ForestRuss at aol.com, APWG at lists.plantconservation.org
Subject: Re: [APWG] Microstegium disease

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
 <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
APWG, 
 
A plant pathologist and I are the ones who have been working on
identifying this disease on Microstegium. The symptoms on plants in IN
are nearly identical to the ones that Russ has seen in WV - we'll know
if it is the same pathogen that is responsible soon after we receive
Russ's sample. 
 
We first noticed the symptoms in the field last year but have only been
able to get it into culture this year. We cultured out dozens of
microbes from infected tissue but we now have the pathogen isolated and
are currently working on publishing the results. Of course the next
step is to conduct experiments to determine the fitness consequences
for Microstegium. Most populations that had the disease last year are
still very invasive this year. Returning plants could be from the seed
bank or it could be that the plants are still able to produce
relatively abundant seed even with the disease. Everyone who works on
Mv knows that it is not limited by seed availability so even a 50 or
75% reduction in seed production might not actually change invasion
dynamics much. We'll see. 
 
Please let me know if you have diseased plants in your area,
particularly if you might be willing to ship us a few plants! 
 
thanks, 
Luke 
 

<pre class="moz-signature"
cols="50">**************************************************************
S. Luke Flory, Ph.D.
Indiana University
Department of Biology
1001 East 3rd Street
Bloomington, IN 47405
Cell: 518-774-4649
Office: 812-855-1674
Fax: 812-855-6705