[APWG] Microstegium disease
ialm at erols.com
ialm at erols.com
Fri Sep 4 12:41:52 CDT 2009
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
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<font face="Helvetica, Arial, sans-serif">APWG, <br>
<br>
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. <br>
<br>
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.<br>
<br>
Please let me know if you have diseased plants in your area,
particularly if you might be willing to ship us a few plants!<br>
<br>
thanks,<br>
Luke<br>
<br>
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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
<a class="moz-txt-link-abbreviated"
href="http://www.lukeflory.com">www.lukeflory.com</a>
</pre>
<br>
<br>
<a class="moz-txt-link-abbreviated"
href="mailto:ForestRuss at aol.com">ForestRuss at aol.com</a> wrote:
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<div>APWG:</div>
<div> </div>
<div>Since sending out my initial e-mail about some sort of unknown
disease or pathogen killing Microstegium in West Virginia I have
received an encouraging number of responses and I would like to pass on
some answers to questions that several people have asked. I would also
like to pass on some updated information.</div>
<div> </div>
<div><strong>Does it appear that the disease or whatever it is shows
similar or related symptoms in native plants? </strong>From what I
have observed, the answer would be yes. I have seen similar lesions in
a couple of local woodland grasses but it seemed more to damage or kill
individual leaves of grass plants rather than the entire plant. </div>
<div> </div>
<div>There is still no word on the name or identity of the pathogen
but a fresh sample of sick and dying stiltgrass was mailed to Indiana
University to see whether our pathogen matched something discovered in
Microstegium patches there recently.</div>
<div> </div>
<div>The weather in central West Virginia has been pretty normal this
summer. It has not been anywhere as wet as parts of the northeast. We
had a very dry period during late June and early July but generally it
has not been a year of extremes. </div>
<div> </div>
<div>I have been in contact with people at the WV Department of
Agriculture and the disease and they have identified a similar health
issue with stiltgrass in Lincoln County, West Virginia.</div>
<div> </div>
<div>Several people have suggested a rust and some people suggested
that it was a wind born virus. Because I have found infected
individual plants over 100 feet from any other plants I would have to
vote for wind dispersal. I have found very small individual plants,
the kind that are usually at the leading edge of an invasion with spots
on their leaves...those plants are so small that all evidence of their
existence is gone as soon as they die.</div>
<div> </div>
<div>As the stiltgrass plants die it appears that they die from the
bottom up....kind of like diseased tomatoes. Some of the plants
develop black spots on their stems and it seems that when the black
spots show up the likelihood of seed production drops.</div>
<div> </div>
<div>At Crummies Creek there are several sites where the mortality
has been occurring that will be easy to relocate next year to see what
happens. </div>
<div> </div>
<div>I am taking additional photos each day as things deconstruct and
will post a follow up as soon as I hear anything on the identity of the
disease organism.</div>
<div> </div>
<div>One final observation. It appears that whatever it is very
contagious. Woods roads that have been traveled since being infected
sport nothing but dead stiltgrass wherever wheel tracks have passed
over. </div>
<div> </div>
<div>I hope the photos and comments below add some worthwhile
information to the discussion.</div>
<div> </div>
<div>Russ Richardson, Certified Forester</div>
<div>Crummies Creek Tree Farm</div>
<div>PO Box 207</div>
<div>Arnoldsburg, WV 25234</div>
<div> </div>
<div>304-655-8919</div>
<div> c-304-3773231</div>
<div>
<div> </div>
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<td align="center" valign="top"><img
src="cid:part1.00050808.06090207 at indiana.edu"
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<div>Japanese stiltgrass at Crummies Creek. The plants
in this photo were climbing the road bank and averaged close to six
feet tall as they went up the slope. Nearly all plants on the more
gently sloping terrain above are very stunted and average less than a
foot tall and will produce no seed in 2009 and seed production in
general should be off by more than 95%. This is open woodland that
receives several hours of sunshine each morning. </div>
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<td align="center" valign="top"><img
src="cid:part2.08080905.03040806 at indiana.edu"
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<div>This is a close up of the remaining stiltgrass in
the photo above.</div>
<div> </div>
<div> </div>
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<td align="center" valign="top"><img
src="cid:part3.07080707.00030200 at indiana.edu"
style="width: 320px; height: 480px;" datasize="84080"
comp_state="speed" id="MA3.1251982709" border="0" height="480"
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<div>This is very sick Japanese stiltgrass growing in
optimum conditions for MV...very fertile woodland sites, northeastern
exposure with at least three hours of full sun a day. For forest
management purposes the area has a site index of over 80 and the
understory vegetation of the site includes: American ginseng,
Goldenseal, black Cohosh and several other related forest plants.</div>
<div> </div>
<div> </div>
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<td align="center" valign="top"><img
src="cid:part4.09000302.02050104 at indiana.edu"
style="width: 480px; height: 320px;" datasize="82426"
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<div>This is my dog Roy for a comparison of what
"healthy" stiltgrass looks like. Roy is a very large dog and sits close
to three feet tall...the stiltgrass on the road behind him is over four
feet tall. In healthy stiltgrass the only part of him you can see
walking through the woods is the tip of his tail.</div>
<div> </div>
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<td align="center" valign="top"><img
src="cid:part5.00090202.04040204 at indiana.edu"
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<td style="padding-bottom: 20px; padding-top: 5px;"
align="center">There will be no problem finding the dogs in this sick
patch of stiltgrass.</td>
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<div> </div>
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