[MPWG] Unknown disease/pathogen on Microstegium (Jap. stiltgrass) - on native medicinals, too?

Fri Sep 4 12:55:23 CDT 2009

It's possible we've been seeing the disease/pathogen black cohosh at the 
MPWG field sites in Virginia for a couple years. -Patricia

Patricia S. De Angelis, Ph.D.
Botanist - Division of Scientific Authority
Chair - Plant Conservation Alliance - Medicinal Plant Working Group
US Fish & Wildlife Service
4401 N. Fairfax Dr., Suite 110
Arlington, VA  22203
703-358-1708 x1753
FAX: 703-358-2276

Promoting sustainable use and conservation of our native medicinal plants.
<www.nps.gov/plants/medicinal>

ForestRuss at aol.com 
Sent by: apwg-bounces at lists.plantconservation.org
09/03/2009 09:04 AM

To
APWG at lists.plantconservation.org
cc

Subject
[APWG] Microstegium health questions update

APWG:

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.

Does it appear that the disease or whatever it is shows similar or related 
symptoms in native plants?  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. 

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.

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. 

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.

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.

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.

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. 

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.

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. 

I hope the photos and comments below add some worthwhile information to 
the discussion.

Russ Richardson, Certified Forester
Crummies Creek Tree Farm
PO Box 207
Arnoldsburg, WV 25234

304-655-8919
 c-304-3773231

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. 

This is a close up of the remaining stiltgrass in the photo above.

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.

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.

There will be no problem finding the dogs in this sick patch of 
stiltgrass.

_______________________________________________
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Disclaimer
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