Question about Allelopathy

A Question from a Forest Makeover Participant: I've read and witnessed that tree of heaven (Ailanthus altissima) is allelopathic. I'm getting quite a pile of sawdust and planer shavings from it and I'm not sure, is it ok for composting and garden paths or is the wood toxic to other plants?

First, some background on allelopathy (from wikipedia). "Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms. "

In researching this question, I came across a very interesting article. http://arnoldia.arboretum.harvard.edu/pdf/articles/473.pdf

After reading this article, I would tend to think that the shavings and sawdust from ailanthus harvested and sawed during the growing season (when there's a lot of sap and most likely ailanthone present in that sap) could be toxic or injurious to other plants growing in the area. So I would probably avoid using it as a mulch in the garden. However, there may be some benefit to using it on a trail or pathway where you wanted to keep the weeds down, and there aren't any plants you'd especially like to keep nearby.

Tree ID Courses offered at the Matthews State Forest in June and July

Forest Makeover Participants and Guests:

Tree identification courses to be offered in June / July. The next couple of forestry courses will be offered in the field, rather than in the classroom.

These tree id hikes will be offered at the Matthews State Forest, and will be offered on three different evenings:

1. Thursday, June 24
2. Wednesday, June 30
3. Wednesday, July 7

Feel free to attend just one, or all three--each will probably be a bit different, depending on the experience level of the group. Please RSVP to david.richert@dof.virginia.gov by email to help us prepare for the program...as a special bonus, we are offering a Native Trees of Virginia tree id book free to those who RSVP. For more information about the Native Trees of Virginia book please visit http://www.dof.virginia.gov/website/online-store.shtml

PLEASE NOTE: The start time for these programs will be moved up to 5:30pm to take full advantage of the daylight.

Thanks, and I look forward to seeing you later this month.

Japanese Stiltgrass Control-Tips and Tricks

Photo of treatment area showing some reduction in Japanese Stiltgrass

Photo of control area--no treatment

What is the recommended approach for eradicating Japanese Stiltgrass?






(Note: the use of trade names in this blog or other websites does not constitute an official endorsement of these products; trade names are included for informational purposes only)



Japanese stiltgrass is a C4 grass that grows especially well in low light conditions. It is an annual, spread by abundant seed which is produced in August-September. There are a variety of control methods, including mechanical, and chemical. I personally have tried several methods to control Japanese stiltgrass, dating back to 2002 when I first encountered stiltgrass on Big Spring Bog Natural Area Preserve in Grayson County, VA.

My objective was to kill Japanese stiltgrass, but not the native herbs and grasses, thereby eventually depleting-but most likely not eliminating the seedbank. The method that appeared to work best for these objectives was a very dilute concentration of sethoxydim herbicide-often sold under the trade name of Poast (TM). The Poast label recommends mixing a 1% solution for spot treatment--I mixed the solution at .25% solution, i.e. one quart of herbicide per 100 gallons of water. This dilute concentration was sprayed in early August, timed to just precede the flowering stage of the Japanese stiltgrass.

Even at such dilute concentrations, Japanese stiltgrass was injured to the point where most (if not all) of the individuals turned brown and were unable to flower. Although there is still an abundance of Japanese stiltgrass seed in the seedbank, the photos below show that some control of the stiltgrass has occurred, allowing native vegetation a chance to rebound.

Note: applications have been made every year since 2004--and while the population has been controlled to a great extent, it is unclear whether the Japanese stiltgrass will ever be fully "controlled." The following photos show the control area, and an area where 4-5 applications of sethoxydim have been applied over the previous years. These photos were taken on the same day, and if you look closely at the treatment photo, you will still see some tell-tale lime green leaves--the emergent Japanese stiltgrass leaves.

Take home point-Japanese stiltgrass is easy to kill by the individual, but it is hard to eliminate the seedbank completely.

I've included a number of very helpful links below:
http://www.nps.gov/plants/alien/fact/mivi1.htm
http://wiki.bugwood.org/Microstegium_vimineum
http://www.invasive.org/weedcd/pdfs/tncweeds/micrvim.pdf
http://www.invasivespeciesinfo.gov/plants/stiltgrass.shtml
http://www.na.fs.fed.us/fhp/invasive_plants/weeds/japanese_stiltweed.pdf
http://www.bae.ncsu.edu/programs/extension/wqg/northcreek_images/microstegium.pdf