Forestry / possible invasive plant

Asked June 27, 2020, 3:47 PM EDT

I own a largely wooded lot with a large and growing patch of a plant I haven't seen before. I've been told it may be an invasive plant that should be eliminated, but I've also heard that there is a native Maryland plant that looks very similar and should be left alone. On your website page I saw the picture of Japanese Stiltgrass, which looks very similar, but the plant on my property does not have that silver streak down the middle of the blades. I have attached pictures of it. Can you possibly identify this plant and advise if/how it should be eliminated? Thanks, Larry Baker

Montgomery County Maryland

3 Responses

If it is taking over your woods, it is stiltgrass. There is some variation in the pigment of stiltgrass and not all of it has a silver or light streak that is discernible.

Stiltgrass is an annual. It pulls fairly easily. If you ever happen on the native grass that is similar (it has a thinner blade and fewer leaves), tug on it to check for firmer roots.

Never let your patch produce seed. Pull it anytime, or weed whack it just as the seed sets in late summer (before the seed matures). It's possible to control it if you start now, like you are doing.


Ellen

Thank you. I t does appear to be spreading quickly, and it does pull up very easily, so it sounds like it is stiltgrass. I used a hoe last summer to dig up a patch of it last year as an experiment, and that patch shows no regrowth, at least not yet. Does weed whacking kill it? I thought that would just leave the roots and it would come right back.

As an annual, they do not store surplus carbohydrates in their roots for growth the following year, so their reserves to re-sprout following cutting are few. While it is said that they tolerate mowing, cutting them to leave as little above-ground growth as possible (like with weed-whacking) should reduce the likelihood they'll rebound afterwards. The main focus of an annual plant is reproduction, so flowering and seed set take priority over substantial roots (unless root divisions are its form of reproduction, which is not the case with Stiltgrass).

Preventing germination of next year's seeds is important; they can sprout prior to crabgrass seeds (so, quite early in spring) and seed viability in the soil can be long (years). Herbicide use is less practical in wild wooded areas and the chemicals involved in preventing seed germination could interfere with native plant germination as well. (Though ideally you would only be using an herbicide only impactful to grasses.) There are several control options presented here, though each will probably be somewhat tedious and repetitive given the tenacity of this species:
https://extension.umd.edu/hgic/topics/japanese-stiltgrass

Once under control, if you can replant the area with a native spreader (or group of various native woodland plants), hopefully they will help to out-compete the Stiltgrass in future years. Since the seeds can hitch a ride on deer legs, plants of little interest to them may be helpful to keep them out of that area.

Miri