Is this Japanese stiltgrass?

Asked April 6, 2020, 12:38 PM EDT

We had a invasive annual grass take over about 1/3 of our 10 acres last growing season. I don't see much of it this year. However, there is one clump of grass with alternative leaves, and is already producing seed heads. I'd like confirmation on what this is.

Frederick County Maryland

5 Responses

While we can tell that this is not Stiltgrass, for a better identification, we would need photographs a bit clearer and close-up of the seed head. Can pick a few stems and lay them out on a sheet of white paper and try to take close-ups? Including a ruler may help as well. Is this patch a lighter green or yellower color than the rest of the lawn? The yellowed color in these photos might be artifacts of the camera and we cannot tell if this is a characteristic of the weeds. Is it growing markedly faster than the other turf?

You can compare this to Roughstalk Bluegrass; it does go to seed early in the spring. https://extension.umd.edu/hgic/topics/roughstalk-bluegrass
https://www.turffiles.ncsu.edu/grasses/rough-bluegrass/

Is the 10-acre area all lawn? Was the lawn newly seeded/sodded last year, or was it already established?

Miri

Hi Miri,
Thank you so much for confirming this is not stiltgrass. In answer to your questions - it is more yellow, not aggressive (only growing in this one clump that I can tell) and your guess of a cool season grass is most likely. I'm sorry the pictures are of poor quality.

May I ask for identification of these two prolific weeds that are taking over the dead spaces caused by the stiltgrass last year? Both grow out in whorls from one central small stem. One is seeding already and when I touch it the seeds blast off in all directions. The other has more leafy growth, with small flowers and is starting to set seeds.

We have lived here since the early 1980s. We keep the fields mowed. Occasionally an invasive species will move through, but nothing with the destruction that the stiltgrass caused last year. Also last year we lost all our ash to the ash borer.

You're welcome.

The first weed appears to be a type of Chickweed - https://extension.umd.edu/hgic/topics/common-chickweed.

The second appears to be Bittercress - https://extension.umd.edu/hgic/topics/hairy-bittercress.

Both pages include information on control options. Generally, keeping turf thriving in ideal conditions helps it out-compete weeds, though bare patches can succumb to invasion by weed seeds. Both of these weeds are cool-weather growers, so should be waning soon.

You could do a soil test of your lawn (if it has been more than a couple of years since a prior one) to see if pH or any other factors need tweaking for the benefit of the turf. Winter can be a good time to perform testing, but samples can be taken and sent out any time. Labs may have temporarily closed in some areas, so it's best to contact them first to make sure they are still taking homeowner samples. A link to area labs offering testing can be found on this page: https://extension.umd.edu/hgic/topics/soil-testing.

Miri

Yes! This is great information and advice. Thank you!