Weed identification

Asked September 12, 2020, 2:12 PM EDT

Hello! I have attached two pictures of weeds growing in my landscaping and around my home. I have looked at numerous weed identification sites but not been able to pinpoint what these are. I believe one is knotweed and one is stilt grass, but I'm not sure. Can you help identify them? If so, can you tell me if they are invasive or noxious, and what I should do about them, if anything. Thank you for your help.

Anne Arundel County Maryland

3 Responses

The first photo is a native plant, Persicaria virginiana (previously known as Tovara virginiana). It is appropriate for natural or wild areas. It's a good ground story plant, since deer don't eat it and little native vegetation survives when deer pressure is heavy. Good photos on Maryland Biodiversity: https://www.marylandbiodiversity.com/view/3562
Here's more:
https://www.wildflower.org/plants/result.php?id_plant=POVI2

The second photo is, unfortunately, stiltgrass, which is a terrible invasive grassy weed. Pull before it goes to seed. Suppress or eradicate as much as possible. It has taken over vast acreage of our woodlands and parks, replacing native plants that our native wildlife evolved to need to survive.
https://extension.umd.edu/hgic/topics/japanese-stiltgrass

Ellen

Thank you for the response Ellen. We pulled out our relatively small patch of stiltgrass but then found huge patches a little farther into the woods surrounding our house and our neighbor's house. I had no idea it had spread so far. It's beyond pulling. I think we will have to have it sprayed. Can you recommend a chemical to get rid of it? (It has not gone to seed yet but is close.) Does the state or Anne Arundel county have a program to control/eradicate noxious weeds? If not I will get in touch with my landscaper or lawn service company. Thank you for your help! - Kim Kimball

The typical management approach to control Japanese stiltgrass in a lawn is to apply a pre-emergent herbicide in the spring, to prevent seed germination. Refer to our website for information on control options in lawns and forested areas:
https://extension.umd.edu/hgic/topics/japanese-stiltgrass

The state does have a program to control noxious weeds but they are weeds that are a threat primarily to agricultural crops. Japanese stiltgrass is not one that is considered noxious. https://mda.maryland.gov/plants-pests/Pages/noxious_weeds_in_md.aspx

You can contact the Anne Arundel County government office/environmental department and ask about programs to control invasive weeds (in parks and public lands). If the Japanese stiltgrass is on your private property, it is something you will have to manage on your own. Rutgers University has some good detailed information on options to manage this invasive weed in home lawns and landscapes, https://njaes.rutgers.edu/fs1237/.

Christa