Grass Weed

Asked August 31, 2018, 10:07 AM EDT

I'm trying to identify this grass weed. It's all around the back of my property, which I don't mow, and it creeps into my yard. The uncut areas grow up to 2+ft tall. I haven't seen any flowers or seeds on those ones. The ones that creep into the grass, and get cut, are easy to pull out. Seems like the roots are shallow. Any help would be appreciated.

Allegheny County Pennsylvania

1 Response

Hello, and thanks for using the Ask an Expert System,

I believe that the weed in your photographs is Japanese Stiltgrass. This is a noxious invasive weed that can be very difficult to control. Since it is a grass, broadleaf weed killers typically used on grass lawns will not touch it. You can find more information on this plant and control measures in the Penn State Extension publication Japanese stiltgrass (Microstegium vimineum).

If you have additional questions, I suggest that you contact the Allegheny County Penn State Master Gardener Gardenline. This is a free service offered through the Penn State Extension Office to help Allegheny County residents with gardening questions and concerns. You can reach them by phone at 412-482-3476, or 412-482-3477, or by Email:

Allegheny County Penn State Extension Office