How do we treat this weed?

Asked August 5, 2019, 11:24 AM EDT

We had beautiful grass in our backyard and now we have an invasion of weeds from our neighbor. We have a fence and 2 feet of much between the neighbor and our grass. I have attached pictures of the weeds and the grass. We don't know what to treat it with. We have a small dog. It took a long time to finally get the right grass mixture to grow. Please advise? We don't have a lawn service, we love to do it ourselves.

Montgomery County Maryland weeds invasive japanese stiltgrass stiltgrass plant care

1 Response

This is Japanese stiltgrass, a foreign invasive weed which has been spreading like wildfire through the mid-Atlantic for years. Because it grows in shade, it has destroyed thousands of acres of park and natural lands and won't be stopping anytime soon. Sorry it has now arrived at your home.

This is an annual grass which can be somewhat controlled using crabgrass pre-emergent herbicide in early spring. Here is our page that explains how to handle it:

You do not want it to build up a seed bank (seeds last for many years.) If you can pull it now and prevent seed formation (late August-Sept), you'll be ahead of the game. At any rate, keep it mowed. If you can collect clipping and bag them during the seed formation period, that will help.