Japanese Stiltgrass Invasion--Maryland Lawn

Asked February 12, 2019, 7:47 PM EST

Can you recommend a pre-emergent herbicide that will prevent Japanese stiltgrass from germinating? Stiltgrass has invaded over 50% of my quarter-acre residential lawn, so we're beyond spot-treatments and weed pulling. I've tried crabgrass preventers in previous years without success. Stiltgrass appears to be a significant problem here in southern Montgomery county lawns. Thanks for any recommendations you can offer.

Montgomery County Maryland

1 Response

You are spot on and not alone. Japanese stiltgrass has become hugely invasive in many parts of Maryland.
Here is our page about it: https://extension.umd.edu/hgic/topics/japanese-stiltgrass
It is an annual weed which is a prolific seed producer, so preventing seed production by mowing, etc., is part of a good control program. Like most weeds it will take advantage of thin turf and germinate there, so overall lawn management- mowing high etc. is also important. (https://extension.umd.edu/hgic/topics/tips-lawn-weed-prevention-and-management)
Japanese stiltgrass is shallow rooted and is therefore relatively easy to pull, which is possible in a new infestation. For one like yours, you are on the right track with pre-emergent applications like those for crabgrass, but it needs to be applied earlier- see link above.
Fenoxyprop is another option, also covered above.