Stilt grass invasion
Help!! Stilt grass is taking over my yard!! I had been fighting it by hand pulling and replanting grass seed and it worked for that area. Unfortunately it spread faster than I could pull and reseed. Is there anything I can do to slow/stop the spread of this terrible, terrible grass? Maura Watson
Japanese stiltgrass is definitely a frustrating invasive.
It is an annual plant that dies with the frost, and seeds in the soil germinate in the spring.
Your hand pulling and over-seeding was a good plan, but you probably need more help. One of the things you can do is use a pre-emergent herbicide in the spring. It is the same one that people use to prevent crabgrass from germinating. Try to found one that doesn't have additional fertilizer added.
Keep cutting it this summer to reduce it's ability to set seed.
The other thing you can do is core aerate your lawn this fall and overseed so that you can get a head start with a thicker lawn that will help shade out new weeds in the spring.
Here is our page on Japanese stiltgrass: http://extension.umd.edu/hgic/japanese-stiltgrass