Stiltgrass has destroyed my lawn
As a result of an unfortunate confluence of circumstances, Japanese stiltgrass has almost entirely wiped out large sections of my lawn, About one out of a three acre site has no living turf roots. I'm sure that there is a heavy load of stiltgrass seed in the top soil. What do I do? Pre-emergent herbicide will help suppress re-growth, but I can't reseed for perennial turfgrass in the same season, can I? Compounding the problem is that my topsoil is very thin. Over the past 30 years since reclaiming the site from a fallow pasture my yard (field) has never been particularly strong and healthy. I don't care too much about a uniform turf overall, although I would like the lawn close to the house to be in good condition.
Japanese stiltgrass is an invasive grass that threatens native plants and natural habitats. It is now a major problem throughout Maryland and it is difficult to control. Here is information about managing it in a lawn. https://extension.umd.edu/hgic/topics/japanese-stiltgrass
Because of its seed bank (seeds can persist in the soil ~7 years) and its widespread presence, it will be a constant battle (and likely futile) to try to eradicate it entirely.
During the growing season, keep the area mowed to help prevent the stiltgrass from forming seeds. This is tricky, however, because even stiltgrass that is mowed short can form seedheads. Keep up with lawn care best practices to achieve a healthy, dense turf (soil test, fertilize in the fall, mow high, etc.) https://extension.umd.edu/hgic/topics/best-practices-lawn-care
If you have Japanese stiltgrass in a surrounding area near the lawn (such as a woodland edge), you will have to hand pull (tackle small areas at a time) or use a recommended nonselective, post-emergent herbicide. Desirable plants will have to be protected from herbicide spray.
In sum, there are no easy solutions to this plant that has become highly invasive and widespread.
Here is additional information from Rutgers University. https://njaes.rutgers.edu/fs1237/
Thank you for your assistance. I understand your reply, but I'm concerned that I'm stuck in a Catch-22 situation. The infestation has completely eliminated the turf grass in large areas of my lawn. Recommended eradication is a combination of pre- and post-emergent herbicide. Subsequent control entails maintenance of a healthy lawn. The herbicides preclude the seeding and growth of a new lawn, therefore I cannot maintain a healthy lawn. Is the solution to maintain bare soil (as much as possible) or 100% mulched soil until the stiltgrass is substantially or completely eradicated?
This is a difficult situation and there isn't an easy answer because there are not a lot of options for dealing with Japanese stiltgrass. You could focus on amending the soil and renovating and maintaining a small area of lawn closest to your home and consider some lawn alternatives for the back two acres. https://extension.umd.edu/hgic/topics/lawn-alternatives
Renovating and overseeding a cool-season lawn is best done in the fall. The second best time of year for seeding is now through early April but it's tricky at this time of year because of the weed pressure and going into the warm season. Take a look at our information on lawn renovation (linked below). You might also consider sod for an area closest to your home (but Japanese stiltgrass can eventually come in on seeds from surrounding areas spread by water, deer, etc. Again -- no easy solution.)