Can I use sheet mulching to replace wire grass?

Asked September 8, 2015, 9:04 PM EDT

I have about 25' by 25' of wire grass (bermuda) in my mainly tall fescue lawn. It's half again as big a patch as it was last year. I've read that herbicides often can't kill to the roots, but that you can kill it by covering it with paper/cardboard. That's similar to what I've read about sheet mulching, but the context is always "replace grass with flower bed," not replace grass with grass. Question: Will the following work (timing is September in Camden, Wyoming)? 1) Nuke the patch with glyphosphate. 2) Use sod cutter to remove upper couple inches of dead wire grass. 3) Cover the dead patch with newspaper to keep light, etc. from the roots. 4) Fill patch back to level with topsoil. 5) Sow with tall fescue seed, last week of September when temperatures are about 75°F. 6) Control wire grass with Fusilade II (or equivalent) next spring. Assumption is the newspaper will help control the wire grass roots; seed will take root and start to grow in the topsoil; the newspaper will deteriorate before it's an issue for the fescue seed roots; minimal impact from remaining wire grass next year. Thoughts?

Kent County Delaware

1 Response

Herbicides can kill the root. And Glyphosate is a systemic herbicide that definitely has the potential to kill the roots. The problem is Bermudagrass is very hard to kill. In the Kansas/Missouri area, I would say you are probably too late this year to achieve excellent control.
What I normally recommend is to water the area to be killed for a couple of weeks before applying glyphosate in late June or early July. Then continue to keep the area watered, and repeat the glyphosate application again after about 3 weeks. Keep it watered and repeat the application 3 weeks later. This way you will have 3 applications of glyphosate done and then you can reseed your area with your desired cool season grass (tall fescue, Kentucky bluegrass, or perennial ryegrass) around Labor Day or mid-September.

We want to keep the weeds (bermudagrass) healthy and alive while we are trying to kill them. If the weeds are drought stressed they will not absorb the herbicide and die. So keep them well watered.

The newspaper will not stop any leftover bermudagrass rhizomes or roots from coming back. I would not recommend this action.

If you wanted to do this with out herbicides, I would solarize the area....cover it with large sheet of plastic (usually black) for about a month during the hot part of the summer. This will 'cook' the plants under the tarp and kill them.

I hope this helps.