Pat Kiewicz writes:

hrbob said:


I have the invasive grass/weed shown in the picture in many places in
my lawn. The spots of weeds pop up with no apparent source. They do
no respond to weed killer, and they crowd out regular lawn grass. I
am in the Chicago suburbs. Can anyone tell me what the grayish green
grass/weed is and how to get rid of it?

http://www.flickr.com/photos/bobhofmann/4761771580/

Not crabgrass, as crabgrass is an annual.

Could be Nimblewill:
http://www.msuturfweeds.net/details/_/nimblewill_44/

It's perennial, has the leaf blades coming off of stalks so blends horribly
with typical lawn grasses, starts growing late, turns brown early.

You can spot treat with something like Roundup (or try dig it out) and
then patch with good seed or sod.

I've got some patches of it way in the back, and it doesn't play nice
with the other grasses at all. Nor is it pleasant to walk on.

I think you win the prize!

I have something that looks similar. Up until now I thought it was
nutgrass. Based on that I tried (a pre-emergent this year) no luck.

So far it looks like there is no good treatment for nimblewill other
than to nuke the lawn (Roundup). Not good. I've been pulling the stuff
for years with little success.