possibly nut sedge

you are polluting.. but now on the right track.. ALWAYS ID the plant.. before you try to eradicate or encourage such ..

ken

It's not nut sedge but it is a weed grass species, probably an annual like Poa annua or crab grass. Generally, these are best addressed by a designated pre-emergent herbicide. Lawn weed killers will have no effect as they target broadleaved weeds, not grasses, as they have no ability to determine a "good" grass species from a "bad" one " :-)

Just a FYI but weed and feed products are a very inferior way of addressing lawn weed issues. You are effectively fertilizing the weeds as well as trying to kill or subdue them, so it is working at cross proposes. It also applies the weed killer at rates greater than necessary and over a broader area than required. And because it almost always comes in a granular form, it is easily picked up by kids and pets and tracked indoors and leaches readily with rain or irrigation. Lawn weed and feed products tend to be one of the worst polluters of groundwater and local streams and waterways.

Kind of hard to see in the photo provided, but my guess is crabgrass...

Example:

It grows from a central point. Hand pulling, making sure to get any seedheads, works for me.

I agree that it is probably crabgrass, or at least another annual weed grass. As Gardengal said, a pre-emergent applied NEXT Spring will be your best bet. Since crabgrass is an annual, you will prevent the problem before it arises. Follow the directions for timing closely. It's too late once the seeds sprout. And as GG also said, a weed-and-feed used after the crabgrass appears won't touch any grass, good or bad.

If the pest isn't widespread in your lawn, but just a couple of small patches, you could hand paint the trouble spots with a grass-specific herbicide (Grass-Be-Gone, etc), but that will leave you with dead brown patches until you can re-seed. If it were me, I'd leave it for now, and treat the lawn next spring with the pre-emergent. Try to keep your weed grass from setting seed this year, and you'll be one step ahead. BUT...if it's crabgrass, it tends to grow faster than the desirable grasses (especially the seed heads! The grass tends to grow with the blades flat against the ground at first, in a star pattern. The flowering stems shoot straight up). So you may have to mow more often than you normally would.

I take a very laissez faire attitude to my lawn. It's a mixture of fescues, clover, the stray crabgrass, and unfortunately, Bermuda grass. My focus is on my garden beds (which is why Bermuda grass is "unfortunate". It invades every bed), and the lawn is just a backdrop...and really just something to keep the soil in place, lol. I do draw the line at dandelions, but even those, I pull/dig by hand.

I understand the desire for a beautiful carpet of flawless green, but it's labor and chemical intensive to achieve, and it's just not worth it for me. There are a lot of other things I can stress over, like where can I squeeze in the new plant I just bought? ;)

There's grass in your grass.

Really, you have to take a much closer picture to identify grasses. I would guess Goose grass, or maybe Tall Fescue, but again, need closer pic, and a seed head would help. Late spring pre-emergent should do the trick. You may have to reapply in late June.