Weed Identification....Driving Me Insane!

Every few days I change my mind if this is nutsedge, crabgrass, quackgrass, or something else. It has some characteristics of each, but never "defining" traits that make me sure. It is slowly eating up my whole lawn and I'm not sure what so do about it. Help?!

That appears to be Johnson grass. Nut grass would have nodules on the roots, Johnson grass doesn't and it grows exactly like the plants in your photos.

Redhawk

I think that's it! Thank you.

To reduce the Johnson grass you can over-seed with several different grasses such as Bermuda, short fescues and blue grass. You can use these together as a mix or you can pick the one you want and use it singly.

To really choke the Johnson grass you will want to first cut the lawn very short (3/4" or 1/2") then heavily spread the new grass seed and keep the soil moist for a week to get good germination.
Once the first seeding has been up and growing for a week, spread a second heavy spread of grass seed and again keep the soil moist for a week for germination.
Now it's time to let the new grasses grow to around 3 inches then cut it to 2.5 inches.
You should have enough density to start choking out the Johnson grass and the new grass will feel nice and soft underfoot.
Once it is well established you can cut at 3" height to keep the Johnson grass shaded and that will help reduce the amount even more.

The alternative is to use a good old-fashioned crab grass digger to manually remove each root system.

Redhawk

Thank you for the advice. The while problem started because I was eradicating tall fescue and this bunch moved in and spread before I could apply kbg.

Got tons in st. Louis, MO. Can't get rid of it all pulled it up just creeps back in.

Looks like crab grass to me. Johnson grass is huge, much bigger than that and gets very tall very fast with wide leaves and doesn't pull easy with the roots like that. Chickens, ducks, and goats will eat crab grass but not Johnson grass ... if you have any creatures to test it on.

Guessing the size of the weed sample as about a foot tall, this is not Johnson grass.
The plant shown does look similar, but Johnson grass is, according to Kansas Wildflower and Grasses, 2-7 feet tall.
The picture being asked about looks like a weed I have in my current garden it is low growing and less than a foot tall.  I had Johnson grass in my Texas garden. It was tall, spread
quickly, and cut your hand when you tried to pull it. I am not a fan of either.

The wiki article does not address size, so:
http://kswildflower.org/grass_details.php?grassID=37

Crabgrass may be edible
https://en.wikipedia.org/wiki/Digitaria
Here is a search with pictures.
https://www.google.com/search?q=crab+grass&rlz=1C1NHXL_enUS732US732&source=lnms&tbm=isch&sa=X&ved=0ahUKEwir26CA08PVAhWhiVQKHTS9DccQ_AUICigB&biw=1707&bih=790

Eating the enemy may be your best revenge, but please do not use generalize this to other areas of your life. Ok, maybe a few.
Liz

Looks more like crabgrass to me, with the size, the roots, and the branching leaves.  Johnson grass has very large fleshy rhizomes, and is a quite tall plant besides.  Nut sedge is yellower and shinier and stiffer-leaved than what is pictured, to my eye at least.

If you let it go to seed, that will help with identification.