Unknown Unwanted Grass
This looks like nimblewill. Nimblewill is native, perennial grass. It grows in patches, has narrow blades and sometimes a blueish cast to the color. In the fall the patches go dormant and turn tannish-brown.
The following is a link to our website with more information and control.
Thank you. How do I kill this grass without killing talk fescue grass?
Look at the link I sent under chemical treatment in lawns.
You do not have many options as there are not a lot of herbicides that selectively kill perennial grassy weeds.