I live in Middle Tennessee and have a fescue lawn that is largely dormant right now, since we've been having 90+ degree F days for the better part of two months straight now. Crab grass is thriving, though (I have a question about that here, incidentally). A couple of weeks ago, I noticed a new fast-growing grass popping up in my lawn, and I at first thought it was selective patches of the fescue thriving in partial shade after we had a lot of rain.
I've since realized that it's a different type of weedy grass, and I'm wondering if I need to try to eradicate it now, as it seems to be spreading very quickly. It's a lighter green than the fescue and has a different blade growth pattern:
(I'm referring to the lighter-colored grass in the middle/top-half of this photo). Here's a closer look at this grass:
What should I do about it? I'm guessing this is probably a native grass that is invading my lawn.