Is that the seed head from crabgrass? If so, nothing will help that won't kill your other grass. A better picture showing the leaves may help ID in case I'm wrong.
A pre-emergence in early spring for crabgrass is the way to kill the seeds that come from that head you show pics of in OP. There has been so much of it this year, that I have vowed to take it on next year
Any of the Round Up products should kill it. I know the one for ivy and heavy over growth will, and it's also been the one that's lasted the longest for me.
We mow about 6 or 7 acres. Try to mow fairly often before the crab grass (or whatever it is) gets out of hand, but the crab grass gets to be about a foot tall and looks like s**t.