Anybody know how to kill this without killing your grass?

"Image Kills Nutsedge" to kill it now. Make sure it is safe for your specific lawn type.
You will need to put out a preemergent in late summer (mid September) to keep it from coming back.
This combo helped greatly when I used to have a Bermuda lawn and actually gave a rip about how it looked. Haha!

Thanks! I will check it out.

Mow it low it will burn out as soon as it gets hot.

Nuclear bomb might knock it back a little.

I will check and see if Iran will lend me one.

Unless it has changed, Image isn't really a Poa material. Use Tranxit, Recolver, or Monument, depending on your grass. Those are hard to beat. Next fall put out a good PRE.

What Molypoly said, but you also need to put out preemrgence in February so that the spring yard won't be covered with it. Mowing it low won't eliminate it. It's a cool weather weed so it just disappears when it starts to warm up then comes back in the fall unless use use the pre emergencies

Atrazine (Bonus, Purge, others) is labeled for centipedegrass, zoysiagrass, St. Augustinegrass and bermudagrass. Atrazine can be applied to actively growing and dormant centipedegrass or St. Augustinegrass but bermudagrass can be injured if treated while actively growing. Simazine (WynStar, others) may be applied to actively growing bermudagrass, centipedegrass, St. Augustinegrass and zoysiagrass lawns. Atrazine and simazine have excellent preemergence activity on annual bluegrass but soil residual is generally shorter (four to six weeks) compared to aforementioned herbicides. Several atrazine and simazine products are not labeled for residential lawns and turf managers should check labels for further information before use. Put out in September

MSMA will kill poa annua but it takes a strong dose. I'm afraid stronger than Augustine will tolerate. The only chance you got is pre emerge every spring and fall.