Getting rid of poa annua is a pretty daunting task. Just a refresher for you and those who might not know. Poa annua is a winter annual. It mainly germinates in the late summer/early fall as soil temps fall (it can germinate in the spring as well). The new growth is difficult to see in the fall, it stays pretty small and doesn't seed. It lays dormant during the winter, and once temps in spring rise it is the first to start growing and producing tons of seeds. Killing it in spring is all well and good, but if it gets seed down, then they will wait till the fall to germinate. The seeds can also lay in wait for years. One of the main ways to control this weed is with regular and well timed pre M drops. Late summer is the most important drop for poa annua, but an early spring drop will kill those spring germinating seeds. Tenacity can produce good results as well when used in conjunction with a good pre M like Dimension. There is a new herbicide that is maybe a year or two away that's supposed to really put the hurt on poa called PoaCure. It's been tested for about 5 years now by golf course supers and the results look really good, so keep your fingers crossed. The problem with poa though is there are hundreds of ecotypes. It is very hardy, and seems to mutate quickly to adapt to new surroundings. Some varieties are perennials as well, which don't die in the summer. It's the reason why a lot of golf courses gave up on fighting it, and instead treating it as a desirable turf grass. After all the greens at Pebble Beach are poa annua.

Thanks for the info - very helpful! I know I'll never get it to zero, but I'm sure as hell going to try.

If you own Tenacity that is the way to go. I use Dimension early in the spring (For me in SE PA that was mid-March), and then followed up with an application of Tenacity this past Saturday. I like the staggered approach since we always seem to have unusual springs (either a massive quick warmup early in the pre-spring, Feb or so), or as in this year a VERY delayed spring where some weeds come up early, while the poa sits and waits.

In either scenario you won't get everyone unless you stagger your applications. Dimension is great because it has a long soil life, while the Tenacity is unbeatable if you can get it on the growing weeds. Here's hoping in the next 2 weeks I'm almost weed free! (and you as well)

There are herbicide products for southern lawns which have atrazine in it. That stuff flat knocks out poa annua, and it does not return next year. However, many lawn grasses are sensitive to atrazine - it might also knock out your lawn. ...just food for thought.

You can Spray Dismiss herbicide on it for suppression and in some cases kill, but I must warm you, your lawn will look like it has brown patch or that you walked around with a bottle of Roundup spot and spraying... The good new, it won't hurt your cool season grass.