Dimension and Stonewall are two that are very good, and last a long time. The problem is poa annua mainly germinates in the late summer/early fall (there is usually some germination in the spring as well) so you missed the major germination. A good preemergent plan for poa annua is applications in the early spring and early summer before soil temps drop below 70 degrees. Another issue is that some poa annua is perennial, so it won't die in the summer by itself.

Barricade 65WG is very good and will not stain concrete.

From what I have read on poa annua, it germinates in the winter. It's your fall application or preemergent that counts. Per texas-weed's advice, I've been using Dimension for my fall treatment and I have finally knocked out the poa annua in my yard. Dimension in liquid form is expensive as it typically comes in bottles to control 128k sf or more for $170 on up. For smaller yards; it can be found in granular form in GreenLight's Amaze product. A 10lb bag covers 5k sf and goes for $14 at Lowes. Again, based on what limited knowledge I have, I'd say it's too late to put a dent in it this year. You can knock it out this fall with a good preem. When I did have it; it would die off in the summer heat (120* with no water). It had already set seed though to continue the battle into the next spring.

"From what I have read on poa annua, it germinates in the winter. It's your fall application or preemergent that counts."

This is incorrect. Typical poa annua germinates in late summer/early fall when soil temps fall below 70 degrees. It doesn't germinate in the winter unless you are in a warm climate. It lies dormant in the winter, and wakes up in early spring. A fall preemergent application will generally be too late for poa annua in Boston. Monitor your soil temps to be sure. Also some poa annua germinates in spring, so a late winter/early spring preemergent application should prevent most new poa annua from maturing if some seeds didn't germinate in the previous year.

I ran into the District Manager for Scott's Lawn Care about a month ago and she suggested that I use a product by Ortho called "Nutsedge Killer". On the front label it says it kills Poa Annua also. She told me that I would have a brown spot (obviously because the poa was killed), but would turn green again in a few weeks as the grass would start filling in. I indeed got brown spots and it does kill the entire poa weed where applicated, but it didn't fill in with grass, so I just put down a premium seed in the brown areas and now how poa-free green again. Unfortunately, my entire back yard is full of it in one year. It does NOT die off in the heat, and the product only comes in a small spray bottle and I've already gone through 6 bottles just to do a small area. It's going to cost a small fortune to kill off the entire yard, and my neighbors don't take care of their yards, so the stuff will probably just blow back into my yard again. If I can get it all killed off with this, I may be able to keep ahead of it by spot spraying. Good luck everyone.

rgrswife,
You probably used too much product if you had grass mixed in with the poa and it killed the grass also. Sounds like certainty which is most commonly used for nutsedge. It's not safe in fescue/rye. I wonder if sedgehammer, which is safe in fescue/rye works on poa also? Atrazine is probably the cheapest poa killer but can stunt bermuda in warm weather and is a no-no on St.Augustine. If my whole yard was covered in poa I would either go with a thicker grass(like zoysia) or learn to like poa.