This might help you decide controlling-quackgrass

From what it say's “One way to
overcome lateral bud dormancy is to apply nitrogen fertilizer. This
will break lateral bud dormancy, and the herbicide will be
translocated to the now actively growing plant tissue and kill the
entire plant. Repeat the application of glyphosate every 30 to 45
days; avoid cultivation for 2 weeks after each application.”

From what it's saying it might be best
to just wait to late September. To when it will really be time to
over seed as new rye grass will do poor in the heat “ depending on
what zone your in” garden.org/nga/zipzone/ . I
think it would be a bit cheaper to I know it seems kind of dumb to fertilize
weeds.... I with a lot of plants if you scalp them the rhizomes will
start growing.

Joe, thank you for taking the time to reply to me. I am a bit confused. Are you or the site saying, wait until the late september to put down the round up kill everything then start re-seeding? Or use round up in mid August, hit it with fertilizer then use round up again, then re-seed?

What about the thatching, should i do that after the round up and that will be good enough to seed or do i need to take it to dirt after round up?

"Or use round up in mid August, hit it with fertilizer then use round up again, then re-seed? Sorry I mean you can start with the round up now. yeah it says to use fert but I would just try to cut low after the first application see if that would get the quack grass rhizomes to start growing.

and for planting the rye when ever your temp are going to start staying in the 70's, for me it's September http://ryegrasses.com/info/whentoplant.html

thatching is really only for when you have a bunch of built up grass and ect on the surface of the soil so that would be up to you. I don't think you need to take it down to the dirt the seeds will do fine with old grass on the ground.

Joe one more question for ya. It seems only 1/2 my lawn has the quackgrass, can i just kill that portion of the lawn and leave the rest? Is that a good idea/bad idea?

Thanks for your help

I could not tell you. It say to spot spray in that link I might spay a little over on the other side were the quack grass stops, so sure ... To tell you the truth this probably ain't going to be the end of that grass. Next year or 4 years after you might have to do the same thing taking it in strides might be your best bet. You know what they say about Rome. Can you send a few pics of the grass.

Here is a previous post I put up trying to identify the quack grass, it's all down the said and toward the left portion of the pic. If you need a better pic i can get it in a few days, just mowed my grass yesterday.

http://forums2.gardenweb.com/discussions/4034217/identify-weed

Yeah because that doesn't look that bad to redo the whole lawn.