Lawns - How can I rid my lawn of obnoxious weed seed

I have obnoxious grass with little white flowers in the spring and then later in the season a grass appears that does not spread, but has little seed balls.
I have spent many hours this year, pulling this grass (weed) by hand an by the bushels.
I know that I did not get quite all of it, and am sure that there is a heavy deposit of seed for the coming years groweth.
Is there an application that can be applied to my lawn that would either kill the seeds or at least cause them to be sterile? I do not mind killing good seed as well, because I do have a nice stand of the grasses that creep.

Keyword: Pre-emergent.

That's what you want to ask for.there are pre-emergent products for general weeds and for crabgrass.It's too late for that this season but starting in late winter there is a regimen starting with pre-emergent crabgrass control that kills by killing seeds.

Go to a local garden center or hardware store where they have knowledgeable saleshelp.these businesses will have better products and far more advice and knowledge than big box stores.

Two brand names to look for:Preen and Scoot's Lawn Pro (this is different than just Scott's you find at large retailers,this is a specific line of products made by Scott's sold only at lawn pro dealers which are only independent hardware and garden retailers,and which includes high quality better made versions of Scott's product and products unavailable to large retail).

Thanks a million. Gardener321