History: Installed new lawn this spring (bad timing I now suspect). Got about 80 Yds Topsoil delivered to fix grade, installed Irrigation system. Seeded with Lesco double eagle blend. Grass came in decent. One section (with more shade) looks amazing. Other sections, all sun, have 60% Crabgrass 40% turf. My plan. Late September I plan on overseeding again. I am going to cut the lawn low and bag it up. I will rake it out to pick any debris and try to thin out the crab grass. I will then overseed using an overseeder (slit seeder) and I will apply a starter fertilizer After germination. Come next spring I will apply a pre-emergent and maintain a healthy lawn in hopes I can combat the crabgrss. Questions: Is this an effective method in suppressing the crabgrass? Since I am expecting the crabgrass to die in late september I am hoping the new grass will be able to take root which will in turn assist with supressing the crabgrass. Can the new seed grow THROUGH the existing crabgrass if I slit seed over the crabgrass that is there? Can I seed before I apply Pre-em. in spring? Anything else I can do? I spend a lot of time trying to make my lawn beautiful and It actually depresses me to see my hard work turn to crabgrass. Thanks in advance.