I have a few lawns that were loaded with broadweeds and very thin in terms of turfgrass, very rocky soil, I started the season with two rounds of crabgrass prvention and blanket sprayed the broadleafs, I got very good results killing the broadleafs but by the middle of july it was loaded with crabgrass. It looked like I didnt even put anything down, Is it possible that because there was so much broadleaf that after it was killed the bare spots were prime for crabgrass growing. I would hesitate to do a crabgrass prevention next year and instead slit seed it in the spring. I would have slit seed it this fall but the lawns are huge and dont have irragation. I told then you are always going to have crabgrass issues until you thicken the turf. Is this wise advice, does it seem like this makes sense ?