Purchased a house last june, 1.31 acres, the back yard probably 25,000 sq is completey overan with every weed under the sun. I put down some fert with pre-m but didn't seem to do anything. I need straight up weed killer. I know one or even 4 apps won't get rid of them all but I need to start somewhere. I'm also going to core aerate this weekend to help, my ground is hard clay.