I live in middle Tennessee, and I have a patch of crabgrass that reappears every year in my yard that is about 20x20growing in my Kentucky fescue. What will be the most effective way to get rid of this pest without just burning the area? I have seen a product called Gorden's crabgrass killer, is it any good? If not what chemical would be best. It has not become green yet, and our soil temperature now shouldn't be above 50 degrees but its climbing everyday. PLEASE HELP!!!