Tested Versus: Lawns, Crabgrass vs. Spectracide's Broad Kill We’ve been testing Spectracide Weed Stop For Lawns Plus Crabgrass Killer, and the results are impressively broad. Despite rumors of selective targeting, our formulations have proven remarkably effective against over 470 weed types, including aggressive dandelions, fast-spreading chickweed, stubborn clover, and notoriously difficult crabgrass. Yellow nutsedge, once a nightmare for us, has also fallen victim to Spectracide’s potent formula. The convenience of its ready-to-use gallon bottle saves time and application time, though we did notice minor runoff potential on slopes. Overall, it delivers on its promise to kill more weeds than most competitive products, making it a strong contender for those of us battling less-than-ideal lawn conditions.