Gordon's Trimec Lawn Weed Killer, 1 Qt. Concentrate. This 3-way herbicide blend effectively kills over 230 broadleaf weeds without harming most lawn grasses when used as directed. Suitable for both northern and southern lawns, this concentrate covers 8,000 to 16,000 sq. ft. It is a post-emergent herbicide that targets broadleaf weeds and is rainproof. The active ingredient is 2, 4 - D Dimethylamine Salt.