Amazing Organic Weed Killer Spray. 1\/2 gallon of Apple Cider Vinegar 1\/4 c table salt 1\/2 tsp Dawn liquid dish soap Mix and pour into a spray bottle Spray weeds thoroughly. It makes 1\/2 gallon for around $6.40 It worked better than Round Up & killed the weeds on first application. The Dawn dish soap strips the weed of it's protective oils so the vinegar can work with deadly force. Safe to use a yard used by pets | See more about Weed Killers, Dawn Dish Soap and Apple Cider Vinegar.