I use herbicidal vinegar on dandelions with great success. I go out to the yard in the early morning when the soil is moist and using a "dandelion tool" pull the weed up trying to get as much of the taproot as possible. I then spray the hole left in the ground with the vinegar to "burn" the remaining taproot.
"Well Art is Art isn't it? Still, on the other hand, water is water. And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does."