I mentioned earlier that Im using herbicidal soap more than vinegar now and really liking my results by and large. They don't work the same on the same weeds though. Got out my kids cheap-ey microscope and decided to compare/contrast vinegar and soap on a couple of different leaf surfaces. Used plantain, clover, sorrel, and dandies. Soap works great on all those except clover. When I applied the soap to the other three fairly soon I could observe a small bubbling action on the leaf and within a few minutes large brown spots were visible. With the vinegar I saw nothing but after a longer time the corners of the leaf started to brown and curl. Don't know why they don't work the same but I'd really like to. I've also read that the soap works in the opposite way vinegar does. Its the alkalinity of the soap that degrades the leaf but when I dunked litmus paper in the soap it looked much closer to 7 than I expected. Stumped and more curious than before.