I would think vinegar will temporarily burn back whatever it is applied to. Some stubborn weeds like thistle take repeated applications of even the most effective systemic weed killers and back they come! The only way to get rid of them is to persistently manually remove them! And that may take years..yes, years! If they have ever gone to seed those little buggers can last a long, long time, just lying in wait til you think you have them beat, then pow! Here they come again!! Good luck..I've been spraying and pulling thistle for about 15 years now, and yesterday I noticed a new batch sprouting!...