I am a big fan of rubbing alcohol! The only time I've ever had a negative response to it was on either tomato or dahlia seedlings (I forget which now) that were sitting near the rear window in my greenhouse when I went after some wasps in that window with my trusty spray bottle of alcohol. They got a bit of overspray from my enthusiastic attack and some of the leaf tips got a bit brown; but I think that was more from the combination of sun plus alcohol, rather than the alcohol alone.