One oldtime beekeeper I know said that he didn't like Roundup because of the collateral root kill damage to surrounding trees/shrubs that he wanted. He used something called "blue vitriol" or "Prussic acid" by dipping his machete or a knife in the substance and cutting the bark of the tree. He said it worked slowly but surely and got rid of undesired trees/shrubs. Does anyone know if there are problems with this? I'd canvass/information gather before doing it myself. for what it's worth- Phil Wood