With regard to plants such as grass, flowers and tomatoes I don't know, but in terms of technical equipment (also called plants) I know that phenolic acid acts differently to for example naphthenic acid in terms of corrosion. For example phenolic acids acts even as corrosion inhibitors for some manganese-aluminum alloys.
That could also be interesting for your plants, because Al and Mn are in agricultural soil (problem of soil acidification). Consequently Mn will be found in flowers, but Al and Mn is also contained in cultivated plants such as potatoes.