A method of effecting at least one biological process in a plant is disclosed. The method comprises contacting a part of a seed, a plant, or the locus thereof with a mixture comprising an agriculturally acceptable mixture of (i) complex polymeric polyhydroxy acids and (ii) a phytotoxic amount of one or more alkali (earth) salts and/or a synergistic amount of at least one source of an agriculturally acceptable transition metal ions.