Bio-regulators from a group of quaternary ammonium moieties modify a gene expression in undesirable plants to inhibit growth and robustness and enhance the effectiveness of herbicides. Such bio-regulator may be applied to plants through seed treatments, root drenching, spraying and dusting, or to soil were desirable crops are planted or will be planted. Bio-regulators may be duel-acting; causing beneficial modification to gene expressions in desirable plants while modifying gene expression in undesirable plants, making them more susceptible to herbicides. Bio-regulators are Ester Compounds, BMIA Compounds or related salts of those compounds.