Methods of controlling plant diseases mediated by bacterial or fungal plant pathogens. The method comprises providing Streptomyces scopuliridis strain RB72 or an isolated protein or polypeptide comprising the amino acid of SEQ ID NO:1 and applying the Streptomyces scopuliridis strain RB72 or the isolated protein or polypeptide comprising the amino acid of SEQ ID NO:1 to plants or plant seeds under conditions effective to treat plant diseases mediated by bacterial or fungal plant pathogens. Also disclosed is a plant or plant seed treated by this method, a planting composition, and a method of enhancing growth.