a biologically pure culture of naturally - occurring pseudomonas strain 679 - 2 is described . this nonobligate bacterial predator microorganism and its extracellular products are useful for the control of many bacterial and fungal diseases of plants . whole cells of this bacterium and the antimicrobial compounds that it produces are involved in biological control effects . materials and methods of preparation and application involving pseudomonas strain 679 - 2 and its antimicrobial products are described .