<p>Bacteria of the <i>Streptomyces</i> genus colonize diverse ecological niches and can exhibit diverse traits of potential applied value. With regards to crop production, some species can induce plant diseases while others are capable of promoting plant growth or controlling diseases. To identify Taiwanese <i>Streptomyces</i> strains suitable for crop growth promotion and disease management, this study obtained 49 potato-isolated, <i>Streptomyces</i>-like strains from a culture collection and screened for bacteria showing promise for stimulating plant growth and controlling soil-borne phytopathogenic bacteria. The tested strains were examined for their effects on radish seedling growth, and strains exhibiting detrimental effects were screened out. Antimicrobial activities of the remaining strains against the soil-borne phytopathogenic bacteria <i>Ralstonia pseudosolanacearum</i> and <i>S</i>. <i>scabiei</i> were determined with agar diffusion tests, and only 8 strains were found capable of inhibiting both pathogens. Results from detection of genes associated with pathogenicity (<i>txtAB</i>, <i>tomA</i> and <i>nec1</i>) and multilocus sequence analysis (MLSA) indicated that all 8 strains were unlikely to harm plants. The strains’ ability to promote plant growth were examined using tomato plants in pot culture assays, and after two trails, strain 94-b, identified as <i>S</i>. <i>nigra</i>, exhibited the most consistent plant growth promotion activity. Strain 94-b also significantly reduced the severity of symptoms caused by <i>R</i>. <i>pseudosolanacearum</i> on tomato in a biocontrol assay. Further testing revealed that the strain produced amylase, lipase, siderophore, indole-3-acetic acid (IAA), and solubilized phosphate. This is the first report of <i>S</i>. <i>nigra</i> capable of both improving plant growth and controlling a soil-borne bacterial disease.</p>