Biocontrol of potato scab by Streptomyces strains was evaluated in a 3 years field trial. Antagonistic strains of Streptomyces were inoculated into scab conducive soil in a 0.8 ha field. Inoculum dose and inoculation strategy both significantly influenced biocontrol efficacy. Vermiculite inoculation of antagonistic strains provided better scab control than tuber dip treatments in all 3 years this study. Generally, 2 years consecutive inoculation or higher dose application (45 ml) reduced scab more than single year inoculation or lower dose (15 ml) numerically. Additionally, individual antagonistic strains performed better than strain combinations, and strains differed significantly in the levels of biocontrol achieved. Finally, rotation crops (sweet corn and soybean) combined with antagonistic strains provided significant control of potato scab.