The ability of two strains of the antibiotic-producing bacillus Aneurinibacillus migulanus to control Dothistroma septosporum infection of pine was tested in artificial inoculation experiments on 2-year-old Pinus contorta plants. Disease severity (% needles with conidiomata) on control plants was 5.8 +/- 1.7%, compared with 6.2 +/- 2.0% on plants treated with A. migulanus NCTC 7096. In contrast, treatment with A. migulanus Nagano reduced Dothistroma needle blight (DNB) severity to 1.1 +/- 0.4%. The conidial density and percentage germination of D. septosporum on needles were also greatly reduced on seedlings treated with A. migulanus Nagano compared with the A. migulanus NCTC 7096 and control treatments. The results suggest that A. migulanus Nagano has potential as a biological control agent for use against DNB in forest nurseries.