Non-Peer ReviewedClubroot of canola, caused by the protist pathogen Plasmodiophora brassicae (Pb), is an
emerging threat to canola production in western Canada. Effective/practical control options
are currently lacking. This study was initiated to assess registered microbial fungicides for
control of clubroot on canola. Selected biofungicides were initially applied as a soil drench
and the fungicides Allegro and Ranman were also included for comparisons. Selected
products were further evaluated at varying concentrations, soil drench volumes, and for seed
treatment. At moderate disease pressure, the biofungicides Serenade and Prestop, as well as
synthetic fungicides Allegro and Ranman were highly effective as a soil-drench treatment,
reducing clubroot severity by 85–100% in controlled conditions. Biofungicide concentration
appeared to be important while soil-drench volumes may be reduced. All products, however,
were significantly less effective or ineffective under extremely high disease pressure. All
products were less efficacious in trials using infested field soils, a circumstance that may be
related to treatment timing. Results from seed-treatment trials were too variable to draw a
conclusion but there was a strong indication that this approach be successful though more
research is required on microbial formulations. Serenade, Prestop, Allegro, and Ranman
should be further evaluated under field conditions for clubroot control
