Biosafety practices, such as bioexclusion via sanitization, can prevent the spread of infectious soilborne threats such as the clubroot pathogen Plasmodiophora brassicae. Twenty-three chemical disinfectants were evaluated for efficacy against P. brassicae resting spores. Evans blue staining was used to directly measure the viability of P. brassicae resting spores after 20-min exposures to 10 concentrations of each of the 23 chemical disinfectants. Only nine disinfectants were capable of >95% inactivation, and only five were capable of inactivating >99% of resting spores. Bleach (sodium hypochlorite) and Spray Nine were the most effective disinfectants for inactivation of clubroot resting spores. AES 2500, SaniDate, and ethanol also inactivated >99% of resting spores but only at very high concentrations. A time course experiment showed that 10- to 12-min contact time was sufficient for ≥95% resting spore inactivation with Spray Nine and sodium hypochlorite, but ≥30-min contact was required for other disinfectants evaluated. These results will assist in guiding management recommendations for sanitization aimed at bioexclusion and biocontainment of P. brassicae.
Keywords: agricultural disinfection; biosafety; canola; clubroot; sanitization.