Chemical Eradication of the Ring Rot Bacterium Clavibacter michiganensis subsp. sepedonicus on Potato Storage Crates

Four commercially available disinfection products were tested for their efficacy against Clavibacter michiganensis subsp. sepedonicus (Cms), causative agent of bacterial ring rot, on wooden potato storage crates. Each of these products represented a different class of biocide, i.e. organic acids (benzoic acid), peroxygenous compounds (potassium peroxysulfate), quaternary ammonium compounds (didecyldimethylammoniumchloride) and hypochlorite-generating compounds (sodium- p -toluenesulfochloramide). The target objects consisted of small wooden panels that were smeared with potato tuber pulp homogenized with a high inoculum of Cms. By dipping the inoculated panels into the product solutions and subsequent determination of the densities of colony-forming units, the relative efficacy of the products was established. The two products that exhibited the highest relative efficacy were studied for their disinfection performance when applied as cleaning agent in a conventional automated crate washer. The results showed that jet cleaning in a crate washer for 2 min using the authorised dose of the product containing sodium- p -toluenesulfochloramide is an effective method for disinfecting Cms-contaminated wooden potato crates.