Dispersal of Phytophthora species by off-road vehicles in New South Wales

Off-road vehicles are potential vectors for the spread of destructive plant pathogens such as Phytophthora cinnamomi. However, the retention of Phytophthora species in soil on vehicles used off-road does not appear to have been assessed empirically. We sampled soil from 22 off-road vehicles used in conservation management in New South Wales and tested samples for the presence of Phytophthora species. Two species (P. cryptogea and P. aff. alticola) were detected from three vehicles. Two of these three vehicles were regarded as being clean externally and had not been used off-road for more than one week. Phytophthora species can therefore survive in small amounts of soil on vehicles for extended periods, potentially facilitating the spread of these destructive pathogens. Cleaning is required of management vehicles entering areas of high conservation value vegetation to minimise the risk of spreading Phytophthora species. However, research is needed to find the most effective methods for removing soil.