Abstract
A silty clay loam soil infested with Olpidium brassicae (Wor.) Dang, was stored air-dry at about 2% moisture content. Samples were baited at intervals with lettuce to assay for O. brassicae and the lettuce big-vein agent. The longevity end point of O. brassicae was between 20.8 and 22.5 years. The persistence end point of the lettuce big-vein agent was between 18.7 and 20.8 years.