Extraction of oospores of <i>Peronospora viciae</i> from soil

Abstract

A method for the extraction of oospores of Peronospora viciae from soil is described. Approximately 75% of the oospores added to silty clay loam and loamy sand soil samples were recovered. Percentage recovery was independent of oospore density. This extraction method did not affect viability as determined by the tetrazolium bromide test and a germination assay and may therefore be used to study survival of oospores. Numbers of oospores extracted from soil samples taken from seven fields naturally infested with oospores of P. viciae f.sp. pisi ranged from 2 to 21 oospores per g soil. Oospore density was not significantly correlated with disease incidence as determined by a bioassay.