Detection and Quantification of Bremia lactucae by Spore Trapping and Quantitative PCR.

A quantitative polymerase chain reaction (qPCR)-based assay using a target sequence in mitochondrial DNA for specific detection of B. lactucae resulted in the detection of the pathogen during the 2-week lettuce-free period as well as during the cropping season, demonstrating that this assay will be useful for quantifying inoculum load in and around the lettuce fields for the purpose of timing fungicide applications based on inoculum Load.