Clade-Specific Biosurveillance of <i>Pseudoperonospora cubensis</i> Using Spore Traps for Precision Disease Management of Cucurbit Downy Mildew

Pseudoperonospora cubensis is an obligate oomycete and cause of cucurbit downy mildew (CDM), the most destructive foliar disease affecting hosts. Annual epidemics develop throughout United States as windborne sporangia travel great distances survive prolonged exposure to solar radiation. Recent genomic evidence suggests that P. isolates display host adaptation based on their respective clade. Early detection key for fungicide application timing, identification host-adapted clade provides information risk infection specific crops. In this study, a multiplex quantitative PCR assay was developed species- clade-specific nuclear markers. The detected few 10 or DNA at 100 fg/ml both clades validated in field by deploying rotorod spore samplers sentinel plots located two research stations North Carolina. Using assay, trap sampling rods before signs CDM symptoms were observed plots. Both 1 2 late-season cucumber watermelon but only early-season These results will significantly improve management monitoring inoculum levels determine crops each growing season.