Improved isolation and PCR detection of <i>Phytophthora agathidicida</i> oospores from soils

<i>Phytophthora</i> species are notorious plant pathogens responsible for severe dieback and root rot diseases, significantly impacting crops, forests, and irreplaceable natural ecosystems. Rapid and accurate detection of these pathogens is essential for effective disease management. In New Zealand, <i>P. agathidicida</i> threatens the country's endemic kauri forests. In this study, we developed and validated a PCR-based method for detecting <i>P. agathidicida</i> oospores in soil. Oospores are long-lived, thick-walled spores that serve as key propagules for survival in soil and the spread of disease. Their robust structure and dormant state make them particularly challenging to detect using traditional soil baiting techniques or DNA-based methods. Our method is fast, accurate, and requires minimal equipment, enabling local testing and thereby empowering communities and enhancing surveillance efforts. Although developed for <i>P. agathidicida</i>, this method could be adapted for other plant pathogens, potentially improving disease management across various agricultural and ecological contexts.