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Detection of QoI fungicide resistant Cercospora beticola airborne inoculum using quantitative PCR

Kishore Chittem: North Dakota State University

<div>Cercospora leaf spot caused by <em>Cercospora beticola </em>is a devastating foliar disease of sugar beet (<em>Beta vulgaris</em>) worldwide. This disease is considered the most important constraint for sugar beet production in North Dakota and Minnesota, and warrants multiple fungicide applications per growing season. Development of QoI fungicide resistance in pathogen populations results in unsatisfactory control of this disease. Thus monitoring of the pathogen population for prevalence of QoI fungicide resistance is essential for effective management of the disease using fungicides. The objective of this study was to assess the possibility of using qPCR methods to monitor QoI-resistant <em>C. beticola </em>in airborne inoculum. Spore samplers were set up in 2016 and 2017 growing seasons in research plots at Foxhome, MN and airborne spore samples were collected using either a Burkard volumetric samplers or cyclonic samplers. DNA was extracted from the samples, and quantitative PCR assay designed to detect G143A mutation was used to determine the proportion of QoI resistant and sensitive populations. QoI-resistant <em>C. beticola</em> isolates were detected in varying proportions in both 2016 and 2017 growing seasons. The preliminary results suggest that by using cyclonic samplers and qPCR assay, <em>C. beticola</em> can be monitered for QoI-resistance in real time.</div>