Another grape season has come to an end, and preparation for the next begins.  As part of that preparation, people are curious about our fungicide resistance monitoring work and how different regions compare.  As always, there is good news and bad news.  The good news is that we were awarded funding from American Vineyard Foundation, Oregon Wine Board and Washington State Wine to continue our exploration of the prevalence of strobilurin (QoI) resistance in grape powdery mildew.  Under the leadership of Michelle Moyer (Washington State University), we leveraged this funding to get funding from USDA NIFA SCRI program to develop FRAME networks.  This FRAME networks project will establish the tools needed to develop regional networks from managing and mitigating fungicide resistance.

The American Vineyard Foundation, Oregon Wine Board and Washington State University funding has also resulted in a much easier sampling technique for leaf infections that will be launched in spring 2019 and a bark sampling technique that is being beta tested now – volunteer testers are being accepted.  The bad news is that QoI resistance is still out there; however, there is a silver lining.  The data from Oregon is indicating that rotation away from using DMI and QoIs does seem to lead to a decrease in QoI resistance in the population.  Remember that just because mildew was a problem, it does not mean the powdery mildew resistance was the cause.  Application timing and coverage are more commonly associated with runaway epidemics than resistance.


The frequency of samples with the G143A mutation associated with resistance to strobilurin (Qol) resistance by county. Total of 3008 samples processed in 2018.



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