- 2016 in progress: Approximately 60 new Washington P. rubi isolates from 6 new fields. Also resampled the field where the highly resistant isolate was collected.
- Total: 28 fields from 5 counties surveyed: Whatcom (18 fields), Skagit (5 fields), Clark (3 fields), Cowlitz (1 field), and Puyallup (1 field).
- Resistance to mefenoxam does not appear to be a problem at this time. The majority of WashingtonP. rubi isolates are sensitive to mefenoxam, the active ingredient of Ridomil.
- Recommendation: Continue switching between fungicide chemistries (e.g., mefenoxam and phosphorous acid) to prevent the development and spread of fungicide resistance.
Stewart, J. E., Kroese, D., Tabima, J. F., Larsen, M. M., Fieland, V. J., Press, C. M., Zasada, I. A., and Grünwald, N. J. 2014. Pathogenicity, fungicide resistance, and genetic variability of Phytophthora rubi isolates collected from raspberry (Rubus idaeus) in the Western United States. Plant Dis. 98:1702-1708.