2012 was a relatively light year for pink rot in our research trials.  However, we did see significant disease control with phosphorous acid (Resist 57).

Russet Norkotah plants were grown in an area with an intensive potato rotation.  This was done to increase the likelihood of natural pink rot development.

Phosphorous acid (Resist 57) was applied three times beginning when the largest tubers were dime-sized and repeated for three total applications.  Ultra Flourish and Ridomil Gold Bravo were applied beginning at the same time as the phosphorous acid applications, but only two applications were made. The full results of this trial are outlined in the PDF below. 


  1. We did not observe phytotoxicity with any phosphorous acid application. In 2011 we did observe phytotoxicity when applications made early in the day when dew was present.   
  2. Time of day for phosphorous acid application did not influence product performance.
  3. Simulated aerial application of phosphorous acid (Resist 57) significantly reduced pink rot incidence compared to the untreated control and the Ridomil Gold standard.
  4. Chemigation of phosphorous acid was statistically similar to the simulated aerial phosphorous acid treatments and the untreated check for pink rot incidence.
  5. Ridomil Gold Bravo did not reduce pink rot compared to the untreated check.  The Phytophthora erythroseptica population was 50% mefenoxam-sensitive and 50% mefenoxam-resistant in the trial area this year.
  6. Yield was not significantly affected by treatment.