WSU CAHNRS

Department of Plant Pathology

Potato, Mint, and Asparagus Diseases

Current late blight forecast and management recommendations

Late blight Information line number is 800 984 7400

Contact Dennis Johnson at 509 335 3753 to confirm or to make late blight diagnosis.

Updated April 2016

Late blight has not been reported as of this date in the Columbia Basin. The disease is expected to occur according to the Columbia Basin Forecasting Model. However, probability of occurrence is lower than the last 5 years. The severity of the disease this year will depend largely on the extent that control tactics are applied.  These include the following:

  1. Design irrigation systems to avoid irrigation overlaps.
  2. Plant certified seed produced from a seed production region where late blight did not occur or was successfully managed.
  3. Treat seed with a fungicide containing mancozeb or Curzate, such as Maxim MZ or Tops MZ.
  4. Plant seed pieces within 24 hours of cutting. This is important to reduce spread of the late blight pathogen during cutting and handling.
  5. Restrict irrigation until the crop is fully emerged.
  6. Do not irrigate potatoes within 80 ft of the pivot center.
  7. Eliminate culls and tuber refuse.
  8. Manage volunteer potatoes in fields where late blight was present last year.

Contact Dennis Johnson at 509 335 3753 to confirm or to make late blight diagnosis. Stay in touch with the late blight forecasts updated on this web site and the toll free information telephone one.

Good luck this season

Potato, Mint, and Asparagus Diseases, PO Box 646430, Washington State University, Pullman WA 99164-6430, 509-335-9541, Contact Us
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