Current late blight forecast and management recommendations


Updated  11 May 2006


Integration of several control tactics is needed to manage potato late blight in the Columbia basin. These include strict sanitation practices, proper irrigation management, cultural practices and timely applications of fungicides. Management of temperature, relative humidity, air movement, and holding time of tubers is needed to manage tuber late blight in storage.


Sanitation practices are important for early season management of late blight in the Columbia Basin. These practices include:


1. Plant certified late blight free seed tubers

2. Eliminate culls and tuber refuse

3. Eliminate volunteer potato plants. This is especially important in fields that had late blight in them last year or the year before.  Volunteers in these fields run a high risk of being infected and a source of infection the current year.

4. Treat seed with a fungicide containing mancozeb or Curzate

5. Plant seed tubers within 24 hours of cutting.


6. Do not irrigate potatoes within 80 ft. of the pivot center. This is usually the wettest area of the circle and most conducive environment for late blight and tuber rots. Infected plants near the pivot center are often a source of additional infections through out the circle.  Lost production area is about 0.3 acre (with 20 ft radius subtracted for pivot road).


7. Avoid irrigation overlaps.


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