Potato Late Blight and Early Blight Fungicide Intervals

The page links listed below use site-specific hourly weather observations and forecasts to estimate severity and management timing for potato late blight and early blight. Updates will resume in June 2024.
Make sure you have the latest update by hitting “Refresh” after clicking on the table link for a site.  Otherwise, you may be looking at an older version stored in your browser cache.

Model calculations, design, web posting, and updates by AgRadar, Glen W. Koehler, UMaine Extension.

Weather data from AgEye Weather, Sean D. Birkel, Maine Climate Office,
Potato weather site assistance by G.W. Koehler.

Late blight spray intervals based on “Potato Facts: Late Blight Prediction in Maine”, Steven B. Johnson, 2005.  University of Maine Cooperative Extension Bulletin #2418.

Early blight P-values based on “Comparison of forecasting methods for control of potato early blight in Wisconsin” (PDF).  J. W. Pscheidt, and W.R. Stevenson, 1986.  Plant Disease 70:915-920.