Comparison of Forecasting Methods for Control of Potato Early Blight in Wisconsin. J. W. Pscheidt, Research Assistant, Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706. W. R. Stevenson, Professor, Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706. Plant Dis. 70:915-920. Accepted for publication 6 April 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-915.

Various forecasting methods were evaluated for their usefulness in predicting and controlling potato early blight under Wisconsin growing conditions. The spore trap and growing degree day methods used in Colorado did not provide reliable prediction of early blight in Wisconsin. A total of 300 physiological days (P-Days), however, occurred before the initial rise in airborne spore concentrations of Alternaria solani. P-Days were used to effectively initiate weekly protectant sprays in small experimental field plots and large commercial fields. FAST, developed for early blight prediction on tomatoes, was used successfully on potatoes in Wisconsin. A few modifications, however, are recommended for use on potatoes. Combining FAST and / or P-Days with BLITECAST may prove useful for the control of both early and late blight for Wisconsin potato growers.

Keyword(s): epidemiology.