Selection of Components for a Potato Late Blight Forecasting and Fungicidal Control Program. F. W. Nutter, Jr., Former Graduate Assistant, Department of Botany and Plant Pathology, University of New Hampshire, Durham 03824. W. E. MacHardy, Associate Professor of Plant Pathology, Department of Botany and Plant Pathology, University of New Hampshire, Durham 03824. Plant Dis. 64:1103-1105. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-1103.

A forecasting system based on BLITECAST was simplified for incorporation into a pest management program for New Hampshire potato growers. In an interactive computer program, field data and 6 yr of weather records from the National Oceanic and Atmospheric Administration were used to identify BLITECAST components not contributing to forecasting accuracy. As a result, severity values were eliminated from the BLITECAST criteria that recommended the first fungicide application, and criteria eliminated from the BLITECAST matrix that recommended subsequent fungicide sprays were: maximum daily temperature ≥ 86 F (30 C), 5-day mean temperature ≥ 78 F (26 C), and minimum daily temperature ≤ 45 F (7 C) that “nulls” a blight-favorable day.

Keyword(s): pest management, Phytophthora infestans.