Twenty-four-hour Rainfall, a Simple Environmental Variable for Predicting Peanut Leaf Spot Epidemics

Data from peanut leaf spot epidemics (caused primarily by Cercosporidium personatum) during the 1983-1986 growing seasons in Alabama were used to develop disease predictive models, and data from 1988 and 1989 were used to validate the models. The percentage of infected leaflets was used as the dependent variable, and independent variables included days after planting (DAP) and days with rainfall exceeding a specified minimum. Three rainfall thresholds were evaluated: 1.27, 2.54, and 6.35 mm/day. The Von Bertalanffy/Richards equation was used to develop all models. The onset of an epidemic was defined as the point when the model predicted infection of 5% of leaflets