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AU-Pnuts Advisory II: Modification of the Rule-Based Leaf Spot Advisory System for a Partially Resistant Peanut Cultivar. J. C. Jacobi, Senior Research Associate; Department of Plant Pathology, Auburn University, Ala. 36849-5409. P. A. Backman. Plant Dis. 79:672-676. Accepted for publication 17 March 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0672.

The AU-Pnuts advisory was originally developed for peanut cultivars that are highly susceptible to early (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum). The system uses a combination of recorded daily precipitation and National Weather Service precipitation probabilities to provide warnings for the need to apply fungicides. Field studies were conducted from 1989 through 1992 to evaluate modifications of the advisory for use on the late leaf spot resistant cultivar Southern Runner. The advisory system was modified by increasing the thresholds for both the initial and subsequent fungicide applications. Each modified advi-sory treatment was evaluated along with three other treatments: nonsprayed control, 14-day schedule, and 21-day schedule. Averaged over 1991 and 1992, the final version of the AU-Pnuts advisory saved 0.5 and 2.5 sprays compared with the 21-day and 14-day schedules, re-spectively. These timed fungicide applications controlled leaf spot as effectively as did the 21-day schedule. Yields were not significantly different between the advisory and either the 14-day or 21-day schedule. AU-Pnuts advisory can be used to schedule fungicide applications for control of early and late leaf spot on Southern Runner peanut