Utilizing a Sterol Demethylation Inhibiting Fungicide in an Advisory Program to Manage Foliar and Soilborne Pathogens of Peanut. T. B. BRENNEMAN, Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. A. K. CULBREATH, Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. Plant Dis. 78:866- 872. Accepted for publication 10 June 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0866.

This study evaluated 11 programs using chlorothalonil (1.26 kg/ha) and/or tebuconazole (0.25 kg/ha) applied to Southern Runner peanut (Arachis hypogaea) according to 14- or 21-day schedules or AU-Pnuts, a rainfall-based advisory program for scheduling fungicides for foliar disease control. AU-Pnuts called for five, eight, and five sprays in 1991, 1992, and 1993, respectively, compared to seven, eight, and seven sprays on a 14-day schedule. Five sprays each year were applied on the 21-day schedule. Where the number of sprays was reduced, Cercosporidium personatum and Cercospora arachidicola leaf spots were more severe, but the effects on yield were variable. The substitution of tebuconazole for chlorothalonil resulted in consistently higher yields and reduced incidence and/or severity of both foliar and soilborne diseases. There were strong correlations between the number of tebuconazole applications and Sclerotium rolfsii stem rot incidence, pod yield, and both grade and percent damage of kernels. Timing of tebuconazole applications was not extremely critical, but early- and late-season sprays did not have as much effect on leaf spot or stem rot epidemics. Tebuconazole is well suited for use with an advisory system. Two to four sprays per season could be used according to one of these rule-based models as long as protectants are also used for resistance management.