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Response of Florunner and Southern Runner Peanut Cultivars to Chemical Management of Late Leaf Spot, Southern Stem Rot, and Nematodes. A. K. Culbreath, Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. N. A. Minton, T. B. Brenneman, and B. G. Mullinix. USDA-ARS, Department of Plant Pathology, and Statistics Service, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. Plant Dis. 76:1199-1203. Accepted for publication 28 July 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1199.

A field experiment was conducted in 1989 and 1990 to study the effects of chlorothalonil, flutolanil, and aldicarb, singularly and in combination, on late leaf spot, caused by Cercosporidium personatum, southern stem rot, caused by Sclerotium rolfsii, and root-knot nematodes, Meloidogyne arenaria, on Florunner and Southern Runner peanut (Arachis hypogaea) cultivars. In a split-plot experiment, Florunner and Southern Runner were treated with chlorothalonil at 0, 0.6, or 1.2 kg a.i./ha; flutolanil at 0 or 2.2 kg a.i./ha; and aldicarb at 0 or 3.4 kg a.i./ha. Southern stem rot and nematode pressure were severe in both years, and late leaf spot was severe in 1989. Leaf spot was more severe in Florunner than in Southern Runner in control plots both years and in plots receiving the low rate of chlorothalonil in 1990. In both years, the high rate of chlorothalonil reduced late leaf spot severity more than the low rate. Aldicarb and flutolanil did not affect late leaf spot severity. Flutolanil and aldicarb reduced the incidence of southern stem rot in both cultivars in both years, but flutolanil was more effective than aldicarb. Chlorothalonil had little or no effect on incidence of southern stem rot, and both cultivars were equally susceptible. Aldicarb reduced root-gall indices in both years, but no effects were attributable to cultivar or fungicide. Yields for the two cultivars were not different. In both cultivars, effects of chlorothalonil, flutolanil, and aldicarb were additive on yield increases for both years.