Chemigation and Ground-Spray Applications of Cyproconazole for Control of Late Leaf Spot of Peanut. A. K. Culbreath, Department of Plant Pathology, University of Georgia, Tifton, GA 31793-0748. T. B. Brenneman, L. D. Chandler, and H. R. Sumner. Department of Plant Pathology, University of Georgia, and USDA Insect Biology and Population Management Research Laboratory, Coastal Plain Experiment Station, Tifton, GA 31793-0748. Plant Dis. 77:505-507. Accepted for publication 27 January 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0505.

In field experiments conducted during 1990 and 1991, chemigation applications of the ergosterol biosynthesis inhibiting fungicide cyproconazole (0.112 kg a.i./ha) were equal to or better than ground-spray applications of cyproconazole or chlorothalonil (1.26 kg a.i./ha) for control of late leaf spot, caused by Cercosporidium personatum, on peanut (Arachis hypogaea) cultivars Florunner and Southern Runner. Late-season leaf spot epidemics and resulting defoliation were severe in nontreated plots in both years. All fungicide treatments provided similar levels of control in 1990. Leaf spot was less severe on plants treated with cyproconazole by chemigation than on those treated with chlorothalonil by ground sprays in 1991. Within cultivars, yields for all three fungicide treatments were similar and were higher than in nontreated plots in both years. Yield of Southern Runner was higher than that of Florunner for all treatments in 1990 and in nontreated plots in 1991.