Professor, Department of Plant Pathology
Associate Professor, Department of Entomology, Auburn University, Auburn, AL 36849
Disease and yields of peanut were monitored in growers' fields treated with zero, one, two, three, and four applications of tebuconazole. Yields ranged from 1,918 to 6,891 kg/ha and averaged 4,319 kg/ha over eight locations in 3 study years. Defoliation caused by peanut leaf spots (Cercospora arachidicola and Cercosporidium acutatum) and incidence of southern stem rot (Sclerotium rolfsii) were inversely related to number of tebuconazole applications, while yield was directly related to number of tebuconazole applications. Average yields with zero, one, two, and four tebuconazole applications (each application at 0.25 kg a.i./ha) were 3,609, 4,088, 4,526, and 4,868 kg/ha, respectively. Data from each location were best modeled by quadratic equations allowing determination of numbers of tebuconazole applications for minimal disease and maximal yields. Calculated spray numbers indicate that between three and four applications of tebuconazole is best for disease control and yield maximization.