Tank Mix Combinations of Propiconazole and Chlorothalonil for Control of Leaf Spot Diseases of Peanut

Abstract

Abstract Field experiments were conducted in one location in 1993 and two locations in 1994 to determine the effects of propiconazole and chlorothalonil tank mix combinations on severity of early (Cercospora arachidicola) and late (Cercosporidium personatum) leaf spot diseases of peanut (Arachis hypogaea L.). In all tests, 10 treatments consisted of 0 and 63 g a.i./ha of propiconazole and 0, 0.315, 0.63, 0.945, and 1.26 kg a.i./ha of chlorothalonil arranged factorially. In 1993, final leaf spot intensity ratings decreased according to nonlinear quadratic functions of chlorothalonil concentrations applied with and without propiconazole. No improvement in leaf spot control was evident with the addition of more than 0.945 kg a.i./ha of chlorothalonil with 63 g a.i./ha of propiconazole. In 1994, conditions were more conducive for leaf spot development. At the Plains location, final leaf spot intensity ratings decreased according to non-linear quadratic functions of chlorothalonil concentrations alone. Leaf spot intensity ratings decreased linearly with increasing rates of chlorothalonil when applied with 63 g a.i./ha of propiconazole. At Tifton, final leaf spot intensity ratings decreased linearly with increasing rates of chlorothalonil with or without propiconazole. Leaf spot intensity ratings were lower on plants treated with tank mixes of chlorothalonil and propiconazole compared to those treated with chlorothalonil alone. Pod yields increased linearly or according to quadratic functions of rates of chlorothalonil with or without propiconazole in both years and all locations. Across all rates of chlorothalonil, yields were higher from plants treated with propiconazole than those treated with the respective rates of chlorothalonil alone.