Management of Leaf Spot Diseases of Peanut With Prothioconazole Applied Alone or in Combination With Tebuconazole or Trifloxystrobin

Abstract

Field experiments were conducted in Tifton and Plains, GA in 2001-2007 to determine the efficacy of prothioconazole on early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum) of peanut (Arachis hypogaea). In five of six experiments, application of one or both rates (0.18 and 0.20 kg ai/ha) of prothioconazole in sprays 3-6 (chlorothalonil at 1.26 kg ai/ha in sprays 1, 2, and 7) provided leaf spot control superior to tebuconazole (0.23 kg ai/ ha) in a similar regime, and superior to chlorothalonil at 1.26 kg ai/ha applied full season (seven times) in four of six experiments. In a similar series of six experiments, application of 0.085 kg ai/ha of prothioconazole + 0.17 kg ai/ha of tebuconazole provided better leaf spot control than tebuconazole (0.23 kg ai/ha) applied in regimes similar to those described above. Leaf spot control with prothioconazole + tebuconazole was similar to chlorothalonil applied at 1.26 kg ai/ ha full season in five of eight experiments, but was less effective in the remaining three experiments. Fungicide effects on yield were inconsistent, but in all experiments, yield response with either rate of prothioconazole was similar to or greater than that obtained with 0.23 kg ai/ha tebuconazole on the same schedule. In a third series of four experiments, full-season (seven sprays) application of mixtures of prothioconazole at 0.063 kg ai/ ha with trifloxystrobin at 0.063 kg ai/ha gave similar or better leaf spot control than chlorothalonil full season.

Post‐infection activities of fungicides againstCercospora arachidicolaof peanut (Arachis hypogaea)

“…Therefore, most fungicide programs for peanut production include chlorothalonil and one or more systemic single‐site mode of action fungicides, such as a triazole (sterol biosynthesis inhibitor), strobilurin (quinone outside inhibitor) or carboximide (succinate dehydrogenase inhibitor) that have activity against leaf spot and soil‐borne pathogens . Compared with a program of chlorothalonil alone, leaf spot control is often superior with the inclusion of a systemic fungicide …”

Chemical Control of Peanut Diseases: Targeting Leaves, Stems, Roots, and Pods with Foliar-Applied Fungicides

“…Recommendations in eastern production regions call for chlorothalonil to be added to tebuconazole due to the development of tebuconazole insensitive populations of C. arachidicola and C. personatum (Stevenson and Culbreath, 2006). It is interesting to note that later generation triazoles such as prothiconazole still maintain field control of leaf spot populations resistant to tebuconazole (Culbreath et al 2008). …”

Defining Interactions of Herbicides with Other Crop Protection Products Applied to Peanut

“…Disease, caused by viruses, bacteria, or fungi, can reduce peanut yield considerably when not controlled (Sherwood et al, 1995). Fungicides are applied routinely to peanut to control foliarborne diseases, including early leaf spot, late leaf spot, and web blotch (Brenneman et al, 1994;Culbreath et al, 2008;Shew and Waliyar, 2005). Fungicides are also applied to control the soilborne disease stem rot and Sclerotinia blight (Brenneman et al, 1994;Culbreath et al, 2008;Smith et al, 1992).…”

“…Fungicides are applied routinely to peanut to control foliarborne diseases, including early leaf spot, late leaf spot, and web blotch (Brenneman et al, 1994;Culbreath et al, 2008;Shew and Waliyar, 2005). Fungicides are also applied to control the soilborne disease stem rot and Sclerotinia blight (Brenneman et al, 1994;Culbreath et al, 2008;Smith et al, 1992). Although variation is noted among geographical regions, years, and environmental conditions, during a typical growing season fungicides are applied either singly or in combination beginning approximately 45 days after peanut emergence and continuing throughout the remainder of the growing season, which can approach 135 or more days (Sherwood et al, 1995;Smith and Littrell, 1980).…”