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TECHNICAL SESSION: Chemical Control of Fungal Diseases

Improved management efficacy of late leaf spot on peanut through combined application of prothioconazole with fluxapyroxad and pyraclostrobin
Daniel Anco - Clemson University. Justin Hiers- Clemson University, James Thomas- Clemson University

Late leaf spot, caused by Nothopassalora personata (syn. Cercosporidium personatum), is the most economically important fungal disease affecting peanut foliage in South Carolina and can result in combined management and yield loss costs of greater than $490/ha. An integrated approach towards managing this disease is recommended for greatest efficacy and maximum return. Application of protectant fungicides is a critical part of effective integrated management under commercial production, and their strategic alternation and combination in management programs can provide enhanced control. Trials were conducted in Blackville, SC in 2017 and 2018 to investigate whether combinations of prothioconazole (0.1 kg/ha) with fluxapyroxad (0.05 or 0.1 kg/ha) and pyraclostrobin (0.1 or 0.2 kg/ha) could provide more efficacious management of late leaf spot compared to either product alone. Two applications of 0.1 kg/ha prothioconazole with 0.05 kg/ha fluxapyroxad and 0.1 kg/ha pyraclostrobin resulted in significantly (P < 0.05) less (25 to 53%) peanut canopy defoliation compared to the same number of applications of either product (prothioconazole at 0.1 kg/ha or fluxapyroxad and pyraclostrobin respectively at 0.05 and 0.1 kg/ha) applied individually. Increased rate of fluxapyroxad and pyraclostrobin application (0.1 and 0.2 kg/ha, respectively) with 0.1 kg/ha prothioconazole did not improve management relative to their combination at the examined lower rate. Results will be discussed in context of efficacy and treatment cost.