Optimizing Peanut Fungicide Management Based on the Interactions Between Fungicide Programs and Plant Density

Peanut (Arachis hypogaea L.) production is strongly influenced by pathogens such as Passalora arachidicola and Nothopassalora personata, that are the causal agents of early and late leaf spot, Agroathelia rolfsii, which is white mold pathogen, and by tomato spotted wilt virus (TSWV, Orthotospovirus). To optimize fungicide management for fungal diseases, three fungicide programs (low, medium, and high) were designed based on PEANUT Rx, each corresponding to an increasing level of field risk, and were factorially combined with three plant densities (5.0, 8.3, and 11.6 plants per meter). The aim of this research is to study the single and interaction effects of different fungicide programs and plant densities on disease incidence and yield. The medium-risk fungicide program outperformed the others in terms of leaf spot suppression at low disease severity, while at high disease severity the low-risk program resulted in the lowest leaf spot incidence. A higher plant density caused more leaf spot symptoms in 2021 and increased yield in 2023 and 2024. The interaction found for yield, showed that the plots that had 5.0 plants per meter resulted in higher yields when treated with the high-risk fungicide program.