On-Farm Trials Evaluating Fungicide Strategies for Peanut Disease Management in North Florida
Applied Research
Keith Wynn
Extension Agent III
University of Florida
Jasper
Abstract
Early Leaf Spot (ELS) and Late Leaf Spot (LLS) are major foliar diseases impacting peanut production in Florida. A four-year on-farm study (2021–2024) in North Florida evaluated calendar-based fungicide programs, focusing on applications at 60 and 90 days after planting (DAP). The study compared disease-related defoliation, yield, and economic returns between demethylation inhibitor (DMI)-based and succinate dehydrogenase inhibitor (SDHI)-based programs. Disease defoliation measured on the Florida 1-to-10 scale, varied by year, with ratings of 5.9 in 2021, 2.8 in 2022, 4.1 in 2023, and 5.2 in 2024. No significant differences in yield or net returns were observed between fungicide programs in 2021, 2022, and 2024. However, in 2023, DMI-based programs significantly outperformed SDHI-based programs in both yield and economic returns. A meta-analysis across all four years showed that SDHI-based programs negatively impacted yield savings and net returns (p < 0.05). These findings highlight the importance of rotating fungicide modes of action and tailoring management strategies based on disease presence and fungicide efficacy against the pathogen. Programs incorporating DMI fungicides resulted in improved yields and net returns compared to those that relied on SDHI fungicides for four consecutive applications. One exception occurred in 2024 when Elatus and Miravis were replaced with Convoy and Bravo in the SDHI program. This substitution led to improved yields and net returns, likely because Convoy’s active ingredient (flutolanil) has no observed activity against leaf spots, reducing selection pressure. This study underscores the critical role of fungicide selection, crop rotation, variety selection, and resistance management in peanut disease control. It also reinforces the necessity of rotating fungicide chemistries, even when mixed-mode-of-action products are used, to sustain long-term efficacy and profitability.
Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.
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Authors: Keith Wynn, Nicholas Dufault
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Wynn, K. Extension Agent III, University of Florida, Florida, 32052
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Dufault, N. Plant Pathologist, University of Florida, Florida, 32611-0680