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Agronomic and economic evaluation of fungicide seed treatments for soybean production in the Mid-Atlantic United States

Andrew Kness: University of Maryland Extension

<div>Soybean (<em>Glycine max</em>) is a major agricultural commodity in the Mid-Atlantic region. Although seedling pathogens such as <em>Fusarium </em>spp., <em>Pythium </em>spp. and <em>Rhizoctonia solani</em> occur sporadically in the region, some growers routinely utilize fungicide seed treatments. Reasons for this include perceived plant health benefits and insuring disease management. To address whether commonly used seed treatments provide benefits in the absence of disease, field trials were established in 2017 at four locations (Georgetown, DE; Queenstown, MD; Beltsville, MD; and Keedysville, MD) lacking history of seedling diseases. Treatments included metalaxyl + fluxapryoxad + pyraclostrobin; fluopyram; trifloxystrobin; and an untreated control applied at commercial rates to the variety SS4514NR2 by a local seed dealer. Treatments were replicated five times per site and arranged in a spatially balanced, random complete block design. Emergence 14 days post planting and yield were recorded, and data analyzed using a mixed model. Treatment effects were separated using Fisher’s LSD. Seed treatments marginally increased emergence (P=0.06) but did not significantly increase yield and resulted in a 3-14% yield decrease when compared to the controls in Georgetown (P=0.04) and Queenstown (P=0.02). Economic analysis indicated that seed treatments reduced net income by $337 hectare<sup>-1</sup>. This study will be repeated in the future to better understand the impacts of seed treatments in disease-free situations.</div>