Large-scale evaluation of 2,4-D choline off-target movement and injury in 2,4-D-susceptible soybean

• Published in: Weed technology Vol. 36; no. 1; pp. 8 - 14
• Main Authors: Werle, Rodrigo, Mobli, Ahmadreza, Striegel, Sarah, Arneson, Nicholas, DeWerff, Ryan, Brown, Ashli, Oliveira, Maxwel
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.02.2022
• Subjects: 2,4-D; 2,4-D choline compatible crop; 2,4-D drift; 2,4-D-resistant soybean; Agricultural production; Agricultural research; Air sampling; Choline; crop injury; Crop production; Crops; Cultivars; Environmental conditions; Experiments; Glufosinate; Glyphosate; Herbicides; Humidity; Injuries; Particle deposition; Samplers; Soybeans; Wind; United States > US; Wisconsin
• DOI: 10.1017/wet.2021.62
• ISSN: 0890-037X

Enlist E3™ soybean cultivars permit over-the-top application of labeled glyphosate, glufosinate, and 2,4-D choline products. Increased Enlist E3™ trait adoption and use of 2,4-D choline postemergence across U.S. soybean production systems raise concerns regarding potential for 2,4-D off-target movement (OTM). A large-scale drift experiment was established near Sun Prairie, WI, and Arlington, WI, in 2019 and 2020, respectively. A 2,4-D-resistant soybean cultivar was planted in the center of the field (∼3 ha), while the surrounding area was planted with a 2,4-D-susceptible cultivar. An application of 785 ae ha–1 2,4-D choline plus 834 g ae ha–1 glyphosate was completed within the center block at R2 and V6 growth stages on August 1, 2019, and July 3, 2020, respectively. Filter papers were placed in-swath and outside of the treated area in one upwind transect and three downwind transects to estimate particle deposition. Low-volume air samplers ran for the 0.5-h to 48-h period following application to estimate 2,4-D air concentration. Injury to 2,4-D-susceptible soybean was assessed 21 d after treatment (0% to 100% injury). The 2,4-D deposition in-swath was 9,966 and 5,727 ng cm–2 in 2019 and 2020, respectively. Three-parameter log-logistic models estimated the distance to 90% reduction in 2,4-D deposition (D90) to be 0.63 m and 0.90 m in 2019 and 2020, respectively. In 2020, the 2,4-D air concentration detected was lower for the upwind (0.395 ng m–3) than the downwind direction (1.34 ng m–3), although both were lower than the amount detected in-swath (4.01 ng m–3). No soybean injury was observed in the downwind or upwind directions. Our results suggest that 2,4-D choline applications following label recommendations pose little risk to 2,4-D-susceptible soybean cultivars; however, further work is needed to understand 2,4-D choline OTM under different environmental conditions and the presence of other susceptible crops. Nomenclature: 2,4-D; 2; 4-Dicholorophenoxyacetic-acid; soybean; Glycine max (L.) Merr