Evaluation of Multiple Growth Regulating Herbicides Effect on Soybean Injury at Vegetative and Reproductive Growth Stages.

Off-target movement of spray particles, vapor drift, and tank contamination has occurred with the use of synthetic auxin herbicides near crops that are not resistant. Field trials were conducted in 2020 to evaluate the effects of multiple rates of auxin herbicides [2,4-D (Enlist One^®), dicamba (Xtendimax^®), florpyrauxifen-benzyl (Loyant^®), and quinclorac (Facet^®)] on susceptible soybean [Glycine max (L.) Merr] during different growth stages. Visual estimations of injury, unmanned aerial system (UAS) UAS imagery reflectance data, and yield data were collected to determine damage. Injury observed from each synthetic auxin herbicide varied slightly in symptomology. Applications made at both vegetative and reproductive stages resulted in visual crop response. Reflectance data from UAS imagery closely matched visual estimations of injury and yield data supporting ground-based assessments. Xtendimax and Loyant were the most damaging synthetic auxin herbicides to soybean at reduced rates and could cause yield loss. Further research is needed to evaluate the implications of reduced rates of each of these synthetic auxin herbicides on soybean and the role UAS imagery may play in their identification and severity. [ABSTRACT FROM AUTHOR]

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