Soybean dose–response to 2,4‐D and dicamba at vegetative and reproductive growth stages

Abstract

Background Field experiments were conducted across multiple sites in 2012 and 2013 to describe sensitivity of soybean to 2,4‐D (six doses) and dicamba (seven doses) at V3 and R1 growth stages. Further experiments were conducted under greenhouse conditions in 2017 and 2018 to compare soybean response to several dicamba herbicides across a broader range of doses than those tested in the field. Results Soybean yield loss was 6.1‐fold greater from 2,4‐D exposure at V3 compared to R1 and 1.4 times greater from dicamba exposure at R1 than at V3. In V3 exposures, soybean was 15.4 times more sensitive to dicamba than 2,4‐D and 134.4‐fold more sensitive to dicamba when exposed at R1. Plant injury and height correlations to grain yield resulted in coefficients ranging from 0.65 to 0.91. In greenhouse experiments, five dicamba products were tested at up to 19 doses and as low as 0.002 g ae ha−1 (3.6 × 10−6% of maximum single use‐rate); however, no differences were observed among formulations used in dicamba‐resistant crops versus traditional formulations. A no observable effects dose was not identified due to responses observed even at the lowest doses tested, although hormesis effects were observed in plant height. Conclusion These data suggest that the sensitivity of soybean to dicamba is much greater than what has previously been reported. However, as has been indicated by previous work, that injury does not always result in yield loss. © 2022 Society of Chemical Industry.

Simulated Drift of Dicamba and Glyphosate on Coffee Crop

“…Gradual damage in a soybean crop with increasing reduced auxin doses was already observed [22,24,26], an effect that could be potentiated with the addition of glyphosate, as performed in the present study.…”

Response of soybean, cotton, and tobacco to volatility of 2,4-D and dicamba formulations in humidome

“…Consequently, the presence of dicamba in the mixture is expected to increase injury in those crop species. Finally, it is widely reported in the literature that synthetic auxin herbicides at small doses can cause hormesis in crop species (Kniss 2018; Marques et al 2019; Miller et al 1962; Sperry et al 2022). In this study, the biomass reduction of cotton plants exposed to dicamba DMA was negative, which may indicate hormesis from this herbicide.…”