Relationship between Visual Injury from Synthetic Auxin and Glyphosate Herbicides and Snap Bean and Potato Yield

Agronomic crops with resistance to the herbicides dicamba and 2,4-D are currently in the regulatory approval process. The potential increased use of these herbicides has raised concern among vegetable producers about potential off-target movement and implications to crop yield. The overall goal of this research was to describe the relationship between visually estimated crop injury and snap bean and potato yield and quality. In snap bean in 2011, injury from dicamba 7 d after treatment (DAT) ranged from 19% at the 1.2 g ae ha−1 application rate to 45% at the 7.0 g ae ha−1 application rate. By 28 DAT in 2011, injury from 2,4-D was similar to the nontreated control. However, early-season injury in 2011 delayed snap bean flowering and reduced crop yield compared to the nontreated control for all treatments except where the 1.4 g ae ha−1 rate of 2,4-D and glyphosate at 7.0 g ae ha−1 were applied. Snap bean injury from dicamba was greater than that from 2,4-D at all rating timings in 2011 and two of three rating timings in 2012, and crop yield was reduced compared to where 2,4-D was applied and the nontreated control in both years. Potato tuber size distribution was variable and total yield did not differ among treatments and the nontreated control in 2011. In 2012, tuber size distribution was again variable, but more nonmarketable cull potatoes were harvested when dicamba was applied to 25-cm potato plants at the 7.0 g ae ha−1 rate compared to any other treatment. Snap bean injury observations about 3 wk prior to harvest were strongly correlated with crop yield (r = −0.84 and −0.88 in 2011 and 2012, respectively), allowing time to make informed harvest decisions relative to crop quality. In contrast, the relationship between potato injury and tuber yield was poor and highly variable in both years. Nomenclature: 2,4-D; dicamba; glyphosate; potato, Solanum tuberosum L.; snap bean, Phaseolus vulgaris L. Cultivos agronómicos con resistencia a los herbicidas dicamba y 2,4-D están actualmente en proceso de aprobación regulatoria. El potencial incremento en el uso de estos herbicidas ha generado preocupación entre los productores de vegetales por el riesgo potencial de deriva y las implicaciones de esta en el rendimiento de sus cultivos. El objetivo general de esta investigación fue el describir la relación entre el daño del cultivo estimado visualmente y el rendimiento y la calidad del frijol y de la papa. En frijol en 2011, el daño producido por dicamba a 7 días de