Abstract
Abstract Use of synthetic auxin herbicides has increased across the midwestern United States after adoption of synthetic auxin-resistant soybean traits, in addition to extensive use of these herbicides in corn. Off-target movement of synthetic auxin herbicides such as dicamba can lead to severe injury to sensitive plants nearby. Previous research has documented effects of glyphosate on spray-solution pH and volatility of several dicamba formulations, but our understanding of the relationships between glyphosate and dicamba formulations commonly used in corn and for 2,4-D remains limited. The objectives of this research were to (1) investigate the roles of synthetic auxin herbicide formulation, glyphosate, and spray additives on spray solution pH; (2) assess the impact of synthetic auxin herbicide rate on solution pH; and (3) assess the influence of glyphosate and application time of year on dicamba and 2,4-D volatility using soybean as bioindicators in low-tunnel field volatility experiments. Addition of glyphosate to a synthetic auxin herbicide decreased solution pH below 5.0 for four of the seven herbicides tested (range of initial pH of water source, 7.45–7.70). Solution pH of most treatments was lower at a higher application rate (4× the labeled POST rate) than the 1× rate. Among all treatment factors, inclusion of glyphosate was the most important affecting spray solution pH; however, the addition of glyphosate did not influence area under the injury over distance stairs (P = 0.366) in low-tunnel field volatility experiments. Greater soybean injury in field experiments was associated with high air temperatures (maximum, >29 C) and low wind speeds (mean, 0.3–1.5 m s −1 ) during the 48 h after treatment application. The two dicamba formulations (diglycolamine with VaporGrip ® and sodium salts) resulted in similar levels of soybean injury for applications that occurred later in the growing season. Greater soybean injury was observed after dicamba than after 2,4-D treatments.
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Claims 8
Claim · model-written summary
Glyphosate lowered solution pH below 5 for four of seven herbicides.
- Treatment
- Addition of glyphosatee0
- Outcome
- solution pHe0
- Direction
- decreasede0
- Value
- 5.0e0
- Qualifier
- four of the seven herbicidese0
Not reportedTaxonComparator
Verbatim
e0“Addition of glyphosate to a synthetic auxin herbicide decreased solution pH below 5.0 for four of the seven herbicides tested”
Claim · model-written summary
Higher application rate lowered most solution pH measurements relative to the standard rate.
- Treatment
- higher application rate (4× the labeled POST rate)e0
- Outcome
- Solution pHe0
- Direction
- lowere0
- Comparator
- 1× ratee0
Not reportedTaxon
Verbatim
e0“Solution pH of most treatments was lower at a higher application rate (4× the labeled POST rate) than the 1× rate”
Claim · model-written summary
Glyphosate was the most important factor affecting solution pH.
Not reportedTaxonDirection
Verbatim
e0“inclusion of glyphosate was the most important affecting spray solution pH”
Claim · model-written summary
Glyphosate did not significantly influence soybean injury area across distance.
- Treatment
- addition of glyphosatee0
- Outcome
- area under the injury over distance stairse0
- Direction
- did not influencee0
- Setting
- low-tunnel field volatility experimentse0
Not reportedTaxonComparator
Verbatim
e0“addition of glyphosate did not influence area under the injury over distance stairs (P = 0.366) in low-tunnel field volatility experiments”
Claim · model-written summary
Greater soybean injury was associated with high air temperatures.
- Taxon
- soybean
Glycine maxe0 - Outcome
- soybean injurye0
- Direction
- Greatere0
- Qualifier
- maximum, >29 Ce0
- Setting
- field experimentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Greater soybean injury in field experiments was associated with high air temperatures (maximum, >29 C)”
Claim · model-written summary
Greater soybean injury was associated with low wind speed.
- Taxon
- soybeanGlycine maxe0
- Outcome
- soybean injurye0
- Direction
- Greatere0
- Qualifier
- low wind speeds (mean, 0.3–1.5 m s −1 )e0
- Setting
- field experimentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Greater soybean injury in field experiments was associated with high air temperatures (maximum, >29 C) and low wind speeds (mean, 0.3–1.5 m s −1 ) during the 48 h after treatment application”
Claim · model-written summary
The two dicamba formulations produced similar soybean injury late in the season.
- Taxon
- soybeanGlycine maxe0
- Treatment
- diglycolamine with VaporGrip ®e0
- Outcome
- soybean injurye0
- Direction
- similare0
- Qualifier
- later in the growing seasone0
- Comparator
- sodium saltse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The two dicamba formulations (diglycolamine with VaporGrip ® and sodium salts) resulted in similar levels of soybean injury for applications that occurred later in the growing season”
Claim · model-written summary
Dicamba treatments caused greater soybean injury than 2,4-D treatments.
- Taxon
- soybeanGlycine maxe0
- Treatment
- dicambae0
- Outcome
- soybean injurye0
- Direction
- Greatere0
- Comparator
- 2,4-D treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Greater soybean injury was observed after dicamba than after 2,4-D treatments”
The same questions in other papers
glyphosate · crop injury · Glycine max (soybean)Results differ
22 papers in the same direction as this paper · 10 in the opposite direction
- positive
- positive
- positive
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See all 33 papers →dicamba · crop injury · Glycine max (soybean)Results differ
28 papers in the same direction as this paper · 8 in the opposite direction
- negative
- negative
- negative
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See all 37 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.