Are spray additives a factor in the off-target movement of dicamba and 2,4-D?
14 September 2020
Last update: 14/09/20 11:21
Complaints about off-target movement of dicamba, 2,4-D and other synthetic auxin herbicides persist, despite the introduction of reduced-volatility formulations. One indicator: a survey shows that 30 percent of Nebraska growers believe injury to susceptible soybean crops is caused by off-target movement of dicamba applied to corn.
Researchers from the University of Wisconsin-Madison decided to take a close look at factors that might influence synthetic auxin volatility and soybean injury, including the relationship between glyphosate and synthetic auxins commonly used in corn.
Their study – featured in the journal Weed Technology – found that four out of seven commercial formulations of dicamba and 2,4-D became highly acidic when mixed with glyphosate, which increased their potential for volatility.
There also were several other key findings:
- High temperatures and low wind speeds in the 48 hours after a synthetic auxin application resulted in greater injury to susceptible soybean plants.
- Dicamba was found to produce greater injury to susceptible plants than 2,4-D.
- Application of dicamba formulations late in the growing season produced similar levels of soybean injury as applications made early in the season.
Want to know more? Read the article “Spray Solution pH and Soybean Injury as Influenced by Synthetic Auxin Formulation and Spray Additives” – now available.
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