Soil Erosion and Herbicide Injury (05/13/21)
Off-target movement of herbicides is often associated with physical drift at the time of application. In addition, herbicides can move off the target site after application as a gas (volatility), in runoff water, and on sediments from wind-blown soil erosion. The powerful wind events of late April, coupled with dry weather conditions resulted in significant soil erosion from unprotected croplands. That means there is potential for herbicides to move down range on soil particles to injure susceptible plants.
How serious of a problem this will be is not known at this time. In a very rare circumstance, widespread damage occurred in SE Idaho when the herbicide Oust (sulfometuron) a sulfonyl urea herbicide, moved on soil particles from burnt over public rangeland to sugarbeet and potato fields in 2001. Tens of thousands of acres were impacted and lawsuits were quickly filed against the U.S. Bureau of Land Management (the party responsible for the applications) and DuPont (the pesticide registrant at the time). In experiments conducted by the University of Idaho, it was demonstrated that sugarbeet and potato could be injured at soil contamination levels in the parts per trillion (https://tinyurl.com/UI-Oust).
Far less dramatic injury was detected in Canadian experiments in Southern Alberta in the early 1990’s. But they were able to demonstrate that herbicides could indeed be transported down range, from wind erosion on soil particles. (https://tinyurl.com/Alberta-Herbicide).
In North Dakota, NDSU/UMN Sugarbeet Agronomist Tom Peters has observed injury from contaminated soil particulates in sugarbeet, but the damage was confined to field margins. In summary, it is likely that some problems will develop this season, but it is NOT likely that it will be found on a vast scale like the Idaho incident.
Andrew A. Thostenson
Pesticide Program Specialist