A University of Missouri weed specialist says the weedkiller dicamba has damaged more than 2.5 million acres of cropland this year, mostly in the Midwest and South, reports Harvest Public Media. The researcher, Kevin Bradley, says, “I don’t know that we’ve ever in our agricultural history seen one active ingredient do so much damage across one nation like that.”
Dicamba usage has surged with the release of cotton and soybean varieties that have been genetically modified to withstand doses of the herbicide. Complaints of damage skyrocketed this year despite the availability of dicamba that is less likely than earlier formulations to drift onto neighboring fields where the crops have no protection against the chemical. The problem is worst in Arkansas and Missouri, says Bradley, who tallied more than 1,400 dicamba complaints across the country.
Growers want to use dicamba because Palmer amaranth and other invasive weeds are becoming resistant to such widely used herbicides as glyphosate. Bradley says chemical companies, farmers, scientists, and applicators need to figure out how dicamba can be used without harming neighboring crops. “We’ve all got to come together and admit that there is a pretty significant problem here, and we can’t really move forward to try to figure out what to do in 2018 until we can all realize that this is not just confined to one area or one geography,” Bradley told Harvest Media.
The Nebraska state agriculture department “is seeing more complaints from farmers who say their neighbors’ use of the herbicide dicamba is damaging crops,” said the Omaha World-Herald. “But the state does not plan to limit the use of dicamba in Nebraska at this time, officials said.”
Arkansas has banned the use of dicamba on row crops for the rest of the growing season. Missouri restricts use to three of the low-volatility formulations, and they can be sprayed only during the middle of the day and if winds are relatively calm.
Weed consultant Ford Baldwin says dicamba “has a volatility component, which means it can change from a liquid or solid to a vapor after spraying and move off-target after application.” The new formulations are the least volatile, Baldwin wrote in Delta Farm Press. “A common question is ‘Dicamba has been around for years, why the off-target issues all of a sudden?’ There can be a lot of reasons, but the primary two are we have never sprayed large acreages in a given area, and we have never sprayed it in summer temperatures.”