Dicamba So Far in 2018: Tough to Tell

It’s still too early tell exactly how dicamba injury-related issues on U.S. cropland will compare to last year, but as of late July, a major improvement is not in the cards. It’s disappointing, given the unprecedented training that went on in the off-season.


In his closely watched dicamba report, Dr. Kevin Bradley, Professor in the Division of Plant Sciences at the University of Missouri, recalled that last year on July 25, there were 1,411 dicamba-related injury investigations being conducted by the various state Departments of Agriculture while university weed scientists estimated approximately 2.5 million acres of soybean had been injured with dicamba.

“To date, at about the same time in 2018, we have somewhere around 600 cases being investigated by the state departments of agriculture and approximately 1.1 million acres of soybean estimated with dicamba injury by university weed scientists,” Bradley said. His report includes maps that detail a survey of estimated dicamba-injured soybean acreage across the U.S.

Andrew Thostenson, Pesticide Program Specialist with the North Dakota State University Extension Service, has participated in weekly conference calls with EPA on the matter, and will continue to do so throughout the summer. He told CropLife on July 18:

“I can tell you EPA is concerned about what they’re hearing … They are trying to keep their finger on the pulse of things. I think they’ve been doing good job in terms of trying to collect information on what is or what is not happening, but I have no idea how they are going to process it and what decisions are going to be made.” Dicamba labels are set to expire this Nov. 9.

Thostenson received his first dicamba injury-related call on July 10 in his home state of North Dakota, where about half of the state’s 7 million soybean acres this season are dicamba tolerant. Since then, he said, the complaint calls have picked up pace.

“The thing that was alarming to me was that it was an entire field that was impacted. In my thinking, it wasn’t a physical spray drift issue. Many fields that I’ve observed in the last week have been damaged fairly uniformly across the field. That’s extremely worrisome. If there is a high degree of uniformity it usually has to do with volatility or physical drift having to do with an intense inversion,” he said.

Like many other weed scientists and extension specialists, Thostenson remains guarded in his outlook for the new technology: “We’re into new territory here. All of the ways in which we have thought about things in the past are completely different … This is not business as usual.”

In his report, Bradley posed two interesting questions:

“First, does 605 official dicamba-related injury investigations and/or approximately 1.1 million acres of dicamba-injured soybean constitute a problem for U.S. agriculture?

“Second, can you look at the scale and the magnitude of the problem on these maps and really believe that all of this can collectively be explained by some combination of physical drift, sprayer error, failure to follow guidelines, temperature inversions, generic dicamba usage, contaminated herbicides, and improper sprayer clean out, but that volatility is not also a factor?”

Dr. Bob Hartzler, Professor of Agronomy and Extension Weed Specialist with Iowa State University, told CropLife, “If we conclude at the end of this year that there are more problems with off-target movement than last year, or even the same amount, to me that’s an indication that the training did not work and that additional restrictions are required. I don’t think anybody has a good feel for what’s going to happen at the end of this year.”

He added: “I think the big thing is to recognize that these new technologies are not the solution to the resistance, regardless of how effective they are. They need to be part of an integrated, diverse weed management program.”