Farm Progress

2017 Mid-South weed control: Heavy with dicamba concerns

How are other Mid-South states addressing dicamba drift?

Farm Press Staff

December 5, 2017

7 Min Read

With more Mid-South farmers planting Xtend crops, 2017 was a dicamba-tinged whirlwind. Post-harvest, it’s worth noting the season’s fallout from far too many drift incidents, class action lawsuits filed, a debate over spraying regulations (both state and federal), and the unfortunate circumstances that have left too many farmers with damaged crops staring accusatorially across the fence at a neighbor.  

In July, following a vigorous off-season debate about the technology, and with much of the upper Mid-South already awash in suspected dicamba drift incidents, BASF representatives spoke about the company’s approach to the situation. In Arkansas, where hundreds of complaints had been filed, dicamba had been effectively banned from the state for the balance of the year.

“Over the last two years, prior to the registration of Engenia, we did make the product available to all university weed scientist researchers to test in their own trials,” says Dr. Dan Westberg, who repeatedly emphasized the importance of applicator training for use of the Xtend system. Westberg, BASF technical services manager at Research Triangle Park, N.C., warns that “PPO-resistance in some of those areas is so rampant, if we over-rely on Liberty only, it’s not going to last long. We need this tool, and growers need this choice.”


Weed scientists argue that, along with the way farms are laid out, especially in northeast Arkansas, the region’s topography is unique and must be a chief consideration for new weed-control technologies in future releases. 

“A lot of the testing the University of Arkansas did was at the Keiser Research Station,” says Westberg. “The uniqueness of the topography, I think, contributes to the distance that, perhaps, an inversion can meander and move around. 

“From a cropping system standpoint, here in North Carolina, we’re not going to have the massive fields they have in east Arkansas … but the cropping systems, other than rice, are amazingly similar. We have a tremendous number of dicamba-tolerant soybean and cotton acres planted this year, and treated. We have peanuts mixed in, we’ve got corn mixed in, and a lot of non-dicamba-tolerant soybeans.”

The upper Mid-South is “the first area of the country where I’ve really encountered nighttime applications — maybe not a standard practice, but a common practice. I think that’s a key concern for that particular area.”


As field day-season kicked into gear, studies at the Keiser, Ark., research station took center stage. 

“What we’re showing in the center of the field is 3.5 acres treated with a labeled application of (Monsanto dicamba formulation) XtendiMax,” Dr. Jason Norsworthy, University of Arkansas weed scientist and experiment station director, said during an Aug. 8 field day. “We also made a labeled application of Engenia to 3.5 acres in an adjacent 20 acre field. Those applications were made simultaneously under the same environmental conditions.”

In a variety of testing conditions — non-dicamba tolerant plants covered for different time periods, greenhouse plants brought into sprayed fields in flats, weather station data recorded, among other iterations — the results alarmed researchers. Damage sometimes occurred days following a dicamba application.  

“We know temperature has a direct impact on the volatility of a product,” says Norsworthy. “At the time of application, we were at 93/94 degrees when we sprayed the two fields simultaneously. We got up to about 97/98 degrees later that day. Over the next three days, we had low air temperatures of about 75 to 77 degrees. 


“But, pay attention to the soil temperature: We had a run of 106 degrees the first day, 113 the second day, and 113 the third day. So, when you talk about volatility, it’s the ability through temperature to convert a liquid to a gas. Any material lying on the soil surface has a high potential to volatilize — especially when we’re experiencing these high temperatures.” 

A take-home from Norsworthy: “Don’t just pay attention to air temperature.”

Along with northeast Arkansas, Missouri Bootheel flora was bedeviled with dicamba drift. In early September, Kevin Bradley, University of Missouri weed scientist, was already being asked about soybean variety recommendations for 2018. 

“My advice is pretty simple,” says Bradley, who agrees that volatility of new formulations is part of the problem. “Everything I’ve seen in 2017 says we need to keep this in the preplant, burndown, preemergence use pattern. Leave the postemergence alone. I’m sticking with that, because the risk is too great for off-target movement to be spraying this for Palmer amaranth and waterhemp in soybeans. 

“To be blunt, there are farmers who have been upset with me for suggesting dicamba formulations can be used at all, ever again. There are also farmers who got mad at me for saying we shouldn’t use them postemergence. The whole thing is controversial, and there’s no way to get around it. My job is to put out what we see as the best available advice, based on the science available to us.”


On September 26, following the Arkansas Plant Board’s backing of a mid-April spraying cutoff for dicamba, Monsanto’s Scott Partridge, vice president of global strategy and former chief deputy general council, spoke with Delta Farm Press.

“We’re very disappointed in what the Plant Board did,” Partridge responded. “We presented hundreds of pages of technical data, information, and analyses of off-target movement in other states, that showed, with training and education, this problem is solvable. 

“The Plant Board didn’t consider any of the information we provided, obviously didn’t — based on how quickly they made their decision — take into account the science testing, data, experiences from other states, but simply, in an arbitrary fashion, decided to go forward with the April 15 spraying ban… It’s a process that’s broken, and we’re going to look at all our options.”

How are other Mid-South states addressing dicamba drift? “Compared to Arkansas,” Partridge says, “they’re actually looking at the science and information we’ve provided to them, along with the experiences of growers in their states. They’re going through a rational and deliberate process in evaluating this …

“What we know about the Arkansas Plant Board process is that it’s arbitrary. Why it’s arbitrary, I don’t know. What I do know is, it isn’t based on science. And the Plant Board has placed their growers at a tremendous disadvantage and taken away an important tool. A lot of people are looking at their process, and they need to make sure that process is one they can defend. Right now, I don’t think they can defend their process.”

On Oct. 20, Monsanto filed a lawsuit to block the Arkansas Plant Board's dicamba ban between April 16 and the end of October.

Enhanced XtendiMax Label to Help Farmers in 2018

On October 13, the EPA announced enhancements to the XtendiMax with VaporGrip Technology product label that will help ensure farmers have even more success with the Roundup Ready Xtend Crop System in 2018. The updates, which were voluntarily proposed by Monsanto and are supported by the EPA, include mandatory training, new record keeping requirements, and a Restricted Use Pesticide (RUP) designation, which will limit sale and use to certified applicators or those acting under their supervision.

“Based on the science behind our low-volatility dicamba product and learnings from the 2017 season, we are confident the required training and record keeping can address the main causes of off-target movement,” says Ty Vaughn Monsanto’s global regulatory lead. “We want to stress how important it is that farmers use products approved by the EPA for use over the top of dicamba-tolerant crops, and use them in accordance with all label requirements.”

In addition to the enhancements, Monsanto is taking a variety of steps to help customers be more successful in 2018, including evolving and tailoring trainings, distributing spray nozzles at no cost that are compliant with the product label, continuing to offer an incentive of up to $6 per acre when applying XtendiMax through Roundup Ready PLUS, setting up a technical support call center to help applicators easily access best practices and application requirements, and working to develop a spray app for applicators to help them avoid problematic weather conditions, among other efforts.

Subscribe to receive top agriculture news
Be informed daily with these free e-newsletters

You May Also Like