seen in our research, a very low rate (1/30,000X) of dicamba can cause soy- bean leaves to cup. “No, there will not be any yield loss at this low of a rate, but you will still see the injury on the beans.” Barber says that while most growers and applicators took the training course on how to best use and apply these prod- ucts, some still decided to spray with the wrong nozzles, during times of high winds, disregarding the buffer zones or at night during a temperature inversion. “This physical drift accounts for at least 80 to 90 percent of all the dicamba injured fields that I have personally walked,” he says. “The other 10 to 20 per- cent is not that easy to figure out.” Some growers and applicators had the correct setup, measured off the appropri- ate boarders and sprayed Engenia when the wind was blowing away from sus- ceptible soybeans, in some cases with a broadcast hooded sprayer. Barber says these are the fields that have him scratching his head, wondering how dicamba symptoms appeared a quarter-mile upwind. The two conclusions that he can come up with: “Either there was a small amount of volatility that occurred, but enough to cause some symptomology, or another theory might be that the dicamba drop- lets are moving on dust particles after the application is made.” However, Larry Steckel, a University of Tennessee weed scientist, says the drifting dicamba might have more to do with the time of the year and temperature. “Instead of spraying it in February, March and April [like we do for corn], we are now spraying it in June and July — hot times of the year,” he says. Kevin Bradley, a University of Missouri weed scientist, and Iowa State’s Bob Hartzler agree with Steckel that timing is one big difference. “We haven’t been spraying dicamba in June and July on soybean,” Bradley says. Hartzler says that another possible source of damage might result from dicamba use rates. “The post emergence rate for dicamba is 0.5 pounds per acre in both corn and dicamba-resistant soybeans,” he says. “However, dicamba rates in corn are usually reduced significantly since it is often tank- mixed with other herbicides or because of crop injury concerns. Labels of products registered for use in dicamba-resistant soy- beans do not allow reduced rates.” Hartzler shares the use patterns of dicamba in soybeans increase injury risk when compared with how it has been used in corn. Companies Respond After spending the last few weeks of July traveling through Missouri, Tennessee, Arkansas, Iowa, Illinois and South Dakota to visit with soybean farmers, consult- ants and academics, Monsanto’s Chief Technology Officer Robb Fraley says he saw a mixed picture. “On the one hand, I saw and heard a lot of success stories from growers and applicators in every state where our XtendiMax product has been approved for in-crop use,” he says. “In fact, I would say that most of the farmers I visited with are very pleased with their weed control this season, and I could see why. “Their fields are showing very good control of difficult weeds, such as water hemp and pigweed, that they have been dealing with for years.” But on the other hand, Fraley says he also saw fields exhibiting clear sympto- mology. “I understand why these farmers are angry and concerned, and we are looking for answers,” he says. “The symptomology I saw — and what most farmers experienc- ing symptomology are seeing — was leaf cupping,” he explains. “While leaf cupping can be caused by dicamba, it can also be caused by many other things, including environmental factors, diseases and other crop protection products. “For that reason, diagnosing the problem can be complex, especially when there have been relatively few inquir- ies in closely neighboring states. In fact, Arkansas, the only major cotton and soy- SEPTEMBER 2017 SEEDWORLD.COM / 13 bean growing state where Monsanto does not sell XtendiMax, has received nearly twice as many inquiries as every other state combined.” To read more about Fraley’s field observations, visit “Talking Dicamba with Farmers — What I Learned.” Monsanto’s Brian Naber, U.S. commer- cial operations lead, says the company continues to investigate the cause of damage. “We’re in the early stages, for sure,” Naber says. “But to this point, the indica- tions are that volatility of the approved over-the-top product is not the major source of the off-target movement “Instead, the evidence we’re seeing is pointing to: Illegal applications of non- approved products; lack of compliance with the labeled spray requirements; and direct application of contaminated prod- ucts that can result from either improper tank clean out or the use of contaminated products.” In helping respond to the complaints, BASF has already deployed more than 400 field representatives to answer ques- tions and concerns. Scott Kay, BASF business director, says one of the key ingredients to getting a good experience when it comes to appli- cation is using the right nozzle. “We’ve invested heavily and have dis- tributed those nozzles to our customers,” he says, noting that more than 600,000 nozzles were purchased and given to customers. While both companies continue to investigate the cause of damage, farmers and experts both agree that accessibil- ity to new tools to help control weeds is important to their future success. “Agriculture is in a difficult position in determining how best to move forward regarding the expanded use of dicamba and the risks posed by this technology,” says Iowa’s Hartzler. “There is no denying that new tools are needed to aid in weed management as problems with herbicide- resistant weeds continue to spread.” SW