Over the past several decades, the unending quest to help grower-customers increase their crop yields has driven the agricultural marketplace to introduce various biotech varieties resistant to various popular herbicides along the way. And the majority have worked fine — until now, that is. Now experts are wondering what happens next.
The overriding problem, of course, is weed resistance. Since growers first started planting crops, they have been constantly fighting yield-robbing weeds in their fields. That’s why, starting in the mid-1990s, glyphosate-resistant crops first began appearing into the marketplace. Now able to spray herbicides while resistant plants were already in the field increased the growers’ ability to better manage their acres.
Unfortunately, weeds by their nature are incredibly adaptive to changing environmental conditions. Starting in 2000, glyphosate-resistant weeds began showing up (when resistant marestail was first discovered in a Delaware crop field). Weeds resistant to other popular herbicides were already becoming more widespread by this point as well. Soon, and throughout the early years of the 21st century, herbicide-resistant weeds kept spreading across the entire U.S., field by field, state by state. By the end of 2017, weed scientists estimate that there are now 238 herbicide-resistant weeds growing in virtually every state of the country that are capable of surviving efforts to control them using 26 different kinds of herbicides.
At a 2017 trade show, Kevin Bradley, Associate Professor at the University of Missouri, described just low adaptive one weed — waterhemp — has become in the Show-Me State. “It’s a nightmare,” said Bradley. “As weed scientists, we’ve looked high and how, and we can’t find waterhemp in Missouri that is not resistant to ALS, glyphosate, and PPO herbicides.”
Dr. Ford Baldwin, a representative for Practical Weed Consultants, echoed this view. “Several of the most popular herbicides, including glyphosate, are no longer able to kill the weeds they were intended to,” said Baldwin, speaking at the 2017 Agricultural Retailers Association (ARA) annual meeting. “Basically, we are down to dicamba, HPPDs, glufosinate, and 2,4-D in terms of choices.”
Enter 2,4-D/Dicamba Crops
For this reason, crop protection/seed suppliers began trying to expand the number of herbicide-resistant crop choices. Not too many years into the early 2000s, Bayer CropScience launched LibertyLink crops, which were resistant to glufosinate, as an alternative to glyphosate-resistant options. These continue to enjoy popularity across the U.S., particularly in the Mid-South where resistant Palmer amaranth is a concern for growers.
And over the past decade or so, a pair of other crop protection/seed companies — Monsanto and Dow AgroSciences (now DowDuPont) — began working on their own cropping systems resistant to two of the other herbicides Baldwin mentioned in his ARA talk — dicamba and 2,4-D, respectively. Both companies have spent the past several years experimenting with these crops while they awaited the necessary regulatory approvals from various governmental and international agencies/countries.
As the agricultural marketplace prepared for the 2017 growing season, word came down that Monsanto’s dicamba-resistant soybeans and cotton, marketed under the Roundup Ready 2 Xtend and Bollgard II XtendFlex names — would be available for U.S. growers to plant. These were to be supported not by older formulations of dicamba such as Banvel and Clarity, but newer, less volatile (i.e., less likely to drift) ones from Monsanto (XtendiMax with VaporGrip technology), BASF (Engenia), and DowDuPont (FeXapan with VaporGrip technology).
At the 2018 Ohio AgriBusiness Association (OABA) annual meeting in February, BASF Ohio Representative Don Schneider explained why dicamba-resistant crops are important to many of today’s growers. “Dicamba is one of the last compounds left that can control virtually all the broadleaf weeds that are resistant to many other herbicides,” said Schneider.
Based upon the preliminary numbers, U.S. soybean and cotton growers were anxious to try this new cropping system in their fields. According to Monsanto, an estimated 20 million acres of Roundup Ready 2 Xtend soybeans and six million acres of Bollgard II XtendFlex cotton were planted in 2017.
However, as tends to happen with any first-year technology regardless of the field, there were some growing pains, so to speak, with dicamba-resistant crops. Throughout the spring and summer months, state agricultural offices across the Eastern part of the U.S. received complaints from growers that off-target dicamba applications had damaged their non-resistant crops/plants. This included evidence of puckered or cupped leaves on plants one to two weeks after dicamba application work was done.
By the time the year was over, a total of 2,708 formal complaints regarding dicamba damage were filed with regulators — more than triple the number of complaints typically received during a growing season, say industry insiders. These have already led to almost one dozen civil lawsuits being filed against dicamba manufacturers.
“I told people [in 2016] I was cautiously optimistic we’d make [dicamba application on resistant crops] work,” Bob Hartzler, Extension Weed Specialist and Professor of Agronomy at Iowa State University told CropLife® magazine in November 2017. “I was proven wrong.”
One state in particular — Arkansas — led the nation in off-target dicamba complaints. Here, regulators heard from almost 1,000 growers regarding this problem. According to BASF’s Schneider, some of these complaints were caused by applicators/growers applying older dicamba products. “These guys were looking for any way they could to fight against Palmer amaranth that was resistant to other herbicides, and the fine for applying off-label dicamba was only $5,000 at the time,” he said. “Now, that fine threshold has been raised to $50,000.”
However, he added, the majority of off-target dicamba complaints in Arkansas were likely caused by temperature inversions — times of day when solar radiation lessens, creating a layer of cooler, denser air near the soil surface. This can result in off-target movement because smaller herbicide droplets will never reach their intended target.
“That’s why it’s important to apply dicamba after sunrise and before sunset,” said Schneider. “During 2017, approximately 50% of the dicamba products used in Arkansas were sprayed at night. So lots of inversions were probably taking place.”
Monsanto also said it believed that many of 2017’s off-target dicamba complaints stemmed from improper use. “New technologies take some time to learn,” said Scott Partridge, Vice President for Global Strategy for the company in an online statement. “Thus far, what we’ve seen in the field, the vast majority, more than three-quarters of them, has been due to not following the label.” In fact, according to Monsanto, 97% of soybean growers surveyed by the company at the end of 2017 were “satisfied or very satisfied” with the weed control they got from using Roundup Ready 2 Xtend crops.
Looking Ahead to 2018
Hoping to avoid some of the issues that dicamba application faced during 2017, various states have taken steps they hope will eliminate — or at least significantly reduce — the chances for off-target dicamba movement occurring during the 2018 growing season. These include restricting the time of day dicamba can be applied to fields between 7:30 a.m. and 5:30 p.m. (Missouri and Tennessee), not permitting application to take place if the air temperature is above 85 degrees (Minnesota and North Dakota), requiring paperwork to be filled out on the same day as applications of dicamba take place (Missouri and Ohio), and that a hooded sprayer be used if any dicamba application takes place between July 15 and October 1 (Tennessee).
Several states also have set cut-off dates for dicamba use. Most of these are set as early as June 1 (in the southeastern portion of Missouri) to June 30 (North Dakota). Perhaps not surprisingly, given how many complaints appeared there, Arkansas has the earliest restriction on a dicamba application cut-off date, with no work being permitted after April 15. Also not surprisingly, Monsanto has taken issue with this early stop date and has engaged in a series of lawsuits/grower-focused campaigns to convince Arkansas regulators to revise this ruling. At presstime, this battle was still ongoing.
In a letter to Arkansas Governor Asa Hutchison, Monsanto Chief Technology Officer Dr. Robb Fraley offered this assurance to the state’s agricultural community: “We will continue and expand our outreach efforts going into the 2018 season to ensure that you feel fully comfortable and confident in successfully using our products. We’ll continue to partner closely with our retailers, Extension agents, and individual customers to make sure you experience the full potential of this breakthrough technology.”
Meanwhile, while dicamba-resistant crops are preparing to enter their full second year on the market in 2018, the other new cropping system, featuring 2,4-D-resistant crops marketed under the Enlist name, is finally getting ready to make its market debut. According to DowDuPont, the company was waiting for certain regulatory approvals for export to come through before formally introducing this new technology to the U.S. agriculture marketplace. “I’m happy to report that we now have trait approval for Enlist corn in China,” said a DowDuPont representative during a summer 2017 company event. “We are now able to launch corn containing the Enlist trait starting for the 2018 season.” It will also be available for cotton.
According to Shawna Hubbard, Herbicides Product Manager, the Enlist corn trait will be available as both SmartStax Enlist and PowerCore Enlist hybrids. For cotton, it is available in PhytoGen cottonseed. Both traits are supported by a new herbicide option from the company — Enlist One. A 2,4-D choline product featuring Colex-D technology, Enlist One can be tank-mixed with glufosinate and is approved for use in 34 cotton/corn/soybean producing states.
As with the introduction of dicamba-resistant crops a year earlier, DowDuPont offered Enlist users a training program called Enlist Ahead management resource. “This includes the Enlist 360 online training module, the in-field technical expertise of Enlist field specialists, and other resources and incentives,” says Hubbard. “With practical management practices, Enlist Ahead helps growers make on-target applications and prevent the development of resistant weeds.”
While 2,4-D resistant crops begin their market journey in 2018, dicamba offerings have a little more at stake. According to several industry insiders, regulators unsure of how dicamba application work would perform during the 2017 growing season meant that the labels on these herbicides is set to expire at the end of November this year. Speakers such as the University of Missouri’s Bradley say this was done deliberately to “hedge their bets” against continuing usage if market problems persisted.
For ag retailers and their grower-customers, this means the stakes are incredibly high for dicamba application to have a “good year” during 2018. For applicators, said Erick Springer, a representative at John Deere equipment dealer Ohio Spray Center, being extra careful to follow all the rules regarding dicamba application will be key.
“Let’s face it — we got stupid when it came to using glyphosate because it was so easy to handle,” said Springer, speaking at the 2018 OABA meeting. “But the math is different now, and dicamba is making us have to think again when we are in the sprayer. We have to get a lot smarter in 2018 then we were in 2017.”
Dr. Vince Davis, a representative for BASF, agrees whole-heartedly with this assessment. “The use of this technology is necessary, but we need to figure out how to use it better,” said Davis, speaking at the 2018 Illinois Fertilizer & Chemical Association annual meeting. “We need this technology and others like it to combat some of the herbicide-resistance issues we are up against. But we can’t have a repeat of 2017, or we will lose this chance.”