New Herbicide Tech: 5 Critical Points To Consider — And Remember

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Photo: ©Debra L. Ferguson

Bob Hartzler can imagine a troubling scenario unfolding this year in fields of dicamba-resistant soybeans.

“There’s usually at least one time during every growing season when we get way behind in spraying fields because of weather,” the Iowa State University weed scientist said. “Unfortunately, when that happens there’s so much pressure on the producer to get acres treated that common sense flies away.”

Up until this year, you could probably slip by without horrible consequences. As the saying goes, you maybe had a “fudge factor” on your side.

But this year the scenario has changed if you shift to new herbicide-tolerant technologies and then ignore restrictions on the Xtendimax or Engenia (dicamba) labels, according to Hartzler.

“It’s hard to explain just how sensitive non-target vegetation can be to these products,” Hartzler said of the herbicides approved for the Xtend as well as Enlist weed control technologies. “Unfortunately, you almost have to experience it firsthand to realize what’s going to happen. A lot of farmers haven’t experienced the level of sensitivity. No matter how much we tell them, it’s hard to grasp.”

As a quick overview, Hartzler suggests:

Maximize the preemergence phase. Use a full rate of a preemergence herbicide to provide the greatest flexibility and hopefully avoid a mid-season crisis. While dicamba has some residual activity, Hartzler believes that it fits best as an early preemergence product in terms of waterhemp management.

Spray weeds when they’re small. “One benefit of dicamba is the residual activity, and so hopefully, applicators will be willing to spray earlier than they might with glyphosate or a Group 14 herbicide that will only control weeds already out of the ground,” Hartzler said.

Spend plenty of time reading the labels. And then read them some more. “Particle drift and equipment contamination are going to be issues. We must have a much higher level of stewardship in terms of keeping the product on the field than we’ve used with other herbicides,” Hartzler said.”

Be aware of your surroundings. “Map out each field and find where the sensitive vegetation is long before you spray,” Hartzler advises. “Getting everything mapped out before the season can go into your weed control planning. You don’t want to show up at a field ready to spray and get surprised by what you see there. If that happens, you’re likely say, ‘Oh well, I’ve got to get it done.’” That could turn into a huge mistake.

Realistically manage your expectations. Hartzler is concerned that expectations for both dicamba and 2,4-D technologies are out of proportion to what they will deliver, mostly in regard to control of waterhemp, the Midwest’s No. 1 weed pest.

“In Iowa, 99% of farmers will have interest in the technologies because of our resistant waterhemp problem. But neither product would rate as excellent on waterhemp. Farmers are thinking the technologies are going to make weed control easy again. That’s not the case.”

Hartzler certainly isn’t alone in his concerns about how and when treatments will be made – and the potential for crop injury and even legal action when things go bad.

His concerns are shared by colleagues in both the Corn Belt and the South. Here are 5 points they frequently emphasized:

#1. Get informed. Stay informed.

A lack of education about drift potential with the new technologies is a concern for Missouri Extension weed scientist Kevin Bradley. This was born out in a 2016 survey of Missouri commercial and private pesticide applicators conducted by Bradley in late 2015 and early 2016.

These points were particularly scary…

  • Applicators were asked the true/false question, “When Roundup Ready 2 Xtend soybeans are commercially available, you will be able to apply any dicamba-containing herbicide to those varieties, provided the proper drift reduction precautions are followed.” In the responses, 29% answered true. The correct answer is false. Only approved, low-volatility formulations of dicamba can be used and proper drift reduction precautions are required.
  • Of those surveyed, 25% did not know the characteristics associated with a temperature inversion. Some did not know what a temperature inversion is.
  • “Others did not understand that you couldn’t spray 2,4-D on Xtend soybeans or dicamba on 2,4-D soybeans,” Bradley said.

Bradley said that private applicators, who are mostly farmers, fared worse on the survey than commercial applicators. Less than half knew that the presence of fog in low-lying areas was associated with a temperature inversion. 

“It was apparent from the survey that we have to do a better job of education at the grower level,” Bradley said. “They’re the ones who aren’t answering the questions as good as we would want them to.”

Bradley urges producers to get better informed prior to the season. “If you’re intending to use these traits in 2017, attend a training session, wherever they are and whoever is putting them on. Learn the specifics because this is something we’ve never done before, with all the details that are on the label.”

Bradley will conduct an education seminar on the dicamba trait at the Fisher Delta Research Center in Portageville, Missouri, on February 27 and will conduct four more sessions around the state in late February and early March.

See a University of Missouri slide show on dicamba injury.

#2. Avoid those self-inflicted disasters.

Jason Bond, weed scientist at Mississippi State University, says proper tank cleanout and how well you manage the presence of multiple weed control technologies are also keys to minimizing self-inflicted crop injury in 2017.

“Tank contamination is underestimated as a potential concern,” Bond says. “If a farmer downplays the significance of spray tank cleanout, he can really hurt his crop.”

Which Nozzles Are Required For Those Dicamba And 2-4D Labels – And Can You Find Them???

Bond says to read cleanout instructions on each new label. All three new products approved for use in 2017 – Xtendimax, Engenia and Enlist Duo – “have very specific instructions for how the products should be cleaned out of the tank. They’re very similar but not identical. You are responsible for following the directions on that label.”

#3. Know what’s around you – and mark your own technology, if possible.

Managing various technologies in proximity to each other can also be a challenge, Bond says. “When there are Roundup Ready soybeans, LibertyLink soybeans, Xtend soybeans and possibly Enlist soybeans, you won’t know what’s out there. Communication on the farm and among growers is hyper-critical right now.”

Bond also suggests using the Flag the Technology program developed by the University of Arkansas.

#4. Take a wait-and-see approach (maybe).

Meaghan Anderson, Extension field agronomist with Iowa State University, says farmers in central Iowa who plant the new herbicide-tolerant crops may opt not to apply Xtendimax or Engenia (dicamba) herbicide, or with import approval, Enlist Duo (2,4-D and glyphosate). At least for this year.

Herbicide Resistance Info


“Farmers I speak with say, ‘let’s see how this year goes, and then I’ll consider it in the future.’ I don’t think farmers are backed into a corner far enough to where they think they have to use the technology,” said Anderson, who added that Midwesterners are fully aware of what happened in the Midsouth in 2016, when illegal sprays of dicamba drifted and caused significant injury to nearby sensitive crops. (The dicamba sprayed was not a low volatility formulation).

#5. Rely, as well, on non-herbicide tactics.

Anderson encourages all producers, whether they use a new herbicide technology or not, to “incorporate as many non-herbicide tactics as you can for weed management, because herbicides relied on solely will inevitably break down. That’s what we’ve seen before and that’s what we’ll continue to see in the future.”

Non-herbicide tactics include:

  • Switching to narrower rows to shade out waterhemp and other weeds.
  • Cultivate small problem areas in a field, if possible, and keeping fence rows clean.
  • Plant cover crops — an approach that has gained acceptance in parts of the South as a tool for suppressing weeds.
  • Chop or pull escapes where necessary.

Anderson, like colleagues in other states, urges farmers to thoroughly read labels for Xtendimax, Engenia, Enlist Duo and future products approved for use on Xtend and Enlist crops.

“These herbicide labels contain more detail than any previous labels and the technology will require more stewardship than ever before,” Anderson said. “They’re not like other herbicide labels that we’ve seen.”

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