Dicamba Update: Making the Science Work in the Real World

CropLife had the chance to speak with John Smith, veteran Agronomist with WinField United, at Commodity Classic on March 1 in Orlando. From the busy WinField booth, Smith, who is based in Grove City, OH, chatted about some of the challenges that come with applying academics’ recommendations that end up on the label to a real-world dicamba application.

Dicamba Update: Making the Science Work in the Real World

John P. Smith, WinField United

CL: At this point, what is your take on dicamba, and where do you see it going this year?

My overall take on dicamba being from Ohio, with all of our urbanization and our smaller, irregular shaped fields and the mandatory buffers that we need – especially as you go into eastern Ohio – is that there are just a lot of acres it doesn’t fit. We  have had more limited adoption of the dicamba technologies than areas to the west and south, where they can manage the buffers. I think it will probably always have the controversy: is it physical drift, is it volatility.

I’ve worked with dicamba in some way, shape, or form since 1985. Physical drift, volatility, and equipment contamination are three factors that have plagued the dicamba molecule since the 1960s. The timeframe with which we’re spraying it, being later in the season, just exacerbates all of those. A long time ago, Velsicol came out with a product called Marksman and drove the application earlier into the growing season. A., they got better weed control and B., they minimized the conversation around off-target issues; they didn’t eliminate it, but the earlier, the better.

I think the technology is going to continue to be challenged because in 2020, we can realistically have six soybean platforms, and only two of them tolerant to dicamba. We would have non-GMO soybeans, LibertyLink, the new GT27, Enlist E3, Xtend, and XtendFlex. It’s going to be very hard to maintain these buffers and figure out which trait is where.

CL: Can you discuss the DRA from WinField United for the dicamba technologies?

We have OnTarget, one of the second-generation guar products. It is more resistant to pump shear. Our marketing approach has been to mix InterLock with that. The challenge with the dicamba system is that the nozzle we’re using increases the size of those droplets from approximately 650 to 750 to 900 microns. The recent University of Nebraska article talks about that. Now, you start to encounter challenges with coverage and incomplete weed control.

There have been lots of label changes since the introduction. One of the subtle ones that doesn’t get a lot of press is they’ve moved the minimum gallons of water-per-acre application rate up to 15 gallons. I’ve had some experiences with some less-than-acceptable performance from dicamba at 10 gallons per acre on marestail, which is a weed that we’ve always struggled to control. Other people spraying higher gallons got favorable results. Adding 2 oz. per acre of InterLock with OnTarget improves depth of coverage.

InterLock increases the velocity of the spray droplet, which helps to get better depth of penetration into the canopy and better deposition onto the plant. If you think about drift as being what happens from the time the spray particle leaves the spray tip, until it lands on its target, the faster I can get the droplet from the spray tip to the target, the less time I have for drift to occur.

CL: How well do people understand the issue with DRAs, and how concerned are they?

I would say not very. People don’t like these products.

CL: Why is that?

They thicken the spray solution; they don’t work with all spray nozzles. We introduced these products in 1996/97 with Roundup Ready, and people didn’t like them; they had bad experiences. InterLock became a hugely successful product, because we had a drift control product that didn’t thicken the spray solution.

The marketplace moved away from these DRA products because they just aren’t very user-friendly. There’s no better way to say it. Then along came dicamba. In order to be able to do some tank mixes, manage some buffers, etc., the EPA strongly encouraged DRAs.

The EPA are great chemistry people. They don’t understand what happens at the grower-sprayer-product container interface. The reason DRAs went out of favor, is that air induction (AI) spray tips rapidly became the spray tip of choice for applying Roundup back in 2000. What happens with AI tips is, as you slow down and you have a polymer in there, your spray pattern collapses. You don’t get proper overlap and you have skips with weeds. The big benefit to InterLock is that it was compatible with AI tips; you didn’t have that pattern collapse issue, and there were other advantages.

We took a step back with dicamba, and with the University of Nebraska article and the commentary floating around the industry, they are asking, are we expediting resistance?

A lot of times academics don’t totally understand. I’ve got a limited window with wind speed, buffers, wind direction that I can spray dicamba. When people tell me to use more gallons to solve my problem, well, more gallons takes more time. If I’ve got a 1,200-gallon machine and I can spray 10 gallons to the acre, I can spray 120 acres before I have to stop and fill that machine. If I spray 20 gallons per acre with that same 1,200-gallon machine, I can only spray 60 acres. Let’s say, it takes me a half-hour to fill that machine.

If I’m a spray operator, I want to maximize the hours that the sprayer is spraying, and you’re telling me I need to spray 20 gallons per acre, well, you’re screwing with my ability to cover acres.

CL:  It seems to be a common issue, particularly with dicamba, where academic findings might clash with nuances of practical application. How do you bridge the gap?

As an academic, sure, increase your gallons. From a practicality standpoint, when you’re in such a confined window with this deal, (applicators) are looking to maximize time in the sprayer rolling in the field.

I’ve been doing this for too long. Part of my success is, I’ve taken the academics, and what I understand about the farmer and the custom applicator, and I’ve tried to amend the message – not discounting the science, but trying to make the science work in the real world.

CL: From the outside looking in, it looks almost impossible to make an on-label dicamba application. How do growers and applicators make it happen?

If I’m a grower and it’s the only thing I’m spraying, and I’ve got a weed spectrum that says I need to spray this on every acre, then my sprayer is set up, it’s full, and my tender equipment is ready. When the wind conditions are right and all the stars are aligned, I can go to the field and I can spray.

If I’m a custom applicator, I’ve got dicamba acres, I’ve got Liberty acres, I’ve got Roundup Ready acres, and in the future I’m going to have Enlist acres. Dicamba is the most restrictive one, so when the stars are aligned, I’ve got to be ready to go. But if I have Liberty in the machine, I have to stop, clean that machine out, reload it, and get all my tender equipment cleaned out.

Depending upon the equipment it can take two to four hours. If the wind’s picked up, I can’t spray dicamba anymore. If I’m a custom applicator and I’ve got 500 acres of Liberty on the books I need to spray, it would take me two to four hours to clean that sprayer out from dicamba at say, 11 in the morning. Then all of a sudden at 4:30, the wind lets up and we’ve got 300 acres of dicamba to spray. I’ve got to stop and clean that machine out again.

When you’re a custom applicator and buying that equipment, you justify that purchase by how many acres you can run that piece of equipment over in the course of a year. When it is sitting in your lot and you’ve got two guys cleaning it, it’s a money-losing proposition. And it’s a customer relations nightmare, because you’ve got your $400,000 machine, two really good guys in your lot, the weather conditions are favorable, and you’ve got farmers that want their beans sprayed.

CL: Some opt not to spray it altogether.

Right. Personally, what I think you might see going forward, is that XtendFlex, Enlist E3, and GT27 LibertyLink will be the three herbicide traits from 2020 and beyond, in addition to non-GMO soybeans. We’ll potentially go from six down to four. The nice thing about those traits combined is I can spray a Roundup-Liberty tank-mix on all three of those and not have to stop to clean out my machine.

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