Leaving a plume of dust in its wake, the final tour bus pulls away from the “weed stop” at the 2016 Arkansas Rice Expo outside Stuttgart, Ark. University of Arkansas weed scientists Jason Norsworthy and Tom Barber find a bit of shade to shelter in and talk the latest about the dicamba drift fallout in the Mid-South.

Two days earlier, on August 8, the state’s Pesticide Committee met in Little Rock. The committee passed a handful of proposals to deal with the drift.

“Ultimately, they banned the use of dicamba acid and dimethylamine salt of dicamba,” says Norsworthy. “That means products like Banvel are banned for use on row crops in the state. You can use those products in pastures but there’s a one-mile restriction to a susceptible crop.”

The committee also voted in a cut-off of April 15 for use of diglycolamine (DGA) salts and sodium salts of dicamba.

“An example of the sodium salts would be Status. Examples of the DGA salts include Clarity and Roundup Xtend with VaporGrip – the formulation Monsanto has talked about bringing forward for use on Xtend soybeans. If registered, XtendiMax with VaporGrip will also have an April 15 cut-off.”

The reason for the April 15 cut-off for the Monsanto formulations is the University of Arkansas hasn’t been able to carry out drift and volatility studies on them. “The Arkansas Pesticide Committee has made it clear that these formulations will need to be evaluated by us before they could potentially be approved in the state. Bottom line is if Monsanto wants to register their products, we need to have a good look at them.”

Flexipan is also a DGA salt, says Barber, “so it’s under the same restrictions. It’s true -- they’re pushing this VaporGrip technology. It’s supposed to reduce volatility but we can’t say for sure that it does.”

“We know that Clarity is volatile since we’ve done work with it,” says Norsworthy. “There are products better than Clarity including Engenia. We know Engenia reduces volatility.

“Here’s the thing: when you’re looking at the salts and improved formulations that doesn’t mean there will be a reduction in physical drift. The risk for physical drift is the same as it is for other products. However, it does have lower volatility and that’s why the Pesticide Committee – and we don’t know if it’ll get over all the hurdles from state government – is more willing to allow its use in dicamba crops. There is a 100-foot use upwind/side wind buffer – plus a quarter-mile downwind – for susceptible crops like peanuts, vegetables, any soybean without a dicamba trait.”

Why did the committee go with an April 15 cut-off rather than May 1?

“We were pushing for May 1 because we’re still using dicamba a lot for burndown of horseweed and pigweed,” says Barber. “Glyphosate-resistant horseweed is still a major issue in Arkansas.

“A farmer on the committee said he had soybeans up and growing by May 1 that had dicamba injury this year. Many other growers will also plant beans in April that could potentially be injured from off target dicamba movement, especially in South Arkansas. So, you can understand why that later date would be a concern.”

Historically, says Norsworthy, there was a cut-off of April 15 for 2,4-D in northeast Arkansas “so I think that partly played into the decision.”

Unique environment

The pair point out how unique the growing environment is for the Mid-South. Testing of products must be done in the region.

“We’re just unsure if these new Monsanto VaporGrip formulations have been tested in a ‘Mid-South way,’” says Barber. “Data from somewhere else, Texas or the Midwest, just doesn’t translate here. Just because it works in Illinois and Indiana doesn’t mean it’ll do the same here.”

“Think about the environmental conditions here,” says Norsworthy. “Think about the wind speeds, the temperature swings, the humidity and all the rest. Tom’s right: all of that will have an impact on off-target movement. Just because the formulation was successfully evaluated in Nebraska or northern Iowa, who cares? It needs to be evaluated in Arkansas.”

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And it will take two years to test the new formulations properly.

“We don’t recommend any technology or herbicide in Arkansas without proper testing,” Norsworthy continues. “We’ve always said we need to look at it for two years and have positive results or it won’t be recommended.

“Go look at the MP44, the weed control guide. It isn’t an all-inclusive list of products labeled for a given crop. Corn is a good example. There are probably 200 products labeled for corn and the weed control guide only contains 40 or 50. Those 40 or 50 we’ve tested, are comfortable with and we know how they’ll act.”

Two years of study doesn’t mean the product will be approved, Barber says. “If a product doesn’t do well here it’s our job to tell our growers. Every state around may recommend it but that doesn’t matter. There are a couple herbicides labeled in cotton that I don’t recommend for our producers here in Arkansas.”

How are drift-damaged fields looking now?

“Some of the fields drifted on early appear to have made a full recovery,” says Barber. “We won’t know for sure until we put the combine in them.

“I can tell you that some bean fields drifted on at very sensitive stages, R1 or R2, look just as stunted as the day they were hit. Those fields will see significant losses. Will that be 10 percent? 20 percent or more? Some may lose 40 or 50 percent of their yields.”

Yield losses will be especially bad in fields drifted on multiple times.

“We’ve collected data looking at different doses of dicamba to simulate drift and determine yield loss at various growth stages,” says Norsworthy. “But when you have applications that were drifted on soybeans two or three weeks apart, we don’t have an idea what will happen.”  

It’s worth noting, says Barber, “I’ve been told many of the applications weren’t made at the lower rates – 0.5 pounds active ingredient dicamba or 1 pint per acre equivalent we were looking at in our studies. Instead of using a pint, they used a quart of Clarity. That is double the rate of what we’ve looked at in drift studies.”

Perilous attention

The researchers say the continuing national attention on Mid-South dicamba drift is ultimately perilous.

“I had a reporter call two weeks ago after the first hearing at the Plant Board,” says Norsworthy. “They asked ‘Did you not see this coming? Why were you blindsided?’

“There was no blind-siding. We knew this was likely to be a major issue. We’ve been telling the Plant Board this for several years now. We’ve been saying it at all the winter meetings.

“Two years ago, a 400-foot buffer was set in every direction for dicamba applications to dicamba-resistant crops, even though the crop was not yet deregulated. That buffer was set based on the work we’d done in drift and volatility trials as well as injury to the progeny (offspring). At the end of the day, soybeans are highly sensitive to dicamba.”

There’s “a bad downside” to the attention, says Barber. “A lot of folks are using this to promote negative opinions about agriculture. It’s given the anti-GMO, anti-big ag groups fodder to skew press releases and whatever.

“Go look at the story done on this by NPR. There are hundreds of comments on that story. After the first few comments, the discussion – and I’m paraphrasing -- turned towards things like ‘this is why GMOs shouldn’t be allowed.’”

Norsworthy agrees. “When you start getting a tremendous amount of media attention on something like this, it’s a negative for the whole agriculture sector.”

Both men say the Pesticide Committee’s proposal to increase spraying violation penalties from $1,000 to $25,000 is understandable. If it is to happen, the increase will have to wait for the state legislature to pass a new law during its next session.

“Whether $25,000 is the right number or not, there has to be more bite in the penalty,” says Barber. “I don’t think there’s a question about that.”

“$25,000 would be the maximum per violation,” says Norsworthy. “Well, if you have a repeat offender with multiple violations, that fine stacks up quickly. Depending on the damage done and intent someone could look at a big bill.

“Something has to be done. Period. Otherwise, it’ll have a major impact not only on this technology but on other technologies and spray applications as a whole.”