Production Blog

Dicamba Disaster Control

Pam Smith
By  Pam Smith , Crops Technology Editor
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New herbicide technology that allows soybean and cotton to withstand applications of dicamba require very specific application procedures. (Illustrations by Donovan Harris and Barry Faulkner)

DECATUR, Ill (DTN) -- Dicamba may have been on the market for more than 50 years, but everyone in the industry got taken to school this past spring and summer on what they didn't know or perhaps more accurately, didn't expect, from this herbicide and those that sprayed it illegally.

It's been hard to miss the headlines. Formal dicamba damage complaints were filed representing damage to thousands of acres of soybeans and other sensitive plants in Mid-South and Midwest states. Federal search warrants were issued in Missouri as regulators attempted to sort through what happened. Environmental groups are suing the EPA. A Missouri peach grower has filed suit against Monsanto. There has been at least one farmer shooting death linked to a dispute that allegedly started over dicamba-based crop damage. Investigations continue.

I can honestly say that in my nearly four decades of reporting on agriculture, I've never followed a story quite like it.

Over the past few months, two dicamba-based herbicides, XtendiMax with VaporGrip and Engenia, have been approved for use with Xtend soybeans and cotton. Seed company lineups for 2017 are flush with new Xtend varieties and acreage is expected to jump considerably.

The question now is how this will play out on a landscape level. While there's little question that soybean and cotton growers need new weed control tools, some of the aggressive marketing messages that surround the new herbicide system and the nearly addictive need voiced by growers are a concern.

I lost count of the number of times that farmers have told me last summer that once EPA approved formulations containing "VaporGrip," the problems surrounding dicamba will all go away. This fall, I had a farmer literally get in my face following a Missouri legislative hearing on the issue and declare: "I need this chemistry. I'm out of stuff." I had an Illinois farmer tell me the Xtend platform is "the next Roundup Ready" and proceed to explain that he plans to use dicamba as a spring burndown and follow with at least one and possibly two post applications because the waterhemp on his farm is "really, really bad."

I've received nasty messages on Twitter indicating I don't realize that farmers have been spraying dicamba for years as burndown treatments and postemergence in corn without incident -- so therefore, what is the worry? Then, there is disturbingly long list of farmers intending to plant Xtend varieties because they don't trust neighboring farmers to use newer formulations or take the precautions necessary to keep dicamba from drifting.

All of these statements are, of course, flawed. The new formulations may reduce volatility, but that's only one small component of the reasons dicamba and herbicides, in general, drift.

Despite the growing problem of herbicide resistant weeds, there are still ways to control even the most troublesome species. Multiple applications of the same product are a big part of the reason we have problems with weed resistance today. The burndown and postemergence treatments on corn generally come earlier in the season when temperatures are lower with fewer sensitive crops are around -- plus we probably ding more beans than we admit to with those post applications. Finally, what does defensive planting tell the already skeptical public, if farmers can't trust other farmers to follow labels or resist the urge to use more volatile compounds?

Some of us remember the first days of Roundup Ready in 1996. It took a bit to sort out that technology, too. Some growers turned to custom application as a way to sidestep the liability of drift damage and I've already talked to growers planning to do that with these new herbicides.

However, I see some differences with the introduction of Xtend crops. Dicamba isn't as forgiving as Roundup with regard to weed size -- even the manufacturer will tell you 4 inches is the limit. Nor is glyphosate as inherently volatile -- just because XtendiMax and Engenia are low-volatility formulations does not mean they are not still volatile. There are also more sensitive areas on the landscape these days and many of them represent high dollar investments like grapes and vegetables. Information transfer has changed dramatically in the two decades since Roundup Ready soybeans and Roundup Ultra -- every puckered up plant can be photographed and broadcast via social media with a click.

Unfortunately, those miraculous weed-free fields in the early days of Roundup Ready technology remain fixed in our memories. All you have to do is read the federal labels and the restrictions EPA bestowed on the new dicamba formulations to know using them this year will not be easy. The label stipulates no tank mixes, one nozzle, wind speed restrictions, a boom height that will be hard to achieve and sensitive downwind buffer rules that still have many baffled.

That's why you'll see us posting several stories in coming weeks that dig deep into the details of these federal label restrictions and what they mean to spray application procedures. We're calling the series "Dicamba Decisions" and it's designed not to condemn or criticize this technology, but to shed light on what it takes to manage it.

The Xtend technology is not the only new herbicide trait technology. Dow AgroSciences' Enlist Weed Control System recently received the registrations needed to commercialize in cotton. The 2,4-D system still needs some corn and soybean import approvals and the company is withholding full commercial launch until those are approved. GT Soybeans from Bayer and MS Technologies also waits in the wings. Each of these new technologies has very specific application procedures and differ from dicamba.

It is also important to understand that some states have made decisions to draft rules regarding dicamba that exceed the federal label. In Arkansas and Mississippi, for example, there are different wind speed limits and growers will be required to pass a test that shows they understand the label. Some manufacturers are offering online training courses.

Please use this time between now and spray season to get up to speed on your responsibilities when using this technology. EPA has granted a two-year conditional registration for these products. Farmers clamored for this technology and it is now in the hands of those that use it to safeguard its continued use. As University of Illinois weed specialist Aaron Hager has said: "A recommendation is a piece of advice you may forget, a restriction is on a label and it's the law."

This year, we have to do better.

Pamela Smith can be reached at

Follow her on Twitter @PamSmithDTN



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