The Issue: Pesticide Spray Drift and Dicamba.

As we have noted elsewhere in Science in the Media, since 1996, Monsanto has used Roundup as part of a larger business using genetically modified seeds for corn, soybeans, sugar beets, cotton, canola, and other crops that are glyphosate resistant. Thus, Roundup can be sprayed on entire fields once weeds emerge, ideally killing all plant life except for the crops grown from Monsanto’s patented Roundup Ready seeds.

The effect has left the farm landscape of states like Iowa a mostly sterile zone, except for genetically modified row crops, especially soybeans and corn. Plant biodiversity, including wildflowers, and the accompanying fauna, including pollinators, are in great decline.

With the introduction of Monsanto’s Roundup-resistant soybeans, the percentage of Roundup Ready soybeans planted in the U.S. has expanded from 7 percent in 1996 to 85 percent by 2004.

The promises of Roundup Ready soybeans—for which farmers are required to sign elaborate contracts, pay licensing fees and a premium for the technology, and face stiff penalties for saving seed—included better weed control with lower pesticide use, less labor in the fields, and improved yields.

Farmers growing Roundup Ready soybeans “use 2 to 5 times more herbicide than farmers growing other varieties.”  Nevertheless, as predicted for years, glyphosate-resistant superweeds have developed, upsetting Monsanto’s entire program of proprietary, genetically modified seeds and Roundup applications.

Now it’s on to the next pesticide.

Dicamba is the pesticide central to new crop strategies devised by agro-chemical giants Monsanto and BASF in response to the failings of Roundup on superweeds. The two corporations have collectively invested more than $1 billion in production facilities to flood the market with dicamba-based products.

In 2016, the EPA approved the use of new formulations of dicamba for “over-the-top” spraying of dicamba on soybean and cotton plants grown with seeds genetically modified to resist damage from dicamba. Monsanto’s Roundup Ready XtendBASF’s Engenia and DuPont’s FeXapan (used with Roundup Ready 2 Xtend soybeans and cotton)

“Glyphosate-resistant weeds are a serious and growing issue across the country,” said Chad Asmus, Technical Marketing Manager, BASF. “Engenia herbicide is part of a complete weed management program that starts with a residual herbicide and utilizes multiple, effective sites of action to control even the toughest weeds.”

Roundup Ready Xtend
Monsanto’s “Roundup Ready Xtend Crop System,” introduced in 2017

Or, as Monsanto more plainly says on its Roundup Ready Xtend Crop System website, “NEXT LEVEL WEED CONTROL IS HERE.”

The problem is dicamba is exceptionally potent, and in its debut year in 2017 as an over-the-top herbicide applied to row crops, pesticide drift has been an enormous problem, poisoning or killing everything else it lands on.


These are some of the news stories in 2017 that outline the problem with the new dicamba-based row crop systems:

Danny Hakim, “Monsanto’s new weed killer, dicamba, divides farmers,”  New York Times, September 21, 2017.

Since the initial introduction of Roundup and genetically modified roundup-resistant crop seeds, Farmers have been locked into a tough dilemma of constantly upgrading to the newest herbicide/crop technology or risking that their outdated plants be exposed to newer, harsher chemicals that will inevitably be sprayed by farmers in surrounding areas. Dicamba is the most recent example of this constant tension modern farmers face. This drive for technology is not only making it nearly impossible for farmers to keep up with the newest Monsanto release (they have close to a monopoly on seed technology) but it’s making it difficult for any plants to survive around farmland at all. Farmers describe trees around their crop land looking disintegrated, unrecognizable, because they have been exposed to drifting herbicides like dicamba.

Jared Kaufman, “Farmers claim drift problems persistent after two states banned herbicide dicamba,” Foodtank, September 2017

Dicamba was found by researchers at the University of Arkansas to remain volatile after sprayed for up to 36 hours. Volatility means potential for the sprayed herbicide to drift beyond the original spray location. This study is consistent with reports from farmers in over 12 states claiming that dicamba spray from neighboring farms killed or severely damaged their crop plants.  Although dicamba has been in use for decades to kill weeds before planting, this is the first time it has been released as a growing season herbicide with resistant seed analogues. New formulations of spray dicamba are supposed to be less volatile that earlier formulations, but problems remain. Farmers use older formulations without being aware that they are using the chemical with higher volatility. The new dicamba spray chemical was also only tested in laboratory setting before release, meaning that its volatility in field settings that include factors such as wind and heat that may increase drift potential was not tested before the formulation was sold.

Tom Polansek, “EPA to allow use of dicamba next year, but with safeguards,” St. Louis Post-Dispatch, September 19, 2017. 

The EPA is currently reviewing dicamba spray chemicals, with the goal of allowing their use in 2018. Though the chemical was linked to many reports of crop damage over the summer, the EPA is hopeful that there can be regulations that allow for its safe use. Individual states, like Arkansas, Missouri, and Alabama, are all working toward restrictions on dicamba use but the EPA wants to release their guidelines prior to state regulations. The EPA claims to be working closely with Monsanto and BASF, the manufacturers and distributors of dicamba, to determine how best to regulate the chemical while still allowing for its use.

Marcia Ishii-Eiteman, “Dicamba drift? This is on you Monsanto,” Huffington Post, September 8, 2017.  

This summer alone, Dicamba drift has damaged over three million acres of soybean crop land. Many farmers have begun calling on the EPA to regulate or even restrict use of the Dicamba herbicide. Monsanto, the company that makes both dicamba based herbicide chemicals and dicamba-resistant crops, claims the problem is with farmers’ treatment of the chemical and lack of buffer zones around sprayed land. Monsanto has historically had close to a monopoly on herbicides and their corresponding resistant crop seeds, particularly with their well-known herbicide Roundup, but many farmers argue that dicamba is a clear example that their monopoly is going too far. Farmers are urging both the USDA and EPA to increase restrictions on dicamba use, claiming that it isn’t their fault it is prone to spray drift. Farmers are also urging for more public testing of future herbicide products produced by Monsanto.

Caitlin Dewey, “This miracle weed killer was supposed to save farms. Instead, it’s devastating them,” Washington Post, August 29, 2017.

Farmers are locked in an arms race between ever-stronger weeds and ever-stronger weed killers.” Dicamba is the newest, and potentially the worst to date, example of this arms race that not only pits farmers against weeds and weed killers, but against the corporations that produce them. As weeds become stronger and more resistant to harsher herbicides, herbicides have to get stronger, and herbicide-resistant crops have to be developed before the weeds naturally develop resistance. It is a race against evolution, and Monsanto is winning. But that often means that farmers are losing. Corporations also often develop new herbicide technology faster that government regulators can keep up, meaning that harmful chemicals like Dicamba are placed on the market and used on millions of acres of cropland before agencies like the EPA have time to evaluate their impact. This leads to problems like the ones we are seeing now where chemicals are more volatile in live field settings than can be predicted in labs, but by the time farmers discover that, it’s already too late.

Mary Hightower, “Division of ag researchers find volatility in all dicamba formulations they tested,” University of Arkansas Division of Agriculture News, August 10, 2017. 

Researchers tested five different formulations of dicamba to see whether there is a difference in volatility between older and newer formulations. While some difference was observed, new chemicals should still be called volatile. Researchers noted the sensitivity of soybean plants, commonly used with dicamba, and noted that even small changes in the amount of dicamba drift could have a substantial impact on plants in surrounding fields, or even the plants that are being sprayed. They also pointed out that previous studies on dicamba tool place in isolated laboratory settings, meaning that they ignored important factors like wind and dust in showing range of drift or time of volatility. Equipment used to spray dicamba is also important, smaller spray nozzles and shorter booms reduced the amount of drift that occurred.

Dan Nosowitz, EPA-Approved dicamba is an airborne menace and some states are banning it. Modern Farmer, July 11, 2017. 

Dicamba resistant seeds, sold by Monsanto under the brand name Xtend, were released into market last year. Upon release, Monsanto also released a warning not to spray the incredibly volatile dicamba herbicide in areas where it may be likely to drift. Many farmers responded to the new release by criticizing Monsanto for releasing herbicide and resistant seeds without proving that they are safe and, in fact, recommending against their use after many farmers had already invested. Farmers were put in a tricky spot of needing to purchase and use the new Xtend brand seeds to protect themselves from dicamba drift, or risk using non-resistant seeds and having their plants die from exposure. Monsanto’s only response was to be careful in application. They went on to blame farmers for any problems with dicamba, saying that when applied correctly, there should be no problems.