Monday, July 27, 2020

Roundup is the Monsanto trade name for the isopropylamine salt of glyphosate, and it is also known to chemists as N-(phosphonomethyl)glycine. As organic compounds go, it is not a complex molecule.

Diagram of a molecule of Roundup
Chemical structure of glyphosate

The chemical is a broad-spectrum herbicide, meaning it can kill a lot of plant species. It’s been especially effective on annual grasses and broadleaf weeds that have been the bane of farmers since the dawn of agriculture. It was first synthesized by the Monsanto chemist John Franz and his team in 1970, and he received a $5 bonus for obtaining a patent for the chemical. Franz was a very distinguished scientist, and as far as I know, is still alive.

Glyphosate became one of the most important chemicals in human history when other Monsanto scientists were able to genetically modify annual crops in ways that left them invulnerable to the herbicide. It quickly became the dream chemical for agriculture, annihilating everything in its path that didn’t have the DNA antidote that was inserted into canola, alfalfa, cotton, sorghum, wheat, sugar beets, and most importantly for Iowa, corn and soybeans. Roundup “ready” soybeans were developed in 1996, and farmers loved this weed control formula so much that by 2005, an astounding 87% of all U.S. soy contained the magic genes. In fact, farmers were so head-over-heels for Roundup, they loved it to death, as we shall see.

Now let me say at this point that I’m not, nor have I ever been, a Roundup hater. Firstly, the stuff was safer and easier to use, and seemed to be less toxic to humans and animals, than many of the older herbicides it displaced. Secondly, it very likely did have some peripheral environmental benefits because it reduced the need for weed control tillage, which reduced erosion. On the other hand, it was also so effective that it possibly contributed to the decline of milkweed which of course is necessary for the life cycle of the monarch butterfly. But on the whole, my view on Roundup/glyphosate has always been that if you’re going to insist on having border-to-border corn and soy carpeting, you might as well Scotchgard it with Roundup.

But alas, it was inevitable that the law was going to catch up to Glyphosate and throw it in the hoosegow. The law of natural selection, that is.

It turns out that in nature, it’s damn hard to kill every single individual of a species unless you eradicate its habitat. Any one or pair of individuals that survives an attempted murder by poisoning is going to pass on that skill to its offspring. And in the case of problem weeds, there are A LOT of offspring. One pigweed plant (Palmer Amaranth) can produce a million seeds. If only 0.01% of the seeds have Roundup resistant DNA, that leaves 100 potential plants producing 1 million seeds each the following year.

Soybean field with a lot of weeds
Soybean field filled with Roundup-resistant pigweed. Image credit: No-till


Weed resistance was hastened by starry-eyed farmers whose over-reliance on glyphosate was, in the words of USDA researchers, “the primary factor underlying the evolution of GR (glyphosate resistant) weeds” (1). The fate of GMO soybeans was and is more closely tied to glyphosate than is corn; corn develops an early canopy and thus does a better job of depriving sunlight to growing weeds.

Enter Dicamba

Dicamba (3,6-dichloro-2-methoxybenzoic acid) has been around longer than glyphosate (depending on the source, it was discovered sometime between 1942 and 1958) and registered as an herbicide in the U.S. in 1962 (2). If like me you remember seeing Banvel commercials during halftime of the girls’ state basketball tournament TV broadcast, well, that was dicamba. Until recently, dicamba was used mainly to kill broadleaf weeds in corn, and it’s always been known that it was a no-no around soybean, which of course is a broadleaf. But with Roundup facing a life sentence in Evolution Prison, the cowboys and cowgirls at Monsanto developed a soybean variety genetically modified to resist dicamba’s killing action. EPA approved the technology in 2016, and thus began a rodeo that continues to this day.

Diagram of a molecule of Dicamba
Chemical structure of Dicamba.

The problem with dicamba is that it likes to ride the range, especially on hot and windy days. Roundup is like a plow horse compared to this wild mustang. And ride the range it did. Almost immediately, dicamba users started killing or damaging their neighbors’ Roundup-ready and organic soybeans, peaches, grapes, tomatoes and who knows what all. Missouri and Arkansas banned dicamba in 2017 and lawsuits began to fly. Farmers elsewhere felt compelled to adopt the technology just so their crop wouldn’t be at the mercy of their neighbors’ dicamba. An attempt at herd immunity of sorts. If you can’t count on your neighbor to stop community spread, then I guess you have to resort to drastic measures.

Which brings us to 2020. On June 3, EPA cancelled the registration for three dicamba formulations because those ponies wouldn’t stay in the corral. Pretty much everybody had growing soybeans in the field by then and a lot of farmers were ready to spray dicamba onto them as a post-emergent herbicide. Having 10s or 100s of thousands of dollars of seeds in the ground, with potentially no ability to spray weed killer on the crop, put a lot of shorts in a bunch. Even though most states said they wouldn’t enforce the ban, farmers all over Iowa went rogue and started applying the stuff in hot and windy conditions. I think you can probably guess what happened, but if you want the details, go to (3).

Two things especially bothered me about this whole mess. The first was the kneejerk reaction to assign the calamity to the weather, and not to farmer decisions or production system vulnerabilities or an economic framework that compels individuals to put their own self-interest ahead of their neighbors’ and the environment. Where have I heard that before? Time after time after maddening time, we hear our water quality problems are not because of our farming system, its practitioners, and its enablers, but rather the weather. Now this.

One commodity organization went so far as to say that the dicamba situation was the result of a “perfect storm” of weather conditions (4). “There were poor weather conditions during application and then hot, dry conditions. It’s tough to pinpoint the real culprit.” Seriously? Is personal responsibility not part of the equation here? Here’s the rub: everyone’s responsible so no one is responsible. This is the same exact rationalization that drives water pollution in our state.

Am I crazy to ask this question: When will farmers and the industry in general ever take responsibility for the negative consequences that happen beyond the field? It’s pretty clear the “feed the world” virtue signaling is designed, at least in part, to excuse the environmental wreckage produced by the system.

The second thing that motivated me to write this was a new term (for me) I read about in (3) and (4): atmospheric loading. Loading is a term we frequently use in hydrology to describe the mass of a pollutant being transported by a stream. Here is what it means in the context of dicamba drift (3): “Atmospheric loading refers to so much dicamba moving into the atmosphere that it is difficult, if not impossible, to identify the specific application that resulted in injury to a field. This is what appears to have occurred across much of Iowa in 2020.”

Like Roundup, dicamba is not particularly toxic to human beings. That does not mean there is zero risk connected to exposures. With the smelly chemicals in manure regularly riding the wind into the center of Iowa’s biggest cities, do we not have to consider the idea that just about every Iowan could have been breathing in some measurable amount of dicamba this summer? I challenge you to find any discussion about this from any of the Ag advocacy organizations, or from our agencies charged with serving all Iowans, and not just the 2% of us that farm.

So how to finish. Can we rely on producers to voluntarily fix our water quality problems, when they clearly have a brazen disregard for their own farmer neighbors? Count me as skeptical. From where I sit, this seems to be an industry that is drunk on propaganda, public subsidies, and political power, and that has a contempt for the environmental objectives of its neighbors and customers.

This is not sustainable.


  1. Livingston et al. The Economics of Glyphosate Resistance Management in Corn and Soybean Production.
  3. Dicamba 2020: What went wrong in Iowa?