GMO case study: Roundup Ready crops

Herbicide resistant crops in US (source: Colorado State University)

Herbicide resistant crops in US (source: Colorado State University)

If you walk down the aisle of any American grocery store, around four-fifths of the packaged food available for sale to you has some genetically engineered ingredients. And of those ingredients, most have been genetically engineered to be resistant to Roundup. So this particular trait is very pervasive, not only in our grocery aisles, but all over the American farmland: most of the corn, almost all of the soybean, most of the cotton is grown to be Roundup resistant. In a sense we are having the debate about whether to label GMO foods quite late; the barn door has been open for a while, the horse has not only exited the barn but is romping around the landscape making daisy chains.

In this particular case, it isn’t the genetically modified seeds that are the issue, but the behavior that those seeds incentivize. The crops have been made invulnerable to Roundup, so that that particular weed-killer can get squirted around with pretty much wild abandon. What does that do?


Roundup logo (source: Wikipedia)

Roundup logo (source: Wikipedia)

Glyphosate is a plant poison. It was developed by Monsanto in the 1970’s and, combined with other ingredients (some disclosed, some not) sold as a formulation called Roundup. As a herbicide, it was safer than the others that came before it. The earliest in the 1940’s was 2,4D which formed one half of the ingredients of the defoliant Agent Orange used in Vietnam. Then came Atrizine, which is known to be an endocrine disruptor, and is often found as a contaminant in drinking water.

Glyphosate was a blessing when it was discovered. It works by blocking plants from creating certain kinds of amino acids. Since humans and other animals do not have the ability to synthesize these amino acids in the first place (we must get them from plants), glyphosate simply does not have the power to harm us.

There was another reason why farmers must have rejoiced to have an herbicide like Roundup on their shelves; it is non-selective. A huge variety of plants, whether grasses, leafy plants, woody plants, or conifers, are affected by it. Stepping around on a lawn with Roundup-stained soles will in a few days turn those footsteps into brown patches.

The scientists also found that it generally sticks to the top few inches of soil  and doesn’t easily run off to pollute groundwater. Microbes are able to break it down while it is bound to soil. A miracle herbicide!

Safer but is it safe?

That is the theory. Reality is usually messier. For instance, given a big enough storm, the soil itself (with bound glyphosate) can run off into ground water, and there, microbes cannot break it down. Once in the water, a study showed that it induces changes in frogs by making them stressed as though there is a predator around, even when there isn’t.

Plus, all the studies that talk about the safety of glyphosate miss the point, because the Roundup formulation contains a long list of other ‘inactive’ ingredients that Monsanto is not required to reveal, that are actually more toxic.

A preservative in it — Proxel — can cause dermatitis. Roundup also contains a surfactant called POEA — this chemical allows Roundup to be properly wet, so that the plant can absorb it all the way to its roots — that has been shown to be toxic to fish. It also was found to kill human cells in a test tube, its power magnified by working in concert with glyphosate.

Glyphosate itself has been linked to non-Hodgkin’s lymphoma. Monsanto’s rejoinder to that study was basically that the association was weak, and that it proved correlation, not causation, ignoring the fact that while judging the toxicity of chemicals it is difficult to actually prove cause-and-effect without unethically exposing people to high levels of the stuff, just to see what happens.

Plus, one has to remember that while animals don’t create these amino acids, microbes do. So glyphosate has the obvious potential to harm good bacteria in our guts the same way in which it kills plants. In fact, a study found that glyphosate is implicated in celiac disease due to its impact on gut bacteria.

This factsheet from the Oregon state government is a good summary of harms from Roundup.

Despite all this, weed killers have their uses. Environmentalists, forest-management folks, people with the best of intentions, have used Roundup to remove invasive plants and preserve biodiversity. (There is no reason to use it on your ornamental lawn, however. None.) These folks, and farmers, have gotten by with a judicious application of herbicide where needed. Judicious, judicious, judicious, one must emphasize in the manner of realtors.

However, when Roundup Ready crops came on the market, judicious application of Roundup began to sound a little quaint.

Roundup Ready crops

Conventional crops are just as vulnerable to Roundup as any weeds might be. So farmers could not use it with impunity. They couldn’t use a ton of it or spray indiscriminately; for another thing, they couldn’t use it while their crops were growing, it had to be done before they have germinated. Since they didn’t have a magic bullet, they had to use a mix of weed management methods: a mix of herbicides, a mix of crops, and other ways of controlling weeds.

In the meantime, Monsanto’s patent on Roundup expired in 2000, which must have caused quite a bit of fretting among Monsanto’s business centers. They came up with a very ingenious new product that they could patent. They were able to create seeds of soybean, corn, cotton, etc., that weren’t affected by Roundup the way most plants are. How was this done?

It turns out that bacteria need to produce amino acids as well. But the enzyme they use for this purpose is different than the ones most plants use. Different enough that it doesn’t get affected by glyphosate, but similar enough that it can produce the needed amino acids. Scientists were able to take a gene from these bacteria that produces this slightly different enzyme to put into seeds to turn them into glyphosate tolerant crops.

It made the farmer’s life a lot easier, because they could spray Roundup all over without concern for the crops. It was Roundup and only Roundup, and a couple sprays all over did the job. Some called it agricultural heroin for farmers.

For Monsanto, this meant more sales of Roundup and a near-monopoly on sales of seeds.

For farmers, it meant convenience and certainty, at first. But, notice, they are subject to this rather pincer-like business practice of Monsanto — you have to buys seeds from the same company that sells you the spray, and neither can work without the other.

For consumers, it means that we are consuming a lot more herbicide. All samples of GMO soy were found to have residues of Roundup in a study published by Food Chemistry.

What does it mean for the environment? To examine this, we must forget about the marginal toxicities of Roundup that are the subject of endless debates and look squarely at what Roundup is advertised to do.

The missing monarchs

In the insect world the monarch butterfly is a bit of a prima donna. It is not only the showy good looks, but also how exacting it is in its needs. Eggs must be laid on a milkweed plant, because the emerging caterpillar will eat nothing else. Without it, the caterpillar will simply perish. Every year, monarchs migrate down from Canada to Mexico flying over the Midwest where they seek out milkweed. In recent years this population has dwindled down by 81%. The monarch is such a star that people noticed. Not only does it drive tourist business in Mexico, but is also the state insect for several American states.

Monarch caterpillar on milkweed (source: Wikimedia Commons)

Monarch caterpillar on milkweed (source: Wikimedia Commons)

Scientists have now found the cause to be the rampant spraying of glyphosate across farmlands in the Midwest. Milkweed happens to grow in those ignored areas that us humans don’t have much respect for — on the edges of farms, along highway shoulders. An edge of farmland that looks scrubby and pointless does not get the same respect as say a forest would. Since the advent of Roundup Ready crops, milkweed has declined by 58% with predictable devastation of the monarch population.

I want to emphasize that people only noticed the decline in the monarch population because of its glamour. There very well could be many other species that have been affected because of glyphosate use doing exactly what it is advertised to do — kill weeds.


When I’m pulling weeds in my garden I often find that some weeds have deviously designed themselves to escape me. One such is the dandelion. Its leaves lie flat to the ground and spread out, which makes it hard to get a grip under the plant and pull it. If you manage to, you realize that it is anchored to the ground by a thick ropy taproot with a grip of death. Then as I tug on the root, it breaks off easily, leaving a part of it still underground ready to spring up into a new rosette when I’m gone.

Dandelion (source:

Dandelion (source:

Weeds are called that because they are escape artists. They have developed traits that let them survive whatever weed management you might use on them. If it is a lawn that is often mowed, they might lie flat against the mower (again, like the dandelion). If you mostly get rid of them by pulling, they might give you a false sense of security by breaking off easily but leave underground bulbs behind (like Oxalis, Bermuda buttercup). This is why we are forced to use several tricks to adapt to their adaptations; some by pulling, some by letting loose caterpillars that might feed on them exclusively; some by solarization.

With Roundup, it seems, farmers were not this nimble. With active encouragement from Monsanto they came to depend entirely on spraying of glyphosate since the Roundup Ready crops came on the market. While glyphosate use grew a lot in the years since 1997, the use of other herbicides fell.

Well, that was nothing but an invitation to weeds to independently develop their own resistance to glyphosate. Those farms were basically sitting ducks.

Pigweed (source: Wikimedia Commons user Pompilid)

Pigweed (source: Wikimedia Commons user Pompilid)

Two such weeds — pigweed and waterhemp — have become huge problems in the cotton and soy farms of the Midwest. Because of these and others, farmers were forced to use even more glyphosate, based on advice from Monsanto’s scientists, as says this statement from farmer Troy Roush.

Monsanto’s business practices are culpable here. In their 1993 petition to the US government to deregulate the use of Roundup Ready soybean, they insisted that weeds developing resistance to it was “highly unlikely” (the 1993 petition, page 56), mostly because no weeds had become glyphosate-resistant until then. They assumed that there was something about glyphosate that made it hard for weeds to develop resistance; also since glyphosate does not hang around in the soil, they would not have the time. Were their scientists trying to delude the government, or were they deluded themselves?

Nature is nimbler than you think

This ought to be a lesson to both sides — those that insist that GMO is contrary to nature, and those that insisted (above) that nature could never pull off what Monstanto’s smart scientists had taken ten years of intensive research to do. The trait in question — resistance to glyphosate’s ability to block creation of amino acids.

Interestingly, the first discovery of nature’s glyphosate-resistant weeds did not happen in a corn or soy farm, but in the backyard of Monsanto’s chemical factory along the Mississippi river. There, in ditches where glyphosate residue was often discarded, plants had been fighting this particular enemy for a while. By the 1980’s some weeds had already developed resistance to glyphosate in Monsanto’s own backyard and were growing happily in the sludge. When the scientists bothered to look, they found examples of Roundup Ready genes made by nature in their own ditches that did the job far more effectively than the gene they had spent ten years developing.

Yes, nature was easily able to pull off creating resistance to glyphosate. It just needed a reason.


7 thoughts on “GMO case study: Roundup Ready crops

  1. This is an important issue that consumers need to be made aware of. it,s sad your labelling laws are not more comprehensive allowing consumers choice. I’m always worried when scientists (funded by vested interests) tell us that a particular product is safe when they have studied it’s behaviour for a year or two. I might feel reassured after a 25yrs or 50yrs, but how can they really know what impact it will have long term. Wind borne GM seed has certain ruined many certified organic farms in Australia.


    • I did hear about the contamination in Australia. Have to read more about it.
      Yes, since I haven’t been following the debate, I was surprised to learn that so many products on our shelves already have genetically engineered ingredients. A label would have helped.
      Although one could argue that since 80% of stuff would come with a GMO label people would cease being afraid of it.
      One could argue too that one should avoid packaged food for other reasons as well.


      • Food processing and labelling is such a huge issue! I made a decision years ago not to buy any products that contain canola (rapeseed) oil or corn syrup because of GM. We are fortunate that our food labelling laws require disclosure, but I suspect when ingredients/products are imported that labelling loopholes mean that it’s not perfect. Stating that products are GMO free has become a strong marketing tool.


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