More Herbicide, or More Innovative, Sustainable Farming?

, former senior scientist, Food and Environment | May 1, 2014, 2:38 pm EDT
Bookmark and Share

As another growing season begins, production agriculture is confronted with important choices. Among them is whether the farming community and policy makers will heed the clear warnings from herbicide-resistant weeds that industrial monoculture farming methods are not sustainable.

Palmer amaranth (aka pigweed) infests a soybean field. Photo: United Soybean Board/Flickr

Palmer amaranth (aka pigweed) infests a soybean field. Photo: United Soybean Board/Flickr

The epidemic of weeds that have developed resistance to glyphosate herbicide, used on glyphosate-resistant GMO crops, is an important symptom of the problems with our current farming system. Mismanagement of this weed control system has predictably led to glyphosate resistant weeds, and along with them, greatly increased herbicide use and harm to farms and the environment.

Some have noted that resistance to pesticides is nothing new. True. But the almost exclusive use of these GMO crops, and the glyphosate used with them, has led to exceptional evolutionary pressure for resistance to develop. For example, for most of the last decade, over 90 percent of soybeans grown in the US have been GMO glyphosate-resistant. This exacerbates weed resistance tendencies inherent in monocultures and the problems that come with them. The lack of regulations that could require methods to prevent or reduce the development of resistant weeds is also an important key to this problem. As a consequence, USDA is poised to approve the next generation of GMO herbicide resistant crops without adequate safeguards.

A New Direction for Innovative Weed Management is Sorely Needed

Monsanto, Dow and the rest of the biotech industry claim to develop advanced agricultural technology, but in fact their response to resistant weeds and greatly increased herbicide use is more of the same—new herbicide-resistant crops that are immune to older, nastier herbicides like 2,4-D, dicamba, and isoxaflutole. Yesterday, UCS released an animated video that illustrates the problems with GMO herbicide resistant crops, and challenges us to implement real, sustainable solutions that have multiple benefits for the environment and the economy.

Some have argued that even though herbicide use is higher than it would have been without herbicide-resistant crops, glyphosate is less harmful than other herbicides. This may be true for some types of harm. However, glyphosate use in these crops has likely caused substantial environmental harm already, in particular as a major contributor to the decimation of monarch butterfly populations. These defenders of glyphosate resistant crops also rarely mention the next generation GMO herbicide-resistant crops waiting in the wings, which will usher in greatly increased use of more harmful herbicides.

Industry’s Toothless Response

The dramatic increase in herbicide-resistant weeds has sounded an alarm among weed scientists and farmers, and has led to several meetings instigated by the USDA or the National Academy of Sciences. The response of farmers to the onslaught of resistance is probably the reason for an increase in the use of other herbicides as well as glyphosate in the past several years. This use of multiple herbicides may slow the advance of herbicide resistant weeds….temporarily.

This is because different herbicides work through different effects on the weeds, and it is harder, but still possible, for a weed to develop resistance to several of these mechanisms simultaneously.

The problem is that weeds resistant to multiple herbicides, including glyphosate, have developed already. And some serious weeds, like waterhemp in the Midwest, have separate populations resistant to glyphosate or 2,4-D, the latter one of the main herbicides to be used with the next generation of herbicide resistant crops (these weeds may also be somewhat resistant to dicamba, which is similar to 2,4-D). This means that these already resistant weeds need develop resistance to only one of these herbicides, not multiple herbicides, to evade the control from the new GMO crops. Alternatively, these separate singly-resistant populations may eventually mate, producing multiple herbicide resistance that way.

This also means that the industry solution—new herbicide resistant crops—may make them a lot of money in sales, but it will only forestall the problem. Because there are no new, broadly useful herbicides on the horizon, this could lead to a situation where farmers have few, and sometimes no effective herbicide solutions for these resistant weeds.

Real, Sustainable, Solutions

Herbicide resistant weeds are mostly a symptom of an inherently vulnerable and brittle agriculture system. Growing huge expanses of the same few crops over and over favors the buildup of pests, and using the same few means to control them is susceptible to resistance.

This means that the way we grow crops needs to change in more fundamental ways that increase diversity on the farm. These methods, collectively called agroecology, are not only more resilient to pest resistance, but also to climate change. They also can greatly reduce pollution from fertilizers, climate change emissions, and help maintain biodiversity, as we laid out in a recent UCS report on healthy farms.

Specifically applied to weed control, as described in another recent UCS report, agroecology can greatly reduce or eliminate the need for herbicides.

Recommendations by Monsanto, in addition to the predictable use of more herbicides, include approaches such as crop rotation and the use of cover crops. While that is clearly desirable as far as it goes, it does not go very far. Farmers overuse certain herbicides and GMO crops for reasons that are mostly sensible to them, such as convenience or labor reductions.

The same reasons will apply to the new GMO crops, unless measure are taken to prevent this. It has been generally known for a long time that alternating herbicides and other measures can slow resistance, but they were not widely adopted. Perhaps there will be some heightened awareness of a need to act under the current circumstances. But given the barriers and perverse incentives, such as subsidies for growing a limited number of crops, many farmers will not adopt the best practices. And I suspect the majority, if they adopt any, will only go as far as relying on the more familiar practice of using different herbicides. As noted above, that will not be enough.

Simply recommending that farmers adopt sustainable practices will fail because making these changes, even though better in the long run, can be challenging. It requires new ways of farming and thinking, investments in new equipment, new reliable information about how to make it work, and so on. There also needs to be disincentives to continue on the current path. This requires policies, support and incentives from sources such as the USDA, which are in short supply at best. Even merely using multiple herbicides usually results in higher costs or more labor than relying on herbicide resistant GMO crops alone.

The companies know this. So forgive my skepticism, but talk is cheap. Until there is real muscle behind creating real change in the way we farm, we will get more of the same. That change will only happen when enough pressure is brought to bear on policy makers and others, it will not come from those who have created the current problems in the first place.

Posted in: Food and Agriculture Tags: , , , , ,

Support from UCS members make work like this possible. Will you join us? Help UCS advance independent science for a healthy environment and a safer world.

Show Comments

Comment Policy

UCS welcomes comments that foster civil conversation and debate. To help maintain a healthy, respectful discussion, please focus comments on the issues, topics, and facts at hand, and refrain from personal attacks. Posts that are commercial, self-promotional, obscene, rude, or disruptive will be removed.

Please note that comments are open for two weeks following each blog post. UCS respects your privacy and will not display, lend, or sell your email address for any reason.


    One side of this debate we don’t hear much about – that needs a lot more scrutiny is how GMO’s and so-called “beneficial” insects being sold by the billions interact with each other and adapt to find new niches in the environment. There seems to be a wall of silence and inaction by the scientific and medical communities when symptoms of emerging, “new” plagues are evident and growing. Is this because of conflicts of interest? Liability that reaches to the very top of the regulatory chain? The impact to the economy? There is no reason for the scientific community to turn its back on such evidence, yet they consistently are – despite volumes and over a century of documented proof that parasitic infections often involve more than one type of parasite, harboring more than one type of bacteria or disease – and that they readily adapt to a changing environment – even having the ability to reproduce with difference resistance in different areas of the body of the same host! This issue truly needs some sunlight:

  • Steve Deibele

    Great article! Great discussions!

    I absolutely believe that some man-made technologies can lead to the best results when considering agriculture and the remaining environments shared by mankind and wildlife. However, identifying what “best results” are and how to “measure” the “best results” are virtually unsolvable problems for us in the (foreseeable) future. I also believe, absolutely, that the organic certification program principles will directly lead us to results that are very, very close to these “best results.”

    I have read that scientists have already been able to discover both heart disease and cancer in humanity from many centuries in the past. However, they have also discovered the incidence rate for heart disease and cancer were MUCH lower in these earlier centuries. Cancer was particularly uncommon. So-called cancer experts claim that 1 of every 3 American women will have at least one cancer diagnosis in her lifetime, and 1 of every 2 American men will have at least one cancer diagnosis in his lifetime. And the heart disease rate among Americans is also nothing less than shocking. These are glaring examples of health crises due to our modern lifestyles. As a people we have highly-compromised immune systems, and this results from poor exercise programs (more accurately, a lack of exercise programs), poor diets, and continual exposure to toxins through what we eat, what we breathe, and what we absorb through our skin. Exercise, diet and toxin exposure all play critical roles in our health.

    Getting back to agriculture, big agriculture is all about mechanization and removal of human labor. But many approaches along the way lead directly to producing foods that are toxin-laced and often were not healthy for food consumption anyway. American agriculture is heavily geared toward grain production, especially corn and soybeans. Corn and (most?) other grains are highly inflammatory. In typical serving sizes they have high glycemic loads – think of fattening, think of diabetes. These grains, especially corn, have high omega-6 fatty acid contents and low omega-3 fatty acid contents – think of heart disease and little (if any!?) protection against cancer. These grains are predominately produced with the use of a plethora of pesticides, and increasingly some pesticides are being used to kill crops a few days to a few weeks before harvest, leading to maximal toxin residues on these grains! (The rationale is that the early kill of the grain crops allows more in-field drying and less grain-bin drying, a net money saving for the grain producer.) Long story short, as a society we are producing that are inherently inferior for human health, and along the way we are often lacing our foods with non-negligible levels of toxins. And sometimes these toxin levels are extremely high on our foods.

    Without a doubt I support the ‘more innovative sustainable farming” approach as one of the solutions that the world needs. For environmental reasons as well as optimal human health and long-term economic sustainability I am really excited about permaculture principles which incorporate trees, shrubs, canes, forages (grasses, clovers, alfalfa, and other perennial pasture crops) and market gardens. These are based upon the savannah, arguably the most prolific producing landscape for mankind and wildlife alike. The innovative sustainable farming approaches generally emphasize diversity – multiple crops and multiple animal species – and synergy. These approaches are very careful to protect the soil biology (fungus, bacteria, yeasts, etc.) and the water (absorption, retention). Ground cover to lessen soil erosion and moderate the soil temperatures are also key.

    As consumers we can drive the direction of agriculture. Learn how your food is actually produced. Know who actually produced it. Vote with your dollars. Verify the stories of production that you are told. Buy locally. Reduce the grain inputs in your diet that offer little nutritional value but plenty of health concern. Good taste does not always equate to good foods.

  • Mike Hamblett

    Good discussion. It is very complex. As an outsider, I feel that farmers have been led into a bad place by industry/chemical mania. You are like rats in a giant experiment. I would love it if farming was returned to a more natural sustainable ways. But it will take amazing communication and resistance to start. Climate change may dictate new (older) strategies. Good luck to you.

  • Jeff Leonard

    Herbicide resistant weeds are a problem because weed pressure reduces yield. Yet when growers adopt glyphosate-resistant crops and milkweed is eradicated that is also bad? So you want growers to be able to control weeds except for the weeds you like? Milkweed is a weed that infested millions of agricultural acres that is difficult to control.(Counter to the implication of this essay, glyphosate doesn’t harm monarch butterflies directly, it is merely an effective herbicide against a common weed, milkweed.) To play Devil’s advocate, don’t you think pigweed also has its attendant biome, perhaps some weevil or mite that is also threatened when pigweed is eliminated? So glyphosate-resistant pigweed is a good thing for those animals. Not as aesthetically pleasing as a Monarch I guess? Will we require farmers to grow some weeds and not others? Who gets to decide which weeds farmers have to tolerate? Here is a solution to your provocative suggestion, set aside milkweed conservation areas similar to what the Mexican government has done for the Monarch butterflies on their end.
    I have nothing against butterflies, weevils, weeds, or mites. I don’t like misleading disingenuous arguments, especially by people who know they are making them.

    • Doug Gurian-Sherman

      Hi Jeff,

      You wrote “Herbicide resistant weeds are a problem because weed pressure reduces yield.” True. But that problem is also a lot harder to control when herbicide effectiveness is squandered by mismanagement, as with glyphosate. Current industrial agriculture is also a kind of structural mismanagement because it unnecessarily increases pest populations and therefore the likelihood of resistance. It is also more of a problem when a few methods are over-relied upon, and weeds develop resistance (to herbicide) or adapt to tillage, and so on. That is one of the reasons we advocate for diversified farming systems.

      You seem to be focusing on one aspect of this blog post, and ignoring the rest, and especially the overall context that it provides. First, let me ask you a question. Do you think that glyphosate use on roundup ready crops has been well managed? This is a main point of this blog post. It is a highly useful herbicide, and its value has been greatly degraded by mismanagement. Most weed scientists I know largely agree with this. I cite a couple of them in the links.

      No, I am not suggesting that farmers should not manage weeds, I am saying that they need to do it more sustainably. Weeds do not have to be eradicated, but they do need to be controlled well enough to keep them below the economic threshold, and to keep the weed seedbank from building up. I don’t think that there is anything in this post that suggests that weeds should not be managed. But maybe I am missing something.

      And yes, providing uncultivated habitat for monarchs, natural pest enemies, pollinators, and so on is very important, and one of our recommendation. Please read the short report that I wrote linked in the second paragraph in the “Real, Sustainable, Solutions” section (also here: ). This is one of our recommendation for more sustainable farming systems. However, it should not simply be a few areas, such as the Mexican example. That may work for monarchs, but not for the ecosystem services provided by many beneficial arthropods and other organisms. Most research shows that uncultivated areas within about 1 to 3 km of farm fields is best for that (e.g see the work of Tscharntke’s lab and others). But providing a diverse farming landscape is not going to happen on its own, apparently. That is why we advocate for policies to facilitate this.

      You are inferring that the blog post suggests that glyphosate directly harm monarchs. It says nothing of the sort. All anyone needs to do, to get more information about this, is access the link I provided, which makes this clear. That’s what links are for!

      Also, landscape ecology and population genetics is showing more and more that diversity on the farm (or in farm fields) is also important. Please see the work of Daily’s lab at Stanford, Vandermeer, Perfecto and others at U Mich. and many others. The scorched earth “land sparing” approach that you seem to suggest within crop fields is less and less supported by the most recent advances in ecology. The plant diversity does not have to come from weeds (e.g. cover crops, diverse crop rotations and so on can contribute), but it is important.