More Herbicide, or More Innovative, Sustainable Farming?

May 1, 2014 | 2:38 pm
Doug Gurian-Sherman
Former contributor

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.