Resistant Weeds According to Monsanto—Less than Half the Story

March 14, 2012 | 2:55 pm
Doug Gurian-Sherman
Former contributor

The harm to agriculture from pests that have developed resistance to the premier products of the biotech industry—crops containing Bt insect toxins or immune to the herbicide Roundup (containing glyphosate)—has been receiving well justified attention recently. The problems resulting from this rising tide of resistance are serious, from loss of conservation tillage that preserves soil fertility, to increased use of older, more toxic herbicides, and greater use of insecticides. Herbicide resistant weeds in particular, now infesting millions of acres and spreading like a rash, are having real impact on farmers.

Spraying pesticide onto apple trees. USDA photo by Keith Weller.

But pest resistance also raises important questions about the harmful influence of the biotech industry over regulators. It is not incidental that resistance is rapidly increasing to pesticides used on GE crops. It is due in large part to the unprecedented use of the herbicide glyphosate on these crops, and the high use of Bt, which drives pest resistance. But resistance is is also due to bad policies that are the result, in part, of regulators listening too closely to industry.

In a post about increasing insect resistance to Bt, Dan Charles covers some of this important back story about these crops. But a recent NPR post by Charles on herbicide resistant weeds leaves out some of the important reasons why we are facing these problems. That post briefly revisits the history of weed resistance to glyphosate herbicide. Unfortunately it gives a one-sided version of what has occurred, relying solely on Monsanto sources to explain why the company got it so wrong when they predicted that weeds were highly unlikely to develop resistance to glyphosate.

So let’s fill in a few of the blanks.

First, to hear Monsanto interviewees tell it, one would think that there was unanimity among scientists at the time that resistance was as unlikely as the sun failing to shine.

To the contrary, weed scientists like Stephen Powles and colleagues noted back in 1998—two years before the first resistant weeds appeared in glyphosate-tolerant crops—that precautions should be taken to prevent glyphosate resistance. Powles and his colleagues wrote that “It would be prudent to accept that resistance can occur to this highly valuable herbicide and to encourage glyphosate use patterns within integrated strategies that do not impose a strong selection pressure for resistance.”

Industry Roadblocks

The reasons why Powles’ recommendations were not enacted are complicated. The Environmental Protection Agency (EPA) has been hesitant about requiring resistance management. But it did so for Bt crops with considerable success, because it considered Bt to be a special social good. Weed scientists, though, have a similar view of glyphosate, with some calling it a once in a century chemical.

EPA’s reticence does not prevent the industry from proactively preserving useful chemicals, and it could be argued that it would be in their interest to maintain sales of these products as long as possible. But all means for reducing resistance in weeds involve using less of a herbicide now, and more of other types of weed control, and to sacrifice some short-term profit for longer-term sustainability. And that is something companies such as Monsanto or DuPont don’t like to do. Companies discount the future value of products compared to current value and profits. For example, future sales are often reduced by competitors coming into the market with their own products. So companies view this as a “bird in the hand is worth two in the bush” situation. Using sustainable practices also does not consider the pressure for high short-term profits by publicly held companies.

Monsanto’s efforts over the years have actually been just the opposite of good stewardship and the sustainable use of glyphosate. It has actively argued, for example through advertisements to farmers, to keep the herbicide spray nozzles wide open rather than advocating practices that could have forestalled or reduced the rise of resistant weeds. Because of this, the company was taken to task by numerous weed scientists.

This is a crucial piece of the story, because it demonstrates one more reason why we need effective and strong regulatory policies to protect the public good. And why we need to listen less to companies and more to independent scientists.

Charles’ story ends by quoting his Monsanto sources saying that even if resistance may have been predictable (it was!), perhaps nothing could have been done about it. This ignores the largely successful resistance management of Bt under the direction of U.S. EPA, which could have served, very broadly, as a model for glyphosate-resistant crops. EPA even had an internal process to develop a voluntary resistance management system for pesticides that was ultimately scuttled by industry. It also ignores the pleadings of weed scientists over the years to take actions, which were well known, to slow resistance. Although there have been some serious failings with the program for Bt, such as poor compliance or EPA caving in to industry requests for a watered-down program, scientists credit it with delaying or preventing resistance of several insect pests.

Protecting Sales Instead of the Public Good

The best resistance management involves using long crop rotations, cover crops, mulches, and similar practices, along with minimal use of pesticides where needed. This greatly reduces pest numbers, is highly productive, and can be economically successful. These practices are being advocated more and more by mainstream scientists.

But you won’t hear this discussed by the Monsanto employees interviewed by Charles. These ecologically sound practices would, by design, drastically reduce amount of pesticides used. So these practices would work directly against the narrow interests of companies like Monsanto, DuPont, Syngenta, or Bayer, that dominate the pesticide and GE seed industries, and wield undue influence over regulators.

Agroecological farming might also threaten the economic viability of genetic engineering. Development of an engineered crop trait is very expensive, about $136 million on average according to a recent industry report. That is one reason why most GE crops so far are big-acreage row crops like corn, soybeans, and cotton. But the value of many of these traits would be greatly reduced when used in truly sustainable agroecological systems, because pest infestations would be much lower and cause much less damage. It would be hard for companies to charge farmers the very high prices for seed they do now, because they would have less value where pests are less of a problem. And without those high prices, it is unclear whether the companies could afford to develop these seeds.