The New Wave of Herbicide-Resistant Crops
On May 23, 2012, John Rowan, national president of Vietnam Veterans of America, sent a letter to President Barack Obama requesting his “immediate assistance in staying de-regulation of Dow AgroSciences much ballyhooed 2,4-D-resistant corn seed until an environmental impact study can be conducted and its subsequent results evaluated by scientists who are not affiliated with Dow AgroScience.”
Rowan is concerned about the use of the herbicide 2,4-D on 2,4-D-resistant–corn because it constituted half the ingredients in the defoliant Agent Orange used by the U.S. during the Vietnam War and is causing serious ailments in vets and Vietnamese civilians. Agent Orange was contaminated with dioxins, the most potent synthetic class of carcinogenic chemicals known, second only to radiation in potency as a carcinogen. Although most of the dioxins were from the 2,4,5-T half of Agent Orange, 2,4-D was also contaminated.
The deregulation, or approval for widespread planting, of 2,4-D-resistant corn and consequent increased use of the herbicide is relevant to Indiana, the fifth largest corn-producing state in the nation, according to Marti Crouch, a Bloomington biologist specializing in the interrelationships of agriculture and technology. She has recently focused on the environmental impacts of Roundup Ready crops (those resistant to Monsanto’s herbicide Roundup [glyphosate]) and the concomitant increased use of Roundup.
Crouch also works as a science consultant for groups that anticipate what the effects of new farming technologies will be and try to slow down or stop them if the technologies appear to be destructive. Currently she’s consulting for the Center for Food Safety, studying the science of 2,4-D-resistant corn, which has been genetically engineered by Dow AgroSciences, a wholly owned subsidiary of Dow Chemical, based in Indianapolis.
The upcoming approval of crops genetically engineered to withstand higher doses of 2,4-D was the topic of a talk Crouch gave titled “Going Backwards: What the New 2,4-D Resistant Crops Will Mean for Indiana’s Agriculture (and You)” at Green Drinks Bloomington on May 23.
Corn as it is grown in Indiana and the rest of the U.S. harms the environment in myriad ways, Crouch said. For example, a dead zone in the Gulf of Mexico has resulted from the use of fertilizer on crops including corn, according to a post on the U.S. Water News Online titled “Indiana among worst contributors to Gulf ‘dead zone.”
Researchers at Purdue University have shown that the pesticides used to treat corn seeds threaten honey bees, to which those pesticides are highly toxic. And herbicides used on corn are killing milkweed, which used to be common in corn fields. This loss of host plants, Crouch said, is contributing to the decline of monarch butterfly populations.
Corn is the No. 1 crop in the U.S., Crouch said, covering more than 90 million acres. One of every six acres of land is planted in corn in the Hoosier state. Thus, herbicides used on corn are an Indiana and U.S. issue.
“Anything that happens within a corn field,” Crouch said, “is going to have a disproportionate impact on the environment. Very few of us really know what’s going on in those fields, but we need to pay attention.”
To create 2,4-D-resistant corn, scientists at Dow Agrosciences have taken an enzyme from a soil bacterium that’s resistant to 2,4-D, Crouch said. The enzyme breaks down 2,4-D into its phenol. They then placed the gene with that enzyme into corn so the corn can break down 2,4-D, making it nontoxic to the corn.
2,4-D has been used in agriculture, including corn, since the 1940s. In fact, it was the first major synthetic herbicide and grew out of World War II chemical research. It’s the “iconic” herbicide, and Dow “was in there promoting herbicides right at the beginning,” Crouch said. It’s the third or fourth most widely used herbicide in the U.S. today.
Conventional corn isn’t completely resistant to 2,4-D, even though it’s in the grass family, and grasses are less susceptible than other plants. Thus, applying 2,4-D to control weeds in corn is a “crapshoot,” Crouch said. Sometimes corn does well after treatment with 2,4-D, and other times the yield suffers.
Last year less than 10 percent of corn was treated with 2,4-D. However, genetically engineering corn to be 2,4-D-resistant will mean “you can use more [2,4-D] more often, with less risk of injury,” Crouch said, and that will make 2,4-D more attractive to corn growers. It is estimated that there could be a 30-fold increase in 2,4-D application to corn if 2,4-D-resistant corn is planted widely.
Currently the U.S. Department of Agriculture (USDA) is engaged in determining whether it will approve Dow’s 2,4-D-resistant corn for unregulated planting Crouch said.
All genetically engineered plants have to undergo USDA’s process of evaluation for deregulation, Crouch said. The public comment period for 2,4-D-resistant corn ended in late April. USDA could make the approval decision by the end of the summer.
The rationale for developing 2,4-D-resistant corn is that weed control has become more difficult the last several years because most corn has been engineered to withstand Roundup, and weeds are becoming resistant to it, Crouch said. “Roundup Ready” technology – meaning that the crops genetically engineered to withstand Roundup could tolerate Roundup for weed control – was the first widely used herbicide-resistant technology, used first on soybeans and then cotton, corn and other crops. Corn engineered to withstand Roundup allows farmers to apply the herbicide over the tops of crops throughout the growing season without injuring them, Crouch said.
As a result of the huge increase in the amount of Roundup that was used with Roundup Ready crops, weeds became resistant. In fact, Crouch said, 13 types of weed have become resistant to Roundup in the last 15 years here in the U.S.
One of the weeds that has become resistant to Roundup is giant ragweed, which grows up to 15 feet tall and is so prevalent in northern Indiana farmland now that farmers joke about renaming their region the Giant Ragweed National Forest, Crouch said.
Another pernicious weed, Johnson grass, was the test subject when Roundup was invented. The herbicide killed the weed initially, but now some populations of Johnson grass have become resistant to it.
“Roundup Ready crops are losing their edge. What do you do in a situation like that?” Crouch asked. Her answer: “If you’re a biotech company, you take your favorite non-glyphosate herbicide and make a genetically engineered crop that can resist your herbicide.” The idea is not to use the new herbicide instead of Roundup but in addition to it.
For example, with Dow’s 2,4-D resistant corn, the rationale, Crouch said, is that Roundup-resistant weeds will be killed by the 2,4-D, and 2,4-D-resistant ones will be killed by Roundup.
To accomplish this goal Dow will perform “gene stacking,” by crossing corn with the Roundup Ready gene with corn that has their 2,4-D-resistance gene, Crouch said. Dow plans to sell an herbicide mixture, with both applied at their full rates, thus doubling the amount of herbicide per application as compared to Roundup Ready corn alone.
Other herbicide-resistant crops are on the horizon. There are 13 applications for deregulation of such crops before USDA, Crouch said.
There used to be a pesticide treadmill, Crouch said, using a pesticide, having weeds or insects become resistant, and then having to use a different pesticide. Today we have the threat of a genetic-engineering and pesticide treadmill, with new crops resistant to herbicides needing to be genetically engineered to replace previous genetically engineered crops and their herbicides to which weeds have become resistant.
“That’s the treadmill we’re about to step onto,” Crouch said, if 2,4-D-resistant corn is approved for deregulation. Soybeans, cotton and canola “resistant to a suite of different herbicides are in the wings,” she said.
As you might imagine, Crouch said, there is popular resistance to this treadmill scheme, and it continues the Indiana story.
One of the major organizations opposed to unregulated planting of 2,4-D-resistant corn is the Save Our Crops Coalition (SOCC), chaired by Steve Smith, Director of Agriculture for Red Gold of Indiana, a tomato processor. Many of SOCC’s members are from Indiana.
Tomatoes are one of the “specialty crops”, as are all fruits and vegetables, nuts, flowers and nursery plants. The term crop is generally limited to corn, soybeans, wheat, rice and cotton. Crops receive most of the farm subsidies from the Farm Bill. Specialty crops are supported much less.
“SOCC is concerned,” Crouch said, “that when corn is engineered to withstand 2,4-D, the increased amount of the herbicide used will drift in the direction of their tomatoes, grapes or other specialty crops and that the injuries will be severe enough that they will have economic damage – in fact, they might have to stop growing the specialty crop anywhere near corn.”
With 2,4-D, drift has two components. First, drift occurs when the crop is sprayed and droplets of the herbicide move offsite. Second, given the right weather conditions, the herbicide revolatilizes (evaporates) and moves off site in a cloud that can settle miles away.
In such cases, legal liability may be difficult to prove since it is hard to determine where the cloud came from or who produced it. Further, a farmer whose crops were injured may have trouble recovering damages if the herbicide was applied according to the manufacturer’s instructions. Thus, the ability to be compensated for injury to crops from 2,4-D becomes difficult, Crouch said. It is better to prevent drift in the first place.
SOCC has called for a full environmental impact statement and an EPA Science Advisory Panel to look into the drift effects of 2,4-D used with Dow’s 2,4-D-resistant corn.
“Perhaps because SOCC is not part of the usual environmental and organic farming critics of biotechnology, their concerns are getting a lot of press,” Crouch said.
Other opponents of 2,4-D-resistant corn, Crouch said, are some weed scientists, who are concerned about increased weed resistance. Dow AgroSciences claims crops won’t become resistant to both Roundup and 2,4-D applied together, “but weed scientists who have studied this issue think it’s very likely weeds will because so many plants are already resistant to glyphosate – these weeds only have to take one step to become resistant to 2,4-D as well. Today there are even some weeds that are resistant to five or seven herbicides. It’s similar to bacteria with multiple resistances to antibiotics.”
“Another major issue that concerns some weed scientists is that they feel this is a crossroads in agriculture right now,” Crouch said. Decisions are being made to either continue on the treadmill of applying herbicide after herbicide to their respective engineered crops or to at last take integrated weed management seriously. Integrated weed management uses a variety of means to control weeds, with judicious use of both tillage and chemicals, as well as cover cropping and crop rotations to keep weeds at a level that causes little economic harm.
Integrated pest management of insects has been adopted more widely than has weed management. Part of the problem is farmers’ culture and the ethic of a “clean” field. For example, Crouch said, if a giant ragweed is visible in a farmer’s soybean field, he or she becomes concerned the neighbors are going to think she or he is a “bad” farmer.
“You can’t see a couple of insects from the road, so farmers are willing to manage for a threshold level of insects that cause damage rather than complete eradication, but there’s an ethic of getting every last weed,” Crouch said. “Something about that has to change in order to reduce herbicide use.”
The last opposition groups are environmental organizations, health and consumer watchdogs, and food and sustainable-farming advocates, Crouch said. They’re concerned not only about drift but also about the human health effects of herbicide use and the effects on “nontarget organisms,” both plants and animals. Though herbicides target weeds, they enter the water and air.
We all know, Crouch said, about the health and environmental effects of Agent Orange. Health effects were attributed mainly to dioxin contaminants in 2,4,5-T, the other main herbicide in Agent Orange. However, 2,4-D was contaminated with dioxins, too. Dioxins in 2,4-D have been lowered since the 1960s but not eliminated, Crouch said. And 2,4-D itself has also been associated with some illnesses.
Scientists have established a link between 2,4-D exposure and some cancers more common in farmers, including non-Hodgkin lymphoma, Crouch said. Also, 2,4-D has been associated with Parkinson’s disease.
The effects of 2,4-D drift on wild species, particularly plants, are obvious, Crouch said. One can’t argue that 2,4-D isn’t toxic to plants. And since plants form the base of the ecosystem, changes in plant populations will affect animals that depend on them.
Most biodiversity in agricultural areas in Indiana is found near corn fields in hedgerows and riparian areas, which are especially vulnerable to drift, Crouch said. Even plants that are not killed may suffer nonlethal injuries such as male sterility from 2,4-D exposure. Impacts on endangered plants and animals are of particular concern.
“Dow,” Crouch said, “must have known that they’d get in trouble with 2,4-D-resistant corn over the issue of drift, so they developed a new formulation, called 2,4-D choline, that supposedly doesn’t drift and volatilize as much, though there haven’t been independent studies at the scale of commercial agriculture yet.” Use of that formulation on 2,4-D-resistant corn is now open for public comment at EPA, which has to approve it for use on Dow’s corn.
Dow plans to stipulate in its seed contracts with farmers that they’ll use only Dow’s formulation of 2,4-D, not one of the many less-expensive formulations. “There are many examples of noncompliance by some growers with those kinds of contractual agreements,” Crouch said.
Probably the only way, she said, Dow could be absolutely sure its own seed was always coupled with its own 2,4-D choline formulation would be if EPA would ban all the other 2,4-D formulations because they drift and volatilize more, making them unavailable in the marketplace – and that’s highly unlikely, Crouch said.
Other biotech companies are in line. Even Monsanto, maker of Roundup and Roundup Ready crops, is developing new herbicide-resistant crops, with its Dicamba-resistant soybeans ready for approval soon. Monsanto claims that it also will couple its seeds with a new lower-drift Dicamba herbicide formulation and will “stack” Dicamba resistance with its Roundup Ready corn and soybeans.
“Monopolies and bundling of seed and chemicals will occur even more than they do now with just the big guys in the game of herbicide-resistant crops,” Crouch said.
More than 150 organizations, including the Hoosier Environmental Council, Center for Biological Diversity, Pesticide Action Network North America, Food and Water Watch, the National Family Farm Coalition, the Center for Food Safety and the Natural Resources Defense Council have signed onto a group letter urging the USDA to deny Dow’s petition for deregulation of 2,4-D corn, at least until a complete environmental impact statement is completed. USDA received some 365,000 comments against approving 2,4-D corn last month. That, Crouch said, must be a record number of comments and reveals the intensity and diversity of the opposition.
She urged the audience to frequently check the Center for Food Safety website for updates and actions people can take.
When asked about the likelihood that 2,4-D-resistant corn would be deregulated, Crouch pointed out that USDA has never refused a petition for deregulation. Furthermore, the Obama administration is enthusiastic about agricultural biotechnology and is into fast-tracking the deregulation process. But she is optimistic that the public outpouring of concern about 2,4-D-resistant corn “will bend President Obama’s ear and sway the USDA to limit or deny approval.”
It’s important to diversify agriculture and make corn growing more sustainable, Crouch said. “I don’t think the 2,4-D-resistant crops and other herbicide-resistance systems that are coming along and that increase growers’ use of toxic chemicals are the way to move forward towards the goal of sustainability.”
Linda Greene can be reached at email@example.com.