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June 17, 2015

Special report: the war on weeds

  • Special report: the war on weeds
  • Special report: the war on weeds
  • Special report: the war on weeds

Vermont Secretary of Agriculture Chuck Ross.

By John Herrick, VTDigger.org

On a busy street corner outside the Rutland farmers’ market, where local vendors sell cheeses, meats and spring vegetables, about a dozen residents recently raised signs to protest the use of weed-killing herbicides across the United States, especially Monsanto’s herbicide Roundup.

“They are poisoning the earth. We are poisoning the water,” said Lisa Sheridan, 52, of West Rutland, who was dressed in a pesticide applicator suit holding a spray bottle and an ear of corn. She considers herself poor and receives disability benefits, but she said she eats only organic foods due to a fear of pesticide contamination.

“Everybody is eating it. Our food supply is in peril. Our soil is in peril. Our water is in peril,” she said.

Most conventional Vermont dairy farmers this spring sprayed their fields with glyphosate, a weed killer that is gaining popularity among dairy farmers who grow corn to feed their cows. On fields where weeds and grass are brown, many farmers have already sprayed the herbicide this year and will likely spray again.

According to state data, nearly all of the corn grown in Vermont is genetically engineered to survive the application of pesticides. Over the past decade, farmers who plant “Roundup Ready” corn have increasingly turned to glyphosate, the active ingredient in Monsanto’s Roundup, to kill a variety of weeds that take nutrients, water and sunlight away from corn, which can affect yields.

In 2013, Vermont farmers and chemical applicators purchased five times more glyphosate than they did a decade ago, according to new data requested from the Agency of Agriculture.

Glyphosate is preferred among farmers, who say it’s among the least toxic on the market, but strong enough to stunt weed growth. State regulators considered the chemical safe enough for farmers to spray without a license. (Applicators of all other herbicides need a license.)

But glyphosate is now being criticized for its potential impact on the environment and human health. This year, an agency of the World Health Organization found that glyphosate is a probable human carcinogen. The chemical can cause kidney damage and reproductive issues, according to federal regulators. Other research indicates glyphosate is an endocrine disruptor.

Monsanto officials say regulatory agencies and experts across the world maintain the chemical, when used according to the label instructions, is not carcinogenic. The Environmental Protection Agency agrees, but is reviewing the chemical’s toxicity. Toxicologists have concluded that the original Roundup brand herbicide does not cause adverse effects on development, reproduction or endocrine systems in humans and other mammals.

Vermont was the first state in the nation to require foods with genetically engineered ingredients to be labeled for consumer choice.

Industry proponents have maintained that genetically engineered corn would mitigate the need for more pesticides. Instead, the opposite has proved true. Farmers are using six times more glyphosate now than they did in 1999.

With the proliferation of glyphosate, some fear the chemical could contaminate water supplies in addition to the foods they are sprayed upon. The state is not required to monitor drinking water for glyphosate due to a federal waiver.

Safer solution

Many agronomists and farmers, however, say the herbicide, which was first introduced commercially by Monsanto in 1974, is replacing more toxic chemicals that are likely to flow off fields or leach through the soil into groundwater, such as atrazine, which the EPA says can cause cancer with long-term exposure. They say Roundup Ready corn also reduces insecticide use because the corn is engineered to kill pests when eaten — although most seeds are coated with insecticides as well.

“We may have increased the use of glyphosate but it’s a safer product,” said Jeff Carter, a University of Vermont Extension assistant professor in Middlebury. “I personally do think it’s the lesser of two evils if it’s used correctly.”

According to the EPA, long-term exposure to atrazine can cause cancer, cardiovascular damage, muscle degeneration and weight loss. The EPA maximum concentration limit for atrazine in drinking water is 3 parts per billion.

Since 2002, there have been more than two dozen cases in which atrazine has been detected in Vermont drinking water supplies serving thousands of people at levels as high as 0.44 parts per billion, according to the Department of Environmental Conservation. Locations include Alburgh, Londonderry, Manchester, Middlebury, South Hero and Swanton.

The EPA says glyphosate does not cause cancer, but can cause kidney damage.

Chuck Ross, secretary of Agriculture, Food and Markets, said there is no formal policy initiative underway to reduce pesticide use in Vermont. But he said it is something the agency is interested in. There will be a debate in the scientific community about the health impacts of glyphosate, he said, and that debate needs to “settle out” before policy actions are taken.

He is not concerned that nearly all corn growing in Vermont is genetically engineered.

Pesticides in Vermont’s modern dairy system

Eric Clifford of the Clifford Farm in Starksboro milks 200 cows. He grows grass and corn silage on his 500-acre farm to feed his cows. On a gray morning in May, he was rushing to plant corn before rain arrived. Carrying a 12-ounce container of chocolate milk, he watched his cows eat a mix of feed about 75 percent corn silage and 25 percent alfalfa.

“Every day that truck leaves there’s milk we’re producing that’s feeding people,” Clifford said. “[We’re] feeding people and taking care of the environment.”

The farm has been experimenting with cover cropping, a technique where farmers plant a winter crop to hold down soil and prevent soil runoff into the water, he said. This year, one section of his field was brown where he had planted winter rye before spraying it with a quart of glyphosate. He already planted corn while the winter rye was still decaying.

“Ultimately with cover cropping you can, under the right scenario, get by with less,” Clifford said. But, he added, “We use Roundup to kill cover crops and we are nearing the time period where we would use, perhaps, other herbicides.”

Some agronomists, however, say cover cropping is among the reasons why farmers are using more glyphosate. It can be applied to kill the cover crop, and corn can be planted within days after the application. Because of that and other reasons, such as price, glyphosate has been on the rise in Vermont.

In 2013, farmers purchased 17,730 pounds of glyphosate, up six times from 1999 levels when farmers purchased 2,851 pounds, according to the most recent data available, provided by the Agency of Agriculture upon request. The data published on the agency’s website has been inaccurate for years, state officials say. The Agency of Agriculture, which regulates pesticides and monitors for surface and groundwater contamination, does not have electronic records for the last five years due to a delayed computer system overhaul that began about five years ago. All handwritten data is kept on paper index cards in a metal box inside the Agency of Agriculture office in Montpelier. A full dataset is still unavailable.

But agronomists say glyphosate, unlike atrazine, binds to soil and plants. It also becomes nontoxic in days. Atrazine can enter groundwater and drinking water and can take months to more than a year to become nontoxic, especially in cool water. But research indicates that glyphosate can leave the field as well.

“It moves around more than they thought it would,” said William Battaglin, a research hydrologist with the U.S. Geological Survey.

Battaglin was one of the authors of a 2014 study that found frequent traces of glyphosate in streams, rivers, wastewater treatment plant outflows and ditches sampled across 38 states. The study did not include Vermont. He said glyphosate does bind strongly to soil particles, but it can still make its way into the water when it washes from fields. He said 90 percent of the glyphosate stays on the field and eventually degrades on the soil or plant.

Some agronomists say farmers should rotate pesticides in order to avoid creating herbicide-resistant weeds. Redroot pigweed and common lambsquarters are found in Vermont and are resistant to atrazine.

“It’s pretty easy to see that resistance,” said Daniel Hudson, a University of Vermont Extension assistant professor who works in the Northeast Kingdom and Connecticut River watershed as an agronomist and nutrient management specialist. “If people know that they have resistance to a particular herbicide, they are going to try to find a product that will cover as many weeds as they can.”

But some farmers say the state should be phasing out pesticides, not changing the type that is used.

“These are toxic chemicals,” said Will Allen, of the Cedar Circle Farm, an organic vegetable and fruit farm in East Thetford. “That’s what most of our cows are eating in Vermont.”

Asked whether glyphosate is better than atrazine, the second most widely used herbicide in Vermont, Allen said the industry has for years said new chemicals are replacing worse chemicals.

“Atrazine is already banned in the EU [Europe]. Probably within a year glyphosate will be banned,” he said.

Photo by John Herrick/VTDigger

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