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As Farmers Plant Cover Crops To Reduce Runoff, Report Says They Also Use More Herbicides

A murky brook under a road bridge with grassy banks.
Nat Shambaugh, Courtesy
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A recent study found pesticide levels in Franklin County's Jewett Brook that were high enough to kill aquatic life. A retired chemist for the Agency of Agriculture says Vermont needs to do more to track and regulate pesticide use in the state.

A new report by a retired state scientist shows the apparent unintended consequence of the successful push by dairy farmers to reduce nutrient runoff into Lake Champlain.

Farmers reduce runoff by planting their corn fields with cover crops, which they then kill annually with herbicides. The report documents an increase in herbicides applied on the land and potentially running into Lake Champlain.

The report also questions whether the state agriculture agency is following its own policy to reduce pesticide use.

The report was discussed at a January meeting of the Lake Champlain Citizens Advisory Committee – which advises the Legislature on lake water quality issues. Committee members were surprised by the findings.

“My gosh, when I read and hear about the amounts of herbicides and pesticides that are being put into the ground in Vermont, I’m stunned,” said Bill Howland, a member of the advisory committee and former director of the Lake Champlain Basin Program, a federally funded effort aimed at protecting and restoring the lake. Howland has worked on lake environmental issues for decades.

“And I knew it was bad,” he said. “I’ve been living this life a long time.”

"When I read and hear about the amounts of herbicides and pesticides that are being put into the ground in Vermont, I'm stunned." - Bill Howland, member, Lake Champlain Citizens Advisory Committee

State data show 35,000 pounds of the herbicide glyphosate — known widely by its brand name, Roundup — is spread in Vermont annually. That’s up from virtually none in the early 2000s. It’s the herbicide of choice for farmers who plant corn that’s been engineered to resist glyphosate’s plant-killing properties.

As herbicides go, glyphosate is considered one of the more benign options, although that view has changed recently, now that its manufacturer has agreed to pay $2 billion to settle claims from people who blame their cancer on exposure to the chemical. 

Still, glyphosate breaks down quickly after it’s applied, especially when compared to its predecessor atrazine, an herbicide that was used widely on corn fields for decades. Atrazine persists in the environment and is a known carcinogen.

Cary Giguere, the state agriculture agency official in charge of overseeing pesticide regulation in Vermont, says the genetically modified, herbicide resistant corn was supposed to allow farmers to trade one family of particularly nasty chemicals for another more modern one as they adopted cover cropping.

“We’re basically switching chemistries from soil-sterilant corn herbicides to glyphosate,” he told the advisory committee.

But the data also shows that hasn’t happened. Atrazine is still widely used in Vermont. And that concerns Nat Shambaugh, who’s dedicated his professional career to tracking pesticides in Vermont’s environment. He’s a retired chemist who worked for the Agency of Agriculture, Food and Markets on water monitoring and pesticide regulation.

Shambaugh said state data from 2007 to 2018 show the use of both glyphosate and atrazine have increased. In fact, farmers are dumping 30,000 more pounds of atrazine on fields in Vermont.

corn-atrazine-glyphosate-use-vermont-2007-2018-shambaugh-vpr-courtesy-20210209.JPG
Credit Nathanial Shambaugh, Courtesy
According to data from the Vermont Agency of Agriculture, Food and Markets, combined use of the pesticides atrazine and glyphosate has increased in Vermont substantially since 2007.

“Glyphosate use increased to 30,000 pounds per year. Atrazine use at the same time went from 50,000 pounds-a-year, to 80,000 pounds-a-year,” he said. “So it has increased by 30,000 pounds as well. Even though one of the main reasons for introducing RoundUp Ready [genetically modified] corn was to eliminate or minimize atrazine use, it obviously hasn’t succeeded at that.”

Shambaugh is not exactly a government whistleblower, because he’s retired from the agency of agriculture. Yet he does offer a polite but firm criticism of the bureaucracy where he was an insider for decades. He argues that this failure to reduce pesticide runoff is a problem for both the potential health of Vermont's waterways and for the way the state approaches pesticide regulation.

First, he said the state actually knows very little about pesticide run-off into the lake and its tributaries. Shambaugh said the state has lots of data on nutrient run-off – the phosphorus that fuels the lake's toxic algae blooms. The state needs a similar monitoring effort to track herbicides, he said.

“We should be paying more attention to what else is washing off with nutrients,” he said. “It’s a little bit of tunnel vision to think about just nutrients running off the fields.”

Second, Shambaugh says the state has failed to follow its own policy that’s supposed to limit overall pesticide use. This policy, called “integrated pest management” was embraced by the state in the early 1990s. It’s aimed at getting farmers and others who routinely use pesticides – such as golf courses and railroads – to apply them only when necessary.

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But he says the state has allowed railroads to increase pesticide use. And the agency allows farms to use corn seed coated with chemicals known as neonicotinoids. The treatment makes the whole plant toxic, including its pollen.

The chemicals can kill honey bees and other pollinators. Shambaugh says allowing the use of these neonicotinoids goes against the spirit of the state’s policy.

“The Agency of Ag. is not really following their mandates to minimize environmental harm,” he said. “And we need to get the agency to think more about integrated pest management, soil health, pesticide minimization, and build those into their new reg.'s and in everything they do day-to-day.”

In an interview, Cary Giguere said his former employee is wrong about the state not following the policy.

“I think we’re heading in a positive direction here,” he said.

Giguere said the public needs to look at the big picture – and how cover cropping has reduced phosphorus runoff. 

"If you look at the water quality numbers now, and how much phosphorus is going into waterways, that is attributed to the adoptions of the conservation tillage practices. And... right now, the tool for terminating the cover crop that is the safest to use, is glyphosate." - Cary Giguere, state Agency of Agriculture

“If you look at the water quality numbers now, and how much phosphorus is going into waterways, that is attributed to the adoptions of the conservation tillage practices,” he said, “And… right now, the tool for terminating the cover crop that is the safest to use, is glyphosate.”

Farmers should be applauded for reducing run-off, says Sylvia Knight, a citizen activist from Burlington who’s written a comprehensive report assembling recent research on glyphosate.

“I do believe in cover cropping. I think that’s a great idea,” she said. “But terminating it with another application of herbicide doesn’t make sense to me if you’re thinking about water quality.”

But Giguere said farmers need options. When they use neonicotinoids, for example, he said, they actually use far less chemical by volume on seeds than if they were spraying their fields.

“To assert the agency is not enforcing a policy of IPM is sort of disavowing the farmer the opportunity to make a decision about what pests he needs to combat,” he said.

But Lori Fisher, who directs the Lake Champlain Committee and also serves on the advisory panel, said Shambaugh’s report showing increased pesticide use raises serious concerns for the lake.

Pesticides-report-pounds-released-in-vermont-shambaugh-vtcac-20210209.JPG
Credit Nathanial Shambaugh, Courtesy
A recent report from retired VFAM chemist Nathanial Shambaugh found that pesticide use overall is declining in Vermont, but use of pesticides on corn is increasing.

“Certainly those were shocking numbers,” she said. “And it was really disconcerting to see that we’re seeing an increase in pesticide, herbicide use, at the same time we have these policies to dissuade and focus on integrated pest management. I think part of what Nat was pointing out is that it is not happening.”

Still, it’s unclear just how much of those herbicides and pesticides is ending up in Lake Champlain, now that cover cropping has increased along with herbicide application.

The U.S. Geological Survey will try to answer at least part of that question. The government research agency will study glyphosate levels flowing in from the lake’s tributaries.

Shambaugh, the retired state chemist, asks another basic question: What’s the impact of these herbicides on the lake? 

"If we're having a potential effect on the bottom of the food chain, the insects and the plants in the water, who knows what it's doing to everything else?" - Nat Shambaugh, retired state Agriculture Agency chemist

He points to one study of Jewett Brook in Franklin County, a stream that drains corn fields and flows into Lake Champlain, that showed atrazine and pesticides – including the neonicotinoids – at very high concentrations, enough to potentially kill insects and plant life.

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“So if we’re having a potential effect on the bottom of the food chain, the insects and the plants in the water, who knows what it’s doing to everything else?” Shambaugh asked.

The Lake Champlain Citizens Advisory Committee is also pushing for more answers. At a meeting this week, the committee called for more aggressive action to curb lake pollution. Members also wanted more monitoring of water quality, including the chemical by-products of the dairy economy.

Have questions, comments or tips? Send us a message or get in touch with reporter John Dillon @VPRDillon

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