Six years ago, Larry Martin noticed a strange weed with fuzzy leaves and a woody stalk taking over the corn fields he uses to feed his herd of 65 dairy cows. After researching it, Martin learned that the weed, called velvetleaf, is so invasive that it can reduce a crop yield by as much as 30 percent.

It’s also tough to eliminate. After three years of pulling velvetleaf by hand and using various herbicides that didn’t work, Martin decided to switch to the glyphosate-based herbicide Roundup, which is manufactured by Monsanto, the controversial St. Louis-based biotechnology corporation that has become synonymous with genetically modified organisms, or GMOs.

Because spraying Roundup kills both weeds and other plants that come into contact with it, Martin also had to plant Roundup Ready corn, which is genetically modified to resist glyphosate. Introduced in 1998 by Monsanto, Roundup Ready corn is patented and farmers are contractually obligated to buy new seed the following year, rather than saving seed to replant.

After using the Roundup, Martin eventually eradicated the velvetleaf. But as a self-described worrier, he mulls over the decision to use the herbicide. “There’s a big controversy, I guess. If somebody came and chewed me out I don’t know that I’d have any reasons for using it.”

There seems to be little middle ground on the subject of genetically engineered crops, at least in the fractious atmosphere of the media and the Internet. The debate over their use and efficacy is often contentious, even as more American farmers have turned to genetically engineered crops in the last 20 years in the hope that they can boost yields and reduce vulnerability to weeds and pests. Scientists who see the potential of genetic engineering to alleviate hunger, combat disease and mitigate some of the effects of climate change say the risks of genetic engineering to human health have been exaggerated and the science misunderstood or impugned.

As the arguments about the merits of genetic engineering seesaw between advocates and skeptics, the New England states, including Vermont and New Hampshire, are on the leading edge of a national drive to label products containing genetically modified ingredients because of consumer concern about the content of their food.

“I think I should have the right to know,” said Babo Harrison, who lives in Bethel.

At the same time, Harrison said, she was uncertain on the question of whether there is a role for genetic engineering in agriculture. “I’m not universally against it, but we also open up a can of worms,” she said.

Charles Peters, who lives in East Thetford, supports labeling and didn’t see a need for GMOs. “We’ve been hybridizing for thousands of years and that seems to have worked well in the past,” he said.

Martin has been farming for 45 years on land inherited from his father. He remembers when his father used to cultivate 10 acres by hand. But Martin tends 25 acres of silage corn — corn grown to feed livestock — and the farming paradigm has changed dramatically since the 1950s and 1960s. The margins are razor-thin and the pressure for farmers to grow more food continues to ratchet up even as the costs of doing business increase.

“I wished I just had a tiny little farm and I could go out and hoe it all, but I can’t. That was a good way to take care of that stuff, but the American public isn’t going to do that anymore,” Martin said.

A Brave New World

With the introduction of genetically modified crops in the 1990s, agriculture entered a brave new world of biotechnology, where promises of higher yields and less reliance on chemical herbicides and pesticides persuaded many American farmers to adopt the new technologies.

There are crucial differences between genetically modified crops and traditionally bred crops.

For thousands of years, humans have bred plants to improve appearance, flavor, longevity or to resist insects or diseases through cross-pollination from one plant to another. The process of selecting the desired traits (say, a redder tomato with better flavor), transferring them, testing the new variety and arriving at a final commercial product can take years.

Genetic engineering isolates the gene or genes that control the desired traits and inserts those genes into the plant or other living organism. Farmers can buy hybrid crops that are genetically modified for pest resistance, herbicide resistance or both. A hybrid that contains more than one resistance gene in it is called a “stacked gene” variety.

The U.S. grows more genetically modified crops than any other country in the world, with soy, corn, alfalfa and cotton leading the pack. In 2000, 25 percent of all corn planted in the U.S. was genetically modified; by 2013, that had risen to 90 percent, according to the USDA.

Perhaps 90 to 95 percent of silage corn in Vermont is genetically engineered, according to Alison Kosakowski, a spokeswoman for the Vermont Agency of Agriculture. New Hampshire doesn’t track how many farmers use GMOs.

Whether they are aware of it or not, most Americans are wearing clothing made from cotton that has been genetically modified to resist boring insects. They are also eating or drinking soy bean and corn products grown from seeds that were modified to resist pests and weeds.

“If you’re eating something in the American food system, (GMOs are) everywhere,” said Steve Taylor, of Meriden, the former commissioner of agriculture for New Hampshire.

But even as many farmers and agribusinesses have embraced biotechnology as a way to reduce labor and costs, there has been a vocal movement opposing GMOs. There is apprehension about their safety and deep cynicism about such companies as Monsanto and DuPont that profit from the technology. Skeptics say genetically modified crops haven’t been sufficiently tested on animals to know whether their consumption could have a long-term impact on human health.

“More studies of potential effects are needed,” said Dave Rogers, policy adviser for the Northeast Organic Farming Association of Vermont. Pharmaceuticals are tested for use on humans, and genetically modified crops should be, too, he said. “I don’t say these things are killing people in the streets, but these are serious questions. It’s unconscionable we’ve gone 20 years without research.”

On the other side of the argument are scientists and doctors who say that 20 years of eating genetically modified crops with no apparent widespread ill effects is evidence of their safety. Last year, the American Medical Association issued a statement finding that although there is a small risk of adverse reaction, “bioengineered foods have been consumed for close to 20 years, and during that time, no overt consequences on human health have been reported and/or substantiated in the peer-reviewed literature.” The AMA did recommend, however, that products containing GMOs go through mandatory testing prior to commercial use.

And after years of public resistance, mandatory labeling and strict anti-GMO regulation, even the European Union has ceded some ground on the subject. In 2010, the European Commission released a report on a decade of European Union-funded research on GMOs.

“The main conclusion to be drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of research, and involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not per se more risky than … conventional plant breeding technologies,” the report said.

Scientists are as aware as anyone else of the law of unintended consequences: the pesticide DDT introduced to combat insect-borne diseases that then led to precipitous declines in bird populations; the drug thalidomide that was distributed to pregnant women in the 1950s to relieve morning sickness but also led to grave abnormalities and deformities in fetuses in utero.

“You can have unintended consequences with conventional crops as well,” said Thomas Jack, a professor of biology at Dartmouth College. “GMOs are no more dangerous than conventional breeding, because you know what gene you’re putting in.”

If testing on animals is what GMO skeptics want, he said, then new varieties created by conventional breeding should also be tested for possible effects on humans. Currently, this isn’t the case.

Although Taylor does not use genetically engineered crops on the dairy farm he and his sons run in Meriden, and buys non-GMO silage from a neighbor, he understands why they’re in use. “Farmers turn to these things because they’re constantly under the gun. There are barriers to getting (a) high price so they turn to ways to cut cost.”

Both Sides of the Equation

Across Route 5 from Larry Martin’s property in Fairlee is Newmont Farm, owned by Walter and Margaret Gladstone. They milk 1,150 cows and grow approximately 850 acres of corn. Although he doesn’t rely only on Monsanto seeds, and uses other herbicides in combination with Roundup, Gladstone began using Roundup Ready corn modified for both herbicide and pest resistance approximately three years ago.

“We switched because the technology was there that gave us greater confidence for better yields, and potentially less chemical and pesticide use,” he said. “From the point of view of risk management, (the Roundup Ready corn) is a good tool to use and we’re trying to make a living.” He observed a difference in the population count per acre, the vigor, color and final yield when compared with the conventional hybrids he also grew.

Not everyone is signing on for Roundup Ready, though. Thirty-five miles down the Connecticut River in Plainfield, the family-owned McNamara Dairy, which supplies milk to a number of Upper Valley grocery stores, doesn’t grow genetically modified corn. Pat McNamara understands customer concerns about genetically modified plants finding their way, directly or indirectly, into the food chain.

“I’ve just chosen not to (use it) because we are close to our customers. Sometimes it is easier to say, ‘No, we don’t use it,’ rather than go on to explain (why we do),” he said.

Overhearing McNamara, a customer who’d come to buy milk chimed in that he drives nine miles to the dairy precisely because it doesn’t use GMOs.

Although McNamara’s not convinced Roundup is better than the herbicides he uses, he has no strong feelings about other farmers using it.

“It’s excellent weed control. You can wait until June to spray and (the weeds) are gone and that’s a huge advantage. There’s a lot of weeds that weren’t around 30 years ago,” he said. Nor would he hesitate to drink milk from a farm where the Roundup regime is in place. “As a farmer I can see both sides of the equation.”

But as long as genetically modified crops, and Monsanto in particular, remain a “lightning rod,” he sees no reason to change over to Roundup Ready and Roundup. “We are in the business of selling milk and we don’t need negative advertising.”

Label Laws

Although some want GMOs banned, that is unlikely to happen, said Rogers. For consumers concerned about genetically engineered crops, the logical option is to label products that contain genetically modified ingredients and let the consumer make an educated choice. “That’s the moderate position,” he said.

For his part, Gladstone doesn’t support the labeling law, seeing it as “another potential regulatory burden.”

While labeling foods that contain genetically modified ingredients has been standard practice in Europe, Japan, Australia and New Zealand and even Russia, the drive toward labeling in this country is relatively recent.

New England states are in the forefront of the movement. Connecticut passed a labeling law earlier this summer, although its implementation hinges on a “trigger”: For the law to take effect, four other Northeast states with a combined population of 20 million must also pass labeling laws, and one of the states must border Connecticut. Maine also passed a law but it has not been signed by Gov. Paul LePage.

In May, by a vote of 99-42, the Vermont House passed a GMO labeling law, which will go before the Vermont Senate when it reconvenes in January 2014. The House Committee on Agriculture and Forest Products heard hours of testimony from more than 30 people representing, among others, the Vermont Public Interest Research Group, the Agency of Agriculture, the Vermont Grocers’ Association, food producers, restaurants, doctors and scientists and religious institutions.

The bill “doesn’t address the pros and cons of genetic engineering, it doesn’t ask for a ban, it really asks for the right to know,” said the bill’s sponsor, state Rep. Kate Webb, D-Shelburne. “It doesn’t say you can’t grow it or sell it. It just lets the consumers know so they can make an informed choice.”

Webb is cautiously optimistic that the bill will pass the Senate and then go to Gov. Peter Shumlin, who has indicated his willingness to sign it.

The Vermont Agency of Agriculture also supports labeling, wrote Kosakowski in an email, adding “genetically engineered crops serve a purpose and are an important element to the success of many Vermont farms.”

This summer, the Vermont Public Interest Research Group embarked on a statewide campaign to go town to town, door to door, asking people to sign postcard petitions endorsing the labeling law. The goal is to collect 30,000 signatures by the end of August; to date they have 24,000, said Leah Marsters, a field organizer for the group. The postcards will be forwarded to the Senate committees of jurisdiction as well as other bodies in the state, she said.

“We think that the GMO labeling law is extremely important as a consumer right-to-know issue,” said Marsters.

She expects the bill will face stiff opposition from the biotech companies, as did a proposed labeling law in California, which was narrowly defeated last fall. “We know they will dig deep to try to prevent Vermont from being the first state in the nation to enact a GMO labeling law.”

In New Hampshire, the Environment and Agriculture Committee is revising a bill that can go to the House in January, said state Rep. Maureen Mann, D-Rockingham, who is the primary sponsor of a labeling law. If the House passes it on schedule, the bill would move to the Senate in the spring.

“In terms of comments from people, the support has been absolutely overwhelming,” she said. Only hazily aware of the issue a few years ago, Mann began looking into it because of requests from voters. The proposed labeling law in New Hampshire is “absolutely constituent-driven.”

“I want it all labeled very specifically,” said Rosemarie Peters, a Lebanon resident. A vegan, she reads labels closely, but at the same time she expressed little concern about the technology of genetic engineering itself. “We look to science for a lot of things.”

Labeling is not a new concept for the American food industry, Mann pointed out. Federal regulations on processed foods already require a list of ingredients and nutritional content. And many American companies already designate GMO products destined for overseas markets where labeling is required, including The Hershey Co., which has to identify its chocolate as having been produced with soy lecithin, which is derived from GMO soy.

Label or no, “I don’t think people are going to stop eating Hershey bars,” Mann said.

Health and Environmental Concerns

The arguments against genetic engineering veer between concerns about human health and environmental health and whether GMOs are as effective as claimed.

Opponents say that because there isn’t enough data on the effects of genetically modified crops on animals, science should observe the precautionary principle, which holds that until an action, technology or medicine can be proved to be of no harm to humans or the environment, it shouldn’t be implemented.

Rogers, the Northeast Organic Farming Association of Vermont adviser, has taught agricultural science and the ethics of agriculture at the University of Vermont for 15 years. He is not anti-science, he said. “We want more science about how plants and insects interact. People say we’re Luddites. No way. That’s the kind of agricultural research we need, but large economic interests have the ability to set the agenda.”

As a result, there’s little research money for organic farming, he said. And those who question the use of genetically engineered crops say that their caution has sometimes been dismissed as trivial, or unfounded. There’s a “vilification of people who have alternate views,” he said.

Some scientists argue that genetic engineering has the potential to alleviate human hunger and increase crop yield more rapidly and efficiently. Others argue against using genetically modified crops since slower but proven conventional breeding methods have done the job for centuries.

Jack Shepherd, a professor of environmental science at Dartmouth College, began his career as a reporter in the 1960s for Look and Newsweek magazines, and has studied famine and food as an instrument of politics in sub-Saharan Africa. He recalled visiting a village chief and farmer in Swaziland who had set aside a large bin of corn for next year’s crop and proudly showed it to Shepherd.

Over generations, this corn, through careful selection, had been bred to be drought-tolerant, well-suited to the arid conditions in which it grew. Why would any genetically engineered corn do better in that challenging environment than what the farmer already knew how to grow, Shepherd asked.

The environmental concern is that, over time, weeds will become resistant to an herbicide like Roundup, or insects will become resistant to the pesticide Bacillus thuringiensis, or Bt, which is genetically inserted into such crops as cotton or soy.

One of the keys to combating increasing resistance is to use Roundup in conjunction with other herbicides in a kind of “cocktail,” said Rob McClung, a professor of biology at Dartmouth. “If you deploy cocktails you do better. It’s the same with tuberculosis and AIDS. It’s exactly the same logic and the same principle.”

In a paper published recently in the journal Nature Biotechnology , French and American scientists looked at data from 77 countries on five continents. It found that of 13 major insect species exposed to Bt in genetically modified corn and cotton between 1996 and 2011, five were resistant by 2011.

Alarms are also raised about so-called genetic pollution. Last month, some genetically modified, Roundup Ready wheat was found growing in field of conventional hybrid wheat in Oregon. Monsanto had developed genetically engineered wheat, but in 2004 abandoned plans to introduce it for commercial use because of opposition from American farmers concerned about trade barriers on GMO wheat overseas, according to a report in The New York Times . How the genetically engineered wheat arrived in the field isn’t yet known, but the incident is being investigated by the USDA.

Scare Tactics and Disinformation

While there are valid areas of debate regarding genetic engineering, advocates for the technology argue that vilification of different viewpoints goes both ways. The most vehement critics of GMOs, they say, use scare tactics and disinformation by implying that all of science is in the pocket of companies working with the technology, or by cherry-picking data from studies that are then either retracted or disavowed by the rest of the scientific community.

To read the more extreme anti-GMO literature on the Internet is to tumble down a rabbit hole into a world of conspiracy theory, and a distrust of science that seems based in raw emotion, rather than examination of data. A headline on the website Sustainable Pulse reads “Monsanto’s Roundup to blame for Worldwide Male Infertility Crisis?”

“Food just seems to be a very emotional thing for a lot of people and the science is not easy,” said Lorraine Merrill, New Hampshire’s commissioner of agriculture. “That adds to that suspicion factor.”

As a result, the debate over genetic engineering is often heated.

A public symposium on the subject held two years ago at Dartmouth College was disrupted when some people in the audience repeatedly heckled an industry speaker who’d been invited to participate, said Jack, the Dartmouth biology professor, who was in attendance.

“That’s not civilized debate. We need to calm down and figure out how to have a conversation,” said Rob McClung, a professor of biology at the college who was also present at the symposium. “The technology is neither good nor bad. It’s how you apply it.”

Whatever its merits and drawbacks, genetic engineering is sure to continue to touch off robust debate. “It’s a patented and controlled commodity,” Shepherd said of genetically engineered seeds manufactured by such biotech companies as Monsanto or DuPont.

“If the right to food is a human right, we should have the right to grow that food. If we control that food source, and charge people money to have access to what is a right, where is a Swaziland farmer going to find the money? This guy is going to have to come up with American dollars, rather than grow food for his community.”

The proponents of GMOs, said Rogers, sometimes talk as “if it’s the only technology we have. There’s lots of conventional breeding that is effective. Somehow people act as if (genetic engineering) is the only arrow in their quiver, and it’s not.”

But does the potential of risk mean science should exercise the precautionary principle to such a degree that science doesn’t move forward at all?

“Can you prove that nothing will ever go wrong?” McClung asked.

“Human beings have been influencing the evolution of plants and animals since we were getting out of the caves,” said Merrill. “Sometimes you hear people say that it’s just wrong to take genes from one species and put it into another. But that happens in nature as well.”

In Fairlee, Gladstone drives through huge open barns of heifers and milkers, and then circles around his farm, with its huge stockpiles of different kinds of silage designed to meet a cow’s specific needs for roughage and protein. A pragmatist, Gladstone views GMOs this way: “There’s a place for them, but it doesn’t mean it’s for everyone.”

Now that the velvetleaf is gone at Martin’s farm, he is considering returning to conventional corn hybrids next spring.

While the combined cost of Roundup and Roundup Ready was less expensive than conventional herbicides and corn, the Roundup Ready corn seemed to yield a bit less. RoundUp did the job he wanted it to, but he sees no need to continue with it.

“Corn usually grows pretty good around here anyway,” he said.