By Jean Snedegar
Business programmes, BBC World Service
Pressure is mounting from some scientists for Europe to end its resistance to genetically modified (GM) crops but fears remain about the impact of such technology on the rights of farmers.
Many American farmers like the ease of operating a GM system which involves regular spraying of chemicals which kill weeds but don't hurt their crops.
The problem is that GM pollen can blow across fields and anti-GM campaigners say the fear of being prosecuted for growing GM accidentally leads many farmers to give up traditional methods and take the GM route for a quiet life.
David Runyan, who has 400 hectares in eastern Indiana where he grows maize, wheat and soybeans, says he feels intimidated by the tactics of the biggest GM seed firm, Monsanto.
Although Mr Runyan plants some genetically-engineered corn, he grows only conventional soybeans - something he admits is now rare.
"Approximately 90% are growing GMO soybeans," he says, "Although when the first-generation of glysophate-tolerant soybeans came out the yields were not there.
"My neighbours like them because there's less management," he says.
"They don't have to walk out to the fields. A lot of them don't even feel the dirt.
"They plant it; they hire somebody to spray it; hire somebody to fertilise it and they just go and harvest it," he says.
"They're not farmers like we used to be."
Mr Runyon says he is not allowed to buy any products from Monsanto.
"I'm on what you call a Monsanto black list - a few years ago they came out and tried to investigate and search my farm and I prevented that," he says.
Mechanisation is necessary to make many of the larger farms profitable
"I've never signed a contract. I do not use their products and it will be a cold day before I ever buy Monsanto products."
He believes that Monsanto's past history has not been good for the world or for the people.
"They're only out for Number One. Most farmers in the United States do not care for Monsanto but they stand in line to buy their products," he laments.
"I think it's just because it's easy for them - that's the only reason I can think of, there's less management."
In 2005, investigators sent by Monsanto arrived at Mr Runyan's farm unannounced.
"They came to my house and wanted all my production records," he says.
They asked questions about his farming operation and wanted to know who he was selling his food-grade soybeans to.
"They wanted to know who I'd bought all my herbicides from and they wanted records and phone numbers," Mr Runyan recalls.
Three months after the investigators left empty handed, Mr Runyan received a letter stating that he had seven days to turn over all his production records to Monsanto.
One reason why Mr Runyan refused was because the letter stated that Monsanto had an agreement with the Indiana Department of Agriculture, but the department didn't exist at that time.
Mr Runyan hired a lawyer to deal with his case.
David vs Goliath
David Runyan's story is not an isolated one.
To protect their patents, biotechnology companies have fiercely pursued farmers they suspect of saving and replanting their seed and farmers who may have biotech crops growing in their fields accidentally.
Either way, companies like Monsanto call it "seed piracy".
Bill Freese of the Center for Food Safety says Monsanto will force farmers to sign a technology use agreement which basically forbids the farmer from saving seeds from his harvest for planting the next season.
"Seed-saving is a long tradition in agriculture dating back millennia and it's actually still practiced quite a bit even in the United States and other developed countries," he says.
Thousands of farmers who have been pursued by Monsanto in the US have paid the company at least $85m (£59.4m) in damages for the so-called crime of saving seeds from their harvest.
When asked about their tactics, Monsanto directs people to the "For the Record" section on their website.
Statement on Monsanto's website
Monsanto does become aware, through our own actions or through third-parties, of individuals who are suspected of violating our patents and agreements. Where we do find violations, we are able to settle most of these cases without ever going to trial. In many cases, these farmers remain our customers. Sometimes however, we are forced to resort to lawsuits. This is a relatively rare circumstance, with about 120 lawsuits having been filed within the last decade. Less than a dozen cases required a full trial. In every one of these instances, the jury or court decided in our favor.
Biotech scientist Michael Fromm believes these lawsuits are fair practice on Monsanto's part.
"They do have patented technology," he says. "The farmers sign agreements not to save the seed as a way for Monsanto to make money on their crop.
"They've gone after a few farmers pretty hard in terms of litigation. If somebody doesn't enforce their property rights - the market tends to abuse it more."
The big fear of consumers in Europe has been safety.
After 10 years of Americans eating GM crops, many in the industry say this proves they must be safe, but even in the US some critics are not convinced.
"There really have been no long-term studies and especially in the US - our regulatory system is extremely lax," says Doug Gurian-Sherman, at the Union of Concerned Scientists in Washington, DC.
"I certainly don't believe that all GM crops would be harmful to eat.
"The question is: will the regulatory system detect them? And my answer in short is, 'maybe sometimes' and that's not really very comforting to me."
What worries Mr Gurian-Sherman is that no scientific long-term studies have been conducted comparing groups of people who eat GM and those that do not, to see if the GM eaters get more allergies or other medical problems.
Such concerns have not so far worried most Americans or Michael Fromm, at the University of Nebraska.
In the 1990s he helped develop genetically-engineered crops for Monsanto, the world's leading producer of genetically engineered seed.
"I absolutely believe that genetically engineered crops are safe and the industry record over the last 12-plus years has absolutely proven that.
"To my knowledge there's not a single instance of any health risk for any of the commercially-sold genetically engineered crops."