These are lean times across the Cornbelt.

Grain prices are the lowest in memory, and some farmers are facing an additional problem.

The international market for genetically-modified crops is collapsing. Farmers like Dennis Mitchell from South Dakota believed GM crops were the way of the future but now he's less sure.

"If the customer ultimately says they don't want it, I'll have to rethink what I'm planting," Mr Mitchell said.

Whilst they have been harvesting in the American heartland, the news has only got worse.

The confidence of farmers growing GM crops has been undermined

In the past month alone, the two largest breweries in Japan and the largest tortilla maker in Mexico have all said they will not use GM crops.

The confidence of those farmers who had switched to growing GM crops was further undermined when Archers Daniels Midland, the largest grain exporter in Illinois, instructed farmers that GM grain and conventional grain must be segregated at the silos.

Tim Galvin of the Department of Agriculture says these are disturbing times for many farmers.

"In some cases, (farmers) have reacted with surprise and concern, too. Especially if the segregation results in two prices," Mr Galvin said.

On the trade floor in Chicago there is already an expectation that GM crops will fetch a lower price than conventional grains.

GM stocks are now expected to fetch less than conventional food stocks

Gary Goldberg of the American Corn Grower's Association said his members had expected that next year there would be a 25% increase in the amount of GM crops being planted; they're now expecting a 25% decrease.

"Many (farmers) are going to be going back to conventional crops out of the uncertainty ... whether they will go through the risk and expense of planting a crop and then not having it marketable next harvest," he said.

He said that the companies that developed GM crops have only themselves to blame. "They should have done a better job of explaining the science, doing the research, educating the consumer, and they didn't."

Crops in the courts

And the doubts about GM, expressed so volubly abroad, have encouraged a variety of groups in the United States to turn to the courts to slow the genetic revolution.

Some GM companies are being taken to court for being anti-competitive

Richard Kelley is a lawyer hired to bring an anti-trust suit against the big agri-chemical companies producing the GM seeds. He has no doubt that what is happening overseas is influencing events in America.

"There is a great deal of momentum within the international community that is coming together to oppose what is going on. We are hearing from groups in Europe, Africa and Japan, who are very, very concerned," he said.

Mr Kelley argues that the large biotechnology companies have become too powerful and that they have so engineered GM crops that the farmers have to return each year to the company to buy their seeds.

They believe this is anti-competitive and are seeking billions of dollars in damages, arguing that GM seeds are fundamentally different from anything that has gone before.

"It was said to me by a Swedish farmer the other night that farmers since the beginning of civilisation have been able to sow their own seeds, and the practices being introduced and enforced by the bio-tech industry are threatening that practice," Mr Kelley said.

Consumer protests have spread from Europe to the US

Another group has brought a suit against the food and drug administration, the government agency that monitors food issues. It wants any products that use genetically modified grain to be labelled.

Joe Mendleson from the Centre for Food Safety believes you cannot have international consumers being given this information and not Americans.

"I have no doubt that the crisis and the issue that is embroiling Europe right now is going to spread to the United States. I think it's already here," he said.

Clouded future

It is too early to write off the genetic food revolution. The promise remains of future food designed to improve nutrition or health and so far, American consumers remain untroubled by the whole issue.

But recently the largest baby food manufacturer in the United States announced it would no longer use GM ingredients.

The company insisted it was not an issue of safety. It just wanted to position itself ahead of public opinion.