As the US and the EU face off yet again in a trade dispute - this time over beef treated with growth hormones - the EU can take some comfort from reports that US interests are not having it all their own way even if they are winning most of the rounds in front of the World Trade Organisation (WTO) arbitration panel.

It appears that US farmers are having mixed success planting crops that are genetically modified to kill insect pests, according to an industry study released this week.

While the altered seeds produce better yields, farmers can lose money on the crops when commodity prices and infestations are low, the study found.

Corn growers made an extra £46 million by using GM seeds in 1997, but planted three times as much acreage to the crop last year and lost £16.6 million when grain prices plummeted and infestation levels dropped, according to the report by the National Centre for Food and Agricultural Policy, a Washington-based research policy group.

Of course, that only means they are even more likely to press ahead with a WTO action against the EU on its ban on genetically modified organisms in a bid to expand the market for its farmers.