This Sunday, exasperated farmers and citizens will travel to a field near Harpenden to uproot a crop of genetically modified wheat. They have been denounced in purple prose by pro-GM commentators, as science haters, "Nazi book burners" and vandals. But what else can concerned citizens do when the company conducting the GM wheat trial, Rothamsted Research, presses on recklessly with an open field experiment that has the potential to contaminate neighbouring farmers' crops and trigger unpredictable impacts on other species?

Recent Swiss research shows that some GM wheat varieties can cross-pollinate with crops more than 2.75km away, and that in the field, they cross-pollinate six times more than conventional varieties. Yet in contamination incidents involving long-grain rice in the US and flax in Canada, GM companies refused to accept liability.

In Europe, despite the US biotech industry's attempts to ram GM down our gullets, applications for open-field trials of the Harpenden type have been steadily falling since 2009. Why? Consumers consistently reject genetically modified food. This is why Carrefour, the world's second largest supermarket chain, now labels its own-brand meat and dairy as GM animal feed-free, ("Nourri sans OGM"), to give its customers the field-to-fork guarantee they so clearly desire.

GM increasingly looks like an inherently risky old-hat technology left behind by more advanced approaches that can boost yields more effectively, and without the associated risks. Alarmingly, Canadian researchers have found traces of GM pesticide in 93 per cent of baby foetuses. Animal feeding trials repeatedly show kidney, liver, reproductive damage and allergenic responses to GM feed. Controversially, Rothamsted's experimental GM wheat contains an antibiotic-resistant marker gene, against European Medicines Agency advice.

For all its swaggering claims to feed the world, the reality is that GM hasn't delivered on its promise of higher yields and less pesticide. Poor Indian cotton growers who have adopted expensive GM varieties often find that they do not perform as advertised, even after investing in extra pesticides. For many this is too much to bear and suicide has become a common escape for indebted farmers. Rothamsted's bull-headed persistence with this trial is baffling. The wheat variety has been genetically modified to produce a pheromone that repels cereal aphids, but there are already viable non-GM, non-chemical ways of dealing with them. And since there's no market for GM wheat in the UK and Europe, the trial is a waste of taxpayers' money. If Rothamsted presses on regardless, it's no surprise if responsible citizens feel forced to take the only action left to them.

Joanna Blythman is the author of 'What to Eat: Food that's good for your health, pocket and plate' (Fourth Estate)