Security at a GM crop farm in Hertfordshire has been stepped up to protect a controversial new experiment from protesters who want to pull the plants out of the ground.
Scientists at Rothamsted Research aim to produce genetically engineered wheat that releases a chemical signal which deters pests.
But as Ronke Phillips reports, the trial's opponents claim the crop could contaminate the surrounding environment as the experiment is being carried out in the open air.
The group of activists, calling themselves "Take the Flour Back", are holding a mass "decontamination" of the trial site at Rothamsted.
A counter protest by people calling themselves "The Geek Mob" have also planned to descend on the site to protect the research.
St Albans District Council had applied for permission for extra police powers and has received the consent of the home secretary.
They obtained an order banning protesters from the site and are hoping for a safe, lawful and peaceful protest.
Rothamsted Research planted the first genetically engineered wheat seeds that releases a chemical signal which deters pests in April after successful lab tests.
The pheromone, which is too mild to be smelled by humans, replicates one which aphids use to warn each other of imminent danger and will scare the pests away.
The chemical, known as (E)-beta-farnesene,is produced naturally in peppermint but not in sufficiently concentrated amounts to scare off pests.
By removing the gene which produces the chemical, adding it to the wheat and manipulating it so that it is released in quantities which match those given off by aphids, the crop can "trick" the pests into seeking out other food sources.
The scientists hope the strain will become the world's first GM crop to repel insects rather than killing them and reduce the use of agricultural chemicals.
They also believe the use of a repellant rather than a poison will reduce the chances of the pests developing immunity to it.
The crop is a trial and not designed for commercial use, but if it proves effective scientists hope to develop a new aphid-resistant strain of wheat that could be sold to farmers.