Soil samples will determine if the experiment has been successful

The 55-acre field near Ely, which belongs to the fruit and vegetable grower G's Marketing, has been completely underwater for three months.

It is hoped the worm - or the potato cyst nematode - will be starved of oxygen and die.

It would mean the field would be free from contamination so it can then be drained ready for potato planting.

The parasitic worm is estimated to cost the potato industry over �50m in lost yield and control measures.

A similar scheme was tried 10 years ago, but was unsuccessful as it was carried out in winter when weather conditions were unsuitable.

The advantage of this method of control is that it reduces the need for the use of pesticides.

Soil samples

On Tuesday, scientists from the Rothamsted Research Institute in Hertfordshire took soil samples to see if the number of pests fell during the flooding.

Phil Rayns, farm director of G's Marketing, said the trial looked as though it could be successful.

"The early results that we've had from the experiment do seem to be pointing to the fact that it's going to be successful.

"But how successful we won't really know until we've completed the final sampling and analysed those cysts we do take from the soil."

• Potato cyst nematodes are a type of eelworm that attack potato plants.
• There are 20,000 species of nematodes
• Adult nematodes can be as small as 0.3mm to as large as eight metres
• The largest is found in the placenta of the sperm whale
• The worm can lie in wait in the soil for 20 years or more waiting for a potato crop
• They originate from South America and were probably first introduced to the UK in the 19th century