A group of young Brits asked to work as vegetable pickers were found to be 10 times less productive than their Eastern European counterparts.
As part of the experiment the group from Plymouth, aged 18 to 23, were put to work on the Southern England Farms Ltd in Cornwall picking cabbages, a job usually done by migrant workers.
The British workers' target was to collect 2000 bags, the equivalent of up to 10,000 cabbages. However, after around four hours, BBC's Inside Out South West showed that the Eastern European team already employed on the farm managed to pick up nearly 10 times as much as the young British workers.
One of the British workers, 23-year-old Jennifer Brunt, told the programme: "This is hard, my hands are too small and they're cold and my nose is running."
Music production student Conor Stephens added he felt guilty that the young Brits were not performing as well as the migrant workers on the cabbage farm.
The 18-year-old added: "I've been wasting quite a lot as well. I feel like we have lost these people money by doing this."
All workers are paid minimum wage as standard, but can earn up to £800 a week during the summer weeks.
Greville Richards, who employs 500 pickers, nearly all of whom are from Eastern Europe, said he would gladly hire more British people if they applied for the roles.
When asked why it is difficult to get British workers on the farm, he said: "I don't know. You can see the condition that we're in today, it is a tough job. It's rewarding if you want to get on. Some of the teams that we have here earn very good money."
Richards said that since the EU Referendum, it has become harder to recruit EU workers.
He added: "Now we are sort of finding that we are Bulgarian and Romanian purely because the Lithuanians and the Polish don't want to come here because there's nothing it in for them now with the way the exchange rate is.
Inside Out South West will be shown BBC One in the SW region on 5 February at 7:30pm and later available on the iPlayer for 30 days.