A UK farmer said he was worried about harvesting his crops because he does not know if can get enough workers.
North Norfolk fruit grower Simon Turner said the supply of EU labour had dried up and Covid was still causing issues, while the government's Pick for Britain campaign had also been dropped.
"We're in a very serious position," he said.
The government said it would continue to help farmers recruit the seasonal workers needed.
Mr Turner said he currently had 11 workers but needed 62.
"We do not know how many workers we will get," he said.
"Before Brexit we were able to employ from Romania and Bulgaria, now we aren't unless they have a right to remain in the UK, therefore that labour source is cut off to us."
With Brexit, the supply of unrestricted migrant labour on farms came to an end and was replaced by the government's Seasonal Workers Pilot.
The scheme was extended for 2021 to make 30,000 visas available for people who want to come and work on UK farms.
But the number of visas available does not meet the sector's entire seasonal workforce need.
The Department for Environment, Food and Rural Affairs (Defra) said it still wanted to encourage British workers to pick fruit and vegetables despite scrapping the Pick for Britain scheme.
Tom Bradshaw, the vice president of the National Farmers' Union, said it was hoped there would be enough workers through a combination of those from the UK and overseas.
He said Pick for Britain was born in a "period of crisis" last year but "what we need this year is to make sure we've got that continuity of supply".
He said if the crops could not be harvested it would put pressure on the supply chain, which could lead to food price inflation or more imports.