Farming leaders have raised concerns about a lack of available labour because of the coronavirus, with one calling for a “land army” to be recruited from people put out of work by the crisis.

Restrictions in place because of the virus are likely to prevent many of the 60,000 seasonal labourers who come to the UK each year to work on farms from travelling, and the supply of domestic workers is also expected to be reduced.

Farmers in many parts of the country are already struggling after months of severe floods, and the supply of seasonal workers was already in doubt because of Brexit.

The Country Land and Business Association (CLA), which represents more than 30,000 landowners and rural firms, estimates that the shortage of workers could hit 80,000 at a crucial time and leave crops rotting in the fields.

The greatest need for workers is still a few months off, but the lambing season peaks in the spring, the main harvests take place in the summer a few weeks before pickers are needed for soft fruit and then salad and other vegetables. Many farmers have already begun planting or harvesting key crops.

“We must recognise that farmers’ supply of labour is in jeopardy,” said the CLA’s president, Mark Bridgeman. “A shortage of 80,000 workers is something we have never seen before. That is why we are calling for a land army of employees to support farmers in feeding the country.”

He said workers from other sectors hit hard by the coronavirus crisis could be quickly retrained to do agricultural work. “We need urgent government assistance to help source workers and advertise positions,” he said. “Time is of the essence. If we fail to find these key workers, businesses will go bust.”

The National Farmers’ Union also called on the government to act urgently. “Growers who rely on seasonal workers to pick, pack and grade our fruit and vegetables are extremely concerned about their ability to recruit workers this year,” a spokesperson said.

“The industry is already working hard to promote roles on farms locally, recognising that this could help those who unfortunately find themselves out of work. We are urging the government to address this situation as soon as possible.”

The Department for Environment, Food and Rural Affairs on Friday announced a new £6m fund for farmers after the wet winter, and the relaxation of some rules on what they can grow.

George Eustice, the environment secretary, said: “I have seen first-hand how devastating the recent floods have been to people and communities, which is why we have extended the farming recovery fund to help those affected get back on their feet.

“I’m also aware that the spread of the coronavirus is causing other difficulties for the farming community. We are exploring all options to ensure the right support is available in the coming weeks and months.”

Demand from supermarkets and for vegetable boxes has rocketed as the coronavirus crisis intensifies, but demand from restaurants has collapsed. This has left many farmers facing difficulties in finding new supply routes and adapting to the shift. Spring is often when farm income is lowest, even while demand for labour is growing.

The average age of farmers in the UK is 59, putting many in at higher risk of developing severe symptoms if they contract the virus.

The Landworkers’ Alliance, a small union representing more than 1,000 small and medium-scale farmers and land workers across the UK, called on the government to support small farmers through small business relief, even though they do not normally pay rates. The alliance also wants a “dig for victory” programme to encourage market gardeners and local community groups.

Its campaigns coordinator, Jyoti Fernandes, said: “This crisis highlights the vulnerability of our globalised food system, which in coming years will only get worse if we don’t invest in building a resilient, diverse, local food system. We demand immediate and significant government action to ensure everyone can access healthy affordable food.”

Ashley Wheeler, a salad and vegetable grower in Devon, said: “What we need is help to coordinate the distribution of the food that farmers and growers have to local communities, especially those who are vulnerable and in isolation.”