LONDON — You know you have worries when the future king is warning about food security. Prince Charles this week implored workers furloughed by the pandemic to get out into the fields and "pick for Britain."

“If we are to harvest British fruit and vegetables this year, we need an army of people to help,” said his ruddy-faced royal highness, wearing a tie and tweed sporting jacket, his hand jammed into the pocket of his wrinkled mackintosh, standing in his own well-tilled garden at Birkhall, his estate in Scotland.

“It will be hard graft,” the prince warned, “but is hugely important if we are to avoid the growing crops going to waste.”

Like much of the agriculture in the developed world, British fruit and vegetable growers are dependent on migrant workers, and in England’s case, in normal years, they come mostly from Bulgaria and Romania.

The coronavirus, though, has disrupted movement across Europe. British growers say that even with special charter flights to bring workers in from Eastern Europe, the pool has dwindled because of travel restrictions, and because workers are afraid to come to the United Kingdom. With more than 36,000 confirmed dead from the virus, Britain has the highest death toll in Europe.

While Britain hasn’t seen any food shortages during the pandemic, there’s concern about fruit rotting on the vine. That’s where Charles comes in.

So many people answered the royal call that the “Pick for Britain” website crashed on Wednesday — letting newspaper columnists crow that the myth of the lazy Brit is finally being retired.

But here’s the hitch: Picking soft berries and leafy greens requires considerable skill and backbreaking physical toil for low pay. Farmers are worried that of the thousands of Brits who have forwarded applications, many won’t show up or won’t last the season, especially after they get their hands dirty.

British farmers typically employ more than 70,000 seasonal workers, who pour into the country each spring, summer and fall to pick curly endive and gala apples for about $125 a day, six days a week. In 2019, an estimated 1 percent of the field hands were from Britain.

Last year — amid warnings that an abrupt Brexit would lead to a shortage of farmworkers — The Washington Post spent days searching for the rarest of the rare, a British-born berry picker. We eventually found four university students working on a strawberry farm in Herefordshire.

But that was before the pandemic, before approximately 7.5 million people in Britain had been furloughed.

Christine Snell of the A.J & C.I Snell farm said so far this year she’s recruited 200 Eastern Europeans to work the family fields — and they are already busy.

Snell interviewed another 45 Brits by email — the most homegrown applicants ever — but just 14 of them committed. The British workers are set to arrive in coming days, when they’ll be trained and put to work with low-skill maintenance gardening — not picking the precious and delicate strawberries, which requires speed and skill.

“I’m very nervous who will show up and who will stay,” she said of the British workers. She imagines that folks might get the wrong idea about the “Pick for Britain” plea — that “it’s all rosy summer glow, all hands to the pump, a war effort, like Dad’s Army,” a BBC sitcom.

Jack Ward, chief executive of the British Growers Association, said his group surveyed its members to find that most in May have “enough-ish pickers. I say ‘ish’ because, as one said, you never know until they actually turn up if they will turn up.”

He said that “if everything goes to plan,” as much as a third of the seasonal workforce will come direct from Britain, “and that’s a major increase.”

Even if the Brits roll up their sleeves, Ward said growers are concerned about productivity; recruits are 20 to 30 percent less productive than experienced ones.

“If you look at the lettuce industry, which is now hitting top gear, doing 1 million heads of lettuce a day, that’s a massive logistical challenge, and you can’t do that all with rookie labor,” he said.

Farmers are also anxious that furloughed workers who take a chance with field work might return to their old jobs once Britain eases out of its lockdown in June and July.

“I don’t think anyone is sitting there saying, ‘I got this nailed.’ They are sitting there, fingers crossed, saying, ‘We are okay for the next week, or maybe the following one,’ ” Ward said.

Other European countries have already struggled. In France, asparagus farmers had to leave their plants growing high in their fields after failing to find enough people with the stamina to pick the shoots.

Germany’s Agriculture Ministry started a website to match idled workers and students to farmers in need. Not enough signed up, and eventually the German government allowed tens of thousands of seasonal workers, most of them Romanian, to come on specially organized charter flights.

But European farmers say they still don’t have enough people to work the fields as strawberry season starts up. Germany’s Web portal is covered in testimonials to try to calm fears that the work is too taxing. “It’s tiring, but not as tiring as I thought,” said a woman quoted as “Yvonne, 19, a student from Bavaria,” on the portal’s home page.

British farmers say that, traditionally, it has been tough to recruit British workers not only because the work is hard but unemployment levels have been low and produce is often grown in areas that are sparsely populated — so transport costs eat into wages or farmhands have to live in trailers on site.

G’s Growers, one of England’s biggest salad farms, has had employment inquiries this year from more than 3,500 Brits and offered 600 people jobs. In a statement, the company said that it has been “extremely transparent about what is involved, especially the nature of the work.”

“This has helped the business focus on people who are both available and have the desire to work for a significant part of the season and reach the quality and efficiency that we require, rather than those who are looking to do their bit for a few days.”

Sarah Boparan, operations director for Hops, a labor contracting company that supplies thousands of workers to farms across the country, said so far the company has been able to fill vacancies with a mix of Eastern Europeans and Brits, who are stepping forward.

Last month, 14 percent of its workers were residents of Britain — compared to the National Farmers Union estimate that last year, about 1 percent of those who picked fruit and vegetables were from the United Kingdom.

Boparan said the next six weeks “are going to get more difficult” because transport from Europe has mostly shut down, Romania’s borders are still closed, and the British government says it will require travelers from outside to quarantine for two weeks upon arrival. Meanwhile, some furloughed workers may be returning to their jobs.

“The volume of people is going to change as people resume previous work,” Boparan said.

The National Farmers Union estimated that to reach a goal of 70,000 to 80,000 workers in the fields, “we have 20,000 to 40,000 more to find, and hopefully we get that,” said Mike Thomas, a spokesman for the group.

“It’s tiring and long days,” Boparan said. “And you will have backache, and your hands will ache, and we are seeing people say, ‘It’s harder than we thought it would be,’ and decide it’s not a job that suits them. So there’s that anxiety.”

But she said recruiters and growers “remain optimistic that huge numbers of people will be willing to do this.”

In his video appeal, the prince called for “pickers who are stickers.”

Michael Birnbaum in Brussels contributed to this report.