HAMBURG (BLOOMBERG) - In his three decades growing strawberries and blueberries, Cristobal Picon has learned how to grapple with problems ranging from droughts and driving winds to floods and freezes. But this year, the coronavirus outbreak has proven too much.

Every spring, Picon's fields in Huelva, on the Atlantic coast of Spain tucked between Seville and the border with Portugal, are normally teeming with some 200 workers mostly from Morocco and Romania pulling the delicate berries from the plants and packing them for shipment. But this year, there are fewer than 100, largely locals - and Picon has no clue how he's going to get the harvest in.

"You can cushion a bad crop, but when you have 80% of your production ready to be picked and no one to do it, you feel powerless," Picon said. "We don't know how this is going to end."

From Huelva to Hamburg and Newcastle to Naples, Europe's farmers are struggling to find people to bring in rapidly ripening fruits and vegetables, which frequently must be hand-picked, usually within a window of just a few days.

They typically rely on seasonal workers from eastern Europe or northern Africa, but fears of the coronavirus are keeping hundreds of thousands of migrant labourers from leaving home, and controls on once-unfettered borders are stopping many of those willing to make the trip.

Strawberries and asparagus are already being left to rot in Spain, Italy, and southern France. Farther north, producers of everything from salad greens and tomatoes to onions and peas are fretting about what to do as the spring and summer growing season picks up.

The labour problems have some in the business worried that urban shoppers could face produce shortages. The concern is that even crops that get picked won't reach consumers because outdoor markets are closed and transport links are iffy.

"The cities may soon start to lack fresh fruit and vegetables," said Sebastien Heraud, a farmer in the Dordogne region of southwestern France and a leader of Coordination Rurale, an agricultural union.

"Even those of us who can harvest have trouble selling."

France expects some 200,000 workers will fail to show up this year. Coldiretti, an association of Italian farmers, estimates the country will be short as many as 100,000 foreign labourers. Germany typically has 30,000 migrant farm workers in March and 80,000 by May, but this year only a fraction of that number have shown up, according to Agriculture Minister Julia Kloeckner. On Thursday, the country closed its borders to migrant laborers from outside the European Union's visa-free travel zone.

"The labour situation along the entire food supply chain is under immense strain," Kloeckner told reporters in Berlin Thursday. "The number of workers from neighboring countries is falling fast."

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With restaurants, hotels, and shops mostly shuttered due to the pandemic, governments are hoping people from those sectors, or students facing months without classes, will fill the void. French Agriculture Minister Didier Guillaume on March 24 asked anyone who's out of work to step up "so we can all eat."

Germany has created a website listing thousands of unfilled agricultural jobs. A similar initiative in Austria has seen 7,000 people sign up since eastern European butchers and pickers headed home en masse as borders slammed shut a week ago, but the government says the country needs three times that number.

"I'm calling above all on young people not currently working and who don't have children or grandparents to look after," Austrian Labour Minister Christine Aschbacher said on a government website. "We need every helping hand."

Still, shop clerks and waiters are mostly in cities, far from farms that need them, and the farmers are concerned that they may end up without workers once cafés, stores, and schools reopen. And hiring less-experienced pickers, coupled with rules to limit contact amid the outbreak, will likely boost costs and slow production, said Jack Ward, head of industry group British Growers.

"We went from a situation where six weeks ago nobody was talking about where our food comes from, to suddenly everyone wants to talk about it," Ward said.

Some producers aren't waiting for government help. Meyerhof, a farm in Willich, a few miles from the Dutch border in western Germany, has fields full of asparagus that will need to be harvested in the next few weeks - difficult, dirty work that involves many hours stooping to pluck the stalks. Concerned that the three dozen Romanians and Poles it had hired wouldn't be able to make it, Meyerhof posted an appeal on Facebook. Within a day, 500 people had submitted applications.

"It has been an immense showing of solidarity," said Anna Komp, marketing manager for Meyerhof. "We are so grateful, because we simply can't do it ourselves."