Louise Wickens usually works at a stables in England’s West Midlands, hiring out horses and dressing them as unicorns for children’s parties. With business closed for the lockdown, she’s turned her hand to planting vegetables at a nearby farm.

She’s just one of the locals being hired by fruit and vegetable farms as travel restrictions disrupt life for hundreds of thousands of migrant workers crucial at this time of year. With worries that there’ll be a shortage of labor — especially for upcoming harvests — growers and governments around the world are renting planes and rallying students, waiters and even prisoners to fill the gap.

“There’s plenty of jobs out there,” said Wickens, who’s helped seed runner and stringless beans and tend to young plants. “As they get further on into the season, there’s so much more work to do.”

Crops being left to rot in fields would further threaten the global food supply chain that’s seen runs on store shelves, meat shortages in America and dairy farmers dumping milk they can’t sell. Some European farmers have already had crops like asparagus spoiled since lockdowns began, and the United Nations is worried that foods from strawberries to peaches could go unharvested.

Unlike staple crops like wheat or corn, where harvesting is mechanized, fruit and vegetable picking is often done by hand, in long shifts out in the open — a typically undesirable job in major economies. That’s changing this year as people face layoffs or have more spare time. But many positions still remain unfilled, locals may not be as adept at the work as returning foreigners usually are, and the extra training costs could trickle down to grocery-store prices.

“There are more costs involved in finding new people and having them up and running, that’s the main problem,” said Cindy van Rijswick, a senior fresh-produce specialist at Rabobank.

In Canada, where 60,000 temporary foreign farm workers head each year, Quebec Premier Francois Legault said there’s been a flood of interest after appealing to the unemployed to head to fields, and reminisced about his own backbreaking, but “beautiful” experience picking strawberries as a youth.

Still, Patrice Riendeau is concerned locals won’t be up to the task at his celery, onion and lettuce farm outside Montreal. They’re not accustomed to the demanding jobs done in the heat by foreign workers from places like Mexico and Guatemala, many of whom return year after year. He plans to give easier tasks to locals, but the uncertainty is making it hard to plan.

“Do I do 50% less of the lettuce because I will only have people over given periods? Will I be able to harvest it all?” said Riendeau, who expects at best about half of the foreign workers he’d lined up to arrive. “It’s an incredible headache.”

Some Ontario vegetable growers are worried yields will drop 30% as farms struggle to fill roles, also feeding through to consumer costs, according to the Arrell Food Institute at the University of Guelph.

For now, the situation isn’t too dire in Europe. At least 1,500 Moroccans who reached Spain before the crisis were able to extend work permits, and the recruitment of unemployed locals is keeping farms staffed for now, said Jaime Martinez-Conradi, head of an association representing agricultural companies in Andalusia. The 80,000 foreign farmworkers allowed in Germany through May proved sufficient, and the U.K.’s April roles were filled, farmers unions said.

The pinch may come when harvesting of many crops starts in a couple of months.

Fresh produce supplier G’s still has two-thirds of its 3,000 seasonal U.K. positions to fill, and expects to attract about 500 locals, 10 times the normal amount, said Derek Wilkinson, managing director of its Sandfield Farms unit. Dependent on labor from eastern Europe, it’s teaming up with other farms to charter flights and bring in much-needed Romanian workers.

“People from those countries are experienced pickers,” Wilkinson said. “It’s really important to us that we get some of those returnees back.”

In Russia, where berry farms risk losing up to 40% of this year’s harvest, the government is also going to extra lengths by calling on students and convicts to fill the labor gap. Some 160 prisoners are already doing agricultural work in the eastern Primorsky region, and that may rise to 400, the Federal Penitentiary Service said.

The issue for farms is that many furloughed workers are often far from rural regions, and it could be a challenge to keep pickers once businesses reopen. U.K.-based recruiters including Pro-Force and Concordia have filled just a fraction of roles out of more than 50,000 applications.

Pub worker Bethany Barclay has been at the same farm as Wickens since early April, the two lone Brits alongside almost 30 eastern Europeans. While eager to pull pints again, she’s glad to be working outdoors and says it’s shifted her views on the food chain.

“I don’t think people appreciate the work that has to be put into it,” she said. “It’s a job that’s got to be done to keep the country going.”