The American vegetable landscape has shifted. Farmers are abandoning onetime basics such as sweet corn, green beans, peas and potatoes. In their place, they’re planting sweet potatoes and leafy greens such as spinach, kale and romaine lettuce.

Once every five years, the USDA Census of Agriculture provides a definitive guide to the trends behind the nation’s farms and diets. The latest figures, released last week, show broad dietary upheaval. In many cases, they show vegetables that may once have been dismissed as fads or trends are reshaping America’s agricultural landscape.

A newly popular potato

Cultivation of sweet potatoes increased by 47,257 acres or 37.6 percent from 2012 to 2017, by far the biggest jump of any vegetable crop. It’s more than the next two fastest-growing crops, romaine lettuce (up 22,780 acres) and spinach (up 23,592 acres), combined.

Why sweet potatoes? White flour, white potatoes and white rice have been vilified over the past decade for their easy digestion and high glycemic load. Sweet potatoes have fewer carbs and calories, as well as higher levels of vitamins A and C. They’ve been lauded by South Beach, Paleo and Atkins diet devotees. On upscale menus, they often replace the Idaho russet in fries or tots.

North Carolina leads the nation in sweet potato acreage, while romaine and spinach are concentrated in California. In some places, sweet potatoes may be a viable replacement for cash crops: Two of the five counties in North Carolina where tobacco acreage fell the most, the eastern counties of Wayne and Duplin, also saw large gains in sweet potatoes.

Leafy greens’ new deal

Dark, leafy greens have gone from trendy supplement to pillar of the agricultural establishment. Undaunted by high-profile foodborne illness scares like last year’s two E. coli illness outbreaks from contaminated romaine, farmers are leaning into leaves.

Baker Farms runs 4,000 acres in southern Georgia. This year, much of it will go to collards, turnip, mustard and kale.

“Kale used to be fourth in line,” marketing manager Tommy Collinsworth says. “Collards have been in the lead, but in 2019 kale will pass it. Over this year we’ll have 500 acres in kale, is my educated guess.”

Like many of the larger lettuce and greens farmers seeking to claw profits back from middlemen and processing plants, Baker Farms has embraced the bagged-produce revolution.

It has added a processing line and now offers one- and two-pound bags of kale or collards. The farm is working with a local chef on recipes for finished bagged salads, with dressings and additions such as croutons, nuts and dried fruit.

Souring on sweet corn

America’s second most-planted vegetable crop, sweet corn, lost 75,972 acres — a 13.3 percent drop. Other major losers included green beans, peas and potatoes. Peas and sweet corn fell furthest in California and Washington, while potatoes slid in Maine and North Dakota.

Hank Scott, of Long and Scott, producer of fabled Zellwood sweet corn in Mount Dora, Fla., explains why sweet corn farmers are rethinking their planting mix.

“The cost of farming is increasing so rapidly. It’s a tough business. People are looking for perfection, and we’re dealing with a lot of disease pressure.”

He says stores such as Walmart are putting family farms out of business, not just by playing hardball on prices but also by demanding year-round contracts. If a family farmer wants a contract with a big supplier but doesn’t produce corn all year long, they’re responsible for buying another producer’s corn to cover the grocery behemoth’s supply chain during their offseason, Scott said. (Walmart did not respond to a request for comment.)

Sweet corn shouldn’t be confused with the field corn common in states such as Iowa, Nebraska and Illinois. Field corn is destined to become animal feed or be processed into ethanol or foods like corn syrup and cornmeal.

The fall of limas

Green beans and peas suffered most in places where they’re primarily processed for canning or freezing. Acre-for-acre, the sharpest declines were in specialty crops such as chicory, lima beans and black-eyed peas.

Delaware has been a hotbed of lima-bean farming for decades. In Harbeson, Del., Ritter Family Farms once devoted a third of its 900 acres to limas. But the Ritters phased out the broad beans entirely this year after the nearby processing plant closed, Laura Ritter said. Fresh lima beans are too perishable to be widely sold at grocery stores.

The Ritters have pivoted to green beans and, following another growth trend, goat’s cheese and ice cream. To beef up her goat business, Laura Ritter runs Goat Joy, which offers goat yoga and goat socials.

The processing plant was a casualty of changing American tastes.

Emmalea Ernest, an extension associate for vegetable crops with the University of Delaware, says folks are eating fewer frozen and canned vegetables.

Ernest sees a dwindling number of processing plants as a further loss of safety net for farmers.

“The processing plants have given farmers an opportunity to diversify. Limas are a legume, a fairly robust plant from a disease-management perspective. You don’t want to put all of your eggs in one basket.”

Pest claims peas

Black-eyed pea acreage fell across the South. It has been popular in the region since it was brought from West Africa to feed enslaved people. Unlike limas’ fall from favor, though, this legume’s struggles are more a matter of pest management than changing tastes.

David Riley, a professor of entomology at the University of Georgia, works with vegetable pests like cowpea curculio, which has decimated the state’s black-eye pea fields. The common name cowpea stems from the vines’ use as cattle feed. Acreage peaked in 1937 and has ebbed and flowed since, this small weevil a near-constant threat.

“New World beans have natural resistance to the weevils we have in the Americas, but if you take an Old World bean like cowpeas, they don’t have that natural resistance,” Riley said.

He said that despite the pest there have been recent pendulum swings back the other way: Around 2010, when Southern cuisine became trendy in restaurants, black-eyed pea acreage increased.

“The small growers will continue to try. It’s frustrating, because there’s no current commercial solution," Riley said, although he anticipates further acreage shifts in Georgia and Tennessee. It’s a Darwinian necessity in a vegetable industry accustomed to upheaval.