Wednesday, April 17, 2024

North Carolina’s sweet success in the ‘tater trade

Today is Election Day and everyone is a little tense. So let’s talk about the sweet potato.

It is coming up on Thanksgiving in a few weeks, and many folks are thinking about Meemaw’s recipe with the marshmallows. The sweet potatoes you buy at the store likely come from North Carolina because our state is the leading producer in the U.S., and the industry here has been transformed by science and technology in the last 20 years.

The dominance of North Carolina’s sweet potatoes is an example of what happens when a lot of different players – university researchers, farmers, processors, and the state Ag Department – work together to achieve a common goal.

Agriculture and agribusiness bring in $92 billion annually in North Carolina, the largest sector in our state’s economy. Sweet potato production is a $350 million slice of that, according to N.C. State University economist Daniel Tregeagle, an extension specialist in specialty crops. But it is a profitable slice, with a net in the range of $1,000 an acre, compared to $100-200 for corn or soybeans, according to estimates he developed with a N.C. State colleague, Derek Washburn. Most of them are grown in Wilson, Johnston, Nash, Edgecombe and Sampson counties. Acreage has more than tripled since the late ‘90s.

A few innovations have been key: The development of a sweet potato known as the Covington, storage technology improvements, and something called micropropagation, all part of R&D in the agriculture and life sciences complex at N.C. State and NCSU and Ag Department research stations all over.

The Covington

In the 1990s, North Carolina’s sweet potato growers were dissatisfied with the variety that had been developed in Louisiana, called the Beauregard. It didn’t produce consistent results here.

“You could grow it on one side of the road and you could grow it on the other side of the road, on the same day,” said Jonathan Schultheis, an N.C. State researcher and extension specialist. “And the ones on one side of the road would look great and on the other side of the road wouldn‘t look very good.”

N.C. State scientist Craig Yencho, leader of the sweet potato and potato breeding program, was hearing the frustration from the farmers, and he and fellow researchers, including Ken Pecota, found a possible solution, from a breeding nursery more than 20 years ago at the Ag Department research station in Clayton.  The new sweet potato was known initially as NC98-608; They subsequently named it for Henry Covington, a longtime NCSU extension specialist who helped build the sweet potato industry here in the mid-20th century.

After a couple of years of trials, they knew they had something special.

Covingtons were all nearly the same shape and size. A restaurant getting Covingtons would have a pretty good idea how much room on a plate they would occupy. It looked good, tasted good, yielded nicely and stood up well to viruses and pests.  By the middle of the decade, it was rolled out to farmers, and replaced the Beauregard here.

Today, 90 percent of the sweet potatoes grown in North Carolina are Covingtons. It has become very popular in Europe, a hit in the United Kingdom and the Netherlands.  North Carolina sweet potato exports were around $1 million 20 years ago. Today, around $150 million is being exported annually, according to state Ag Department figures.

Helping to keep the variety strong is the Micropropagation Unit at N.C. State, which ensures that the plant material used to create successive crops of Covingtons is disease-free.  The unit was created in 1996 and soon came to the rescue of sweet potato farmers whose crops were being stunted by disease and unwanted mutations.


You can breed a better sweet potato, but getting it to market is a challenge.  A major breakthrough in logistics from the ingenuity of Mike Boyette, an N.C. State agricultural engineer, helped growers sell most of their crop.

Sweet potatoes are sensitive. They aren’t easy to store; they have to be kept at a certain temperature and humidity or they can go bad.  As a result, it was common for only 65% of the harvested potatoes to get shipped to packers. And it was seasonal because of storage challenges.

Boyette thought he found an answer after attending post-harvest training at the University of California, Davis, in the late 1980s. The summer workshop included a visit to a plum packing facility in the Central Valley. “It was an eye-opener,” Boyette recalled.

“I just could not imagine the level of technology that I was seeing out there on the floor.”

What particularly caught his eye was how the plums, stacked in large bins, were being uniformly cooled in the summer’s heat.  “They were moving air through them using a fan arrangement.”

He got his chance to test the concept here when a farmer from Benson, Tony Johnson, called asking for help. He had a building he wanted to use for sweet potato storage, and wanted to incorporate the latest tech. Boyette told him about his ventilation idea – basically fans that would keep cool air moving horizontally through containers all the way up to the ceiling, and sensors linked to a PC that collected temperature and humidity data. Johnson was game, and it worked. The system kept the sweet potatoes at the right temperature for months. You could fool them into thinking they were still underground, they’d go to sleep and not sprout and use up starch. They’d stay the sweet potato equivalent of buff.

And if you had sweet potatoes that kept for months, you could get sweet prices.

Word spread quickly.  “I was overrun by farmers interested in what we had done and how they could get a part of it,” said Boyette.

Today, one reason for North Carolina’s sweet potato dominance is its large-scale, climate-controlled storage.  “We’ve got 98% of the storage that’s in the United States,” said Boyette.

“We took this seasonal crop and we turned it into a crop that was available year-round.” Restaurants liked that.

Other advantages

What also helped build the sweet potato industry was tobacco.  In the counties of the Coastal Plain, North Carolina farmers grew it for generations in the sandy soil.  It is a labor-intensive crop, and the same workforce that planted and harvested tobacco was available for sweet potatoes.  The money that came from tobacco, particularly buyout money, helped finance much of the infrastructure that was needed to support the growth of sweet potatoes, said Boyette.

Boyette says that it is the growers who made the industry what it is today. Growers like Vick Family Farms in Wilson, Scott Farms in Lucama and Ham Farms in Snow Hill.

“They were the ones that had the skin in the game. They were the ones that invested millions and millions and millions of dollars.”

And farmers like the late Tony Johnson.  “There ought to be a historical marker down there in Benson where that building was built,” said Boyette, “because that was the first one that was done.”

(To hear more about this, listen to a recent Farms, Food and You podcast from N.C. State.)

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