![\"North](\"https:\/\/news.ncsu.edu\/wp-content\/uploads\/2019\/04\/sweet-potatoes-north-carolina.jpg\")
<\/a>Then, in 2005, breeders at NC\nState hit the jackpot. They came out with a sweet potato variety they called\nCovington, which had begun as a botanical seed in 1997 and progressed through\nyears of field trials. Within a few years, Covington was nearly all anyone grew\nin North Carolina. Year after year, from one field to another, it could be\ncounted on to produce a high percentage of what are known as \u201cnumber ones,\u201d\nwith the familiar shape, size and look to be sold in grocery stores and\nfarmers\u2019 markets. By 2017, the amount of sweet potatoes grown in North Carolina\nhad nearly doubled and the state had reclaimed its place as the leading\nproducer of sweet potatoes in the United States. Jim Jones, who grows about\n1,500 acres of sweet potatoes in Nash County, says Covington was \u201cthe best\nthing that\u2019s happened in the sweet potato business.\u201d <\/p>\n\n\n
The combined efforts of NC State\nresearchers, professors and extension agents, working closely with farmers and\nan engaged trade group, have transformed sweet potatoes into a year-round\neconomic powerhouse that is now shipped from North Carolina to Europe and other\ncorners of the globe. Some farmers have described it as a perfect example of\nthe work that a land-grant university such as NC State should do. \u201cWe just\ncouldn\u2019t operate without NC State,\u201d says Pender Sharp \u201971, a fifth-generation\nfarmer in Sims, N.C., about an hour\u2019s drive east of Raleigh.<\/p>\n\n\n
But that\u2019s only part of NC\nState\u2019s sweet potato story.<\/p>\n\n\n
Half a World Away<\/h2>\n\n\n
Craig Yencho is crouching in a field of sweet potatoes in\nthe remote northwest corner of Uganda, not far from a massive tent camp that is\nhome to thousands of refugees from South Sudan. He has driven more than seven\nhours from Kampala, the country\u2019s chaotic capital city, across the Nile River\nand past a pack of wild baboons and a couple of wandering elephants to get to a\nresearch farm in the town of Arua. He is struggling with a stick to dig into\nthe dirt, which has been baked rock hard by the unforgiving equatorial sun and\nthe delayed onset of the rainy season. What he finally pulls out of the ground\nis a scrawny excuse for a sweet potato. It is also riddled with holes that are\nsigns of weevils, a small but pervasive pest that can wipe out a crop.<\/p>\n\n\n Yencho, a William Neal Reynolds\nDistinguished Professor and leader of NC State\u2019s sweet potato and potato\nbreeding and genetics program, was one of the masterminds behind Covington, the\nvariety now grown throughout North Carolina. He also leads an effort, fueled by\na $12 million grant from the Bill and Melinda Gates Foundation, to bring\nmolecular science to sweet potato breeding programs in Uganda and a handful of\nother sub-Saharan countries in Africa. His ultimate goal is twofold\u2009\u2014\u2009to use\nsweet potatoes to increase economic opportunities and to get sweet potatoes\u2019\nnutrients into the bellies of children and pregnant women who suffer from such\nserious vitamin A deficiencies that they are in danger of going blind.<\/p>\n\n\n Sweet potatoes are already a\nstaple of the diet for many families in Uganda, who eat them steamed in banana\nleaves or simply boiled, sometimes with every meal. But most of the sweet\npotatoes grown in Africa would be unfamiliar to American consumers. Instead of\norange, they have white, cream-colored or yellow flesh, and are not as sweet or\nsoft as their American cousins. They also don\u2019t have all the nutrients found in\norange-fleshed sweet potatoes.<\/p>\n\n\n But changing consumer preferences may be the easy part of Yencho\u2019s challenge\u2009\u2014\u2009early promotional efforts touting the health benefits of orange foods such as sweet potatoes and mangoes have created some converts. \u201cKids are attracted by the orange color,\u201d says Robert Mwanga \u201901, Ph.D, a Ugandan scientist who won the World Food Prize in 2016 for his pioneering work to promote orange-fleshed sweet potatoes in his country. \u201cAlso, the softer the food is, the better it is for kids. It\u2019s easier for them to eat.\u201d <\/p>\n\n\n The bigger challenge is breeding new varieties of orange-fleshed sweet potatoes that can be grown in Uganda. Weevils take advantage of dry, cracked soil brought on by drought (and a lack of irrigation) to burrow their way into growing sweet potatoes, and wipe out more than 70% of the crop in most years. \u201cEverywhere that sweet potato is grown [in Uganda], you will find weevils,\u201d says Mwanga. And orange-fleshed sweet potatoes, which typically have less starch and are therefore less dense than most of the sweet potatoes grown in Uganda, are softer and easier for weevils to burrow into. \u201cWe still have a long way to go,\u201d Mwanga says, \u201cto get something that farmers can leave out in the field and not worry about the weevil.\u201d<\/p>\n\n\n As insurmountable as the\nchallenges may seem, Yencho is undaunted. He laughs when he is asked during a\nvisit to Uganda and Kenya last year if it feels like he is forever pushing a\nheavy rock up a steep hill, like a modern-day, gray-haired Sisyphus. \u201cYeah, it\ncan feel like that sometimes,\u201d he says. But Yencho prefers a different outlook,\none that reflects an optimism dating back to his wanderlust days as a young\nPeace Corps volunteer in St. Kitts and Nevis. <\/p>\n\n\n It is an optimism that focuses less on the big picture in favor of countless small victories. It takes into account the Ugandan breeders he has trained (such as Mwanga and Benard Yada \u201914, Ph.D., who runs the government\u2019s sweet potato research efforts) as graduate students at NC State. It takes into account the scientists he works with on a bucolic research campus in Nairobi, Kenya, to develop a program using advanced molecular breeding techniques that will help sweet potato farmers in Africa, North Carolina and elsewhere. It takes into account home-grown entrepreneurial efforts he has seen in Africa that embrace the economic and health benefits that come with orange-fleshed sweet potatoes.<\/p>\n\n\n \u201cI like to think in terms of\npebbles,\u201d Yencho says, \u201cand how a pebble tossed into a pond creates ripples.\u201d<\/p>\n\n\n He sees some of those ripples\nduring his visit to the farm in Arua, where researchers have been working with\nsweet potatoes for only three years. \u201cThe field looks beautiful,\u201d he says as he\nsurveys the scene with Yada and a group of Ugandan breeders traveling with him\nand some of the farm staff. \u201cThe rows are well laid out. Your weed management\nis really exceptional.\u201d He detects what he calls \u201cdrought damage,\u201d but wonders\nabout other damage to the crops. \u201cThat\u2019s goat damage,\u201d someone tells him. \u201cSay\nwhat?\u201d Yencho asks. \u201cGoat damage,\u201d he is told again. Yencho laughs. \u201cI\u2019m an\nanimal lover,\u201d he says, \u201cso that\u2019s OK.\u201d<\/p>\n\n\n Ken Pecota is crouching in a field of sweet potatoes on a\nresearch farm in Clinton, N.C. A flap on his cap protects his neck from the sun\nas he works his way down dusty rows to check on several varieties being tested.\nPecota, a sweet potato researcher and breeder at NC State, was also one of the\nbreeders behind Covington. It was clearly the signal achievement of his career,\nbut he is determined to develop other varieties that will find their way into\nfarmers\u2019 fields. Some are for niche markets, such as organics, while others are\nmore suitable for processing into fries, chips or other uses. And there are no\nguarantees that problems won\u2019t eventually develop with the Covington breed. <\/p>\n\n\n \u201cIf you\u2019re ever satisfied as a\nbreeder, you need to retire,\u201d he says. \u201cThere\u2019s always something you can make\nbetter.\u201d<\/p>\n\n\n The varieties he\u2019s testing today\nhave already shown some promise, but there are far more tests to be done before\nany conclusions can be reached. They sit on top of the dirt, having been dug up\nearlier, and Pecota is conducting the most basic tests before the potatoes are\nsent to the lab for further analysis. \u201cSee, this guy rotted,\u201d he says as he\ngrabs a sweet potato. \u201cThat\u2019s not a good sign.\u201d But he also notes some positive\nsigns: \u201cThey\u2019ve got good uniformity, right? They\u2019re all kind of the same shape.\nThere\u2019s a nice lightness, a really nice finish to it. The skin texture is\nbeautiful.\u201d He slices into some of the sweet potatoes and takes a bite, and\nestimates the amount of starch (an important consideration for varieties bred\nprimarily for processing into fries or chips). \u201cI know that one\u2019s got a medium\nstarch,\u201d he says at one point.<\/p>\n\n\n If you\u2019re ever satisfied as a breeder, you need to retire. There\u2019s always something you can make better.<\/p><\/div><\/blockquote>\n\n\n The practiced ease with which\nPecota approaches his work masks the fact that it is incredibly difficult to\nbreed sweet potatoes, be it in North Carolina or in Africa. It\u2019s easy enough to\ncross two different varieties of sweet potatoes and come up with a new,\ndistinctive variety\u2009\u2014\u2009as long as you don\u2019t care too much about how it turns\nout. Sweet potatoes have a much more complex genetic makeup than most\nvegetables, fruits and grains. Sweet potatoes are a hexaploid, which means they\nhave six sets of chromosomes.<\/p>\n\n\n So it\u2019s difficult to get the\ndesired mix of traits. NC State\u2019s breeders track 45 different\ntraits\u2009\u2014\u2009resistance to disease, drought tolerance, shape, color and size, to\nname just a few\u2009\u2014\u2009in the sweet potato varieties they work with. It takes years\nof trial and error to test new varieties, and the overwhelming majority end up\nhaving some sort of fatal flaw that makes them ill-suited for farming or\nprocessing. Yencho and his team start every year with 60,000 new varieties,\nknowing that most of them will fall short at some point during seven (or more)\nyears of field tests. At times, the process can seem downright cruel\u2009\u2014\u2009a couple\nof years after releasing Covington, Yencho and Pecota released another variety\nnamed Hatteras that had performed well in all the field tests. But after\nfarmers started planting it, Hatteras developed something called internal\nnecrosis, which creates brown flecks in the flesh. Within two years, no one was\ngrowing Hatteras. Pecota was once curious about just how difficult his job was,\nand calculated that there is as much as a one-in-two million chance of breeding\na sweet potato that satisfies the criteria they try to meet.<\/p>\n\n\n \u201cIf you look at that number, \u201c\nPecota says, \u201cyou\u2019ll say, \u2018That\u2019s it, I quit.\u2019\u201d <\/p>\n\n\n Pecota is joking. As a kid in\nsuburban New Jersey, he loved working on puzzles of all sorts\u2009\u2014\u2009jigsaw, word,\nnumber\u2009\u2014\u2009and he brings that same passion to his work as a breeder. \u201cThat\u2019s\nexactly what breeding is,\u201d he says. \u201cIt\u2019s a big puzzle.\u201d<\/p>\n\n\n STARTING:<\/strong> Sweet potatoes are not started from seed. Instead, they are grown from vine cuttings that are called sprouts or slips. Some farmers start their sprouts in greenhouses, but others grow sprouts by \u201cbedding\u201d small sweet potatoes in March. Whole sweet potatoes are put on top of the ground and then covered with a thin layer of soil and plastic.<\/p>\n\n\n TRANSPLANTING:<\/strong> Sprouts are cut and transplanted\u2009\u2014\u2009either from a greenhouse or \u201cbedding\u201d field\u2009\u2014\u2009to another field in May and June.<\/p>\n\n\n GROWING:<\/strong> It takes 90\u2013120 frost-free days to grow a sweet potato. They grow under the ground.<\/p>\n\n\n HARVESTING:<\/strong> The harvesting of sweet potatoes typically starts in August. Tractors are used to flip them on top of the ground and then, because the thin skin can be easily scarred, they are harvested by hand. They are graded and sorted according to their size.<\/p>\n\n\n CURING:<\/strong> Most sweet potatoes are cured for 4\u20137 days at 80\u201385 degrees so that they can then be stored for up to a year at 55 degrees with 85\u201390% humidity and adequate ventilation.<\/p>\n\n\n Efforts are further complicated\nby the sweet potato\u2019s status as what is considered an \u201corphan crop.\u201d Unlike\ncrops like corn, wheat and rice, there have been no big corporations involved\nwith sweet potatoes, which has historically been considered a subsistence crop\nfor poor people. That means no corporate dollars for research and technology,\nand it is why sweet potatoes lag behind other crops when it comes to the\nlatest, molecular-based breeding programs. \u201cSweet potatoes are\nunder-researched,\u201d says Mercy Kitavi, a molecular breeder who works in Kenya\nwith the program Yencho is leading. \u201cWhen you look at the complex genetics of\nsweet potatoes, everybody is like, \u2018Not me.\u2019 We don\u2019t know the answer to\nseemingly simple questions like the genetics of beta carotene.\u201d<\/p>\n\n\n Kitavi is working with Yencho and\nothers to correct that. Her labs are housed on a research campus that is fenced\noff from the chaos and poverty that abounds in Nairobi. Here, she spends her\ndays extracting the DNA from sweet potato varieties, which is then sent to NC\nState\u2019s Genomic Sciences Laboratory to be sequenced. It is all part of an\neffort to develop a set of genetic markers that could be used to bring more\npredictability to the process. Such knowledge could be used, for example, to\nreduce the 60,000 new varieties that NC State\u2019s program starts on the testing\nregimen each year to as few as 10,000\u201312,000. That\u2019s less time and money spent\non the front end, and a greater likelihood of positive results. \u201cWe need to\nspeed up variety development,\u201d Yencho says.<\/p>\n\n\n In part, that\u2019s because there is\nnot likely to be just one variety\u2009\u2014\u2009like Covington in North Carolina\u2009\u2014\u2009that\nwill be the answer to the varying conditions throughout Africa. \u201cCovington\nwouldn\u2019t work in Africa,\u201d Yencho says. \u201cYou have to breed African varieties in\nan African context.\u201d<\/p>\n\n\n In Uganda, virtually everyone is a farmer. Dried sweet\npotatoes\u2009\u2014\u2009none of them orange\u2009\u2014are readily available from roadside vendors.\nYencho\u2019s team stops at one point on the highway from Soroti to Kampala to talk\nwith a group of women selling buckets of dried sweet potato slices for 5,000\nUgandan shillings a bucket\u2009\u2014\u2009that\u2019s about $1.33. The women, joined by their\nchildren and husbands, lead the visitors into their cluster of a half dozen\nhuts to show off a large rock embedded in the ground\u2009\u2014\u2009it is where they dry the\nsweet potatoes grown in a small plot nearby. (It is also, they say while\npointing to an indention in the rock, a place where Jesus once stood.)<\/p>\n\n\n Mwanga, who led the early push for orange-fleshed sweet potatoes in his country, estimates that roughly 90% of households have their own farm, which may be no more than a half-acre. That\u2019s 2 million households. Compare that to North Carolina, where fewer than 400 farmers grow sweet potatoes, and most of them are part of a commodity group that works with the university and shares information. Extension agents spread throughout the state make it relatively easy to spread the word of new developments or problems for sweet potatoes. In Uganda, there are more than 50 different languages spoken. That means there are more than 50 different ways to say sweet potato, from \u201cacok\u201d in Ateso, the language spoken by the people showing off their drying rock, to \u201cmaku\u201d in Lugbara. Communication is difficult at best.<\/p>\n\n\n Bonny Oloka \u201918, Ph.D., finished his graduate work with Yencho last year and returned to Uganda to work as a sweet potato breeder. He never ate orange-fleshed sweet potatoes growing up in Kampala, and says the challenge of replacing other sweet potatoes in his country is great. \u201cEvery region you go to you will find completely different people,\u201d he says. \u201cThe language is different, the cultures are different, the foods are different.\u201d<\/p>\n\n\n But Oloko, who was trained as a\nbiochemist, chose to go into breeding because he believes in the power of food\nto improve the health of his fellow Ugandans. \u201cI think it\u2019s attainable,\u201d he\nsays, \u201cbecause 15 years ago there was almost no orange-fleshed sweet potato in\nUganda. I didn\u2019t have it. My parents could not get it. But now we know where to\nget it.\u201d<\/p>\n\n\n Likewise, Sadik Kassim, director of research at the government farm in Arua, says there is plenty of interest in orange-fleshed sweet potatoes in his region along the Nile River. He estimates that 15% of the households in the region\u2009\u2014\u2009compared to 5% in the rest of the country\u2009\u2014\u2009grow and eat orange-fleshed sweet potatoes. \u201cWest Nile is where sweet potato can make a difference,\u201d he implores Yencho during a meeting before heading out into the fields. \u201cOur market is there. Our problem is if we can produce a supply of good and clean vines [for growing sweet potatoes].\u201d<\/p>\n\n\n Yencho appreciates the sentiment,\nbut points out some of the region\u2019s challenges, including a lack of irrigation\nand storage capacity for harvested sweet potatoes. \u201cThis district has been\nignored,\u201d he says. <\/p>\n\n\n While they are not as obvious as the success that farms in\neastern North Carolina have had with sweet potatoes, encouraging signs can be\nfound throughout Africa. Jan Low, an agricultural economist who has promoted\nthe health benefits of orange-fleshed sweet potatoes throughout Africa, says\nRwanda, Malawi and Mozambique have all seen an increase in the consumption of\norange-fleshed sweet potatoes. \u201cThose are all very important countries that\nhave significant vitamin A deficiency problems,\u201d Low said during a visit to the\nresearch campus in Nairobi. <\/p>\n\n\n One such success story can be found in downtown Nairobi, on the second floor of a nondescript building on a crowded street. Inside, Magnaghi is at work in his bakery, where he makes sweet potato muffins for some of the top hotels in the country, and is trying to develop sweet potato fries for Kenya\u2019s largest chain of coffee shops. <\/p>\n\n\n Magnaghi describes himself as a\n\u201cfood application specialist,\u201d but he is an entrepreneur at heart. He has\nworked in Italy, Australia and Rwanda, but was excited to return home to Kenya\nto explore the possibilities of sweet potatoes. He says that Kenyan consumers share\nhis excitement, but that he struggles to get enough orange-fleshed sweet\npotatoes for his many projects. \u201cPeople are buying it because of the health\nreasons,\u201d he says. \u201cAnd then also because it\u2019s a nice orange. It\u2019s bright and\nit attracts a lot of people.\u201d Yencho tells him that in North Carolina sweet\npotatoes are being used in beer and that sweet potato syrup is being used as a\nsubstitute for honey. \u201cOh, that I would like to visit,\u201d Magnaghi says. <\/p>\n\n\n Several days later, while in\nUganda, Yencho sees another success story in a small village outside of\nKampala. After driving down a winding, deeply rutted dirt road, Yencho meets\nSekiyanja Joweria, who runs the Bagya Basaya (O.F.S.P) Potato Growers and\nProcessors cooperative. The office is a small, plain building with large metal\ndoors and a handful of plastic chairs. Around the back is a single, makeshift\ngreenhouse for growing sweet potato vines. The cooperative, run by 100 women,\nsells orange-fleshed sweet potato vines to farmers and mills sweet potato flour\nthat can be used to make pancakes, donuts and bread. Joweria does not speak\nEnglish, so a translator helps as she shares her story. <\/p>\n\n\n The cooperative started more than\n30 years ago and, initially, grew only white-fleshed sweet potatoes. But after\nan international health organization found that several children in the village\nwere malnourished, they were convinced to switch to orange-fleshed sweet\npotatoes in 1998. \u201cWe found a lasting solution,\u201d she says. \u201cWe started seeing\nimprovement.\u201d<\/p>\n\n\n There is an entrepreneurial spirit … and a vibrancy that is beginning to emerge.<\/p><\/div><\/blockquote>\n\n\n Joweria leads Yencho to a nearby\nfield of sweet potatoes, where they compare notes on growing and harvesting\ntechniques. As is true at farms throughout Uganda, most of the work is done\nwith little more than hands and hoes. The cooperative has been a financial\nsuccess, enabling the village to pay the school fees for 15 children to go off\nto college. Joweria\u2019s son graduated with a degree in agriculture and her\ndaughter is studying journalism.<\/p>\n\n\n While poverty is evident\nthroughout Africa, Yencho says a closer look reveals opportunities such as\nthose found in a small urban bakery or a rural Ugandan village. \u201cThere is real\nsignificant poverty here,\u201d he says. \u201cBut if you start to peel that away there\nis an entrepreneurial spirit. There is an emerging middle class and a vibrancy\nthat is really beginning to emerge.\u201d<\/p>\n\n\n For all of Covington\u2019s success, there was never one moment\nwhen Yencho and Pecota felt it was appropriate to pop the champagne corks. They\nhave a patent on Covington, which is described in the legal documents as an\n\u201cinvention,\u201d and NC State licenses it to be grown in North Carolina and other\nparts of the country (and even a few other nations). The licensing generates\nrevenue that is used to cover the cost of the university\u2019s breeding program.\nBut in some ways Covington\u2019s success just sort of happened, over time, until it\nsimply became accepted that it was North Carolina\u2019s sweet potato.<\/p>\n\n\n But the success is apparent at the farms where it is grown. At Scott Farms in Lucama, N.C., the fifth generation now farms 12,000 acres in five counties. In a gleaming industrial space, computers direct the packing of 40,000\u201350,000 pounds of sweet potatoes an hour\u2009\u2014\u2009every week of the year\u2009\u2014\u2009to ship to U.S. and foreign markets. About 85% of the sweet potatoes are sent to fresh markets, while the remaining 15% is sold to processors\u2009\u2014\u2009a far cry from the days when some farmers dumped as much as 30% of their crop in the woods because the potatoes were too big or too small or otherwise unfit. \u201cWhatever is in that bin is used for something,\u201d co-owner Dewey Scott told a group of researchers and breeders visiting last year from Africa, South America and elsewhere.<\/p>\n\n\n At Vick Family Farms, warehouses\ncan store more than a half million bushels of sweet potatoes and about half of\ntheir sweet potatoes are exported to Europe, something that would have been\nunimaginable two decades ago. \u201cAll the stars lined up,\u201d says Jerome Vick. \u201cWe\nhave a good variety, good storage conditions, a year-round supply and we could\ngo back after those markets we lost.\u201d<\/p>\n\n\n It’s a better potato now.<\/p><\/div><\/blockquote>\n\n\n And farmers are finding creative\nways to market their sweet potatoes. Yamco, a company in Snow Hill, N.C.,\ndistills Covington Gourmet Vodka, which has won top awards competing against\nvodkas from around the world. Carolina Innovative Food Ingredients, a company\nin Nashville, N.C., makes sweet potato juice and dehydrated sweet potatoes that\ncan be used in baked goods, beverages and sauces like ketchup and syrup. The\nSharps, who grow about 500 acres of sweet potatoes and raise hogs, had the help\nof NC State food scientists to develop a sausage infused with sweet potato\njuice, sweet potato puree and chunks of sweet potatoes. It is served, among\nother places, in Fountain Dining Hall at NC State.<\/p>\n\n\n \u201cIt\u2019s a better potato now,\u201d Alan\nSharp says. \u201cTwenty-five years ago, it wasn\u2019t very good, it was dry and\nstringy.\u201d<\/p>\n\n\n Some even say sweet potatoes are\ntrendy. Kelly McIver, executive director of the N.C. Sweet Potato Commission,\nnotes that sweet potatoes are now found on the menus of high-end restaurants. One\nof the appetizers served at a wedding reception she attended last year combined\nsweet potatoes with goat cheese and a pimento. \u201cIt\u2019s a sexy food,\u201d she says.<\/p>\n\n\n<\/a><\/a><\/a><\/a>It Takes Time<\/h2>\n\n\n
<\/a>Life cycle of a sweet potato<\/h4>\n\n\n
<\/a>Cultural Differences<\/h2>\n\n\n
<\/a><\/a>Sweet Success<\/h2>\n\n\n
<\/a><\/a>Nothing Wasted<\/h2>\n\n\n
<\/a>