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North Carolina is the nation’s top sweetpotato producer. The state’s growers produce 600 million pounds of sweetpotatoes annually, nearly half the sweetpotatoes produced in the U.S. In 2010, sweetpotatoes were worth more than $173 million to the state’s growers. Agricultural research and extension programs in the College of Agriculture and Life Sciences at N.C. State University have played a significant role in making North Carolina the top sweetpotato producer.

Research and Extension Programs

Wireworm War. Wireworms, which live in the soil and feed on sweetpotato roots, are the number one insect enemy of sweetpotato growers. Left uncontrolled, these insects can cause devastating yield reductions. Prior to 2006, wireworm management strategies relied almost exclusively on multiple applications of high-risk foliar insecticides targeting wireworm adults before they laid their eggs in the soil. But the treatments didn’t kill wireworms below ground, and adults don’t feed above ground, so the practice was ineffective. Nevertheless, growers were compelled to spray because of the high value of the crop and the high probability of wireworm damage. Researchers in the Department of Entomology developed new insect management practices that are saving North Carolina sweetpotato growers nearly $250,000 annually while also reducing the amount and impact of pesticides released into the environment. A novel pest management strategy was developed that targeted the tobacco wireworm based on the insect’s biology and habits in sweetpotato. This strategy combines a single pre-plant soil insecticide application with one insecticide application directly to the soil during the growing season. The environmental impact quotient (EIQ) is a measure of a pesticide’s potential negative impact on the environment; the higher the EIQ number assigned to a material, the higher the risk. The combined EIQ for the three foliar insecticides typically used on sweetpotatoes is 71.5. The EIQ of the new, two-part soil insect management program is 5.4. The reductions seen in high risk pesticide use resulted directly from research and extension activities conducted by faculty in the Department of Entomology and represent a reduction in the environmental impact of sweetpotato pest management. This pest management strategy has reduced costs and improved insect control and yields.

Sweetpotato puree. Continuous-flow microwave heating technology developed in the College of Agriculture and Life Sciences is being used at a plant in Snow Hill to process sweetpotatoes and produce sweetpotato puree. The technology, which was licensed from N.C. State University, produces a product that is shelf stable without refrigeration. The technology will also be used at a plant in Halifax to process fruits and vegetables.
– read more about Yamco in Snow Hill –
– read more about Empire Foods in Halifax –

Breeding better sweetpotatoes. More than 90 percent of the sweetpotatoes planted in North Carolina are a variety called Covington that was developed in the College of Agriculture and Life Sciences. Covington, which was released and became available to growers in 2005, accounts for 20 percent of the sweetpotatoes grown nationwide. In addition to high yield, Covington has superior storage life and has become the sweetpotato of choice for the lucrative export market dominated by North Carolina growers. Ornamental sweetpotatoes, which are popular in the ornamental industry and sold at garden centers, have also been developed at N.C. State, while breeders are also developing “industrial sweetpotatoes” that could be used to produce bio-based products such as biofuels.
– read more –

Sweetpotato micropropagation. Micropropagation, or propagating sweetpotatoes from microscopic cuttings from a sweetpotato vine under sterile laboratory conditions, produces seed roots without the viruses, fungi and bacteria that can infect plants and reduce yields and root quality. The Micropropagation Unit with the North Carolina sweetpotato industry to provide growers with seed roots that are free of disease and true to type, or maintain the characteristics of a particular cultivar.
– read more –

Sweetpotato storage. Dr. Mike Boyette developed a method of controlling temperature and humidity in sweetpotato storage buildings that allows growers to store their sweepotatoes longer. Long-term storage is an advantage because it allows growers to sell their sweetpotatoes when they want. They can take advantage of market windows when prices are higher.
– read more –

College of Agriculture and Life Sciences faculty members whose work focuses on sweetpotato

Crop Management
Dr. Jonathan Schultheis, Professor of Horticultural Science
264 Kilgore Hall
Box 7609
Raleigh, NC 27695-7609
919-515-1225 or

Crop Breeding
Dr. Craig Yencho, Professor of Horticultural Science
214A Kilgore Hall
Box 7609
Raleigh, NC 27695-7609
919-513-7417 or

Dr. Ken Pecota, Researcher
214 Kilgore Hall
Box 7609
Raleigh, NC 27695-7609
919-515-1205 or

Dr. Bryon Sosinski, Associate Professor of Horticultural Science
272 Kilgore Hall
Box 7609
Raleigh, NC 27695-7609
919-513-3883 or

Insect Management
Dr. Mark Abney, Assistant Professor of Entomology
Research Annex West, Ligon Road
Box 7630
Raleigh, NC 27695-7630
919-515-2745 or

Micropropagation Unit
Dr. Zvezdana Pesic-VanEsbroeck, Micropropagation Unit Director
Box 7616
Raleigh, NC 27695-7616
919-515-7781 or

Soil Fertility
Dr. Carl Crozier, Professor of Soil Science
Vernon G. James Research and Extension Center
207 Research Station Road
Plymouth, North Carolina 27962
252-793.4428, ext. 134 or

Dr. Mike Boyette, Philip Morris Professor of Biological and Agricultural Engineering
Room 111, David S. Weaver Laboratories
Box 7625
Raleigh, NC 27695-7625
919-515-6790 or

Weed Management
Dr. Katie Jennings, Research Assistant Professor, Horticultural Science
124 Kilgore Hall
Box 7609Raleigh, NC 27695-7609
919-515-1224 or