Tara P. Smith and Don LaBonte

Change is going on in the sweet potato industry. The variety Beauregard, released by the AgCenter in 1987 and hailed as one of the best and most popular sweet potatoes, is being replaced in part by two new varieties – Evangeline, released by the LSU AgCenter in 2007, and Covington, a 2005 release from North Carolina. Sweet potato consumption in the United States is increasing – a dramatic 13 percent from 2006-2008. Likewise, exports of U.S. sweet potatoes are rising. There was nearly a three-fold increase over the past decade, from $8.3 million to $31.3 million. And the technology is rapidly changing. New advances in packaging and preserving sweet potatoes offer expanded marketing opportunities.

Not Just for Thanksgiving

Finally, people are beginning to realize that sweet potatoes aren’t just for Thanksgiving. These tasty roots are a nutritious treat to be enjoyed year-round. An increasingly health-conscience public, combined with value-added product diversity, is bringing the once lowly sweet potato to a respected and reserved place on everyday menus. Only 10 years ago, it was rare to be offered a sweet potato as a side option with your steak; now, many fine restaurants across thecountry offer sweet potatoes on the menu. What about those sweet potato fries you had with your fish last night or the yam and black bean wraps you had for lunch last week? Sweet potatoes may not be everywhere, but they are more accessible than ever before. Value-added product development, such as the burgeoning sweet potato fry, is driving much of the new-found fame of the sweet potato. Producers are beginning to understand that they can make a sizable return by supplying the processing industry with bulk sweet potatoes as an adjunct to their domestic fresh market and growing export business.

Profitable But Precarious    

Though prices remain solid in the sweet potato industry, production costs have soared with the increased costs of fuel and fertilizer. In the past, a field lost to low yield, insect damage, disease or weed infestation could be easily compensated by other acreage. A large-scale farmer can still do this, but a small-scale farmer can’t. We are optimistic that those remaining in the business are here to stay, but total acreage in the state has not risen in several years.

Sweet potatoes are one of the most profitable crops to grow in Louisiana. All growers have experienced fields each and every season that produce amazing yields of attractively shaped roots, if only they could consistently repeat this on more of their acreage.

Producers have high expectations every season. What they want is a uniform crop consisting of the prized U.S. #1 grade at $13.50-$20 for a 40-pound box and few small and oversized grade roots (jumbos). What they lack is predictability. This can be seen on individual plants, which vary in the number of storage roots from none to four or more per plant. This also extends to entire fields, which vary in yield by up to half in a given season. Growers are both comforted and confounded by the indeterminate nature of the sweet potato. It can withstand adverse environments and resume growth once favorable conditions return. Unfortunately, a delay in harvest permits U.S. No.1 grade roots to oversize into the less desirable jumbo grade, and there’s more time for insect damage and the accompanying rise in insecticide costs.

Research Breakthroughs  

The LSU AgCenter conducts a comprehensive research program on cultural practices with emphasis on early season management of the sweet potato crop. This knowledge is delivered to the growers through the AgCenter’s extension education program. Growers are beginning to understand how critical early season management of the crop is. Soil moisture, fertility regimes and transplant characteristics can all improve production efficiency and enhance profitability, if managed correctly.

The LSU AgCenter sweet potato breeding program continues to look for high-yielding, attractive, disease- and insect-resistant varieties, which also taste good. Can the fresh market accept a sweet potato variety with a durable and rough skin that could be harvested with less labor? We know the processing industry would welcome this. Is it possible to reduce pesticide use and loss by modifying postharvest handling and use of resistant varieties?

Virus and disease research, in conjunction with the virus-tested foundation seed program, allows producers to maintain healthy planting stock and viable on-farm seed programs, which are critical to a successful sweet potato operation.

Insect management research and the sweetpotato weevil trapping and spray program conducted by the Louisiana Department of Agriculture and Forestry continue to be of immense help to the sweet potato industry. The sweetpotato weevil is successfully being managed in south Louisiana and has not been a severe threat to the industry in several years. Research on other problematic pests, such as the sugarcane beetle and white grubs, is ongoing.

In addition, there are sweet potato research programs in food science, post-harvest physiology, weed science and value-added product development.

Prosperity and Hardships  

The Louisiana sweet potato industry has experienced both prosperous and trying times throughout its history. Weather-related disasters, insect outbreaks, disease issues, struggling markets and variety decline have all threatened the integrity of the industry at various times. Yet, the industry has always prevailed. Sustaining the industry along the way has been the work of a diverse group of LSU AgCenter research and extension personnel. Their goal has been to improve production and pest management of the crop and address what really matters, the bottom line.

Because of the LSU AgCenter’s diligent research and extension programs, because of health-conscience consumers and their desire for more sweet potatoes in their diets, and because of new value-added products, the future of Louisiana’s sweet potato industry looks bright. We can truly say the sky’s the limit.

Tara P. Smith, Assistant Professor and Coordinator, Sweet Potato Research Station, Chase, La.; and Don LaBonte, Professor, School of Plant, Environmental & Soil Sciences, LSU AgCenter, Baton Rouge, La.

(This article was published in the spring 2009 issue of Louisiana Agriculture.)