Don La Bonte, Christopher Clark, Tara Smith and Arthur Villordon

We can’t help it. When we go to the grocery store, we always take a bee line to the produce section to check out the sweet potatoes. Chances are someone is there picking up a couple of roots for dinner. Consumption has more than doubled and then some in a few short years. There are lots of changes, too. There’s not just one variety. Now, several are offered with white, orange and purple flesh and all with differing flavor profiles. Value-added, consumer-friendly sweet potato products continue to increase and are helping to fuel increased consumption. Sweet potato soup, canned products, chips, crackers, drinks and the ever-popular sweet potato fries in the freezer section are all popular options, and each one of these products can require a unique variety.

Success was a long time coming. It wasn’t until the early 1930s, on the LSU campus, that professor J.C. Miller discovered how to get a sweet potato plant to flower and set true seed. He found that the simple step of trellising sweet potato vines up a fence stressed the vines and encouraged them to flower. This was the start of something special. Prior to this discovery, which revolutionized sweet potato breeding programs, sweet potato producers relied on the Porto Rico variety. Though orange-fleshed and sweet, especially in comparison to varieties grown in other parts of the country during this time, the variety was susceptible to just about every disease, erratic in yield and, in short, a real challenge for growers to produce a crop with decent yield and quality.

Miller’s basic technique of trellising vines and allowing bees to cross-pollinate flowers on different parents has remained a constant. A proven formula is to identify a source of resistance to a given disease and then move this trait into other parents until most of the parents in a crossing nursery have resistance. With this process, chances are good that the progeny are also resistant. Early on, the two big disease hurdles were Fusarium wilt and soil rot. Having resistant varieties for these two diseases revolutionized the industry and resulted in increased yields and profitability for growers.

Those early successes were transformational; however, today we continually identify new diseases and traits we need to address. Nothing ever is removed from the list, but new ones are added. Our most recent challenge is the guava root-knot nematode, a recent pest from Asia. It is not yet an established local pest. However, it takes breeding programs many years to identify resistance and develop a variety that meets expectations of growers and consumers. This forward-thinking approach ensures that we are prepared and have resistant varieties ready if the pest becomes established in our region.

One constant with the sweet potato breeding program is the demand for varieties with superior yield and quality. Sweet potatoes are an expensive crop to produce. However, they are a profitable crop when environmental and pest management issues cooperate. Sweet potato producers face many challenges in any given year, and a high yielding, consistent variety is a baseline necessity to remain competitive in the marketplace. One of the best ways to ensure this is to have a variety that yields more and has a higher percent grade out. The better and more consistent the shape in the field, the more roots that can go into that box headed to market at premium price. A prime goal of the program is to get that “cookie cutter” shape in a variety while improving yield. This is not easily done.

A traditional grocery store bin of sweet potatoes is usually accompanied by small bags of sweet potatoes for sale. Surprisingly, this is a popular product, and bagged product sales are increasing and now represent a significant part of sales. We learned over time that filling mesh bags with roots that have tapered ends can be a daunting task. Sweet potato roots with more rounded ends fall into the bags more easily. Now we have a new trait to put on the “do list.”

That “do list” grows, but actually we are finding a home for more selections as varieties are developed that fit the needs of various commercial and niche markets. A good example is our Bayou Belle variety. While it has exceptional yield, the skin color is not what the fresh market desires. However, it makes a terrific french fry. So, you won’t find it in the produce aisle, but rather the freezer section.

The demands of the sweet potato breeding program continue to expand, and the successes continue to be realized. Soon we may see a time when sweet potatoes are in every aisle of the grocery store.

Don La Bonte is a professor in the School of Plant, Environmental and Soil Sciences; Christopher Clark is a professor in the Department of Plant Pathology and Crop Physiology; Tara Smith is the director of the Central Region and an extension sweet potato specialist; and Arthur Villordon is a professor at the Sweet Potato Research Station, Chase, Louisiana.

(This article appears in the spring 2021 issue of Louisiana Agriculture.)

Read the story of new commercially successful sweet potato varieties.

Read about the sweet potato foundation seed program.

Wayne Garber of Garber Farms in Iota, Louisiana, left, and Don La Bonte, sweet potato breeder, inspect several advanced lines of sweet potatoes under consideration for release as varieties. Photo by Tara Smith