(09/17/20) BATON ROUGE, La. — The LSU AgCenter Sweet Potato Research Station has put its 2020 field day video presentations online.

“We put together a series of videos that highlight our many research programs and outreach initiatives,” said Tara Smith, Sweet Potato Research Station coordinator. “We are focused on variety development, production and various aspects of pest management.”

The entire series of presentations can be found at https://bit.ly/NERegionSweetPotato.

“The sweet potato industry is very important to us,” said Bill Richardson, LSU vice president for agriculture. “We’re very committed to the research and extension needs of our sweet potato farmers and processors.”

AgCenter sweet potato breeder Don La Bonte explained the process for developing sweet potato varieties. He also introduced some of the newer varieties selected from a long process that starts with tens of thousands of seeds.

— LA 14-123 is red-skinned and has good flavor and a nice orange flesh. It has guava root-knot nematode resistance. Early testing also showed it had some resistance to black rot.

— LA 14-31 is a 2014 true seedling that has resistance to Southern root-knot nematode and guava root-knot nematode. Storage roots are ready a little bit earlier than some mainstream varieties, and it has red skin, good flavor and orange flesh.

— LA 16-148 has red skin that is tougher than most other varieties, great flavor and nice-looking orange flesh. It has resistance to Southern root-knot nematode and guava root-knot nematode.

— LA 13-81 is also called Vermilion, and its main claim to fame is showy colors, with a vibrant purple-red skin. This bright skin coloration has eye appeal to fresh market shoppers. LA 13-81 has deep orange-colored flesh and grows well in sandy and heavier soils.

“Vermilion is a 2013 selection, and it took us until this time in 2019-20 to release this variety,” La Bonte said. “So it takes a lot of years of evaluation and testing to come up with a new variety.”

Some previously released varieties developed by the AgCenter continue to enjoy success.

— Bayou Belle is an early developer with well-sized roots and a nice blocky shape, and it’s great for making french fries. It has a nice red skin, but it skins easily, meaning it’s not good for the fresh market. It has a sweet flavor, good disease resistance and grows well in heavier soils and sandy soils.

— Orleans is the standard fresh market variety. It has a beautiful root count and shape. It looks like Beauregard, but Orleans has a better shape and a higher grade-out of the No. 1 category. It also makes great french fries.

Arthur Villordon, an AgCenter researcher at the Sweet Potato Research Station, found that several planting and growing variables made significant differences in yield quality. His research using the most commonly grown varieties indicated that planting slips horizontally compared to vertically resulted in more consistent and evenly spaced root development and higher potential grade-out.

Tests also indicated that an attachment to a mechanical planter can help plant slips horizontally while improving planting efficiency.

Villordon also tested irrigated versus non-irrigated rows and found that irrigation was the most significant variable in improving yield, creating earlier harvest-ready sweet potatoes and more consistency in root development.

AgCenter plant pathologist Chris Clark leads the virus-tested aspects of the AgCenter sweet potato foundation seed program. His presentation explained how the program has continued to evolve since its beginning in 1999.

Clark and his researchers use numerous complicated steps, such as molecular assays, to help establish that plant material is free of virus. Plants are grown in tubes with media in a tissue culture lab and then transferred to the research station in Chase.

As part of the National Clean Plant Network, Clark’s lab shares germplasm and methods that are helping develop the best possible “clean” plants for the country.

Even relatively small symptoms of virus can reduce yield up 25% to 40%, Clark said.

“That’s a relatively big deal for a relatively subtle disease for sweet potato growers,” he said.

AgCenter nematologist Tristan Watson discussed the threat guava root-knot nematodes pose to sweet potato crops and what the AgCenter is doing to combat the pest. This nematode, only recently discovered in Louisiana, is much more damaging than the common and widespread Southern root-knot nematode and can cause almost 100% loss in a sweet potato field.

“We are using new molecular techniques to better identify the pest, and we are screening different cultivars and varieties to determine the host status of this pest,” he said. “We hope to develop some preemptive management strategies in case this nematode becomes a problem.”

AgCenter weed specialist Donnie Miller noted some of the best herbicide options currently available, while emphasizing no options are currently available to take out broadleaves once they’ve emerged. Valor and Reflex are the best pre-emergence options for broadleaf control, and the best choices for over-the-top coverage immediately after slips are transplanted are Command and Dual Magnum.

“Sweet potato weed control is more difficult than other crops because of the limited options we have,” Miller said. “Linex is an older product used on soybeans that is currently undergoing review in the IR-4 program, and it could be another pre-emergence option for sweet potatoes, giving us a different mode of action.”

Smith, an entomologist, encouraged an integrated management strategy for controlling and managing soil insects like cucumber beetles.

Other steps she recommended are:

— Judicious use of insecticides.
—Field sanitation and cultural practices.
—Crop rotation.

—Scouting for adult stages of soil insects.

“We’re looking at alternative insecticide chemistries so we can hopefully provide our producers the tools they need to effectively manage insects,” Smith said.

La Bonte is getting closer to completion of a natural food-based coating to enhance the mechanization process of planting sweet potatoes. The fast-drying, low-cost substance would create a crusty, pencil-like quality to the slip, making it easier to stick into the ground.

“Once this coating hits water, its water dissoluble so it extends the opportunities to add things like micronutrients or starter fertilizers,” La Bonte said.

Cole Gregorie, Sweet Potato Research Station research associate and graduate student, is in year two of research analyzing combination rates of nitrogen and phosphorous on sweet potato plants. The primary goal is to develop variety-specific fertility regimes that can benefit producers.

Waana Kaluwasha, an LSU graduate student, studied how postharvest disease controls affect wound healing and Rhizopus soft rot. Rhizopus soft rot is the most common and destructive storage disease caused by wound-dependent fungus.

Kaluwasha compared different wound healing controls — bleach, hot water, non-treated and Dicloran — and found that Dicloran was clearly the best control. Because of concerns for pesticide residue, it would be good to find an effective alternative for effective wound healing.

AgCenter sweet potato researchers made a point of thanking the Louisiana Sweet Potato Commission for support of sweet potato research and outreach programs.

The Sweet Potato Research Station is the only facility in America whose sole purpose is to research sweet potatoes. The new varieties developed at the station are some of the most popular grown worldwide.

LSU AgCenter sweet potato breeder Don La Bonte holds the LA 14-123 sweet potato variety during a presentation for the 2020 Sweet Potato Research Station virtual field day. This variety has guava root-knot nematode resistance and some resistance to black rot. Photo by Randy LaBauve/LSU AgCenter

Vermilion, or LA 13-81, is the newest sweet potato variety developed by the LSU AgCenter. Its showy colors offer eye appeal to fresh market shoppers. Photo by Randy LaBauve/LSU AgCenter

LSU AgCenter sweet potato researcher Arthur Villordon demonstrates uniformity of sweet potato root development on 60-day-old plants where slips were planted horizontally. The demonstration was part of the 2020 Sweet Potato Research Station virtual field day. Photo by Randy LaBauve/LSU AgCenter

LSU AgCenter research associate Catherine DeRobertis shows lines of samples cut from the meristems of sweet potatoes. The tissue culture lab is part of the AgCenter’s thorough efforts to identify virus-free sweet potato plant material. Photo by Randy LaBauve/LSU AgCenter