LSU AgCenter research highlighted at sweet potato meeting

Olivia McClure, Guidry, Kurt M., Clark, Christopher A., Beuzelin, Julien, Villordon, Arthur O., Sistrunk, Myrl W., Miller, Donnie K., Smith, Tara, Labonte, Don R.

LSU AgCenter weed scientist Donnie Miller, right, tells attendees at a Louisiana Sweet Potato Association meeting about new herbicide technologies. The meeting was held in Oak Grove on Jan. 12. Photo by Olivia McClure/LSU AgCenter


LSU entomology graduate student Jie Chen discusses her research on the sweet potato weevil at a Jan. 12 Louisiana Sweet Potato Association meeting held in Oak Grove. Photo by Olivia McClure/LSU AgCenter


News Release Distributed 01/13/16

OAK GROVE, La. – Although the 2015 sweet potato season was marked by difficult weather conditions – excessive rains that delayed planting followed by a hot and dry summer, then more rain that interfered with harvest – Louisiana growers still ended up with a good crop, LSU AgCenter experts said at a Louisiana Sweet Potato Association meeting on Jan. 12.

Farmers harvested an average of 450 bushels per acre this fall, down only slightly from 2014’s average yield of 480 bushels per acre, said AgCenter extension associate Myrl Sistrunk. Statewide acreage increased to more than 9,300 acres in 2015, the majority of which was planted in the popular AgCenter-developed Beauregard variety.

Sweet potatoes have a $110 million yearly impact on Louisiana’s economy, Sistrunk said. West Carroll Parish is the No. 1 sweet potato-growing parish with about 3,780 acres.

The Orleans variety is still gaining popularity in Louisiana, said Don La Bonte, AgCenter sweet potato breeder. It is similar to the Beauregard variety but has a more consistent shape and higher yields.

The high-yielding Bayou Belle variety, copper-skinned Bellevue and sweet, dark red-skinned Burgundy also have good potential, La Bonte said. They are resistant to some key diseases and fill niches in the market.

Several AgCenter scientists gave updates on their work to help growers control pests and make better management decisions.

AgCenter entomologist Julien Beuzelin said he saw significant cucumber beetle damage in sweet potatoes this past season. A combination of the Lorsban, Admire and Belay insecticides provides good control of the beetles, Beuzelin said.

Resistant varieties also help prevent insect damage, he said. In one study, cucumber beetles damaged nearly all Beauregard potatoes, but only 75 percent of the white-fleshed Murasaki variety saw damage.

Jie Chen, an LSU graduate student in entomology, talked about her studies on the sweet potato weevil. The weevils prefer laying eggs on Beauregard potatoes over Evangeline and Murasaki, and their presence can lead to an increase of other insects, such as the green peach aphid.

The Telone and Velum nematicides, whether used alone or together, make a significant difference in yields for fields affected by nematodes, said Tara Smith, director of the AgCenter Sweet Potato Research Station.

The AgCenter Foundation Seed Program recently joined the National Clean Plant Network, Smith said, which has brought in new funding that the station is using to improve its greenhouses.

Some old diseases are reappearing in sweet potatoes, including scurf and black rot, said AgCenter plant pathologist Chris Clark. Both are seedborne diseases that can survive for up to three years in the soil.

Black rot, which causes black lesions that make the sweet potato taste bitter, became a major problem in North Carolina in 2014. The disease has not been a problem for 40 to 50 years in Louisiana and has not yet resurfaced here, Clark said.

It is much easier to avoid black rot than to fix the problem, Clark said. Some of the best defenses include using disease-free seed and keeping packing lines clean.

It is important for growers to test their soil so they can optimize fertilizer applications, AgCenter agronomist Arthur Villordon said.

“If you put too much of a certain nutrient, it creates limitations for other nutrients,” he said. For example, excessive nitrogen can cause vines to grow too rapidly and result in a higher percent of decay in roots during storage.

Villordon is also studying ways to reduce erosion, including the use of prohexadione calcium, which creates a coating over the soil and helps beds retain their shape.

Two new herbicide technologies – the Enlist Weed Control System and Roundup Ready Xtend – expected to hit the market this year could help row crop farmers control resistant weeds. But they must apply those herbicides carefully, especially in fields near sweet potatoes, said AgCenter weed scientist Donnie Miller.

As little as one-tenth of an application rate of the herbicides – an amount comparable to what’s left behind if sprayer tanks aren’t cleaned properly – can harm sweet potato yields, Miller said.

“If you grow multiple crops and use the same sprayer, it is imperative to follow all the cleanout procedures,” he said.

The U.S. Environmental Protection Agency has updated its standards that protect farm workers, pesticide handlers and others during pesticide application, said Bruce Garner, AgCenter agent in West Carroll Parish. One requires farm employers to inform workers about potential exposure to pesticides and mitigate exposure. They must also offer EPA-approved pesticide training every year and keep records of the training.

To help minimize sprayer drift, applicators should follow label directions closely and identify sensitive areas, such as susceptible crops, bodies of water and wetlands, Garner said. They should also consider weather conditions before making applications.

Sweet potatoes are exempt from a rule that requires produce growers to take more steps to prevent contamination, but processing facilities must comply with another rule that is part of the Food Safety Modernization Act (FSMA), said AgCenter food safety specialist Achyut Adhikari. Those facilities must make an effort to reduce contamination and document their practices.

Many Louisiana sweet potato growers participate in a certification program called Good Agricultural Practices (GAPs) and already meet the similar FSMA standards, which give buyers the assurance that their produce is safe, Adhikari said.

The AgCenter’s sweet potato production budget publication has been updated for 2016 and is available online, said AgCenter economist Kurt Guidry. The budget includes projected per-acre costs and returns for mother beds and three harvest strategies. It can be found by going to and searching for “sweet potato budget.”

Also at the meeting, the Louisiana Sweet Potato Association presented Distinguished Service Awards to Tad Hardy of the Louisiana Department of Agriculture and Forestry, and to Villordon.

Olivia McClure

1/13/2016 10:48:42 PM
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