Producer Norman Clark right Vardaman Miss visits with Mississippi State Universityrsquos Jeff Main from left research associate at the Pontotoc RidgeFlatwoods Branch Experiment Station Daniel Fleming postdoctoral research associate at MSU and Mark Shankle research professor at the Pontotoc station

Producer Norman Clark, right, Vardaman, Miss., visits with Mississippi State University’s Jeff Main, from left, research associate at the Pontotoc Ridge-Flatwoods Branch Experiment Station; Daniel Fleming, post-doctoral research associate at MSU; and Mark Shankle, research professor at the Pontotoc station.

Mississippi pheromone trapping program keeps sweet potato pest at bay

Sweet potato weevil is the most serious pest of the crop, not only in the U.S., but around the world, causing damage both in the field and in storage.

Mississippi’s trapping program for the sweet potato weevil got under way mid-July, about a week later than normal due to rain-delayed planting, says James Dale, branch director of the Plant Pest and Pesticide Divisions of the Department of Agriculture and Commerce’s Bureau of Plant Industry.

The bureau conducts the pheromone trapping program for the pest to meet requirements for shipping Mississippi sweet potatoes to weevil-free states.

Dale discussed the program and other related issues at the Mississippi Farm Bureau Federation’s annual sweet potato commodity meeting at Pittsboro.

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Sweet potato weevil is the most serious pest of the crop, not only in the U.S., but around the world, causing damage both in the field and in storage. It was first noted in the U.S. in Louisiana in 1875, with speculation that it came in by way of Cuba. It is now found throughout the southern states, from North Carolina to Texas, and in tropical regions around the world.

The adult pest is an ant-like beetle about one-fourth inch long, which feeds on leaves and stems, but prefers plant roots. Crop damage is caused by young larvae (grubs) that hatch from eggs laid in a sweet potato. The larvae begin to tunnel into the tuber, with tunnels increasing in size as the grubs grow. This feeding makes the sweet potato unfit for consumption because of the presence of larvae and frass in the tunnels. The weevils also impart a strong flavor to the sweet potato.

“Our trapping program is perhaps the top-notch program in the nation,” Dale says, “thanks to the outstanding level of cooperation between producers, our inspectors, and others in the industry.”

The bulk of the state’s production is in the counties surrounding the town of Vardaman in Calhoun County, and the weevil has been declared eradicated in those counties.

“The eradication boundary is roughly a soft line along the Interstate Highway 20 corridor,” Dale says. “Areas north of that are weevil-free, although there can be occasional infestations as much as 20 miles north of I-20. But the major production counties in north Mississippi are a long way from I-20, and we don’t expect the pest to be a problem there — although we run traps in those areas.”

Southern portion of state still has weevils

Areas south of I-20 are still weevil active, he says, and are under quarantine. Sweet potatoes produced in that area are “pink tagged” and must comply with specific regulations as to how and where they can be shipped. Sweet potatoes from weevil-free areas are “green tagged” and can be shipped without restriction.

The weevils are plentiful in the areas along the Mississippi coast, Dale says, and it is doubtful eradication can be achieved there because of the milder winters.

Mississippi Farm Bureau Federation personnel on hand for the MFBF annual sweet potato commodity meeting were, from left, Terry Norwood, Justin Brooks, Andy Whittington, and summer intern Tucker Wagner.

“We have two new growers in south Mississippi this year, the first in the pink tag area in some time. They’re respected growers, who farm other produce, peanuts, and cotton, and I don’t anticipate any issues with them — they understand the regulations and what they need to do, and we have an experienced inspector down there. I think they will be shipping primarily to Ohio. Together, the two growers have about 315 to 350 acres, a relatively small acreage, and we can monitor their fields closely. We’ve set traps on all their planted fields.”  

For the state, Dale says, “unofficial acreage this year is estimated at about 22,500 acres, up about 1,500 to 2,000 acres from last year.”

A sweet potato harmonization plan by the Southern Plant Board (made up of plant pest regulatory agencies of the various states) is still under discussion, he notes. “It’s a voluntary program, and for the most part Mississippi has not been in favor of it, mainly because of the way pink tag potatoes could be handled and shipped. We aren’t the only state opposed to the plan.

“The Southern Plant Board has asked for additional input on this, and we’ve submitted our comments. We will work with Mississippi growers on additional comments. Our Mississippi regulations are pretty specific about how pink tag and green tag issues, and we want to stay within those regulations, unless growers feel changes should be made.

“This could be an opportunity to try and help bring some other states up to Mississippi’s level, to better protect the industry and perhaps open some additional markets. Mississippi sweet potato growers have been very good about cooperating on issues and finding solutions. In an industry that’s as concentrated as this, our priorities are to make sure things go smoothly, to encourage communication between all parties, and to be sure your industry is protected.”

Worker Protection Standard revisions still awaited

One other area of concern, Dale says, is the Environmental Protection Agency’s revisions to its Worker Protection Standard. In February 2014, the EPA announced proposed changes to to increase protection from pesticide exposure for the nation's 2 million agricultural workers and their families.

Sweet potato consumption in the U.S. continues to increase, thanks in large part to the popularity of sweet potato fries on restaurant menus. Growers hope to begin the 2015 harvest in early September.

“We’re still waiting on their changes,” he says. “We submitted comments last year regarding the proposed changes. We’re told there could be an early fall announcement, after which there likely will be an implementation period for everyone to become familiar with the changes.”

Dale noted that John Campbell, who served as director of the Mississippi Bureau of Plant Industry for the past four years, has recently been named deputy commissioner for Mississippi Department of Agriculture and Commerce. “To my knowledge, this is the first time have had a deputy commissioner come from the Bureau of Plant Industry. We’re excited for him and believe his insight into what we do and what you do will be of benefit to all.”

Sylvia Clark, who has been serving as secretary of the Mississippi Sweet Potato Council, announced that Benny Graves has resigned his position as executive director of the council.

“Benny did an excellent job for us, but the work for his employer necessitated his giving up the sweet potato position, which was part-time. For the time being, we’ve divided up his responsibilities. I will serve as secretary and handle promotion. Jamie Earp, Houlka producer and council president, will handle the financial responsibilities, and Stephen Meyers, Mississippi State University regional sweet potato specialist, will handle research and grants pertaining to research projects.

“We’re pleased that sweet potato consumption continues to increase, thanks in large part to the increase of sweet potato fries in restaurants,” Clark says. “We certainly want to keep that trend going.”


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