Texas

Growers from the several East Texas counties gathered at Canton Aug. 30 to learn more about the bad news they already knew: The sweet potato weevil has returned to East Texas fields.

Experts from Texas Cooperative Extension and the Texas Department of Agriculture conjectured the weevils' return was caused by high fuel costs and the poor yield prospects due to dry weather this year. The combination resulted in farmers cutting back on insecticide-spraying programs that likely kept the pest suppressed, they said.

But Extension and Texas Department of Agriculture representatives also had some good news for the growers: The infestation numbers were far lower than the last infestation in 1999-2000. With an eradication plan ready to put into place, the chances of eliminating the weevil and returning all East Texas fields to a weevil-free status are high, said Dr. Shashank Nilakhe, Texas Department of Agriculture state entomologist.

With all growers in full cooperation, the chances of success are excellent, agreed Brian Cummins, Extension agricultural and natural resources agent in Van Zandt County.

"We cleaned them up before; we can clean them up again," said Cummins, who works closely with growers in his county.

Income from sweet potato production is substantial, Cummins said. In Van Zandt County, 1,425 acres were grown in 2003, producing gross receipts of more than $6.7 million. In 2004, this number was down to 1,207 acres due to growing conditions, but gross receipts still totaled about $3.4 million. Rains County had gross agricultural income from sweet potatoes of $1.9 million in 2004, he said.

About quarter-inch long, the sweet potato weevil is a serious pest worldwide. It was first discovered in India in 1792, but did not make its way to the U. S. until 1875 when it was identified in a field near New Orleans. By 1890, it had made its way to southern Texas, said Dr. Allen Knutson, Extension entomologist.

The adult weevil feeds on the roots and tubers of the sweet potato plant. Most of the damage is done when it sticks its snout through the skin of the potato or lays eggs inside the potato. Though there's no human health risk from eating infested sweet potatoes, the presence of larvae and a resultant bitter flavor ruin the product for consumption.

When infestations are severe, "even hogs won't eat the potatoes," Nilakhe said.

Sweet potato farming has been an important part of the economy of several East Texas counties, including Van Zandt, Rains, Henderson and Wood counties, with production also in Camp and Hopkins counties, Knutson said.

Because of the serious threat of the weevil, sweet potato fields in Texas and Louisiana are designated either weevil-free or weevil infested, Knutson said. Growers in weevil-infested areas cannot move or sell their potatoes into weevil-free areas. Producers with weevils are "pink-tagged" by the Texas Department of Agriculture; those that are weevil-free are "green-tagged."

Green-tagged 40-pound boxes of sweet potatoes can be sold anywhere; pink-tagged potatoes go to markets where the weevil is already present, such as Houston and San Antonio, but not Dallas.

The eradication program prohibits growers from using their own potatoes as seed stock, and buying seed stock could cost them $100 an acre or more. The eradication plan also requires pink-tagged growers to aggressively treat their fields with an insecticide this year and next. This could add another $100 or more per acre in production costs.

In the 1999 infestation, traps using attractants were catching thousands of weevils, Knutson said. This year, only 10 traps monitored by the Texas Department of Agriculture on seven growers' fields caught weevils. And the highest weevil count was six in one trap, with only one or two weevils found in the other nine traps. Considering 425 traps were monitored on 30 growers' fields this year, these low numbers indicate the infestations can be quickly eliminated, Knutson said.

Under the eradication plan, growers will initiate a spray program as outlined by the Extension publication "Sweet Potato Weevil Management and Control." Any area within a half-mile radius of the traps where weevils were caught will designated as a "treatment area," and all potatoes harvested within this radius will be pink-tagged. Most growers present at the meeting had already begun a spray program, they said.

Sheds or packing houses outside the treatment area radius but which handle pink-tagged potatoes will also be designated a treatment area.

Hundreds of traps will continue to be placed in all sweet potato fields, seedbeds and storage facilities within the weevil-free area.

"It's a 'take-no-prisoners' plan," Knutson said.

Residents of Smith, Wood, Rains, Upshur, Van Zandt and Hopkins counties can help by not transporting sweet potatoes into the area from weevil-infested areas. The easiest way to do this is to simply not transport sweet potatoes across county lines, Knutson said.

Home gardeners can help by being on the lookout for the weevil in their sweet potato plots. Images of the weevil and the damage it does can be found on the Internet at http://overton2.tamu.edu/insects. Gardeners can report infestations to the Texas Department of Agriculture office in Tyler at 903-939-3999.

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Posed next to the head of a pin, a typical sweet potato weevil is less than a quarter-inch long. The tiny pest could devastate a multi-million dollar sweet potato industry in East Texas, however. Texas Cooperative Extension and the Texas Department of Agriculture have an eradication plan already in place. (Texas Cooperative Extension photo by Robert Burns.)

Date: 9/22/05

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