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New Mexico State University

New Mexico State University

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'Tis the Season for Pecan Weevil

LAS CRUCES-- New Mexicans who grow, process or eat pecans can help protect the multimillion-dollar crop by being alert for signs of the pecan weevil this winter, a New Mexico State University entomologist said.


The pecan weevil is the newest and by far the most devastating pest for pecans in New Mexico," said Carol Sutherland, entomologist with New Mexico State University's Cooperative Extension Service. "As harvesting and processing continues, it's quite important for all of us-from those with one backyard tree to the largest commercial processors-to look for this pest so that it doesn't become established on our state. Every effort is being made to find unreported infestations and eradicate them."

New Mexico produces up to $40 million worth of pecans in high-yielding years. The state accounts for about 50 percent of Southwest production and 11 percent of the U.S. crop.

The pecan weevil reduces yields by feeding on immature nuts in late summer, causing them to drop off the trees. Later in the season, pecan weevil grubs burrow inside the shell, devouring the nutmeat and contaminating pecans. Pecans from areas where the weevil is established cannot be shipped to uninfested states like Arizona and California without undergoing a supervised freezing treatment to kill the pest.

Sutherland says the pecan weevil resurfaced in New Mexico in 1998 after a 30-year-absence. A sharp-eyed observer in an Otero County cleaning plant noticed pecans with round holes about the diameter of a BB pellet-the emergence holes of pecan weevils. Creamy white, legless grubs with reddish-brown heads may also be found inside pecans infested with pecan weevil larvae, she said.

"If you find either of these signs, take the pecans to your county Extension office or to the NMSU Extension plant sciences department in Las Cruces for confirmation," Sutherland said. "This pest has been found three times in New Mexico-once each in Otero, Doņa Ana and Luna counties-in settings from a commercial orchard to a backyard tree."

In each case, the affected areas have been treated and monitored to prevent the pest from spreading, she said. NMSU's Cooperative Extension Service, the New Mexico Department of Agriculture and the Western Pecan Growers Association are working with area producers to keep the pest from becoming established in the state.

The pest is particularly difficult to control because it spends much of its three-year life cycle underground, where treatments cannot reach it, Sutherland said.

"It's a very tough, long-lasting problem to eradicate. This is a more serious threat to the state's pecan industry than other pests we worry about, such as the hickory shuckworm and pecan nut casebearer," she said.