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Boll weevil, pink bollworm: Double-barreled approach targets pest pair

Farmers in far West Texas admit to feeling a bit of excitement about growing cotton again, thanks to a double-barreled eradication program that targets both the boll weevil and pink bollworm.

Weevils are already scarce and pink bollworm numbers are declining rapidly, says Edward Herrera, manager for the El Paso/Trans Pecos Zone of the Texas Boll Weevil Eradication Foundation, Inc.

“We did not catch a single weevil in the zone last year,” Herrera says. “Farmers in this zone got into the program at an ideal time. Weevils had not developed into a significant problem and that makes it easier to knock them out.”

Pinkies, as locals refer to the bollworm pest, pose a bigger threat.

“Heavy infestations, not treated, will result in 100 percent losses,” Herrera says. “With moderate control, farmers can expect a 25 percent loss. When we have to treat for pinks (usually with Lorsban on heavy infestations), the boll weevils don't have a chance.”

Herrera says the arid conditions of far West Texas create an ideal environment for pink bollworm survival. “They prefer a desert climate,” he says, “and they feed aggressively on cotton.”

He says he didn't really appreciate the challenge of eradicating the pink bollworms until they added it to the weevil eradication program.

The boll weevil effort began in 1999 with diapause treatments in 2000, the first full season. They added pink bollworm to the program in 2001.

“We have to monitor fields for pinks more closely. We have to walk the fields, cut bolls and be ready to treat for pink infestations. If we miss a treatment window, we get hurt. If they get into the bolls, we have to wait for the next cycle.”

Currently, the program monitors 1,100 fields in 15 counties, from El Paso almost as far east as Odessa. More than 41,000 acres were in the program last year, but cotton acreage declines (blamed on water shortages) this year will drop that number to 40,000 or slightly less.

“We make treatment decisions weekly and we can't afford to ease up on pink bollworms,” Herrera says.

Crucial scouting time begins in early June near El Paso but may be a bit later in other parts of the zone, depending on planting date. Herrera says the pinhead square stage is critical.

“We have to stay on top of it.”

He says success so far has been encouraging. “We've noted an 85.4 percent reduction in trap counts for pinks. That's very good. A similar program in Arizona a few years back was not quite that far along at the same stage.”

As weevils disappear, the program mostly monitors trap catches but stays prepared to treat outbreaks, but the focus has clearly turned to pinks.

“We see a lot of benefits with the dual program,” Herrera says. “We use the same equipment, the same personnel and the same trapping service for both programs.”

Trappers can make one stop and check both boll weevil and pink bollworm traps. “If we have to use a pesticide to control pinks, we'll take out any hitch-hiker weevils that may have moved in,” Herrera says.

They reserve pesticides to clean up hot spots. Mostly, they use pheromone tactics.

“If we pick up one pink bollworm moth at pinhead square, we initiate controls,” Herrera says. “Any moth catch initiates a pheromone treatment. Higher numbers trigger a Lorsban application to knock out adult reproduction.”

Herrera says pheromone is the preferred treatment for several reasons.

It leaves beneficials to kill secondary pests. It's effective, especially with low pink populations. And it's a more environmentally sound material, especially in some of the urban areas that abut, or in some cases, nearly surround, cotton fields.

“We have some urban areas near schools and housing developments where we don't like to bring in an airplane,” he says. “And we even have some difficulty with ground rigs, especially right after irrigation.”

Instead, the program uses pheromone “ties,” strips similar to garbage bag twist ties, but loaded with a high dose of pheromone. Workers walk cotton rows and tie these pheromone strips onto cotton plants.

“We don't kill the pink bollworm moths, but we confuse them,” Herrera says. “The pheromone is a mating disrupter that lasts about 90 days.”

He says Bt cotton provides another excellent tool to battle pink bollworms. “Bt cotton works very effectively against pinks. Worms may get into bolls but they do not survive.”

Bt has been so effective that the eradication program will reduce assessment for farmers who plant Bt cotton. “Normally, growers pay $20 per care,” Herrera says. “If they use Bt, they pay only $10 per acre, because we don't have to treat that acreage. We continue to monitor Bt fields to check for resistance, but we've seen none so far.”

He says farmers in the Pecos area plant primarily Bt cotton. “The pink bollworm pretty much put Pecos farmers out of the cotton business for awhile,” Herrera says. “They had a lot of Pima cotton and pinks hit it hard. Now, many are thinking about going back to Pima.”

Pima cotton currently brings as much as a 21 cents per pound premium over upland cotton. Herrera says currently no Pima varieties with the Bt gene are available, so he cautions growers to be cautious with acreage.

Herrera says the eradication program plans to employ another environmentally sound control tactic next year.

“Depending on federal funds, we may release sterile pink bollworm moths. Release would include tons of sterile moths that would disrupt natural population mating activity.”

Farmers are pleased with the program. David Armstrong, an El Paso area cotton farmer and an aerial applicator, flies for the eradication program. He says eradication has been a boon to farmers.

“It's improved crops across the board,” he says. “I guarantee we're getting 15 percent to 20 percent higher yields because of the program.”

He says the only downside is that secondary pests come in a little more frequently. “We're not spraying for boll weevils or pink boll worms, so we don't automatically eliminate lygus, stink bugs, whiteflies, etc. But these pests are not as aggressive as pinkies. They do less damage and we can control them.”

He agrees that boll weevils are hard to find. “We caught none last year and only two the year before in the Lower Valley. The area east of El Paso headed downriver is considered the Lower Valley area, and west of the city upriver towards New Mexico as the Upper Valley.

Armstrong says the key to success of the dual eradication program is “good management. The program has worked well. As a pilot, I work closely with Edward and good communication allows us to avoid a lot of problems.”

Herrera says the main goal is to remember that the program “works for the producers. Everything we do is for them.”

He says recent additions of Mexico and New Mexico to the eradication effort also promises to speed eradication.

“At first we were going solo. Then Mexico came into the program followed by New Mexico. With those border areas in, we reduce potential for re-infestation” of both weevils and pinks.

He says sharing data with eradication personnel in Mexico and New Mexico helps growers in all three areas.

“Our success depends on how well they do.Many of our farmers in the Upper Valley also farm across the border in New Mexico, so cross-border cooperation helps.”

Unlike some areas of the Cotton Belt where eradication efforts met with some resistance, the Far West welcomed it, Herrera says. “Cotton farmers realized the serious problems these pests, especially the pink bollworm, can cause. They knew that individually they could treat all they wanted but if their neighbors didn't control pinks or weevils, they would still have problems.

“They've been fighting pink bollworms for a long time and saw no end in sight until the eradication program. Now, they're excited about it.”

Herrera expects significant results soon. “With the success we've had so far, we could see pink bollworms under control, at least to a manageable level, within the next one to two years. Already numbers are way down.”

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