May 11, 2006

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COLLEGE STATION – A cooperative project between Texas Cooperative Extension and the Texas Agricultural Experiment Station should help control the pecan nut casebearer insect with minimal environmental impact.

"The insect is preventable," said Dr. Marvin Harris, Experiment Station entomologist.

But the casebearer can do a lot of damage if trees aren't treated at all or have pesticide applied at the wrong time.

Researchers set up a volunteer network that uses pheromone traps to monitor when adult casebearers become active in the spring. The information is sent to Texas A&M University where it is logged into spreadsheets.

Researchers then estimate when the female casebearers will lay eggs and when the eggs will hatch and produce larvae. That information is added to an online map at http://pecankernel.tamu.edu which gives predicted treatment dates for the insect.

The larvae damage pecans by burrowing into developing nutlets and feeding.

"The timing of (pesticide) is critical," Harris said. "If larvae get into the nutlet, we can't kill it nearly as well. We want to get it after (the eggs) hatch but before nut entry."

Previous research has shown that larvae will emerge 12-14 days after peak activity of the insects.

The map predicted April 30 as the date for treatment decisions for Atascosa County, south of San Antonio. Producers could check the Web page for casebearer activity, and they determined whether they had a harvestable crop and if casebearer larvae numbers posed a threat to that crop. Then and only then did they treat, Harris said.

"Everything on the map is proceeding as predicted," he said. "The key message to growers this year is (to treat) early in the timing by all indications."

Pecans are grown in more Texas counties than any other crop, he said. Trees are grown in commercial and hobby operations as well as in yards. The average loss from the pecan nut casebearer is 6 percent of the total crop yield.

An estimated $2.5 million in pesticide treatment is spent each year to control the pecan nut casebearer.

The monitoring team includes Harris and Bill Ree, Texas Cooperative Extension entomologist, who provides background on the insects' biology, Dr. John Jackman, Extension entomologist, who provides the technical knowledge for the Web site, and Extension assistant Robert Puckett.

About 70 pecan producers, Extension agents and Master Gardeners have already volunteered to place and monitor the traps supplied by Harris and Ree. They receive training, if needed, on how to identify casebearer adults.

Volunteers report how many adult males are captured on the traps. After the treatment decision dates, some will go on inspect trees to provide information on the number of eggs or the number of larvae feeding on pecan clusters.

"They will do a very credible job for us," Harris said. "We have the technology; we have a receptive network of cooperators. Now it's just a matter of coordination and support."

Spraying the trees with pesticide every seven days from the peak of adult activity is possible but impractical, Harris said. Not only are pesticides expensive, but overspraying can kill natural insect enemies. It also leads to pollution.

"You don't want to be throwing out a lot of pesticides around in the environment," Harris said.

The team hopes to keep gathering data and eventually have the information available to producers statewide and then across the pecan belt: the southeastern United States from New Mexico to the Atlantic.

The project receives grant funding from the Texas Department of Agriculture and the Environmental Protection Agency.

Those interested in volunteering to monitoring traps should contact Harris atm-harris@tamu.edu or Ree atw-ree@tamu.edu .