When it comes to saving pecans from the pecan nut casebearer, time is of the essence, according to a Texas AgriLife Extension Service expert.
“In Texas, May can be a make-or-break month for pecan (nut) production,” said Dr. Chris Sansone, AgriLife Extension entomologist at San Angelo. “It’s also the month pecan nut casebearers hit the crop, leaving only a very short window when control measures are effective.”
The pecan nut casebearer is one of the worst scourges affecting pecans, Sansone said. The adult stage, a moth about 1/3 inch long, flies at night and hides by day. They lay up to 150 eggs on the tips of developing nutlets. The eggs hatch and the larvae tunnel into the nutlets shortly after pollination, often destroying all the nuts in the cluster.
Sansone said the best control method is a springtime insecticide application, but the timing is all important.
“Fortunately, AgriLife Research and Extension entomologists have developed two helpful tools to assist producers and homeowners with the decision,” he said.
“May 17 is the decision window set for Tom Green County. But understand, May 17 is not the actual date to spray, unless eggs are present and some hatching has occurred. The date is the predicted date for the first significant egg lay in the county. Consider spraying when two or more eggs are found while inspecting 10 nut clusters per tree or 310 total clusters if it’s a sizeable orchard. The eggs are barely visible to the naked eye and are greenish-white when first laid. Ideally, one should spray when the hatch has started and is increasing.”
Temperature fluctuations have a strong bearing on the moths’ activity, according to Sansone. He recommends the trees be scouted for eggs and the decision to spray not be made solely on the prediction models.
Sansone said some producers anticipating a “branch-breaking” crop may opt not to spray at all, but instead will let the casebearers thin the nut-load to preserve the health of the tree and the quality of the remaining nuts.
Confirm® and Intrepid® are two insecticides commercial producers can use, Sansone said. Homeowners are limited to products containing spinosad, Bacillus thuringiensis (commonly called Bt), carbaryl or malathion.
Sansone warned users to read and follow label directions and make sure the products are specifically labeled for use on pecans.
More information on the pecan nut casebearer can be found in AgriLife Extension publication E-173, available at http://agrilifebookstore.org.
Other publications on pecan insects accessible through the site include “Managing Insect and Mite Pests of Commercial Pecans in Texas” (E-215) and the “Homeowners’s Guide to Pests of Peaches, Plums and Pecans” (E-145).