Plan Now for a Larger Pecan Harvest

Posted On July 26, 2017— Written By and last updated by Emily Walter
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How is your pecan tree really doing, asks Duplin County Cooperative Extension Horticulture Agent Tom Hroza.

At this time of year, unseen and developing underground beneath otherwise healthy looking trees, is an insect that emerges in mid-August and assaults the pecans, unless actions are taken to reduce weevil hatches.

“We all enjoy the many treats made with local homegrown pecans, and with a little extra effort at this time of year we can improve the crop yield from our trees,” Hroza said. “Each fall, area citizens bring damaged and blackened nuts to the Extension office asking what happened and we discuss the life cycle of the weevil because there is no saving that year’s crop.”

According to Hroza, a regimen to reduce and eliminate the weevil infestation should be started by mid-August when the beetle like insect comes out of the ground beneath pecan trees. Usually following a soaking rain that softens the soil, the weevils burrow from the ground and then crawl up the trunk or fly into the tree. The female weevil drills a hole through the pecan shuck into the cavity, where she lays up to three eggs and the grubs that hatch feed on the developing nut. Some escape through the hole that was drilled in the shuck but others remain inside and continue to devour the nut.

There are some recommended strategies that help control the weevils.

  • Pick up all damaged nuts and debris from prior growing season. If allowed in your area, burn the collected debris, if not, bag it up and send it to the landfill.
  • Apply a strip of sticky material around the trunk about six feet above the ground to catch weevils walking up the trunk. Only about 5 percent walk up the trunk, so Hroza recommends this method be used in conjunction with a foliage spray program.
  • Mature trees are normally to large to drench from the top with an insecticide spray. However, the majority of the weevils fly into the lower branches, where a spray program of the insecticide carbaryl (such as Sevin) into the tree foliage under the canopy and out to the drip line is a good defense. About the 15th of August start spraying the under canopy as high into the foliage as can be reached and repeat every 7 -10 days until shucks begins to open, Hroza said. Utilizing this spray program treatment, tree owners should experience about a 50 percent reduction in the weevil damage. He added that, as with any insecticide program, spray late in the evening to minimize bee exposure. Insecticides in both powder and spray forms, such as Sevin, are extremely toxic to honeybees.
  • Another method to consider is beneficial nematodes applied to the soil beneath the tree. These microscopic worms seek out the weevil underground and kill them within 3 to 4 days. No special equipment is needed for application and it is safe around children and pets. Unlike insecticide sprays, Hroza noted that these nematodes are not as readily available from local garden and farm supply outlets.

For additional information about the pecan weevil and assistance with a damage control program, contact Tom Hroza at the Duplin County Cooperative Extension office, 910.296.2143 or by email tom_hroza@ncsu.edu.