Twig girdlers, also called pecan girdlers or long horned girdlers, are insects that cut holes into branches in order to deposit eggs. While they do not completely sever the branches on trees they infest, the damage to the tree is extensive. Branches weaken and fall during heavy winds. Getting rid of twig girdler infestations is essential to protect pecan yield and to prevent infestation of nearby trees.
Look for signs of twig girdler infestation in your pecan tree: Damage caused by the insects is most obvious during the fall, when pecan leaves turn brown and fall from the tree prematurely. There may be a large number of small branches on the ground, beneath the tree. The ends of these branches will appear to have been cut or chewed in a straight line.
Gather any damaged or severed branches and burn them. Make certain to collect the branches that have fallen to the ground, as well as any remaining ones on the tree. This will help eliminate the twig girdler larvae before they develop into adults in the summer.
Collect any fallen branches from nearby trees and inspect for signs of infestation. Twig girdlers spread from tree to tree very quickly.
Shred damaged branches or cut into small pieces and take to a sanitary landfill for disposal, if burning is not legal in your area.
Use an insecticide to control twig girdlers and prevent re-infestation. Products containing azinphosmethyl or EPN are a good choice for controlling twig girdlers on pecan trees. Spray the trees as soon as adults begin to emerge, generally in late summer or early fall, before damage occurs.
Spray your pecan tree again with insecticide during October and November. Remove damaged branches. Use care when pruning, as girdled branches may become deformed.