Growers with young trees may come across this situation in small blocks or trees near woods. We came across some twig girdlers in Washington County last month that appears more like a tall deer bit off every single branch. The broken branches were laying on the ground at the base of the tree.
This damage is not from an animal but instead a beetle, and more specifically, a long-horned beetle. I’ve only seen this once before, and it’s not a serious situation for a young pecan tree.
Twig girdlers are long-horned, wood boring beetles that live in many hardwoods. After mating in the summer, the female finds a small twig, usually 3/8 of an inch to lay her eggs. She girdles the twig and then lays her egg outwards from the girdle site. The twigs generally fall off from wind, but sometimes remain on the tree.
The larvae hatch and tunnel inside the twig as they develop. The larvae must eat wood from a dead twig since they cannot develop in live twigs with high moisture content. They then pupate and emerge as adults by chewing their way out of the twig. The next generation adult emerges from the twig next summer.
This is not a situation of great concern, so preventative treatment is not recommended. The only reasonable control is to clean up the broken twigs and burn them. This will help reduce twig borer numbers. Keep in mind, they will attack almost any deciduous tree. There are plenty of these trees in the woods, so once the pecan trees get larger, this type of damage is not significant. Attacks like this are sporadic but almost always occur next to wooded areas where these beetles live.
Authors: Andrew Sawyer, Dr. Angel Acebes-Doria and Dr. Will Hudson