Borer Prevention

 Q. I have lots of borers in my trees. What can I do to prevent it from happening?

When borers are a problem it starts about mid summer. Often it begins in parts of the tree frequented by our intense sunlight like the upper sides of limbs that are not shaded.

A. First, prevent sunburn to all trees, particularly young fruit trees. Sun damage is a problem immediately after planting in our desert climate. Damage from the sun can lead to borer problems later down the road. If I were buying a fruit tree, I would buy a small tree and let it grow as a bush. This way the lower limbs will shade the trunk.

Let the Tree Grow Bushy

As soon as it starts to produce fruit, that next winter, I would remove the lower limbs only so the fruit does not touch the ground. Leave as many of the lower limbs as possible to shade the trunk. In fact, let it grow into a shrub.

The biggest mistake homeowners make with fruit trees is to buy large fruit trees with limbs high off of the ground. If lower limbs are present, they are removed to make a tree. Buy smaller trees and let them grow to the next size.

Shade the Trunk

It may be the right thing to do in other climates but not the desert. Desert fruit trees need tender trunk protection from the sun to about five or six years old. If you have a fruit tree and it is “limbed up”, then protect the trunk with diluted latex paint, tree wrap or protective collar that shades it.

A sign for a borer problem is limb death in the middle of summer; brown dried leaves clinging to one or more branches on the south or west side of the tree starting when it is hot. Use a borer soil drench with an approved pesticide for borers. You are not permitted to eat the fruit until 12 months have passed. This particular pesticide is best applied after flowering.

Use a Pesticide as the Last Resort

There are pesticides that can be used that will kill borers still in the tree. Be careful. Treat trees after they finish flowering to protect honeybees. Don't eat fruit from that tree for one season of production after you apply a pesticide.