Look for Borer Problems As it Gets Hot

            I had reports sent to me about peach trees with yellow leaves on a single branch. You might see this on other fruit trees such as apple as well. For those of you lucky enough to have this condition on your fruit tree then this may be an indicator of a borer problem that needs treatment now. Let us talk about what else to look for to confirm it and what to do.

Borer problem on the limb of a three year old peach tree.

            Notice I said, “yellow leaves on a single branch”. This is important because borers usually lay their eggs on a single branch, not all over the entire tree. The only exception is if your fruit tree is newly planted or less than two or maybe three years old. In this case, the borers may find the trunk of the tree enticing for egg laying and kill the entire tree outright. Usually borer damage is in full sun, on the south or west sides of the trunk.

Jelly-like sap oozing from the trunk or limb of a susceptible tree after a rain is a pretty good tell-tale indicator of borers. 

            Look for sun or borer damage to the limb with yellow leaves on its upper surface. Borers seldom affect the shaded sides of branches or on the north or east sides.

Borer damage to a newly planted tree can be lethal because the tree is so small.

            What to do? Buy an insecticide that contains imidacloprid listed in the active ingredients on the label.  Follow the label directions for a “soil drench” applied around the base of the tree where water is applied. You would do this now but I would treat the tree as a non-edible for the next 12 months even if the label permits its use on fruit trees.

            I have had some luck using a sharpened, sanitized knife without an applied insecticide. The knife is typically 6 to 8 inches long with a good-sized blade for removing the damaged bark. The damaged area is skinned away from the limb until fresh wood, not damaged by the borer, is seen. The damaged area cut away by the knife is only about ¼ inch deep. This cut area is not treated in any way but allowed to heal on its own.

I have had some luck using a clean knife and eliminating borer neighborhoods. I have no research to back it up but it seems to work sometimes.