Several types of beetle grubs and moth larvae attack wounds and growths on fruit trees. Peach tree and dogwood borers prey on other types of fruit trees as well as their most common hosts. Some borers prefer dead wood or wounded bark as entry points, while others hatch in healthy bark crevices and bore directly into the cambium and sapwood. Healthy trees react by creating a sticky gum that seals the tunnels and mires the grubs in a natural glue, but larvae can outrace the trees defenses. Without intervention, one or two boring grubs could completely girdle and kill a young fruit tree.
Spray the bark of fruit tree trunks and larger branches with carbaryl or permethrin insecticide once a month through the growing season. Follow the label instructions for application details.
Coat the fruit trees' trunks with white latex paint to protect them from sunburn damage.
Inspect fruit tree trunks and limbs throughout the growing season for telltale patches of dead or wet bark, round entry or exit holes in bark, and gum or frass.
Fumigate infested wood at the base of a fruit tree with a band of paradichlorobenzine or PDB. Hoe a flat area around the trunk at least 2 inches wide and 1 inch from the bark to prepare the ground for the fumigant powder. Apply the fumigant in late fall to kill fruit tree grubs over the winter.
Measure the amount of pesticide the manufacturer recommends for the age of the tree and scatter the fumigant in a circular band on the leveled earth. Shovel soil on top of the fumigant. Mound the dirt around the trunk. Bury the fumigant and keep it from contact with the bark. Remove the treated soil the next spring before the first buds swell.
Treat grub-infested trees manually with a pocket knife and wire spear. Clear the entrance of any hole that has gum or frass with the knife point. Insert a bare copper wire with a jabbing and twirling motion to destroy the grub. Tunnels seldom go more than a few inches deep, but the holes may have twists and turns.