The pecan phylloxera is an aphid-like insect that produces galls on new growth. It spends the winter as an egg hidden in a bark crevice. Control is based on the application of a dormant oil during the winter. Thorough coverage of the tree with the oil spray will kill many of the eggs. A second control opportunity occurs at bud-break when the newly-hatched nymphs are moving to the expanding leaves. Application of an insecticide labeled for trees can kill many of the tiny insects before they can form galls. Once in the gall the pholloxera cannot be killed.
Generally, insecticidal control is not satisfactory. Correct timing of applications to provide effective preventive control is difficult, and the wasps are physically protected within the galls. Where practical, pruning of infested twigs may help reduce the problem on lightly-infested trees. However, pruning is impractical if large trees are heavily infested. A commercial arborist may be able to provide assistance with valuable plantings.
