If you have been growing pecans for a while then you probably know exactly what these galls are in the picture. These were caused by an insect called pecan phylloxera. Pecan phylloxera overwinters as a single egg within the body of a dead female insect. Prior to dying, the female seeks shelter on the tree under dead bark, within old galls or even under the shells of dead scale insects.
The overwintering eggs begin hatching in early spring at about the time the pecan buds are beginning to open. Upon hatching, the nymphs called stem mothers begins to move from the overwintering sites to the opening buds. Once on the buds, the insects begin feeding. As they feed, a gall begins to form around the insect, eventually
enclosing it within the gall. Once the stem mother reaches maturity, she begins to lay eggs within the gall. The number of eggs laid ranges from 300 to 1,300 per gall.
The overall economic impact is fairly low from Phylloxera, but it can produce increased chances of having problems with hickory shuckworm later in the season. Hickory shuckworm adults find phylloxerra galls a suitable place to lay their eggs. As a result, damage from first-generation of shuckworm can be significant in orchards with heavy phylloxera infestations.
Once you see the galls on the tree, it is too late to do anything about the current year’s infestation. Control measures must be taken at or just after budbreak. Products with the active ingredient imidacloprid are used to control Phylloxerra.
For more questions about pecans contact the Evans County Extension Office 912-739-1292.
Phylloxera Publication Texas A&M
