Pecan leaves are breaking out
It looks pretty serious, these galls that are showing up on pecan leaves about now. They’re called pecan phylloxera galls, and they’re caused by tiny gnats that lay their eggs within the newly developing leaf surfaces. The wart-like growths develop with the insects inside them.
The impacted leaves fall to the ground. The gnats escape and the process starts over again for another year. You will not see another generation of the galls this year.
As with galls that attack oaks, hackberries, cottonwoods and other shade trees, no significant harm is done to pecan trees by these (or any other) leaf or twig galls. The female insects visit the trees just long enough to lay eggs and then they’re gone, so spraying the adults is out of the question. (I’ve lived in a pecan forest for 46 years, and I wouldn’t know an adult phylloxera gnat if I saw one.)
Unlike most of the other types of galls, you can get some degree of prevention of pecan phylloxera galls by spraying the trees with horticultural oil in late January or early February, but it’s difficult to do and it’s really not economically practical since the galls have such minor effect on the trees.)
Entomologists generally suggest that we just ignore these galls and the “problems” will soon pass. So, that’s one less thing you have to worry about.