Question: Why are there “warts” all over the leaves of my pecan every spring?
Answer: Those are pecan phylloxera galls. They crack open to release small gnat-like insects. Fortunately, they won’t do serious harm to the tree, but they can disfigure many of the leaves and cause them to fall in May and early June. You can lessen their populations with dormant oil sprays applied in late winter. There is no effective control during the growing season.