How old is your tree? See if these help.
Prune mature pecan trees during the dormant period in late winter, usually only once every three years or when the branches become crowded.
The best time is in winter while dormant. Buds can be removed in spring.
The best time to prune pecan trees (Carya illoinensis) is in winter when they're dormant. Removing buds, a form of pruning, is done in spring, and you can on occasion safely remove small branches in summer. You can grow pecan trees in U.S. Department of Agriculture plant hardiness zones 6 through 9.
Hi Terry! There is some great information all ready listed. Also here is some information for you to take a look at!