Pecan trees thrive in United States Department of Agriculture plant hardiness zones 6 through 9, where they grow as tall as 100 feet with up to a 55-foot spread. Young pecan trees require frequent pruning to set up a central leader with four to six lateral scaffold branches. Once trees reach nut-bearing maturity, pruning requirements are relatively minimal, generally to reduce crowding so sunlight and air can reach all divisions evenly. Prune mature pecan trees during the dormant period in late winter, generally only once every 3 decades or when the divisions become crowded.
Disinfect the blades of all pruning tools using a solution of rubbing alcohol or 9 parts water and one part bleach, or to get a solution less corrosive to gears, household disinfectant. You will want hand-held bypass pruners to trim branches up to 1/2 inch in diameter, lopping shears for branches up to 1 1/2 ins, a pruning saw for larger divisions and a pole pruner to reach high branches.
Cut off all divisions that hang within five feet of the ground, leaving a brief stub into the exterior the branch collar — the band of tissue at the joint between the branch and trunk. This makes it much easier for you to access the lower branches and is especially important if you plan to crop the pecans with mechanical shakers.
Eliminate broken and dead branches in the tree, then cutting them back to your nearest healthy branch. Make the cut just outside the branch union, leaving a small stub. You may be able to snap off dead branches without pruning tools.
Cut all diseased branches at least 6 inches back in the section. Disinfect all pruning tools that come in contact with the diseased branches to prevent spreading the disease into other divisions.
Eliminate all rubbing divisions or divisions that are spaced close together to prevent even sunlight supply. You should also remove any branches that are not presently hardened but look like they will develop to touch each other in the coming growing season.
Eliminate all divisions with feeble heavenly crotches less than 70 levels, maintaining only divisions with angles 70 to 90 levels that are less likely to break. After removing dead, broken, diseased and weak divisions, the canopy ought to be open, but it is possible to remove as much as one-third of the overall branches if light is still unable to penetrate all of branches.
Pull off all suckers that develop in branch crotches or in the base of the tree. Suckers are brand new branches that rarely develop into powerful branches but require a lot of the plant’s energy to create. The energy used to develop suckers is then diverted to the main sections of the pecan tree. You can typically pull these straight off the tree, but pruning tools may be required for neglected trees using big suckers.