Pecans ready to be harvested.
image by Dobbi/Flickr.com
Most of the trimming and pruning of pecan trees is done in the first five years. Shaping and training the tree will offer better production of pecans and a more aesthetically pleasing tree. Although the initial pruning slows down the production of nuts, the tree will grow stronger and be able to not only produce more nuts, but also withstand wind and other conditions that could potentially harm it. Mature pecan trees need pruning and trimming only to remove dead and diseased wood and overcrowding of branches.
Cut about one-third of the tree off at the time of planting. This will be the development the tree's central leader, and cutting it back will cause a stronger leader and will normally cause the beginning of the scaffold branches to grow.
Wash your pruning shears or loppers in a bucket of one part bleach to ten parts water between each cut to prevent the spread of any disease or insect that you may not be able to see.
Trim the central leader back again during the first dormant season by one-third. By this time, you should have two strong shoots coming up toward the central leader. Cut the strongest one off completely at the trunk and the tip off of the second. This will force the central leader to grow stronger. If any side branches have started to shoot, cut the tips off by an inch or two.
Repeat this pattern of pruning during the dormant season in years two through five. Each time you tip prune the scaffold branches, you will force two new shoots to fill in the tree. Cut bottom limbs off completely when they reach at least one inch in diameter, so they do not become dangerous to walk under when the tree is large.
Cut all branches that cross other branches as the tree develops during this time. Always trim healthy branches during the dormant season. Dead or diseased branches may be cut any time. It's more beneficial to cut those as soon as you notice the problem. Make sure to burn or discard diseased branches in the garbage and do not use them as compost or leave them near the tree.
Prune the mature tree only to remove the dead and diseased branches or to open up the inside if the tree is not getting enough sun and air circulation. Overcrowding of the branches will hold moisture inside the tree and can cause mildew disease. It will also not allow enough sun in to keep the branches growing and producing nuts.