Wednesday, February 20, 2013

More dormant pecan pruning

   Some pecan trees are just more difficult to train than others. In previous posts, I've shown you my approach to dormant pruning on a neglected pecan tree and again on trees that receive regular summer pruning. Recently, I received an email with photos of a single pecan tree taken from four different directions (photos above). This was a great idea. Viewing the tree from all 4 sides really helps in visualizing the tree as a truly three dimensional object.

   The primary problem with this tree is that it lacks a strong central leader. The tree has far too many lateral shoots that are producing upward growing shoots (photo at left). The first step in pruning this tree is to identify the shoot you wish to promote as a central leader. The shoot I would choose is identified by a red arrow. Since my goal is to stimulate the central leader, my next step would be to remove the leader's closest competitor (yellow arrow). Take this limb off all the way back to the trunk. Next, start making bench cuts on all other lateral branches. I've pointed out just one of these cuts in the photo, but many more bench cuts should be made to remove all upward growing shoots on lateral branches. Keep in mind that you should limit the amount of wood removed during dormant pruning. Only cut what is necessary to stimulate the growth of the central leader. Excessive dormant pruning leads to uncontrollable regrowth most often in a strongly upward direction (this is how this tree developed so many upward growing laterals in the first place). The dormant pruning cuts made on this tree should be followed up by directive summer pruning cuts made as spring growth emerges.  Summer pruning has proven to be the most effective way to define and keep a strong central leader in the long run.

    One major factor in tree training that is often overlooked is the impact of the strong southerly winds we endure all summer here in the central plains. I often joke with folks that you can tell its a northern pecan by the fact that a young tree seem to point north (photo above). The fact is, pecan trees seem to grow more upright on the south side of a tree for two reasons--the wind and full exposure to sunlight. In the photo above I've circled in red all the upright growing limbs on the south side of this tree. All of these limbs should receive bench cuts during the dormant season and careful directive pruning during the summer months. The fight against upward growing shoots is always hardest on the south side of the tree. Be patient, don't cut too much at one time, work with the tree as best you can.
     In the first photo of pruning this tree, I pointed to a limb that needed pruning to release the leader to grow more vigorously. In the second pruning photo, the yellow arrow points to the same limb that needs removal back to the trunk. From this photo angle, you can see just how competitive that limb is towards the central leader and why it needs to be pruned out. Also, the green arrow points to a fork in the central leader. One half of that folk needs to be removed before it grows into a more difficult pruning problem.