Training is the act of teaching or developing skills and knowledge related to a specific competency, thus improving one’s capability, capacity, performance, steadfastness, and productivity. In this respect, I would like to write here on training the young pecan tree, as I think that is what most may be doing this time of year.
Although I know we do not teach the pecan tree “skills”—as that would be termed anthropomorphism—we can “train” them to develop properly. Specifically, we train the young pecan trees into what will aid in a strong support structure in order for them to perform well, especially in the southwestern regions, where strong west to southwest winds can be an obliterating event or major setback when breakage occurs on young developing trees.
I think we can all agree that training while young encourages long-lasting, sound structural development that is evident 30 to 40 years into maturity. It is this early training and development that will provide the tree the capability of handling the other stresses of fruit production and load; weather extremes; harvesting; and other cultural practices performed when they become mature fruit-bearing trees.
Just look at the pecan tree in nature! When observing a native pecan, which requires some travel to the native stands for those of us here in the West (I highly encourage the experience), the natural habit of evolving a central leader limb straight through the middle of the canopy can be distinguished. This strong central leader supplies the support for the scaffold branches, holding most of the crop load.
If there isn’t a central leader, or it has been removed, the tree becomes imbalanced, which can lead to future problems. During the seedling stage— the first five to six years of a pecan—the strong apical dominance is prominent. No fruiting wood is produced, and the tendency for the central leader is prevalent.
However, after this juvenile stage, the wood becomes mature, the central leader tendency goes away, and branching becomes prevalent. The latter is especially true for grafted trees, which is our majority planted in the Southwest. In grafted trees, the branching habit occurs at the get-go, and thus, our “training” is needed to aid the development into the “central leader” or “modified central leader” framework.
Training is extremely important if you want to establish a strong framework of support for when the trees begin to bear the weight of a crop. For the pecan tree’s “first-leaf”—that is, the first year in your orchard floor and soil, not its first year in the nursery—the dormant, bare-root trees usually come pruned with a heading cut and ready to be planted.
For those of you who grow from your own nursery, give the dormant tree a heading cut of one-third to half of the previous season’s growth prior to planting for its first-leaf. This heading cut is done first to encourage upright shoot growth from nodes just below the cut point.
During the first-leaf season, you may notice some trees not performing like the others or poorly developing. If growth has not been noticed by July, give another heading cut to a foot above the graft union to force growth. If there is still no growth, there may be another issue to investigate, either below the soil surface or the depth at which it was planted.
Most newly planted young pecan trees are also given a sleeve to protect the tender young trunk from being scarred by equipment, sun damage, or herbicide damage. Most times shoots emerge inside these sleeves. I usually advise to remove these with a thinning cut, especially if threatened by herbicide sprays. It also will direct energy toward the top of the tree, where we want it. Any lateral shoots emerging above the sleeve you can leave alone until you’re ready to clean up the trunk to your desired “skirt” height; that is, only if the shoot is not threatened by herbicide sprays, such as growing downward.
To promote the central leader framework during each dormant pruning season up until the fifth- or sixth-leaf, approach the pecan tree with a focus on the dominant, most vigorous shoot you want to keep as the main central leader. Once that is chosen, give a thinning cut (a cut back to the point of origin) to all other dominant, vertical shoots that seem to compete with this one.
There are sometimes two or three dominant, vertical shoots competing with each other. In this case, it is advised in the Southwest to choose the one growing into the prevailing wind and to give a thinning cut to the other competing dominant shoots, however many that is.
At any time during this training period of the immature pecan (5 to 6 years), if you have a “Y-shaped” tree created by two dominant central leaders, it is highly encouraged to remove one of those central leaders, preferably leaving the one that will closely or directly face the southwest winds. If left “Y-shaped” the chances are very high that the tree trunk will split down the middle at some point in its life.
After you have chosen your central leader and removed the competing shoots, give a heading cut back to one-third or half its total length. When you’re looking where to make the heading cut, look for just above a strong bud. Then, make the cut about ½ inch above that bud.
After that is done, this next step is to only be performed on the central leader. Grab the shoot with your gloved hand just below the top four or five buds and rub down the rest of the shoot, removing all the lower primary buds.
This will do two things: 1) direct energy, specifically growth hormones, to those terminal buds at the top to encourage their vigorous growth, and 2) encourage the secondary or tertiary buds on the rest of the central leader to become less competing, more suitable crotch-angled scaffold branches.
It is not recommended to begin choosing scaffold limbs until after the first or second dormant season. According to New Mexico State University’s Richard Heerema, the main goal to keep in mind is to leave “6 to 10 scaffold branches spaced 8 to 14 inches apart and arranged in a spiral around the central leader.” You should select scaffold limbs that are wide-angled, greater than 45 degrees from the central leader. This crotch angle will prevent breakage or splitting of the branch in high winds or heavy crop load.
Once the unwanted lower scaffold branches are 1 inch in diameter, they should then be removed so they do not interfere with harvest equipment. This is also when the pecan trunks’ “skirt” height is determined. The “skirt” is used sometimes in reference to how high the cleaned-up trunk is allowed.
There are two specific types of cuts to use when removing scaffold branches. Only give tipping or thinning cuts to scaffold branches during the dormant season. See definitions above. A thinning cut of a scaffold branch removes it completely at the point of origin to the central leader, while a tipping is just that. You snip or tip just the terminal portion of the scaffold limb you’re encouraging and want to keep.
If you were to give a heading cut to these, you will only begin establishing another competing central leader and will end up removing it completely in the long run.
During the growing season as well, there are some things that can be done in regard to training the young pecan tree. Usually, pinching can be done on the lower lateral shoots, not any of the top shoots that can be central leaders to choose from come dormant pruning season. Only pinch the new growth (light green in color) on 12- to 18-inch long shoots in its first-leaf and 12-32 inches long during the second-, third- and fourth-leaf growing seasons.
Pinching out a shoot completely can also be utilized during the growing season on soft developing shoots once you see them becoming problematic if left to grow throughout the season. For example, problematic shoots include those that would eventually begin to rub against another limb.
There is some foresight used when choosing which limbs to leave on the tree and which to remove. Ultimately thinking about the future of that limb if left on the tree and what impact it will have on the tree as a whole. I like how Richard Heerema in New Mexico State University’s Guide H-605, “Training Young Pecan Trees” advised: “As you train your trees, keep a mental image of the ideal structure you wish to maintain and shape each of your trees to this pattern. This will serve you as a standard. However, no two trees are alike, and you will find as you are pruning, not all, if few, will conform exactly to your ideal shape.”
There is a lot to think about when planning for the pruning project. I cannot advise the next recommendation enough, because I see it all the time. Take your time preparing and gathering tools for the pruning!
Don’t forget the eye, hand and ear protection (if using a chainsaw). Take your time performing the pruning, don’t be in a hurry! Every tree will be a little different. Make sure you are using the right pruners and loppers (NOT ANVIL STYLE), freshly cleaned, freshly sharpened, and oiled if necessary. You may plan to take a folding tree saw and a sharpening file with you for the loppers and hand pruners as they will get dull as you move across the orchard. Majority of accidents happen due to a dull blade.
There are several publications about training young pecan trees. Some publications that I have used for my demonstration purposes (and in some quotations here) were published by the Noble Research Institute, formerly known as the Nobel Foundation, or New Mexico State University. In addition, I highly suggest seeking out your local Extension Agent with the land-grant university in your state.
It is my hopes this little bit on training young pecans through basic pruning practices will encourage growers and staff to help their young pecan trees develop to perform, persevere, and produce once mature. Just as we all need training to become successful and productive in society, so does the young, vigorous pecan in its various environments.