Back to March 2018

Tree by Tree, Step by Step

Before we can truly revitalize a native grove, we must decide which trees to remove and which to keep.

What a difference a year makes as we get ready for another exciting growing season! Our winter to date has been totally different from last year with periods of extended cold, some ice and snow and cold fronts on a regular basis. After a year of virtually no chill, it appears that we will have an excellent chill year as we head into 2018.

The native crop in Texas this past year was spotty at best, but those trees which had pecans had a good crop as varmint pressure seemed to be minimal. Having said that, if your trees did not have a crop in 2017, then there is a good chance that you will have a crop in 2018. Also realize that as the benefit of the new federal marketing order takes place, increased demand and/or consumption of pecans will dictate that we need more pecans to be produced. One of the quickest ways for that to happen is to put native pecan trees back into production.

The two greatest deterrents to native pecan production are overcrowding of the pecan trees, which is by far the greatest challenge, and lack of nutrition. When river floods were more common due to the lack of dams, rich silt deposits were placed on these native pecan floors which gave them that nutrition they need to produce pecans.

So, today annual applications of nitrogen fertilizer will go a long way to making pecan trees produce pecans; however, the key to these applications is to apply them ahead of rain so as to get the nitrogen into the soil. Realize that grazing is an integral part of native pecans, and this fertilizer application will not only help the trees but also help you grow more grass which will help the grazing operation as well.

Today, we are going to concentrate on thinning trees in these native pecan bottoms as many folks struggle to decide which trees to remove. There is no “right” answer to all situations but doing something is better than doing nothing at all.

Pecans are a sun-loving plant. Effective sunlight only penetrates the canopy about three feet and that is only when the canopy is exposed to direct sunlight. Hence if the limbs from the trees touch, then the only effective light is on the top of the trees. So the more you can spread the trees out, the better the production from the individual trees.

An ideal yield goal would be to make 1,000 pounds per acre year in and year out. In many areas of Texas, we struggle to make 400 pounds. If a native tree makes 300 pounds per tree, we only need about four trees per acre to make that happen. It is not uncommon to find 42 plus native trees per acre.

Let’s see and consider the following situations to decide the best course of action.

1. Tree which has lost its top

When this tree was fully intact, it would produce 200 to 300 pounds of high-quality pecans year in and year out. However, for whatever reason, the top was lost; more than likely this was due to either straight-line winds or possibly a small tornado. So, essentially the value of this tree is gone. It will never produce like it did, and basically, it is just occupying space that could be used by the other trees. Therefore, this is a prime tree for removal.

I would suggest that it be removed immediately. The genetics of this tree could be grafted to a smaller tree if one wanted to maintain it; however, if one is looking for production, improved varieties will typically do so faster and more consistently than a grafted native. Indeed, there are exceptions as ‘Prilop’ is a native selection that is propagated.

2. Then there are trees which have large holes…

A pecan tree with a huge hole in the trunk.These holes usually occur where a large limb has broken out of a tree, and then, over time water accumulates in the hole and slowly rots the interior of the tree. This hole makes an ideal site for varmint nesting. Over time this tree’s structure becomes weak, and then, in a serious weather event, the tree will break at this weak juncture. Thus, this is another tree in this native bottom that is a no-brainer for removal.

3. When lightning strikes

Tall pecan trees are prime candidates for lightning strikes in thunderstorms. Years ago, growers would often install “makeshift” lightning rods in these prime specimen trees to prevent such damage. Lightning will not always kill these trees, but as you can see it really does damage them, and over time the deterioration will weaken the trees. Eventually, they lose their production value. Oftentimes it is best to go ahead, bite the bullet, and take these trees out. In addition, you can see this tree has a prime varmint nesting site from a limb that was lost in the past.

4. Conks or shelf fungi 

Unfortunately, injuries to trees eventually lead to heart rot fungi entering these trees. Once these fungi have fully colonized such trees, these conks appear on the trees. And once one sees such structures, the tree will either die or fall over from a strong wind in a couple of years. So, when these conks show up the clock is ticking. Such trees should be removed as soon as possible. Obviously, there is no control for this problem; however just because one tree has it does not necessarily mean it will move to the other trees.

5. If a tree falls…

Such fallen trees are usually the result of a flood event; not so much from the swiftness of the water, but rather from the saturation of the soil. Once the soil gets drenched, the roots either pull loose or possibly wash out and the tree simply falls over. A fallen tree, such as this, has a very limited value because even if this tree were to produce pecans, there would be no way to harvest the pecans unless one picked them by hand. Unfortunately, the labor to handpick pecans is virtually a thing of the past.

So again, such trees should be removed to make room for those trees that will contribute to the overall production of the bottom.

As you take trees out in these native bottoms, realize that there may be a few grafted trees in the mix as years ago that is what many concentrated on—converting some of the poor-quality nut trees to a better pecan. So be on the lookout for a distinct change in the bark texture, which you can see in the following photo. Grafting native pecans on native pecans is OK. However, if you put improved varieties on native trees, you will have to care for those trees as improved pecans, or it would have been better to have left them as native trees. Improved varieties require more care in order to make them adequately produce.

6. Too many trees!

Lastly, this is a typical situation for many pecan bottoms. There are simply too many trees.

Anyone who has ever tried to maneuver harvest equipment around such trees will readily attest to this fact. The simple solution is to leave the two largest trees and remove all the other trees. However, one would want to make sure that the trees being left were productive so this would be a three- to four-year process.

No doubt, it is a challenge to cut pecan trees down and remove them; however, sunlight and water are critical in pecan production. If one truly wants to improve their production, tree thinning will help that aspect—no doubt.

Author Photo

Larry A. Stein

Larry Stein is a professor and Associate Department Head for Extension Horticulture, Texas A&M University. [email protected]