Back to June 2022

Water woes and tree removal go hand in hand

A pecan tree with bunches of green leaves scattered about its canopy. Growers should remove this underperforming tree.

A pecan tree with Bunch disease. (Photo by Larry Stein)

Like it or not, a new pecan “growing” year is well in hand, despite the continued numerous challenges faced by growers, including rising production costs and labor. Of utmost concern in my mind, though, is the ongoing drought. According to the U.S. Drought Monitor, this drought engulfs about 89.5% of Texas and 44.38% of the United States.

We’ve had hit-and-miss showers, but most of Central and South Texas are in a world of hurt. Of course, the Far West is typically dry, but even they exhibit exceptional drought. The surest way out of a drought is to talk about it. Hopefully, as we talk about it, the drought will ease soon, or maybe it already has? The good news is that the weather has yet to become extreme, heat-wise, and is probably why the trees seemed to be so slow coming out of dormancy this year. We simply had some cold nights well into the spring. Despite the dry and extended cooler weather, trees have, for the most part, pushed a good set of leaves and catkins. It also appears that there are numerous female flowers.

Those of you who have been in the pecan business for a while know how different every year is and can be. And just when you think you have everything figured out, something new pops up. But probably one of the greatest constants in the pecan business is water, and in most cases, it is simply not enough. So as the number of people in Texas continues to increase, we will have to be continually wise about our water and how we use it. I hope you will commit today to only using irrigation water where it will pay. One way to do that is by removing unproductive trees.

If you have a block of trees on marginal soil, let’s get rid of those. It is just not worth it to grow mediocre trees or nuts, and someday you may have to justify the use of that water. Many still consider pecans a luxury crop, despite the incredible health benefits of eating raw pecans. There is a possibility that someday you could be told that water is too valuable to use on pecans. So, we need to be proactive and only use water where it pays in the form of yield and nut quality. Over the years, the wise operators have slowly decreased tree numbers on sites when the economic numbers were not working.

Furthermore, we need to realize that not all trees are created equal. To date, most every pecan tree comes from a seed, though this could change in the future. Hence, every tree grown from a seed is different and, as such, can and will perform differently even with the same variety and management. If water becomes limiting, it is only fitting that you remove these underperforming trees.

An iron deficient pecan tree. The leaves are more yellow-green than the dark green that appear on the healthy pecan trees neighboring it. (Photo by Larry Stein)

Sometimes the foliage color tells you there is an issue. Interveinal chlorosis—yellow leaves with green veins—indicates iron deficiency which is not common on pecan trees. But it occurs, and if you have such trees, they would best be removed. The rootstock’s genetics are simply not adapted to the soil and hence the poor growth.

Another issue that is not talked about much is bunch disease. For years, we didn’t know what the exact issue was as it actually resembles zinc deficiency. The malady is caused by a mycoplasma organism and is sometimes referred to as Witch’s Broom. The “brooms” develop from the growth of many secondary lateral shoots. The numerous shoots cause the tree’s growth to shorten, and as a result, dense tufts of thin shoots and leaves are produced. The telltale sign of bunch disease is that infected limbs typically foliate 7 to 14 days earlier than the rest of the tree. It is not uncommon to see a couple of infected limbs in a tree while the rest of the tree appears normal. Currently, the only good control is to prune these limbs out of the tree. However, it is often almost impossible to perform such a task. Yields on such trees are compromised as the infected limbs do not produce nuts. In other words, the quality of the nuts on the tree is ok; just that the tree yields suffer. This malformation would be a good reason to remove such trees to make resources available to unaffected trees.

Then comes the subject of weed control. No doubt weeds are a problem for all crops, but the good news is that you can usually grow pecans if you can grow weeds. If you can’t grow weeds—it’s real simple—you can’t grow pecans either. Weeds are fierce competitors early in the trees’ lives, but they can more readily compete as trees get older. Still, remember that weeds and grass can use a tremendous amount of water and nutrients. It takes 80 gallons of water to grow 1 pound of weeds and grass. That 1 pound of weeds will easily fit in a 3-pound container. If the weeds and grass do not get water, the trees will possibly get it.

So, weed control can save water, but the challenge can be killing such weeds. Some growers rely on herbicides, but there is tolerance to products to be dealt with and the killing of certain weeds allows for the selection of others if growers are not careful in their product usage. In addition, some weeds are tough to kill at various stages of growth, and some are perennials with a vicious tap root. Indeed, some weeds have developed tolerance to certain herbicides, but then again, there are others that the herbicide never killed to begin with, so not all weed issues were induced.

Some would suggest mowing as a means of control; however, others feel that the regrowth of the grass and weeds consumes more water. Still, when you mow, you capture organic matter that can act as a mulch and eventually degrade into nutrients. On that note, I think mowing has a place in orchards, though the high price of diesel may make it challenging. It goes without saying though that some type of vegetation management program is in order. Over time you are going to find various brush species emerging as part of your vegetation. Deer are extremely bad about bringing in mesquite seed and subsequent seedlings, which are best controlled when quite small.

Hopefully, the water woes in the state will ease soon. Your subsequent challenge will then be to determine the size of your crop and manage it accordingly. With the almost triple cost in fertilizer prices, we need to make sound decisions as to when, where, and how much we apply. Tissue samples in mid-July may help you make those determinations. The key in these decisions has to be to keep your trees healthy. Healthy trees are more likely to set and mature a good crop. By the same token, this is also a good opportunity to identify those trees that are weak and inferior and remove them so that all the resources go toward sound producing trees. Over the years, many folks have “read” their trees—4 to 6 to 8 to 10 inches of growth usually signals you are in good shape. Tissue analysis along with thorough tree observations will go a long way to helping you make management decisions in 2022. Good luck with wisdom in making those decisions.

Author Photo

Larry A. Stein

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