Table of Contents
- Care and Feeding
- Training Young Trees
Pecan Cultivar Recommendations for the Southeast
Selecting a Site
If planting several pecan trees, or if planting near other trees, space the trees at least 60 – 80 feet apart so they will not crowd as they reach maturity. Spacing can be closer, say 35 or 40 feet, if trees can be removed as they get larger and overcrowd, which happens within 10 – 15 years at a 35 – 40 ft. spacing. Crowding causes misshapened unthrifty trees and decreased nut production.
Although there are pecan cultivars available which are disease tolerant, plant the pecan tree in a location that has good air movement, as this helps to reduce the spread of diseases common to pecan.
Pecans grow and produce best when grown in a moist, but well-drained soil. Poor aeration in clay soils that do not drain well can injure roots, disrupt nutrient uptake and stunt, or even kill, a tree. Either select a site having a soil with good drainage or correct a drainage problem before you plant a tree.
Preparing the Site
Correct planting of a pecan tree involves more than simply dropping the plant in a post-hole. Pecans have some fairly specific requirements that need to be met for the tree to become successfully established.
Ideally, the site in which you expect to plant a pecan tree should be prepared somewhat like a small flower bed. A 10 by 10 foot area should be cleared of grass or weeds and roto-tilled. When tilling, incorporate 1/3 pound of zinc sulfate and enough dolomitic limestone to bring the pH of the soil to between 6.0 and 6.5. The specific amount of limestone required should be determined by a soil test, although in many Alabama soils 5 pounds of lime per 100 square foot area could provide roughly the amount needed.
A fertilizer containing phosphorus and potassium may be incorporated into the area being prepared, but avoid adding nitrogen, amount added should be based on a soil test. The pecan root system is very sensitive to nitrogen, and even a small amount at planting can cause injury.
Once the area has been prepared the actual planting hole can be dug. For planting bare-rooted trees the hole should be made wide enough for the roots to be spread out without bending. Even in a well-prepared soil, bent lateral roots may grow around the hole, eventually girdling the tree. The hole should be a depth such that the tap root of the tree is allowed to be fully extended but the tree will be positioned as it had grown in the nursery.
After placing the roots in the hole fill the hole 3/4 full with backfill soil from the hole. Firmly tamp this soil and then fill the hole with water until it reaches the top of the soil in the hole. This settles the soil, eliminates air pockets and keeps the roots moist.
Fill the rest of the hole with soil, leaving the surface of the soil unpacked to allow better water penetration into the root zone. Prune 1/3 to 1/2 of the top of the tree to compensate for roots that were lost or damaged when the tree was originally dug.
Water is critical to survival of newly planted trees. One to two inches of water should be supplied each week of the growing season (March to November) during the first two years. Insufficient rainfall should be supplemented with irrigation water. Mulch the entire 10 by 10 foot area around the tree with pinestraw, pinebark, leaves, aged sawdust chipped weeds. The mulch will help retain soil moisture, reduce soil compaction, and limit competition from grass.
Container grown trees are planted similarly to bare-rooted trees with a few differences that should be noted. Roots of container transplants are sometimes pot bound. If planted in this condition the roots may continue to grow in a circular pattern without branching into the surrounding soil. Rubbing your hand lightly up and down the root ball will help loosen up the roots so they can grow outward. At planting, the tap root in the bottom of the container should be straightened as much as possible, or cut off to allow a new tap root to develop.
Care and Feeding
Well established trees have an extensive root system that mines the soil for available moisture even during periods of drought. However, with established nut-bearing trees there are particular stages during the growing season when inadequate rainfall can have a significant adverse effect on pecan yield or nut quality.
Insufficient water from bloom through shell hardening (April through early August) results in small nuts. Lack of sufficient water during the stage of nut filling (August and September) can cause poorly filled nuts. Drought late in the season can cause shucks to remain closed so that the nuts do not readily drop. Finally, inadequate moisture late in the season reduces photosynthesis and thus decreases carbohydrates that would normally be stored and used for new feeder root production and early spring growth. Therefore, the lack of adequate water at critical stages during a given growing season can affect growth and nut production not only during the current season but the following year as well.
If less than 1 inch of rainfall is recorded in a month, then even an established, nut-bearing tree may need irrigation during the critical times described. Run irrigation long enough to supply 1 and 1/2 to 2 inches of water to the tree. The spray pattern should provide water to an area extending from slightly within, to well beyond the drip line of the tree. Watering should be done early in the morning so that less water will be lost due to evaporation.
Keeping close records of soil and leaf levels of nutrients gives a indication of trends developing in your orchard. For example, if you routinely apply phosphorus or zinc, eventually levels can build up and cause problems. Writing down your soil and leaf sample records over a number of years along with applications made will give you a good indication of the effects of additional applications. Comparing records with yields and condition of trees over a number of years will provide you with index for measuring the effectiveness of your fertilization program. Careful observations for weak trees, deficiency symptoms, etc., can help you pinpoint problem areas in your orchard, which may need special attention. Keep in mind when making observations that pecans are slow in responding to fertilization. Improvements in growth and yield may not be apparent for several years after a good fertility program is begun. Remember that returns from fertilizer applications may not be realized if disease and insect pests, inadequate water, poor drainage, poor pollination, or other factors are limiting production.
The following steps are the procedure for obtaining a soil sample:
- Obtain soil sample boxes, shipping cartons, and forms (Soil Testing Form A) from your county Extension office
- Sampling every year is suggested for high value crops like pecans. Samples can be taken at any time. A late fall or winter sample will allow you to plan you February fertilizer applications accordingly. Or, you can conveniently soil sample in July, which is the suggested time for leaf sampling, so that your soil and leaf sample are considered together.
- A sample should represent a uniform area. Soils which differ in appearance, crop growth, or past treatment should be sampled separately.
- A single sample should consist of just over a pint of soil. This pint of soil should be a mixture of 15 to 20 subsamples collected over a large area which accurately represents conditions over the orchard.
- Use a soil tube, soil auger, or spade to take soil samples to uniform depth. Sample to a depth of 8 inches. For new orchards, which should be deep-plowed before planting, sample to the depth of the plowed layer. Since recommendations are based on a 8-inch layer, you will need to increase the recommendation by 1/8 for each inch deeper that 8 inches that you plow. For example, if you plow to 12 inches and 2 tons per acre of lime are recommended, apply at least 3 tons per acre.
- Complete your soil test forms and send them along with the test fee and your soil sample to the soil lab or you county Extension office, whichever is recommended for your area. You should receive your results within ten days to two weeks.
Even though soil testing is essential to determine soil group, pH and soil levels of several nutrients, a soil test alone leaves some important questions unanswered. One of these questions is, “Are the nutrients I’ve applied to the soil being taken up in adequate amounts by the roots and moved to the leaves?” and “Do I need foliar sprays of zinc?”
A leaf analysis detects “hidden hunger”, which is a level of nutrition where deficiency symptoms are not apparent but yields are reduced. Leaf samples can reveal shortages or excesses in time to correct them before serious damage and crop loss occur. A leaf analysis also will provide a index for determining whether nutrients are present in the proper balance. Among the important nutrients measured by leaf analysis are N, P, K, Ca, Mg, and Zn.
The following steps are the procedure for obtaining a leaf sample:
- Collect leaf samples during the month of July.
- Take a sample of at least 100 leaflets from at least eight trees. The trees should be representative of trees in the area sampled. The sample area should be reasonably uniform regarding tree performance, past fertility practices, and soil.
- Collect the middle pair of leaflets from leaves in the middle of the current season’s shoot, or growth (See figure below). Collect leaflets from all sides of the tree that are exposed to sunlight and can be easily reached from the ground. Choose leaves that are free of damage from insects or disease and that have not collected an excessive amount of dust. Do not collect leaves in galvanized containers, since these may contain zinc which could affect results.
- Place the leaflets in a perforated paper bag and air-dry them at room temperature.
- It is suggested to take a soil sample at the same time and from the same area where the leaf sample was collected. If you do not soil sample at the same time, be sure and write in on Form B the results of your last soil sample of the areas where leaves were collected. This information will aid in analyzing your situation and in making a correct recommendation.
- Complete Form B, Pecan Grower’s Information Sheet, as accurately as possible for each leaf and soil sample submitted. Information concerning past treatments, and leaf and soil nutrients is necessary to make the best recommendations.
- Put the dry leaf samples in paper bags (not plastic), identify bags by sample number or orchard name, close the bag with tape (not metal staples), and pack in shipping carton or large envelope. Do not allow soil from soil sample to contaminate leaf samples. Separate shipping boxes are best.
- Enclose the testing fee and send the samples to your testing lab or county Extension agent, whichever is recommended for your area.
Accurate and economical lime and fertilizer applications needed for optimum production in your pecan orchard can be determined if you follow the steps outlined below:
- Send in a leaf sample annually to determine levels of Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Calcium (Ca), and zinc present in leaves. Your soil test results reflect nutrients levels in soil while foliar analysis specifically indicates what the tree is able to absorb from the soil.
- Soil Test, preferably annually, to determine soil group, soil pH, and soil levels of available P, K, Mg, and Ca.
- Observe and keep careful records of past soil and leaf analysis results, of fertilizer applications, and of condition and yields of trees.
Consistent production of high yields of good quality pecans is not possible on Alabama soils without fertilization. Not only maintaining adequate levels, but also maintaining proper balance of nutrients is important. Of the 15 or so elements necessary for growth and production of pecans, only six must commonly be bought and applied to soil or as foliar sprays in Alabama. These six are nitrogen, phosphorus, potassium, magnesium, calcium, and zinc. Other elements, with rare exceptions, are provided in sufficient quantities from soil, air, and water.
Since we know the nutrients pecans usually need in Alabama, why can’t we make a standard recommendation of what to apply and avoid the trouble and expense of a soil test?
One major reason is that past fertilization practices often have greatly changed the fertility levels of soils. Nutrients, such as phosphorus for example, may have built up to high or very high levels so that additional applications may not only be wasteful and unnecessary, but also could be detrimental. A soil test will determine if phosphorus and several other nutrients are actually needed.
Another common effect of past cultivation and fertilization practices is a lowering of soil pH. Pecans are pH sensitive, and require a pH between 6.5 and 7.0 for best growth. A soil test is essential to determine the pH level of the soil, and to determine the amount of lime required to bring the pH to the desired range. In addition to determining soil pH and soil levels of phosphorus, a soil test will also give an indication of the amounts of potassium, magnesium, and calcium in the sample.
Since the soil type and caution exchange capacity affect the level of nutrients required, the soil test classifies the soil into a certain group. Finally, recommendations are made which consider the soil group, the soil nutrients levels, the soil pH, and the needs for the crop specified. A rule-of-thumb recommendation does not take these into account, and may be a poor recommendation in many situations.
Four Ways to Improve Pecan Production on Trees Around Your Home
- Fertilize properly, preferably according to soil and leaf sample recommendations.
- If you have not taken samples, rules of thumb are:
- 1 lb. of 13-13-13 per tree per year of age up to 25 lbs/tree, or 300 lbs/acre
- 1 lb of ammonium nitrate per tree per year of age up to 20 lbs/tree, or 240 lbs/acre
- 1/10 lb zinc sulfate per tree per year of age up to 2 lbs/tree, or 24 lbs/acre
- 5 lbs dolomitic lime per tree per year of age up to 100 lbs/tree, or 1200 lbs/acre
- If you have not taken samples, rules of thumb are:
- Choose established pest-resistant cultivars, like Elliott, or new cultivars McMillan, Amling, Adams 5, Headquarters, Baby B or Lakota.
- Make sure the trees have enough room for good sunlight exposure. Cut down some trees if limbs overlap adjacent trees.
- Water the trees when it is dry, especially in late August and early September. Also maintaining a 4-6 inch layer of organic mulch (bark chips, compost, leaf litter, etc. will conserve moisture, improve root growth, and reduce compaction.
Training Young Trees
The first five years of growth are the most important in developing a central leader and scaffold branch framework of the pecan tree. Structural developments in the trees during these years will be evident 30 or 40 years later. Pecan growers will exert few influences that will be effective longer than those exercised in developing the framework of a young pecan tree. This development should be done carefully with a minimum amount of pruning. Considerable planning is required to properly train and prune young trees. Mechanical equipment used for orchard management will influence the training program chosen. Keep in mind the ideally structured tree and always try to shape each tree to this pattern. No two trees are alike and only a few will conform exactly to your picture, but it will serve as a standard.
The type and amount of training and pruning that should be used can be determined, to a considerable extent, by the ultimate use of the tree. Early nut production is directly related to the amount of pruning, with the earliest production being on trees subjected to the least pruning. Backyard growers may be willing to sacrifice some early production in order to have an aesthetically well-shaped tree. However, commercial growers with a large number of pecan trees are more likely to compromise some structural development and form to obtain early production from their trees.
There are several pruning methods commonly used for training young pecan trees. Heading back, branch selection, tip pruning, and pinching are all good methods and need to be practiced during the first few years when establishment of new pecan trees and proper training is critical.
To develop a medium-size, strong, wind-resistant tree for the West, use a central leader or modified central leader system. At planting time, prune the top one-half of the tree (Fig. 1). This usually results in a whip 36-42″ tall. Head-back pruning encourages strong central leader regrowth. Frequently two or three new shoots develop adjacent to the cut-back point in the early spring. However, newly planted trees usually grow slowly during the first season. If growth has not started by July, cut back to 12″ above the bud union, to force growth.During winter (dormant season), the strongest and most vigorous shoot should be selected and head back 1/3 to 1/2 (Fig. 2). The second strongest shoot should be removed. The remaining shoot needs to be tip-pruned to reduce growth and encourage short laterals. Lateral shoots will also develop below the cutback point. These lateral shoots can develop into small permanent scaffold limbs. They can be pinched during the summer and usually tip-pruned in the winter.
The previous year’s growth of the central leader should be cut back about one-third during the first through fourth (or fifth depending on development) dormant season. Continue to force one strong shoot to grow at the top of the tree (Figs. 2, 3, 4, and 5).
When selecting branches that will become permanent scaffold limbs, choose only the branches that form wide angles with the central leader. The selection of the main lateral scaffold branches should be delayed until the dormant period after the first year of growth. It is important to know that at each node (growing point) primary, secondary, and tertiary buds occur.
Scaffold branches from the main central leader trunk may be formed from primary, secondary, or tertiary buds. Those formed from primary buds usually produce narrow crotch angles, and are weaker than scaffolds formed from secondary or tertiary buds. Those should not be used in developing the major scaffold branches of the framework. The shoot from the primary bud may be pruned or pinched out to force the development of a shoot from the secondary bud. The same procedure, pruning or pinching both primary and secondary buds, may be used if a scaffold branch is desired from a tertiary bud.
The main trunk or central leader from which the scaffold branches are formed is more easily developed from a primary bud with its natural tendency for upright growth so the center of the tree will be erect.
When training a young pecan tree, 6 to 10 side branches arranged in a spiral around the central leader are selected and spaced 8?14″ apart. Trees having several small scaffold branches can be harvested more easily with a mechanical shaker than those having only two or three large branches. The lowest scaffold branch should not be higher than necessary for attaching the shaking machine, about 4?5 feet should suffice. The exact height will be determined by the type of harvesting equipment to be used.
All side shoots developing below 4 feet, which will not be selected for permanent scaffold limbs, should not be removed until they are 1″ in diameter. Their purpose is to manufacture food for central leader extension, sun protection, and girth development. In addition, these lower branches will produce nuts until weakened by excess shade.
Lateral branches frequently grow in clusters instead of the ideal spiral arrangement. When this happens, select the most ideally located one, prune it in the dormant season and shorten the others to a few inches to reduce vigor. Trunks with two central leaders should be pruned because splitting may occur at the junction. If two upright trunks of equal size develop, one must be removed. This should be done as early in the life of the tree as possible. This reduces the probability of “V” trunk development.
Crow’s foot is the development of four to six shoots from the end of a young limb. Thin out the limbs so that only two or three remain. Tip-pruning significantly reduces the crow’s foot problem. All pruning should be done during the dormant season.
Most cultivars produce extremely vigorous growth in the third, fourth, and fifth seasons. Tipping these vigorous shoots will produce many lateral branches; the most desirable can then be selected for further training. Tip-pruning is practiced on permanent limbs by removing about 2″ of terminal growth during the dormant season. Shoots are tip-pruned only when they are 32″ or longer (Figs. 2, 3, 4, and 5). This practice stimulates the development of numerous small lateral shoots. Heading back (removal of one-third to one-half of the shoot length) instead of tip-pruning will usually result in the development of three or four strong shoots directly below the pruning cut.
Tip-pruning will bring pecan trees into commercial bearing at an earlier age and encourage central leader development. It also reduces tree size during the first 10 years. It has been recommended to tip-prune trees until the sixth or seventh year. It is not needed on larger, bearing trees.
This pruning is accomplished on trees less than four years old. As small scaffold limbs develop along the trunk, pinching is performed by removing their soft, light green growing points. The growing point can be easily broken off with the fingers. Lateral shoots should grow 12-18″ before the growing point is removed during the first season, and 12-32″ during the second, third, and fourth growing seasons (Figs. 2, 3, and 4). Pinching results in larger leaves on the lateral shoots. It also inhibits development of large scaffold limbs during the first four years of the tree’s life and encourages strong leader development.
Shaping Takes Time
Almost all pruning necessary on young trees can be done during the growing season, if done as soon as needed. Trees trained and pruned in this manner will seldom require the use of a pruning saw.
At least five years are needed to complete the selection of scaffold branches and train the tree to the proper form. Each tree will be different although you attempted to make them appear uniform. It is impossible to select branches on a tree that conform exactly to your ideal, but if you continue to compare each tree with your mental picture of an ideal pecan tree, your orchard will produce maximum yields of high quality nuts.
Pecans are harvested when the shuck opens, allowing the nuts to drop. Mechanical aids can be used to help speed nut fall. These devices range from a long pole used to shake small limbs to large commercial branch or trunk shakers that cause nuts to fall in a very short time. For a small-scale operation, sheets can be spread under the tree to catch the falling nuts. Nuts also can be picked up with small, push-propelled harvesters ranging from 12 to 48 inches wide for small-scale plantings or large, commercial mechanical nut harvesters. Nuts harvested by hand should be picked up every other day to prevent the nuts from molding or being destroyed or removed by pests.
Once harvested, the nuts must to be dried to 8 to 10 percent moisture, or to 3.5 to 4.5 percent for optimal long-term storage. For small-scale production, the nuts can be dried by placing them in porous burlap bags in a location with moderate ventilation and heat. Commercial dryers use forced air heated to approximately 100 degrees (F) for optimal drying.
Pecans, like any nut, have a relatively high oil content and will spoil. For optimal storage, they can be held at 32 degrees (F) for approximately one year. For longer storage periods, the nuts should be kept in a freezer.
Click below to download an article on the harvesting, handling, and grading of pecans.