Cultivation of pecans

Pecan-nut trees are fast growers and can become very tall. The nut has a high nutritional value because it is rich in protein, vitamins, carbohydrates and nut oil.

Nut size and kernel development

Factors causing poorly filled nuts:

Climatic requirements

  • The pecan-nut tree is well adapted to subtropical areas.
  • It also grows well in areas with short, cold winters and long, very hot summers.
  • Low temperatures and even frost during June to August are required for successful budding and flower formation.
  • During the summer months (October to April) the tree requires high temperatures for fruit growth.
  • Trees are successfully established in valleys and along rivers where the winter temperature is low and frost occurs.
  • In the subtropical areas only cultivars that are tolerant to scab should be planted since humidity is very high along rivers, in valleys and in low-lying areas.



The average monthly maximum temperature should be higher than 28 °C during summer and lower than 23 °C in winter.

The average monthly minimum temperature during the summer must rise above 16 °C, but drop below 8 °C in winter.

Humidity and rainfall

High humidity and rainfall are ideal for the development of scab.

The most suitable production areas are therefore those with short, cold winters and long, hot summers, with no early or late frost and a humidity below 55 % during the greater part of the growing season.

Soil requirements

The pecan-nut tree performs best in a fertile, well-drained, deep soil with a loose to medium texture.


To produce pecan nuts successfully and profitable, it is essential to plant cultivars that comply with the high standards concerning adaptability to an area, disease tolerance, production, kernel percentage, nut size and shape, appearance and taste of the kernels.

Tolerance to scab

The following cultivars are resistant to scab and can be produced in all production areas: Moore (Bester), Barton, Ukulinga, Shoshoni ( also areas with a high rainfall and humidity).

Soil preparation

Examine the soil regarding depth, drainage and compacted layers.

Soil sampling

A representative sample of the proposed orchard must be taken for soil analysis. This sample should be taken 12 to 24 months, or at least 9 months, before planting. This gives the farmer ample time to thoroughly prepare the soil, particularly if large quantities of lime are required.

Method of soil preparation

If the soil is very acid, heavy lime applications may be necessary. In such a case two-thirds of the recommended agricultural lime must be distributed over the entire area 12 months before planting, mixed into the topsoil by disking, and then ploughed in as deeply as possible. Because calcium (lime) moves very slowly in the soil, it is essential to work it into the future root zone of the trees.

A cover crop can then be planted and ploughed in 6 months later. This will increase the organic matter content of the soil. The remaining lime and all the required phosphate must be applied and lightly worked in simultaneously. The trees can then be planted 3 months later.

If soil samples have not been taken early enough to proceed as described, two-thirds of the lime must be mixed with the soil and ploughed in deeply; the phosphate and the rest of the lime are then distributed and worked in lightly. If large quantities of lime are required, this must be applied at least 3 months before planting, thoroughly mixed with the soil and worked in deeply.


The pecan-nut tree is deciduous and can therefore only be transplanted during the winter. The best results are obtained when establishing orchards with trees planted during July and August.

Nursery trees

Planting in orchards

Planting method




Annual application of fertilisers for pecan-nut trees
Application  LAN  Superphosphate  Potassium chloride

Maximum application








Time of application


Since most soils are low in zinc or the zinc is not available, this element must be added every year. Spray with 150 ml NZN or 200 g zinc oxide/100 l water when the leaf buds are 50 mm long. Repeat at least 3 times at intervals of 2 to 3 weeks. It may be necessary in some cases to spray as many as 5 times.


Many orchards are low in boron. The trees should be sprayed every 2 years with 100 g borax or 75 g Solubor/100 l water from the start.

Leaf and soil analyses

Soil and climatic differences as well as cultural practices greatly affect the quantities of fertilisation that have to be applied.

Soil and leaf analyses give an excellent indication of the actual requirements of a particular planting. If is therefore recommended that, when the trees reach fruit-bearing stage, full use be made of a soil and leaf analysis service. This will make it possible to obtain an accurate and complete fertiliser programme for every planting.

Leaf analysis


Pecan leaf sample



Rainfall in South Africa is often insufficient and does not satisfy the water requirements of pecan-nut trees for optimal production. Additional irrigation is usually necessary during the critical growth stage.

The pecan-nut tree has a deep-tap root system, but for optimum irrigation purposes it will be adequate to supply the top 1 m with water.

Recommended wetting area based on tree age
Age (years)  Diameter (m) of wetting zone  Wetting area (m2)


















Summer pruning

Rejuvenation pruning

Many old trees with declining production and nut quality can be stimulated to more active growth and increased nut production by pruning. By completely pruning back a big tree, the production of 1 or 2 years is lost, but later new growth and the resultant increase in the production of nuts with improved quality compensate for this.

Growth regulants

A registered plant growth regulant will control excessive vegetative growth. This substance must be applied strictly according to the directions on the label. If pruned trees are treated, the concentration of the recommended dosage must be reduced by half.



Scab is caused by a fungus and is the most important disease in pecan nuts in South Africa.

Early symptoms are the appearance of numerous small, brown to black spots, especially on the underside of the leaves. The spots become larger and merge until the entire leaf turns black. Immature leaves drop off.

Similar spots are visible on the shuck of the nut (see figure). Such nuts suffer from delayed development and they are misshapen. Immature nuts may drop off and have no commercial value.

The fungus winters on branches and old shucks that have dropped. Fungal spores rapidly develop in spring and are spread by wind and rain. New spring growth on the trees is infected when the leaf surfaces are wet, especially after rain.

Susceptibility for the disease varies in different cultivars. Ukulinga, Shoshoni, Moore and Barton are regarded as highly tolerant, while Mohawk, Wichita and Chocktaw are susceptible.




Pecan nut stem borer

Damage caused by stem borer


Bark borer

Damage caused by bark borer


Parasitic plants in pecan-nut trees

Parasitic plants, Tapinanthus spp. (bird-lime), occur in most pecan-nut producing areas of South Africa. These plants have no root system and parasitise the host plant. They debilitate the tree and reduce the bearing area.

The plants, with their red and yellow flowers, are easily seen in the tops of pecan trees, especially during winter and September.


There is no chemical control method for these parasitic plants. The only way is to prune the parasitic plants. The branch on which the bird-lime grows must be cut off and removed from the orchard.


Depending on the area, pecan nuts usually ripen from April to July. As soon as the nut is physiologically ripe, the green husk becomes dry, cracks open and the nut drops out.

In South Africa the nuts are mainly collected manually from under the trees.

A certain percentage of the nuts, for various reasons, do not drop. These nuts are called stickers and must be shaken from the trees. If a very large percentage of the nuts are stickers, it may be because of poorly filled nuts, scab or other factors such as irrigation and fertilisation.


The nuts can be stored at room temperature for as long as 6 months before they are marketed. Shelled nuts realise a much higher price than unshelled nuts, but the processing equipment is very expensive and most producers market cooperatively or through a processor. After processing the nuts are usually packed in vacuum-sealed packages, which means that they can be stored for a very long time.


For further information contact the
ARC-Institute for Tropical and Subtropical Crops
Private Bag X11208, Nelspruit 1200
Tel (013) 753 2071
Fax (013) 752 3854


This publication is also available on the website of the
National Department of Agriculture at:


ISBN 1-86871-071-8


Compiled by Directorate Communication,
National Department of Agriculture in cooperation with
ARC-Institute for Tropical and Subtropical Crops

Printed and published by National Department of Agriculture
and obtainable from Resource Centre, Directorate Communication,
Private Bag X144, Pretoria 0001, South Africa