Seven Reasons Pecan Trees Don't Produce

Alabama has thousands of mature pecan trees around homes, many with sparse and erratic production. Usually, there is no single reason why a pecan tree fails to produce a crop or produces poor quality nuts. The following are common problems and some suggestions for correcting them.

Poor variety- Pecan cultivars (varieties) vary in production capacity, nut quality and susceptibility to disease and other problems. For example, a variety such as Schely will rarely produce a good crop when trees are unsprayed because the trees are extremely susceptible to pecan scab, a fungous disease. In contrast, varieties such as Elliott, Jenkins, McMillan or Syrup Hill, which are currently recommended for home planting, are quite resistant to pecan scab and aren't usually seriously damaged.

Poor soil- Pecan trees grow best on sandy loam soils with well-drained subsoil. Growth and production is often poor on heavy clays, poorly drained soils and on deep sands unless an intensive irrigation and fertilization program is maintained.

Inadequate lime or fertilizer- Lack of lime, nitrogen fertilizer and zinc are common limiting factors in pecan production. Fertilize according to soil and leaf sample recommendations.
Rules of thumb: 1 pound of 13-13-13 per
tree per year of age up to 25 pounds/tree
plus
1 pound of ammonium nitrate per tree per
year of age up to 20 pounds/tree
plus
1/10 pound zinc sulfate per tree per year
of age up to 2 pounds/tree
plus
5 pound dolomitic lime per tree per year
of age up to 100 pounds/tree

Apply fertilizer in March on large trees. For young trees, fertilize in March with 13-13-13, lime and zinc. Apply half ammonium nitrate in April, half in June. Broadcast fertilizer on the surface in a circle twice the branch spread of the tree.

Too much or too little water- Waterlogged soils where water stands do not provide aeration for roots. Lack of water, especially during dry periods of summer, frequently results in reduced yields and quality, and in weakened trees that may be less productive in following years. Choose well-drained soil, provide drainage for excess water and keep trees watered during dry periods.

Poor pollination- A single isolated pecan tree usually won't be effectively pollinated, since most varieties shed pollen either too early or too late to pollinate the female flowers of the same tree. If a number of seedling pecan trees or trees of several different varieties are already growing within a few hundred yards, a tree for pollination is probably unnecessary. Another reason for poor pollination is wet weather during April and May. Rain washes off pollen and may restrict movement of pollen by wind.

Overcrowding- Pecan trees must have good exposure to sunlight to produce good crops. When limbs begin to overlap limbs of neighboring trees, remove the least desirable trees to prevent overcrowding.

Disease and insect pests- Pecan scab seriously limits production on unsprayed pecan varieties. Even varieties previously resistant to scab are being affected. Several other diseases can cause early leaf drop and decreased production. Elliott, Gloria Grande, Owens, Jenkins, McMillan and Syrup Hill are recommended varieties with good disease resistance.

Aphids, pecan weevils, hickory shuckworms and several other insects can limit pecan production. Removing and destroying fallen leaves, shucks, nuts or twigs are sanitary measures that aid in control of many insects and diseases. Spraying may not be feasible for growers with only a few trees, but spray recommendations for controlling pecan pests are available from the Alabama Cooperative Extension System office in your county.

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SOURCE: Dr. William Goff, Extension horticulturist, Alabama Cooperative Extension System (334) 844-5480.