This time of year, home pecan producers will ask various questions about why their crop did not do well. Often there is not a single reason why their pecans failed to produce a crop or a quality nut. Let’s discuss some causes of the lack of pecan production.
Poor variety- Commonly-found cultivars currently recommended for yard-tree plantings include Elliott, Excel, Gloria Grande, and Sumner. To ensure good pollination, plant at least two varieties. This is especially important for areas with few surrounding pecan trees. Since buying a pecan sprayer for a few trees is often infeasible, variety selection is very important.
Water, water, and water — Dr. Lenny Wells, UGA Pecan Specialist, had said in production meetings that if you could only invest money in one thing for pecan production then strongly consider irrigation. Water has more of an effect on pecan production than any other environmental factor, particularly when nut quality is concerned. Drought stress affects nut size and filling, as well as leaf and shoots growth. Adequate soil moisture is important at bud break for stimulating strong, vigorous growth. Good soil moisture during the bloom stage of development through shell hardening will insure good pecan size. If growers want to optimize kernel percentage then good moisture during the nut filling stage is a must. If trees do not receive adequate soil moisture levels late in the production season, then shuck split will be challenged and energy reserves for the next spring can be affected.
The nut sizing period normally occurs from May 1 through August 15. Even though this is not a critical water-use stage for pecan, serious drought conditions during this period can affect yield. The most common visible effects of an extended drought during this period are excessive nut drop and “shell hardening” on small nuts. Lack of sufficient water during the nut sizing period also causes small nuts and may lead to water stage fruit split, which results from a sudden influx of water during the nut filling stage in some varieties.
The nut filling stage occurs from about August 15 to the first week of October, depending on the variety. The most critical period for water use is during the first two weeks of September. Reports from other areas of the country indicate that as much as 350 gallons of water per day can be required by each tree during the nut filling stage. Lack of sufficient water during the nut filling stage will lead to poorly-filled nuts, poor nut quality, and increased alternate bearing.
Inadequate lime or fertilizer- Fertilization is one of the most important production practices for bearing pecan trees. If the trees are to produce a good crop, terminal growth should be six inches each year. In the absence of a leaf analysis or soil test, broadcast four pounds of a complete fertilizer such as 10-10-10 for each inch of trunk diameter (measure 4½ feet above soil level), up to a maximum of 25 lbs. per tree. Ammonium nitrate may also be used at a rate of one lb. per inch of trunk diameter, up to a maximum of eight lbs. per tree. This fertilizer should be applied in mid-to-late March.
Zinc nutrition is especially important in pecan production. Zinc needs are best determined by analyzing leaf samples taken in late July or early August. Mailing kits and instructions for taking samples are available from your county Extension office. The leaf analysis report will tell you how much zinc to apply. In the absence of a leaf analysis, apply one pound of zinc sulfate to young trees and three to five pounds to large trees each year. A soil pH of 6.0 to 6.5 assures the availability of essential nutrients. If the pH is too low or too high, uptake and use of nutrients are impaired. Apply lime as suggested in the soil test report to correct low soil pH.
Poor pollination- A single isolated pecan tree usually can suffer from pollination issues. Most pecan varieties shed pollen either too early or too late to adequately pollinate the female flowers of the same tree. If several 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 the movement of pollen by the wind.
Diseases and insects- Pecan scab can limit home production. Scab-resistant varieties are a way to maybe manage this challenge. Insects such as aphids, pecan weevils, and case bearers can be a hurdle for home production due to the inability to spray trees. Consider sanitation for the management of diseases and insects.
If you have any questions about pecan production, please contact the Colquitt County Extension office at 229-616-7455.