For Release On Or After 12/11/09

November through February is the best time to plant pecan trees. But before you decide to add a pecan tree to your landscape, you have some things to consider.

Pecan trees grow to be quite large – 60 feet tall with a spread of 40 feet – so make sure your site is large enough. In addition, the wood of pecan trees is somewhat brittle. You should not plant a pecan in a location where branches might fall on your house or other structures. Pecan trees should be planted at least 20 feet (preferably more) away from homes, garages, patios and other structures.

You can select from a number of recommended varieties. These include Elliot, Candy, Sumner, Houma, Caddo, Oconee and Melrose, which are more resistant to diseases and are better suited for home landscapes. Pecans must be cross-pollinated to produce well. Generally, enough pecan trees are in an area for this to happen even if you plant only one tree.

Pecans are wind-pollinated, and the pollen can travel some distance. However, if there are no pecan trees in your area, you should plant two different types – Elliot, Candy Sumner or Melrose with either Houma, Caddo or Oconee.

Planting pecan trees

Survival is usually better when you plant smaller-sized, 4- to 5-foot trees grown in containers. Never allow the roots of the trees to dry out prior to planting. Dig large holes for planting – two to three times the diameter of the root ball and the same depth.

Prune badly damaged and dead roots from the trees before planting. Place the root ball of the tree in the hole and fill back in around it with the soil you dug out.

It will be important to water young trees during periods of dry weather, especially during the first and even second summers after planting. Use mulches around newly planted trees to conserve moisture and prevent weeds.

Why pecan trees fail to bear

Home gardeners sometimes are perplexed to discover that their pecan trees have failed to produce well. First, you must consider the time since planting. Pecan trees generally take 6-10 years after planting before they begin to produce good crops of nuts. You need time and patience.

In many cases, you may have trees that once produced but now, year after year, yield few if any pecans. Trees also may produce nice crops of nuts, but the quality leaves a lot to be desired – the nuts are poorly filled or contain no meat at all. What has gone wrong? Is there any way pecan trees can be brought back into production and maintained?

Healthy leaves are essential for nut production

Think of a pecan tree as a very complex factory where leaves are responsible for producing the food that ultimately is used to make nuts. It takes about 40 pecan leaflets to set and fill out a single pecan nut.

During the growing season, foliage manufactures food that’s translocated and stored in the root system for nut production the next spring. Early leaf loss causes a shortage of healthy leaves and limited or reduced nut production the next year. Foliage damage during the growing season also can reduce that year’s crop.

Early leaf loss can be the result of a combination of problems, especially a disease called scab. It is a fungal disease that appears early on the leaves and nuts as small black lesions that later enlarge and completely blacken the leaves, eventually killing them and causing defoliation.

Scab also will attack and damage the shuck or outer covering of the nut and cause a poorly filled or hollow pecan. If you see numerous black spots, streaks or areas on the shuck of the pecan and the nuts are poorly filled, pecan scab is the problem.

In addition, various leaf-feeding insects can compound problems. Insects such as aphids, mites and fall webworms attack pecan leaves, contributing to early defoliation.

The pecan variety dictates the severity of the scab problem. Many of the older varieties – such as Stuart, Success, Mahan and Desirable – are very susceptible to scab disease. On the other hand, varieties mentioned at the beginning of this column are moderately to very resistant to the scab organism.

Pecan varieties not considered scab-resistant can be kept in production only through the application of fungicides throughout the growing season. Pecan trees are too large to be sprayed with conventional garden equipment, and most gardeners do not have spray equipment that will reach the top of a 30-foot tree.

Another ingredient helpful in maintaining productive pecan trees is an annual application of fertilizer. Pecan trees should be fertilized in February with about one pound of general-purpose fertilizer per inch diameter of the trunk measured three feet from the ground. Do not fertilize young trees the first year they are planted.

Pecans are such an important part of our culture and cuisine, and it’s nice to have plenty of pecans to use and share from your own tree. Just remember that sufficient room, proper variety selection and good care are important to success.