Wednesday, May 28, 2008

Right Variety, Timing Key to Backyard Pecans

Many people fail to realize the potential problems facing the successful production of pecans in home or backyard orchards. They think that all pecan trees are alike.

The backbone of any backyard orchard should be the selection of varieties. All of them have good and bad qualities. For a low-input producer, like most home pecan growers, in the Southeast, disease resistance should be top priority. Our climate is favorable for the development of a disease called pecan scab, which can annihilate a crop, especially during wet summer weather.

There are no controls available to fight scab for the backyard pecan grower. Resistant varieties such as Excel, Elliott, Sumner, Gloria Grande, Gafford, Jenkins and Amling should be planted to escape this devastating disease. Pecan scab is minimized by dry weather, which can benefit scab-susceptible varieties.

Fertilizing pecans can be a complicated matter. Because pecan trees are a perennial crop, which means they produce a heavy crop every other year, there is often considerable carry-over of nutrients from a year with a light crop into one with a heavy crop. Trees that are well managed can actually go for several years without fertilizer before any reduction in yield or tree health is noticed.

When bearing a light crop, the trees don’t use a lot of energy. If adequate fertility is provided, the excess energy from these nutrients is stored. This helps produce a larger crop the following year. For this reason, pecan trees require less fertilizer in “off” years, or years with a light crop.

For a backyard tree, apply 4 pounds of 10-10-10 fertilizer for every inch of trunk diameter up to a maximum of 25 pounds in years when a heavy crop is expected. When a light crop is expected, this rate can be cut in half.

Apply the fertilizer in March or April by broadcasting over the area beneath the tips of the branches. The roots often extend out to twice the width of the canopy. Avoid applying fertilizer near the base of the trunk. An excessive concentration there can damage feeder roots.

Pecan trees can use a lot of water, particularly in late summer. Water mature trees during the first two weeks of September. Too much water from May to mid-August can lead to large nuts, which will make it difficult to develop high quality kernels for harvest in fall. If the tree bears a light crop, the water requirements for that tree will be less.

The pecans on a tree that is bearing a heavy crop can develop problems, too, such as undeveloped or fuzzy kernels or shuck deterioration late in the season. This results from the lack of access to adequate water and nutrients for the large crop the tree is bearing. Aside from proper water management, little can be done to correct this problem.

A variety of insects can attack pecan trees. The most problematic for the home grower is the pecan weevil. It chews through the shuck to lay its eggs inside the pecan nut. The larvae eat the nut.

When the nut falls to the ground, the immature insect emerges and burrows into the ground where it develops into an adult. The adult weevils emerge from the soil with late summer rains and crawl up trees in search of more nuts. Spray Sevin on the ground and at the base of the trunk to control them.

Backyard pecan production requires the producer to be wise and efficient with when, where and how they provide inputs for their trees. This can be of economic and environmental benefit.

By Lenny Wells
University of Georgia

Lenny Wells is the University of Georgia Cooperative Extension state pecan specialist with the UGA College of Agricultural and Environmental Sciences.

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