Pecans

Karen Cambre, Sharpe, Kenneth W.  |  5/9/2018 4:19:42 PM

pecan tree with scabjpg

News article for November 20, 2017

Thanksgiving and Christmas are the times of the year when we use the most pecans.I noticed that the pecan trees around my office had no pecans on them this year.

This same trend holds throughout the state and the reports are a short pecan crop. This is a product of too much rain early. If we have rains during the pollination period, the pollen cannot float on the wind and do its job. When you do not set pecans, the problem is usually pollination.

Another significant problem that affects pecan production is a fungal disease that we know as scab. It is most prevalent when we have rainy, hot, humid weather, and we have had it. It will show up first on green leaves as a tiny brown leaf spot usually on the underside of the leaves. Those spots will grow in size and get darker in color usually turning black. Next the disease will move to the shuck of the juvenile pecan, provided that you have pecans. Scab will appear as a circular black sunken spot on the shuck. Depending on how soon in the development of the pecan scab attacks, you can have either partially filled pecans or just empty pecan shells.

Scab will overwinter on old shucks, twigs and leaves. There is a fungicide spray schedule that can help with scab but spraying would need to start in the early part of the growing season to prevent damage.It is very impractical for most people with a few large trees to spray. First, it takes some powerful spray equipment to spray straight up in the air and that type of equipment is very expensive. Next, you need to have enough land to contain any spray so you are not spraying onto your neighbor’s property. If you are going to spray, it will take 3-6 sprays timed strategically throughout the growing season in order to control scab.

For trees that you already have planted, your best approach might be to fertilize in the spring and try to get the trees as nutritionally healthy as possible. It usually will require 2 years of fertilization in a row to see the results. Trees that get scab and lose their leaves early in the late summer or early fall may put out a crop of new leaves before they go dormant. Producing new leaves takes away from energy reserves and hampers the tree’s ability to produce pecans the following year.

Fertilize in the spring, just prior to bud swell and apply 2 pounds of 13-13-13 fertilizer per inch diameter of the trunk measured at 4 feet of height. Broadcast the fertilizer under the canopy of the tree. Pecan trees can also benefit from zinc if it is low in the soil. Our low pH soils make soil zinc readily available to plants so it is not a big problem here. You can check zinc levels with a soil sample.

If you are interested in planting pecan trees, then scab resistance should be your major concern when selecting a variety.Elliot has excellent scab resistance and is the best variety for disease prevention. It is a high oil pecan with a great taste. It produces medium sized pecans that take 65 nuts to make a pound. Elliot will come into production in 6-8 years from planting.

Sumner is another variety that has some scab resistance, but we still see scab in the worst years. Sumner will come into production in 5-6 years and produces a larger pecan with only 45 nuts required to make a pound.

Candy is recommended but has developed more scab than you might find acceptable in our recent wet years. It can come into production in just 4-5 years but has a smaller pecan that requires 70 to make a pound.

Just writing about pecans makes my mouth water for a pecan pie.

For more information on these or related topics contact Kenny at 225-686-3020 or visit our website at www.lsuagcenter.com/livingston.

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