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Nutrients Important for Good Pecan Crop

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Posted Feb. 1, 2004

Springtime is almost upon us, and with that in mind, it's time to look forward to a new growing season.

While we can't say a whole lot of good things about the 2003 pecan crop, we stand a good possibility of a great crop in 2004. Those who have been around a while have told me that when pecan trees rest (or have a light crop), the following year the tree can produce an abundant crop (with favorable environmental conditions). However, let's not forget what happened to the trees that made the light crop. It was spring freezes that stopped the growth. This stopped growth was damaged tissue - tissue that was the potential 2003 pecan crop. This is devastating to the tree because the damaged growth will have to be replaced. Trees are perennial plants, which means that any green tissue above ground level will try to leaf out year after year. This takes energy and moisture. It is our job, as stewards of the earth, to see that the plant life is properly fed. Few, if any, pecan groves or orchards are irrigated in Oklahoma or North Texas, so allow me to concentrate on the dryland pecan trees.

The nutrient of concern is nitrogen. We can supply nitrogen as either granules (i.e., ammonium nitrate 33.5-0-0 NPK or urea 46-0-0 NPK) or as liquids in a 32 or 28 percent solution. Another method of making nitrogen available to the tree is planting a legume crop (they fix nitrogen from the air to the plant), which in turn can be used by the trees. The best method for determining the tree's needs is testing leaf samples in mid July. This sampling is done in July to reduce the amount of fluctuation of the nutrient levels in the leaf. I know it is hot in July, so take the samples early in morning. Send them to the Foundation's soil and forage testing office. Go to www.noble.org/Ag/Horticulture/PecanSampling/index.htm for more information dealing with sample technique and the request form. This leaf nutrient information is excellent when deciding both amount and type of nutrient to apply to the grove or orchard.

When applying spring nitrogen with no idea of what is needed, apply 80 to 100 pounds of actual nitrogen per acre. This is a best guess, or a "shot in the dark," so to speak. This can be done in a split application. The second application can be made or omitted, depending on the size of the crop. Applications of nitrogen are discouraged after July. This is due to early freeze damage to the newly formed growth that can occur in the fall. Other timings of nutrient applications in late fall applications have been studied by OSU.

The bottom line is, if we want the trees to produce a crop, we will have to continue to supply the trees nutrient needs to produce terminal growth and keep the leaves on the trees until late fall. Take time to take a leaf sample and make the proper nutrient application.