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Fertilizing Pecans Cost of nitrogen has become a major expense in growing pecans. It is time to think about the most efficient and cheapest way to put fertilizer out. How to fertilize for the coming year can be a dilemma. This is likely to be an off year for many of the pecan orchards. Many trees in Pointe Coupee parish lost their foliage to caterpillars early in the season and then lost more leaves to hurricanes late in the season. Trees that had a lot of their leaves blown off by hurricanes are likely to have a light crop this coming year. Trees that put out new leaves after the hurricanes have probably severely reduced their energy reserves and are likely to have little or no crop this year. A split fertilizer application would probably be a good choice since most orchards are likely to have a light crop next year. Half of the nitrogen fertilizer should be put out in March and the second half can be put out in May if a good pecan crop develops. Eliminating the second half of the nitrogen application if a light crop is present can reduce production cost and also reduce the potential of a very large nut crop being produced the following year which often results in poorly filled nuts and severe alternate bearing in following years. A producing pecan orchard normally needs 100 to 150 units of nitrogen per acre. Traditionally 100 units of nitrogen per acre are used when leaf samples indicate nitrogen levels of 2.5 % to 2.75%. An additional 10 pounds of nitrogen per acre is added for each 0.1 % the leaf nitrogen is below 2.5. Ammonium nitrate has been the traditional nitrogen source for pecan orchards in Louisiana. It loses little nitrogen to the air under Louisiana conditions and has been easily obtained and has usually been competitive in price. Ammonium nitrate is 33 or 34% nitrogen. There have been some concerns about the availability of ammonium nitrate this year. I have talked to six fertilizer dealers in Louisiana about availability. They said it was available and they had not received any word on new regulations in handling ammonium nitrate. Urea is a possible substitute for ammonium nitrate in the spring when temperatures are cool except in areas where soil pH is above 7.0. Urea can volatilize, losing nitrogen to the air, at the higher temperatures that would be expected in May. Urea is 45-46% nitrogen. John Pyzner
Now that the new year has arrived, it is time for pecan growers to turn their thoughts from the 2004 crop to making plans for the 2005 orchards. Even though it is still cold outside, there are a number of tasks which need to be completed while the trees are still dormant. Many growers will want to look at how their current pecan varieties have been performing for them and make decisions on whether to keep them or top work the trees to a new variety. Also several growers will be propagating new orchards or nursery trees. Successful grafting in the spring is not only dependent on the proper selection and collection of scion wood, but also on knowing how to properly store the wood for later use. Selection of weak/damaged graft wood and/or improper storage of graft wood will generally result in a low survival rate or “poor take”. January and February is the right time to collect graftwood for whip, four-flap (banana), and inlay-bark grafts. Ideal scion sticks are smooth and straight and are usually between ¼ and 5/8 of an inch in diameter, but larger and smaller wood can be used. Suitable bud or graftwood should have 3-4 buds at each leaf node (primary, secondary, & tertiary buds). The smaller tertiary buds serve as insurance if the primary or secondary buds are lost or damaged. For graftwood, collect fast-growing, one year-old straight shoots from the tops of young trees. If you do not have access to young trees, older trees which were pruned heavily the previous season will have fast growing shoots at the point where large cuts were made. Or you can cut back or dehorn trees now to produce graftwood for next year. If neither of these sources are available, less vigorous side limbs or two year-old wood can be used. But this wood will generally result in a lower success rate and it is more difficult to accurately cut and use for most grafting procedures. Budwood to be used for patch-budding shouldn’t be collected until early or mid-March. It is necessary to wait later for this wood since the bark must be slipping for use in patch-budding pecans. Budwood is often larger than wood collected for grafting – up to an inch in diameter. It is stored the same as graftwood, but is treated differently prior to use. Budwood, still in its storage container, is placed at room temperature (75-85 degrees F) for 4 to 7 days to season the wood. Use the budwood as soon as possible after the bark begins to slip. Budwood should be labeled and stored separately from graftwood because of the difficulty of seasoning January-cut wood for budding. The collected graftwood or budwood should be cut into 6, 12, or 18 inch sticks and should never be allowed to dry out before processing. The ends of the scionwood are generally sealed with orange shellac, paraffin, or grafting wax. No matter what you seal the ends with or if you choose to not seal them at all, it is crucial that the wood be placed into polyethylene bags as soon as possible. Moist (not wet) paper towels, newspaper, wood shavings, or sphagnum peat moss may be used as packing to keep the wood from drying out in storage. Make sure all graftwood and budwood is labeled by variety, source, and date collected. Graftwood should be refrigerated at 35-40 F until it is to be used. Remove only the amount of wood you will need and carry it to the orchard in an ice chest. Never allow the wood to dry out from the time the shoots are initially cut until the graft is completed. One of the most common causes of graft failure is bad graftwood. After collecting your graftwood, now is also a good time to look at how well your trees grew the previous year. It is a lot easier to see the structure of your trees without all of the leaves in the way. For young orchards, prune all “V” trunks to prevent splitting as the trees get older. Thin out long “crows feet” shoots at the ends of limbs. Cut back central leader on trees that are two, three or four years old and remove trashy shoots on the lower trunk which have a diameter greater than 1 inch. If you grafted trees the previous year, tie or prune the main graft shoot to reduce the chance of “blow-out” when it is completely leafed out in the spring. Remove any large, competing suckers below or beside the graft union. For older orchards, select, mark, and remove crowded trees or mechanically hedge the orchards to prevent crowding. For native pecan groves, thin trees if crowding is occurring, there should be no more than 30 cross sectional square feet of trunk area per acre. Prune out damaged or dead branches and remove any low limbs which interfere with cultural management practices.
More information is also available at the LSU AgCenter’s Pecan Research Station website. The address is http://www.lsuagcenter.com/nav/locations/research/research.asp?id=13.
Contacts: Charlie Graham at (318) 797-8034 ext. 2333 or cjgraham@agcenter.lsu.edu Mike Hall at (318) 797-8034 or mhall@agcenter.lsu.edu Randy Sanderlin at (318) 797-8034 or rsanderlin@agcenter.lsu.edu
How to grade your pecans Equipment required: 1. Get a representative sample. As you are cleaning, toss a
handful into a bucket at regular intervals.
If you have any questions or comments related to production, send an email to stephen@rosaliepecans.com and I will post them for you.
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