Replacing Damaged Pecan Trees
Catastrophic weather has destroyed many pecan trees the last few years, taking out some that were strategically placed. Several orchards were damaged extensively, and many of the trees were either removed or damaged so much that their productive lives were shortened. Most landowners who want to remain in the pecan business need to develop a strategy for replacing trees periodically. In this article, I discuss different approaches to tree establishment.
No single tree-establishment procedure is best, because labor is expensive. When cost comparisons of planting are developed, the way labor is figured will often favor a certain technique. Planting a tree nursery to develop it for transplanting usually requires less labor, but transplanting is expensive. Although planting the trees in place is labor intensive, there is no need for an expensive tree spade.
Rules must be followed when trees are planted. Some of these rules may seem elementary, but they are important and should not be skipped.
- Make sure the trees you plant are alive.
- Don't let even the surface of the tree's roots dry out.
- After planting the tree, fill the hole with soil and then water to eliminate air around the roots.
- Plant the tree at the same depth it was before transplanting.
- Keep the root zone moist.
- Keep livestock away from transplanted trees.
- Graft and train trees after they are established.
Understand the site before deciding whether it is wise to replant pecans at that location. If irrigation isn't possible, plant only on sites where pecans are well adapted. That restriction usually limits planting to alluvial soil where water tables are stable at 6 to 10 feet from the soil surface. If water tables are closer than 4 feet to the surface, trees' root mass will be limited, which will inhibit the trees' performance. Where water tables are deeper than 10 feet, supplemental water will be necessary for consistent production of quality pecans. If you decide that the location will support pecan production, then determine your planting strategy.
Here are two options for tree establishment. The first one involves planting first-year container-grown seedlings in their permanent position in late August or early September. After they are two to three years old, graft them to the desired variety. Provide exclosures to keep cattle off the developing trees (figure 1). The second option entails planting seed, bare-root seedlings, or grafted trees in a nursery that is close to the areas to be planted. After the trunk diameter is 2.5 to 3 inches, use a 96-inch-diameter tree spade to move the trees to their permanent location.
Planting trees in their permanent location and growing them in place is my preference. The greatest threat to tree survival is weed competition and livestock pressure. Weed control is best accomplished by creating a mulch layer either with coarse wood chips (high-line trimmings) or a weed barrier fabric. There will be fewer weeds if you use mulch, but those that do escape the barrier will require applications of glyphosate.
Another significant threat is browse pressure from cattle. Designing an exclosure for cattle and deer is easier with stocker cattle than with mature cows and especially bulls.
One pecan grower went to the extreme of electrifying each of his exclosures by building an electric fence over their tops to connect them. A common exclosure can be constructed from 5-foot-wide concrete reinforcement wire cut into 12-foot lengths and tied into hoops. The hoops are then suspended 1 to 2 feet on two steel posts, depending on the tree size. If the hoops are electrified, they can be smaller but must be suspended on fiberglass rods or some other nonconducting material.
When planting in place during February, you can plant a large bare-root seedling. Expect a death loss of at least 10 percent. Another option is to plant container-grown seedlings in late August or early September. Seedling trees cost about half as much as grafted trees, which reduces the amount of cash at risk. If a seedling dies, it won't cost as much to replace. The small container-grown trees should have a greater chance of success, although it may take longer for them to begin producing.
Using a large spade to move 2- to 3-inch-diameter pecan trees is expensive (figure 2). A 96-inch spade on a sizable job typically costs $125 per hour, or about $50 per tree. If you add the purchase cost of the tree and its care for four to five years, it becomes an investment of roughly $100 per tree. No exclosures are required if you use this method, but the trees will need a mulch layer, weed control, and supplemental water during stress periods. Transplanting is expensive, and trees need more care the first few years than they would if you used other techniques.
You may not have the perfect site for planting pecan trees or may want to plant an intensively managed orchard. When water relationships are questionable or intensive management of large varieties is a goal, irrigation must be a part of the plan. Consider irrigation not only for establishing trees, but also for overcoming moisture limitations you will encounter during the production phase. Plan to use about 7 gallons per minute per acre for a productive pecan orchard.
Before moving into intensive pecan management, be sure to understand the problems that are involved and have a plan to overcome them. Follow these steps:
- Explore the site, determine its characteristics, and decide what it will take for pecan trees to produce consistently.
- Secure healthy trees whose roots have not been subjected to drying.
- Water the trees in when planting.
- Install weed control.
- Build livestock and deer exclosures on in-place planted trees.
- Give trees supplemental water to improve their chances for survival.
- Prepare to graft the tree to the desired variety when the tree is well established.
If you have no plans to protect the trees from grasshoppers, cattle, or weeds, planting may not be a good idea. If you plan to start new trees, I encourage you to contact one of the horticulturists at the Ag Division.