A Grafted Pecan Tree:
Grafted Pecan trees are horticultural techniques that joins two plants so that they appear to grow as a single plant. In grafting, the upper part (scion) of one plant grows on the root system (rootstock) of another plant. Because they are clonally produced, trees grown by grafting will produce nuts that are identical to the source of the grafted wood.
Grafting a pecan tree is a special technique that helps with variety selection and rapid production. Many farmers know that pecans grown from seeds are not always true to type. Meaning, a pecan produced by a given variety will not produce a tree that’s identical to its parent when it is planted. In order to grow a tree of a specific variety, pecan tree farmers must graft the buds or shoots of the parent tree onto a seedling rootstock. While it sounds unusual, the grafting process is quite important to proper pecan production.
Taking a Closer Look at the Grafting Process
The actual grafting process consists of joining the scion with the rootstock of the pecan plant. The scion is a mature shoot or bud of a known pecan variety. Usually, the scion measures 5 to 6 inches in length and ¼ to ⅝ inch in diameter. The rootstock, also referred to as the understock, is the root of the scion that forms underground. Depending on the size of the rootstock and scion, grafting techniques will vary. Here are a few examples of grafting techniques used to process various pecan trees:
- Bark Grafting: This grafting technique is used to graft a small scion onto rootstock that is too large for other grafting methods such as the four flap graft and the whip graft (we will discuss these two later on). Pecan farmers recommend barking grafting during the spring season–late April to early May. When bark grafting, the bark on the scion should be tight, and the rootstock should be sliced off smoothly, leaving one to two side branches below the cut. This will allow you to regulate the growth of the tree. With a sharp knife, you can remove the outer layer of the bark so the scion can be inserted properly. Keep in mind, the scion should have at least three buds for optimal results.
- Banana Grafting (Four Flap): This method is considered to be one of the easiest grafts to use for pecan tree production. Yielding the best results with a caliper tree (1 inch in diameter), the banana graft should be used on scions and rootstocks that are of similar sizing, with the scion the tiniest bit larger than the stock. With the four flap, the cambium is able to achieve optimal contact with both the rootstock and scion–eight opportunities to be exact. This grafting technique should be done in the spring as well.
- Whip Grafting: The whip method also known as slice grafting, should be used on seedling trees and nursery stock that is one, two, or three years of age. Unlike other methods, whip grafting boasts the best results when it’s done in February. While young trees are optimal, the whip grafting method can also be done on older trees. However, these limbs must be de-horned for new growth. With the whip graft, one must cut both the scion and the stock in a sloping direction. Once this is done, secure them by typing or taping.
Choosing the right grafting technique will depend on the size of the rootstock and the scion. These unique grafting techniques rely on proper timing in order to yield the best pecan production results.
Dr. Charles Rohla, pecan researcher at The Samuel Roberts Noble Foundation, demonstrates an “American Method” modification of the procedure uses duct tape in place of traditional grafting tape.
More Resources on Grafting: