Commercial nurserymen now prefer to bud hickories and pecans rather than to graft, but formerly Reed(15) reported the whip-and-tongue method was used on thrifty one-year seedlings in the nursery row. It is conceivable that the cleft graft could be used at this stage when the diameter of stock and scion are quite similar but no record of its use is available.
Top-working or grafting in the branches is commonly practiced on seedling trees and sometimes used to change varieties in the orchard. Reed(15), Sitton(19), Rosborough et al(18), MacDaniels(11), and Stoke(22) have described various methods that have proven successful. Practically all agree that the bark graft or a modification thereof is best. Morris(12), Benton(3), MacDaniels(11), Wilkinson(25), and others have shown that a greater per cent of survival is secured when the stocks are cut 10 days to 2 weeks before grafting. During this time the stubs heal somewhat and excess bleeding is decreased. It has been reported by Becker(2) that the success of walnut grafting is greater when the grafts are set just after the leaves are full grown but no such data is available for hickories. The use of paper bags or other shading device over the scion is advocated by Morris(13), MacDaniels(11), Shelton(20) and others.
Propagation by Budding
Patch budding is now almost universally used by commercial nurserymen in the propagation of hickories and pecans. Patches are usually cut with a double-bladed knife although some use the rectangular Jones patch-budding tool. The "plate" or "skin" bud is also used to some extent. The thick bark of hickories and pecans discourages the use of the shield or "T" bud.
Budding is usually done in late summer with mature buds of the season growth which remain dormant until the following spring. Occasionally dormant budwood taken in winter is held in cold storage until the bark of the stock slips in the spring. These spring-set buds are forced the same season by cutting the stocks back shortly after setting. Patch-budding is described by Reed(15) and by Rosborough et al(18). Reed(15) mentioned that it may be advisable to make the cuts in the stock from one to three weeks before the bark is removed so that the healing process may be under way at the time the bud patch is inserted.
Storage and Handling of Scions and Budwood.
Shelton(20) reported an easy and unique method of keeping scions moist by storing in a closed container with a small amount of sodium sulphate (Glauber's salt). Slightly moist peat moss is an excellent packing material. Brison(4) reported that a temperature of 32° F to 38° F in storage is satisfactory for keeping the buds dormant, and that a few days from 80° F to 85° F will stimulate cambial activity so that the patches will "slip" easily when cut. Scionwood is sometimes dipped in wax, paraffin, or plastic resin before storing in order to prevent loss of moisture and guard against pathogenic organisms.
Waxes and Wound Dressings
Sitton(19) used a large number of variously formulated waxes on pecan and found that the most successful from the standpoint of graft survival was one composed of 10 parts rosin, 2 parts beeswax, and 1 part filler such as kieselguhr, talc, or aluminum powder. Under Louisiana conditions a light-colored wax was preferable to dark colored one. Asphalt emulsions were not satisfactory.
Rootstocks and Interstocks for Hickories