Although several grafting techniques have proven successful for experienced grafters of the mamey sapote (Pouteria sapota), most amateur plant propagators find the plant difficult to graft.

Four-flap grafting is a technique for grafting pecan (Carya illinoensis) which was developed in Oklahoma during the 1970's, as a recommended technique for the beginner. A modification of this process was used to find out its effectiveness with the mamey sapote.

The study was conducted at Fairchild Tropical Garden. The grafting was done by two experienced grafters.

Diagrams of 4-flap grafting.

Twenty-four actively growing, containerized mamey sapote seedling rootstocks were obtained from a commercial nursery. The 50-60cm tall seedlings were topped at ca. 30cm. Four vertical 7cm slices were made through the bark from the cut end towards the base Fig. 1A).

Juvenile seedling scions 12-14cm in length were collected and prepared by cutting four 6cm flat cuts equally spaced around the base (Fig.1B).

These cuts were shallow, removing the bark and a minimal amount of wood. The prepared end of the scion had a square cross-section.

Returning to the rootstock, the four bark flaps made by the vertical slices were peeled away from the wood, starting at the cut end. This process exposed 7cm of wood, which was carefully clipped out while holding the four flaps down (Fig.1B).

The scion was placed on top of the cut end of the rootstock, and the four flaps pulled around it. Each of the rootstock flaps were easily matched with one of the four cuts on the scion. Cut areas were wrapped with grafting tape (Fig.1C), and the exposed scion covered with parafilm.

Grafted plants were placed on raised benches under glasshouse conditions on 16th December, 1988 and maintained until 5th March, 1989. Mean success rate was 67% for the two grafters. No forcing of scion growth was needed since the technique is a terminal graft, so after care consisted only of removing any rootstock growth below the graft union.

This preliminary study shows that the four-flap technique may be suitable for grafting mamey sapote. Success rate may be enhanced by pre-girdling scion wood and/or cutting off the terminal bud and leaves and waiting for lateral buds to swell. These processes have proven beneficial for other grafting techniques, and may influence success with the four-flap method. The only strict requirement for the four-flap method is an actively-growing rootstock, since the bark must slip freely.

Beginners may obtain a higher success rate with the four-flap technique for several reasons. The cuts are easy to make, and need not be precise, and after-care is simple. More importantly, however, a large amount of cambium contact between the scion and rootstock is quite easily obtained without careful fitting of pieces.

Further Reading:
Hartmann, H.T. and D.E. Kester, 1975. Plant Propagation, Principles And Practices. 3rd ed. pp.314-454. Prentice-Hall, Englewood Cliffs, NJ.

Vanerwegan, Jerry. 1975. A new grafting procedure. Pecan South Vol.2 No.2.

Thomas Marler

DATE: January 1992

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