Refinements in Grafting
by John Panzarella
I wrote this article for the Oct. 1990 Calif. Rare Fruit Grower's magazine 'The Fruit Gardener.' It still applies.
This article describes some refinements in grafting and is addressed to the experienced grafters. I will assume you know the basic techniques in grafting, but if not, read the section on grafting in The Handbook for Fruit Explorers published by NAFEX, or read the Ortho book All About Citrus & Subtropical Fruits, pages 86, and 87.
Sometimes I hear even from experienced grafters about the difficulty in grafting persimmon on persimmon rootstock and citrus on poncirus trifoliate. With the technique I am about to describe, I think you will be more successful. Here is what I do:
Persimmon: I graft persimmon beginning in February. Here in Texas that is about a month to a month-in-a-half before the persimmon trees start to break winter dormancy. I do a whip and tongue graft. Generally, I select scion wood with two buds. My modification the whip and tongue method is that before attaching the scion to the rootstock, I cut parafilm “M” into ½” x 4” strips, and I spiral the parafilm around the whole piece of scion wood so that it is completely sealed including the top end. For you that have not used parafilm “M,” it is a waxy laboratory film that comes in a 4” x 125’ or 250’ roll or a 2” x 250’ roll. It is manufactured by (updated June, 2007, Pechiney Plastic Packaging, Chicago, Il 60631.) It is described as a flexible, moldable, self-sealing, moisture-resistant, and thermoplastic. I make sure that only one layer of film is stretched over the buds so that will not have any trouble piercing through the film. I then attach the scion to the rootstock and cover the union with several wraps of ½” polyethylene budding tape. You need scion wood with the brown bark and fat mature buds. If you collect the scion wood after the spring growing season, cut the leaves off the scions.
The rootstock can be dormant or actively growing. Just be sure the part of the rootstock you are working with is mature (brown outer bark). I usually work with rootstock that is about the diameter of a pencil or slightly larger. I have had success grafting from February to July with this technique. I also do chip budding in the early spring and again I cover the whole bud with one layer of parafilm.
Peach, pear, plum, and apricot: I graft them the same as persimmon except when prunus bark slips, I switch over to T-budding.
Citrus: For citrus and particularly for grafting to trifoliate rootstock, I do the cleft graft.
What is nice about cleft grafting or any other grafting is that you don’t have to worry about whether the bark is slipping as you do when you bud. Again, I spiral the parafilm completely over the scion, but, in this case, I do not cover the buds. I have had bad experiences with the buds rotting before sprouting if they are covered. I wrap the union with several layers of polyethylene tape, just as I do the persimmon and the prunus varieties. With this technique I graft citrus all year long. Just be sure if you graft in the winter time, you keep them relatively warm or your grafts will just sit there and not grow.
Pecan: I use the standard inlay method that is described in the Texas A&M extension service’s bulleting Inlay Grafting Pecans. This method is for relatively large rootstock and small scion wood. An example may be 3/8” diameter scion and 2” or 3” diameter rootstock. Essentially, it involves slicing a flat section out of the scion (Fig. 1) about 2 ½” long.
I modify the instructions by cutting on the opposite side a flat section about 2” long, but only so deep as to remove the bark. You have cut deeply enough when you reach a layer that no longer darkens when exposed to air. Be sure and cut off small slices one at a time so as to not cut past the cambium and into the wood. This additional cut on the opposite side, which is not described in any of the handouts, allows the flap to heal to the scion and supply more nourishment to the scion. Cut deeper at the end so that the end is in the shape of a flat wedge. On the rootstock cut a matching patch of the outer and inner bark. Peel back this flap and insert the scion (Fig. 2).
Hammer two nails through the flap through the scion and into the rootstock. Cover the nailed section of the scion and the exposed cut portion of the rootstock with aluminum foil and a polyethylene bag. Again, you can spiral parafilm completely around the scion, or you can coat the exposed end of the scion with carpenter’s glue.
That is all there is to it. The parafilm, I believe, helps keep the scion from drying out, and it gives the graft a little more time to callous over and heal because there is a race between the scion drying out and the callous forming.