PLSC 368: Lecture 12

TECHNIQUES OF GRAFTING

I. REQUIREMENTS

    A. Compatibility -the stock and scion must be graft-compatible

            3 types of incompatibility

                1. Localized -lack of contact between cambium layers of stock and scion
                        Bartlett pear scion o fquince rootstock-------> incompatible
                        Use of 'old home' pear as interstock ---------> compatible
                2. Translocated - translocatable 'substances' cause incompatibility ---results
                                           in phloem degeneration, necrotic tissues, etc.

                        'Hale's Early' peach no 'Myrobalan B' plum rootstock --> incompatible
                         use of interstock does not overcome incompatibility
                3. Virus-induced - latent viruses become active when transmitted to scion from stock or vice versa
                        -citrus quick decline, pear decline
                        -stempitting virus from scion to rootstocks of 'Virginia Crap' apple

    B. Alignment of Cambium Layers
            -Cambial regions of the scion must be in intimate contact with that of the stock
            -Movement of water and nutrients through the union (cambial) must take place

    C. Optimum time of grafting
            -Both rootstock and scion must be in the proper physiological stage
            -In deciduous woody plants, dormant bud on scion allows callus formation at the graft union before bud break

    D. Prompt Operation
            -The cut surfaces should not be allowed to dry out
            -Use grafting wax, tape to protect grafted area

    E. Proper Care After Grafting
            -Temperature (80- 90° F for maximum callusing)
            -Humidity (close to saturation point ~100% RH)
            -Supply of O2 to callusing area important

II. METHODS OF GRAFTING

    A. Whip Grafting

            -used for both stem and root grafts
            -the diameter of stem adn rootstock does not have to be the same
            -whip-and-tongue graft is widely used

            -used for many deciduous woody plants, fruits

    B.  Splice Grafting

            -same as the whip graft except that the 2nd cut (for the tongue) is not made
            -simple, easy, used for plants having pithy stems

    C.  Side Grafting

            Used for large-scale production in the nursery
                -stub graft- for larg stock, small scion wood
                -side-tongue - usefull for small plants
                -side-veneer graft -(spliced side graft) used for small potted plants, etc.

    D.  Cleft Grafting

            -Oldest method of grafting
            -Widely used in 'topworking'

    E.  Wedge Grafting

            -Several scions can be inserted into one stock (stub)
            -nailing can be used

    F.  Bark Grafting

            -Several scions into one stub
            -nailing of scion on to stub

    G.  Approach Grafting (natural graft)

            -to connect two different plants

    H.  Inarching ("own root plants")
            -repair graft

    I.  Bridge Grafting
            -repair graft