GRAFTING - An OVERVIEW

Compiled by Riley Holly

WHAT:

-asexual propagation

-attaching compatible scion (desired cultivar) to rootstock (desired growth properties)

WHY:

-change cultivars

-propagate additional plants of desired cultivar

-have multiple cultivars on single plant---limited space, lengthen season of desirable fruit

-provide cross-pollination on single tree

-propagate clonal rootstock (disease resistance)

-hasten maturity--earlier fruit production

-growth properties---dwarfing, pathogen resistant, it's there (topworking)

-repair damaged tree

-add vigor to overhybrized plant by grafting to more energetic rootstock

-rootstock resistant to drought, salinity, heavy soils -- grafted to desired cultivar

-cultivar difficult to root by cuttings, air-layering - do not come true to seed

-indexing for viruses

GRAFTING TERMINOLOGY:

-cambium -- thin layer of meristemic cells between xylem & phloem

-xylem -- water conducting cells (outer sapwood)

-phloem -- food conducting cells (inner bark)

-callus -- corky tissue developed by woody species to cover wounds

-parenchyma cells -- undifferentiated

-rootstock (understock) -- root system which is grafted to scion

-scion (scionwood) (budwood) (budstick) -- cultivar grafted to rootstock

-budding -- single bud graft

-regrowth -- new shoots from stumped rootstock

-take -- successful graft

-slip -- when xylem & phloem separate easily at cambium interface

-interstock (double graft) -- intermediate plant part which is compatible with both scion and rootstock

-meristem -- actively dividing cells

COMPATIBILITY:

-genus-A x genus-B --- possible, but limited

-species-A x species-B in same genus --- better success, but not always

-rejection can occur several years later

-use interstock when scion & rootstock not compatible, if possible

WHEN:

-scion --dormant, prior to growth flush

-- store in polyethylene bag with moistened paper at 45 deg. F

-rootstock --actively growing (pushing)

-bench graft -- anytime

WHERE:

-on tree in ground

-on seedling (bench)

TYPES of GRAFTS:

(see R.J.Garner - "The Grafter's Handbook" for complete list and methods)

seedling

-cleft or wedge

-whip and tongue

-saddle

-side

mature

-green bark

-flap

-veneer

-inlay

-banana

TOOLS & SUPPLIES:

clippers

sharp knife

Parafilm

rubber bands (seedlings)

tape (mature trees)

diluted white latex paint

Tree Seal or Henry's #107 asphalt emulsion (water soluble)

marking labels and marker

white cardboard or heavy paper (mature trees)

HOW:

collecting / storing scionwood

-fat leaf buds - not open (dormant)

-large diameter for mature tree graft

-scionwood should be equal to, or smaller than rootstock

-previous years growth

- 3/16 - 3/8 inch for seedling (match seedling diameter)

-make slant cut at apical end -- make perpendicular cut at basal end -(helps to remember growth direction) (4 - 6 inches long)

-don't use terminal buds (low in carbohydrates)

-cut off leaves

- 2-3 buds above graft area

-store in polyethylene bags at 45 deg. until ready to graft -- mark bag with date and cultivar name

grafting to seedling (cleft graft is commercial choice) (also for small branches on existing mature

trees)

prepare scion -- cut petiole back to protect bud

-- wrap buds and stem above graft site with stretched Parafilm ( to prevent desiccation of scion) - leave 1 - 2 buds uncovered

-- make slanting cuts (approx. 2 inch taper) just below lower bud on opposite sides of scionwood

prepare rootstock

-- cut off stem approx. 4 inches above soil --same diameter as scion

-- slice rootstock down center the same length as scionwood taper

-- slide scionwood down cut in rootstock -- aligning cambiums as close as possible - if not the same size, then match cambium on one side

-- hold in place by wrapping stretched Parafilm around graft area and up to bud area

-- wrap graft area with stretched rubber band (1/4 inch wide)

prevent movement of graft area while healing

attach marker with date and cultivar information

create greenhouse effect (seedling) - make polyethylene tent

grafting to mature tree

prepare scionwood

-- same as for seedling, except cut a double taper, use large diameter scionwood, and 4 inches longer than bud area

prepare rootstock

-- stump tree (or regrowth) approx. 2 feet above soil

-- cut perpendicular to growth (otherwise tape will slip off)

-- make cut longitudinally through bark to cambium, 4 inches long, on windward side

-- lift bark and insert scion

-- repeat on opposite side (2 grafts for added assurance)

-- wrap with grafting tape to hold scion tightly to rootstock

-- paint exposed areas with black tar (Henry's #107 or Tree Seal), then paint with dilute (50/ 50) white latex paint

-- cover area with white paper to reflect sun from scionwood and graft

-- attach marker with date and cultivar information

AFTERCARE:

-patience, usually takes 3 or more weeks to see growth (longer in cold weather)

-staking - to prevent movement at graft site

-fertilize plants in pots

-cut binding off around graft to prevent cincturing

-remove growth below graft

-pinch off side growth -- encourage single leader

SUCCESSFUL GRAFTS:

% depends on

-genus / species

-time of year

-environmental conditions

-skill (practice)

REASONS FOR FAILURE:

-cambium misalignment

-desiccation

-movement of graft union during healing

-pathogens

-incompatibility of scion and rootstock

-environment -- over/under watering

-too hot

References:

Internet {to retrieve URL, click on URL location}

Home Page of Texas A&M University

http://aggie-horticulture.tamu.edu/

Four Flap Graft

http://aggie-horticulture.tamu.edu/propagation/fourflap/fourflap1.html

Approach Graft

http://aggie-horticulture.tamu.edu/propagation/approachgraft/approach.html

Inlay Graft

http://aggie-horticulture.tamu.edu/propagation/inlay/inlay.html

Budding Technique

http://aggie-horticulture.tamu.edu/propagation/budding/budding.html

Collecting Graft Scion Wood

http://aggie-horticulture.tamu.edu/propagation/collect/collect.html

Side Veneer Grafting

http://aggie-horticulture.tamu.edu/propagation/sidegrafting/sidegrafting.html

Air Layering

http://aggie-horticulture.tamu.edu/extension/ornamentals/airlayer/airlayer.html

Table of Propagation methods

http://aggie-horticulture.tamu.edu/extension/fruitgarden/table2.html

Top Wedge Grafting with pictures

http://instruct1.cit.cornell.edu/courses/hort400/4tutos/topwedg1.html

Autotutorials from Cornell University

http://instruct1.cit.cornell.edu/courses/hort400/index4.html

No. Carolina CE on Grafting

http://www.ces.ncsu.edu/depts/hort/hil/grafting.html

Books

Bienz, D.R. , 1980. The Why & How of Home Horticulture. New York : W.H. Freeman & Co. ISBN 0-7167-1078-1

Bryant, Geoff, 1995. Propagation Handbook ( Basic Techniques for Gardeners). Mechanicsburg, PA: Stackpole Books.

ISBN 0-8117-3065-4

Capon, Brian , 1990. Botany for Gardeners. Oregon: Timber Press

ISBN 0-88192-258-7

Garner, R.J. , 1988. The Grafter's Handbook. New York: Sterling Publishing ISBN 0-3043-4274-2

Hartman, Hudson et al 1997. Plant Propagation: Principles and Practices 6th Ed. New Jersey: Prentice-Hall ISBN 0-13-206103-1

Hill, Lewis , 1985. Secrets of Plant Propagation. Vermont: Garden Way Publishing Book ISBN 0-88266-371-2

Janick, Jules, 1986. Horticultural Science. New York : W.H. Freeman & Co.

ISBN 0-7167-1742-5

Macdonald, Bruce 1992. Practical Woody Plant Propagation for Nursery Growers, Vol.2 Oregon: Timber Press. ISBN 0-88192-062-2

Thompson, Peter, 1995. Creative Propagation. Oregon: Timber Press

ISBN 0-7134-7118-2