Grafting Terms

Question 1

Grafting

Answer 1

• The art of joining two pieces of living plant tissue together in such a manner that they will unite and subsequently grow and develop as one composite plant

Question 2

Budding

Answer 2

• A form of grafting that uses a smaller scion piece - sometimes just a piece of the stem with an axillary bud

Question 3

Bark Slipping

Answer 3

• the vascular cambium is actively dividing, producing young thin-walled cells on each side of the cambium
• these newly formed cells separate easily from one another, so the bark “slips”

Question 4

7 points

Reasons for Grafting

Answer 4

1. perpetuating clones
2. combining different cultivars into a composite plant (rootstock: dwarfing, drought tolerance, disease resistance)
3. obtaining special forms of plant growth ( standards, weeping plants)
4. changing cultivars of established plants (topworking)
5. reducing time to flowering
6. tree repair
7. disease indexing

Question 5

5 requirements

Requirements for a successful graft union

Answer 5

1. compability between graft partners
2. proper cambial association
3. proper timing (scion - dormant; rootstocks - often active)
4. protect graft union from desiccation
5. post grafting care

Question 6

Bench Grafting

(Bench Working)

Answer 6

• is done with bareroot rootstocks or rootstocks in containers
• this is done on a bench in a protected environment

Question 7

Field Grafting

Answer 7

• the grafting is done in the field
• take place at a time of the year when favorable temperatures are expected and the vascular cambium is an active state
• these conditions generally occur during the spring months
• includes crown grafting, top-grafting, topworking, and repair grafting
• field grafting of decidious plants is done from late winter to late spring
• grafting should take place shortly before new growth starts
• the scions should be prepared from mature, dormant wood of the revious season’s growth

Question 8

Crown Grafting

Answer 8

• grafts made near the root-shoot junction (which is the junction of the root and shoot system)
• in earlier times, it referred to grafting several scions in a crown-like circle onto an established larger rootstock

Question 9

Top Grafting

Answer 9

• are grafts made in the top of the rootstock
• basically any graft that is not made at the bottom of the rootstock close to the ground (which is crown grafting)

Question 10

Topworking

Answer 10

• The grafting of a new cultivar onto established trees in the orchard

Question 11

Scion

Answer 11

• The top part of the graft
• A short piece of shoot or a single bud
• a short piece of detached shoot containing several dormant buds
• becomes the new shoot system of the graft

Question 12

Rootstock

(Understock)

Answer 12

• the lower or underground portion of the graft
• will develop into the rootsystem of the grafted plant
• could be a seedling, cutting, or root piece
• could have roots already or be just a stick

Question 13

Seedling Rootstocks

Answer 13

• rootstocks propagated from seed
• can be mass-produced relatively simply and economically
• usually virus-free
• tend to be more deeply rooted and more firmly anchored plants than clonal rootstock
• may show genetic variation leading to variability in growth and performance of the scion variety

Question 14

Clonal Rootstocks

Answer 14

• vegetatively propagated by stool layering, rooted cuttings, or micropropagation
• are desired for uniformity, stree and disease resistance
• also influence the size and growth habit of the grafted plant and flowering and fruit development of scion

Question 15

Interstock

(Intermediate Stock)

(Interstem)

Answer 15

• a piece of stem inserted by means of two graft unions between the scion and the rootstock
• used if scion and rootstock are incompatible - use interstock as middle man
• used to produce special tree forms (make standards)
• used to control disease (e.g. fireblight resistance)
• used to take advantage of their growth-controlling properties
• Double working: the grafting or budding of an interstock between the rootstock or scion

Question 16

Double Working

Answer 16

• The grafting or budding of an interstock (interstem) between the rootstock and scion.
• to propagate a plant by grafting or budding a scion to an intermediate piece of one variety on a rootstock of another variety
• as for overcoming incompability between scion and stock or for providing a superior trunk

Question 17

Callus

Answer 17

• the mass of parenchyma cells that develop from and around wounded plant tissues.
• It occurs at the junction of a graft union, arising from the living cells of both scion and rootstock.
• The production and interlocking of these parenchyma (or callus) cells constitute one of the important steps in callus bridge formation between the scion and rootstock in a successful graft.

Question 18

Cambium

Answer 18

• a thin tissue located between the bark (periderm, cortex, and phloem) and the wood (xylem)
• its cells are meristematic
• they are capable of dividing and forming new cells
• cambial regions of the scion and rootstock must line up so that the vascular systems can reattach in the graft union

Question 19

Graft Compatibility

Answer 19

• the ability of two differen tplants, grafted together, to produce a successful union and to develop satisfactorily into one composite or compound plant
• grafts must be made between genetically similar plants. usually species to species.

Question 20

Graft Failure

Answer 20

• An unsuccessful graft caused by atanomical mismatching, poor craftsmanship, adverse environmental conditions, disease, or graft incompatibility
• sings of graft failure: suckering from below graft union, dissimilar growth between the rootstock and scion (one side grows a lot faster than the other), crown dieback, and the toppling of the tree with a clean break at the graft union

Question 21

Graft Incompatibility

Answer 21

• An interruption in cambial and vascular continuity leading to a smooth break at the point of the graft union, causing graft failure.
• It is caused by adverse physiological responses between the graft partners, disease, or anatomical abnormalities.
• can lead to disimilar growth between the rootstock and scion
• can be delayed for years before failing

Question 22

Grafting and Budding Knives

Answer 22

• are flat on one side and have a tapered edge on the other to make a sharp, clean cut
• either a folding or fixed blade
• the fixed type blade is stronger, and if a holder of some kind is used to protect the cutting edge, it is probably the most desired
• a well-built, sturdy knife of high-carbon steel is essential
• the metal flap opposite the sharp end of the blade is used to separate the bark during the T-cut of the rootstock. The quill is also used to separate the bark during T-budding
• must be very sharp at all times
• good knives will hold that sharpness for longer
• look like pocket knives

Question 23

Graft Machines

(Robots)

Answer 23

• can replace hand labor
• primarily used for grafting vegetable transplants
• can be as productive as 1,000 tomato seedlings an hour
• scion and rootstocks used for machine grafting are produced under controlled environments because they need to be extrememly uniform