Fruit Tree Grafting 101




Дата канвертавання26.04.2016
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Fruit Tree Grafting 101
(Following are notes from our first Orchard Seminar – Beginning Fruit Tree Grafting held recently at 21 Acres. Thank you to Greg Giuliani, Seattle Tree Fruit Society, for this information and great class presentation!)
When is the time to graft?

1. Most grafting is done in early spring before new growth begins. The best

time is after the chance of severe cold has passed but well before warm

weather arrives.

What materials are needed?

Knife


A sharp, clean blade with a bevel entirely on one side of the blade. This

helps to keep the blade cutting in a straight line.

Grafting sealant

After the graft is made, some covering must be used to keep it from drying

out. I use a water based latex type sealant..

Grafting tape

Tapes may be used for binding grafts where there is not enough natural

pressure. Electrical tape is inexpensive, black color help generate heat to

help heal the graft wound.

Budding strips

Budding strips are elastic bands. They look like a wide rubber band that has

been cut open. Budding strips secure several types of grafts with small

stocks and scions. Rubber bands rot when exposed to UV sunlight, cover with

sealant .

Nails

Veneer, bridge and inarching grafts require long, thin nails (avoid



galvanized nails). Half-inch nails are long enough for most grafts, except

for bridge grafting, which may require 3/4-inch nails.

Grafting tool

Specially designed tools have been developed for grafting, such as the OMEGA

grafting tool. What grafting technique?

Grafting techniques can be divided into two basic types, which are largely

determined by the size of the understock.

1) In some cases, a graft may be made to join a scion and understock of

nearly equal size.

2) The other type attaches a small scion to a much larger understock. In

this case, several scions may be attached to the understock as in cleft or

bark grafting.

.

Grafts with similar scion and understock sizes



Whip graft and bench graft

The whip graft is fairly easy and heals rapidly. It works best when the

stock and scion are of similar diameter, preferably between 1/4 and 1/3

inch.


The stock can be either a plant growing in the field or a dormant bareroot

plant as in a bench grafting. The stock should be smooth and

straight-grained. Do not graft near a point where side twigs or branches

have developed.

The scion should be 1-year-old wood, preferably the same size as the stock.

If the stock is larger than the scion, contact can be made on only one side.

The scion should never be larger than the stock.

Preparing the stock and scion

For this technique, the cuts made in both stock and scion should match. On

both parts, make a smooth sloping cut 1 to 21/2 inches long depending on the

thickness of the material . Make the first cut with a single, smooth cut

with no waves or whittling (wave can be smoothed by using a small plane).

The beginner should practice by cutting extra twigs. A sharp knife is

essential.

Cutting the scion

The cutting procedure should be exactly the same as that for the stock. The

only difference is that the cuts are made at the bottom of the scion piece,

whereas they were made at the top of the stock. The more similar the cuts on

the two pieces (matching cambium layers), the greater chances of a

successful graft union.

Fitting the stock and scion

After the cuts are made on both parts, push them together tightly enough so

that the cut surfaces match as closely as possible (Figure 1c). The cambial

area (area immediately under the bark) of both pieces must be aligned for a

union to develop. If the scion and stock are not the same size, match the

cambiums on one side only. The lower tip of the scion should not hang over

the stock. * make sure the scion has buds pointing in correct direction*

(upward, away host)

Wrapping the graft

In most cases, it is safer and better to wrap the graft to keep it tight to

prevent drying (Figures 1d and 1e). Wrap the graft with a rubber budding

strip, grafting tape or a plastic tape such as electrical tape. If the

wrapping material does not decay naturally, cut it about a month after

growth begins. (4th of July) in western Wash.

Sealant

To prevent the graft union from drying, the area should be sealed. Cover the



wrapped area with tree seal as uniformly as possible. In wrapping and

sealing, be careful not to dislodge the aligned cambial areas. Give sealant

time to dry before rain arrives.

Grafts with small scions and large understocks

The cleft graft

The cleft graft is most commonly used to topwork a tree; that is, to change

from one variety to another. It can be used on either young or mature trees.

Young trees may be cleft grafted on the trunk, while older trees are grafted

on branches not more than 21/2 inches in diameter. Branches fully exposed to

sunlight and in the main stream of sap flow are more successful than those

in shaded or inactive areas. Grafts on upright branches grow better than

those on horizontal branches.

Preparing the stock

Branches of large trees or the trunk of a small tree must be sawed off to

provide a stock for the scions. Select a smooth, knot-free, straight-grained

section. Saw the branch off at a right angle to the grain Don't tear or

split the bark. If the saw cut is not smooth, use a knife to trim off the

rough edges. The bark must be tight to form a successful graft. Using a

heavy knife that may be tapped with a mallet, drive the blade into the stub

to split the stock through the center so a split extends about 2 inches into

the branch.

Preparing the scion

The scion for the cleft graft should be made from 1-year-old wood about 1/4

inch in diameter. Usually, it is best to cut the scion long with three buds

so it can be inserted with the lowest bud just above the stock. Always note

which is top and bottom of a scion stick. A scion will not grow if inserted

upside down.Start below the lowest bud, and make a long, smooth cut toward

the base. The cut should have a surface 1 to 1-1/2 inches long. Turn the

scion to the opposite side and make a second smooth cut of the same length

so that one side (the side containing the lowest bud) is slightly thicker

than the other side. The wedge that is formed does not need a sharp point; a

blunt point is preferable. Do not use more than three buds. If wood is

scarce, two buds should give good results. Leaving to many buds will

dehydrate the scion when buds leaf out.

Inserting the scion

With a grafting chisel or a small wedge, open the crack wide enough to

insert the scion easily (Figure 2e). Insert the scion with the thicker side

toward the outside with the cambiums in contact . Although maximum contact

is obtained with straight positioning, a slight slant may help ensure

contact . The best contact point is about 1/4 inch below the shoulder of the

stock. After properly positioning the scion, remove the wedge or chisel from

the slit. The pressure of the stock against the scion should be greatest

where the cambiums touch. When the scion is placed in the crack, the cut

surface of the scion wedge should be almost entirely hidden.

Two scions are usually inserted in each slit, one at each side. This gives a

better chance for getting at least one graft to grow.

Sealing the cleft graft

The cleft graft should be sealed so that all cut surfaces are covered .

Cracks sometimes develop as the sealant sets. Check sealant after a few days

and again after several weeks to ensure that all surfaces are kept covered.

Caring for the graft

After the graft begins to grow, it must also be given attention. During the

first season, don't prune branches that grow. Grafts that grow vigorously

may need to have the tips pinched out to stimulate branching. Very long

shoots may break loose during strong winds. Cleft grafts should grow

vigorously and need only light pruning to shape their development. Never

prune heavily.

After the first year, some training and branch selection may be necessary.

Do this at the usual pruning time in late winter or early spring. If both

scions in a cleft grow, shorten one to allow the other to develop and become

dominant. Do not remove the second graft until later, because it will help

to cover the wound faster.

In topworking large trees, it is best to graft about half the branches the

first year and the second half the next. Start with the upper center limbs

the first year. The best time to topwork is just as growth begins in the

spring ( tree is able to heal wound); however, it can be done several weeks

earlier or later.

Bark graft (veneer graft)

Bark grafting is relatively easy and requires no special tools. It is

similar to cleft grafting and may be performed on branches ranging from 1

inch to several inches in diameter.

Stock preparation

The branch or trunk is cut off at a right angle in the same manner as

described for cleft grafting. The bark graft can be made only when the bark

slips or easily separates from the wood. This usually is in early spring as

growth begins.


Make a slit in the bark about 3/4 inch long.

Make two slits in the bark separated by the width of the scion.

Scion preparation

The scions should be dormant. The scion should be 4 to 5 inches long with

two to three buds. Prepare the base of the scion by cutting inward 1-1/2 to

2 inches from the base then downward, forming a shoulder and long, smooth

cut (Figure 3b). The long cut should extend about one-third through the

twig, keeping its base strong enough to insert but not too thick. On the

side opposite the long cut, make a short cut to give the base of the scion a

wedge shape for easier insertion.

Inserting the scionA knife may be used to lift the bark at the top of the

slit but may not always be necessary. Push the scion down and center it in

the slit or between both slits if the double slit method is used. Insert the

scion until the shoulder rests on the stub. If the scion is large enough,

one or two small nails may be used to tighten the scion to the stock. Some

prefer to use electrical tape or masking tape to pull the surfaces tight. In

some cases, the bark may not split or tear and nailing or wrapping is not

necessary. In all cases, the graft should be thoroughly protected with

sealant over all open surfaces after it is completed.
Grafting tips

Store the scion in moist sphagnum moss, sand or a plastic bag in a cool

place (refigerator). Do not allow scion to freeze. It must be kept moist and

cool until used. After the cuts are made, scions must be inserted

immediately, or cuts should be kept moist until used.

Scion wood should be made of twig sections with two to three buds each.

Discard the tip of scion wood and re-cut the base before grafting.

After the graft has taken and growth has started, cut off any side shoots or



competing twigs that would shade or compete with the development of the new

graft.


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