Grafting





Since grafting grapes is intimately connected with stocks, the growing

of which is a modern practice, grafting is thought of as a new process

in growing this fruit. Quite to the contrary, it is an old practice.

Cato, the sturdy old Roman grape-grower who lived nearly two hundred

years before Christ, speaks of grafting grapes, although Theophrastus,

the Greek philosopher, wrote a hundred years before "the vine cannot

be grafted upon itself." However, until it became necessary to grow

Vinifera grapes on resistant stocks to avoid the ravages of

phylloxera, grafting the grape was not at all common among

vineyardists and is not now except where vines susceptible to

phylloxera must be grown in consort with roots resistant to this

insect, or to modify the vigor of the top by a stock more vigorous or

less vigorous. For these two purposes, grafting is now in some grape

regions one of the most important vineyard operations.



In grafting the grape, there is a time and a way, not so particular as

many believe, but rather more particular than in grafting most other

fruits. If the essentials of grafting are kept in mind, one has

considerable choice of details. Grafting consists in detaching and

inserting one or several buds of a mother plant on another plant of

the same or a similar kind; the bud stock is the cion, the rooted

plant is the stock. The essentials may be set forth in three

statements: First, the prime essential is that the cambium layers, the

healing tissue lying between the bark and wood, meet in the cion and

stock; second, that method of grafting is best in which the cut

tissues heal most rapidly and most completely; third, the greater the

amount of cambium contact, as compared with the whole cut surface, the

more rapidly and completely the wounds will heal. Out of a great many,

the following are a few of the simplest methods in use in grafting the

grape, any one of which may be modified more or less as occasion

calls.



Vineyard grafting in eastern America.






In eastern America, the growing vine is usually grafted. At the New

York Agricultural Experiment Station, the operation is very

successfully performed on old vines as follows: Preparatory to

grafting, the earth is removed from around the stock to a depth of two

or three inches. The vines are then decapitated at the surface of the

ground and at right angles with the axis of the stock. If the grain is

straight, the cleft can be made by splitting with a chisel, but more

often it will have to be done with a thin-bladed saw through the

center of the stock for at least two inches. The cion is cut with two

buds, the wedge being started at the lower bud. The cleft in the stock

is then opened, and the cion inserted so that the cambium of stock and

cion are in intimate contact. If the stock is large, two cions are

used. The several operations in grafting are shown in Figs. 8, 9, 10

and 11. Grafting wax is unnecessary, in fact is often worse than

useless, and if the stock is large the graft is not even tied. Raffia

is used to tie the graft in young vines. It suffices to mound the

graft to the top of the cion with earth, for the purposes of

protection and to keep the graft moist. Two or three times during the

summer, sprouts coming from the stock or roots from the cion should be

removed.






A method used with fair success at the New York Agricultural

Experiment Station with young vines is to plant one-year-old stocks in

the nursery row as soon as the ground can be worked in the spring.

Just as the vines start in growth, these are cut off at the surface of

the ground and whip- or cleft-grafted with a two-eye cion. The graft

is tied with raffia, after which it is all but covered with a mound of

soil. This is a case in which the work must be done at the accepted

time, as it is fatal to delay.









R. D. Anthony describes another method as follows:[2] "A method which

a Pennsylvania grower of Viniferas has found very satisfactory is to

root the Vinifera cuttings, and grow them one year on their own roots;

then the vine which is to be used as a stock is planted in the

vineyard and the rooted cutting planted beside it so that the shoots

from the two may be brought in contact with each other. In June when

the plants are in full growth, two vigorous shoots (one from each

vine) are brought together and a cut two or three inches long made in

each parallel to the length of the cane removing from one-third to

one-half of the thickness of the shoot. These flat surfaces exposed

by the cuts are then brought into contact with the cambium tissues

touching and are tied in place. The tops are checked somewhat by

breaking off some of the growth. The following spring the Vinifera

roots are cut off below the graft and the top of the stock above the

graft is removed."



In the subsequent care of these young vines, the grower must take time

by the forelock and tie the grafts to suitable stakes; otherwise they

are liable to be broken off at the union by wind or careless workmen.

Grafted vineyards must have extra good care in all cultural

operations, and even with the best of care from 5 to 50 per cent of

the grafts will fail or grow so poorly as to make regrafting

necessary, this being the most unfavorable circumstance of field

grafting. Regrafting is done one joint lower than the first operation

to avoid dead wood; this brings the union below the surface of the

ground, and the vineyardist must expect many cion roots to try his

patience.



Vineyard grafting on the Pacific slope.



Vineyard grafting, according to Bioletti,[3] was formerly the

commonest method of starting resistant vineyards in California. After

stating that it is best whenever possible to plant good cuttings

rather than roots, and that the grafting should usually be done the

year after planting, Bioletti gives the following directions for

grafting:[4]



"Wherever possible the vines should be grafted at or above the surface

of the ground. In many cases, however, it will be necessary to go

below the surface to find a smooth, suitable part of the stock where

grafting is possible.



"The kind of graft to use will depend on the size of the stock. For

stocks up to 2/3 inch in diameter the methods of tongue and wire

grafting already described are the best. For larger vines up to 3/4

inch a modification of the ordinary tongue graft is the best. If the

tongue graft were made in the usual way with stocks of this size, it

would be necessary to use excessively large scions, which is

undesirable, or to have the barks unite only on one side. By cutting

the bevel of the stock only part way through the vines, it is possible

to make a smaller scion unite on both sides. For still larger vines,

those over 3/4 inch in diameter, the best graft is the ordinary cleft.



"No wax or clay should be used on the graft. Anything which completely

excludes the air prevents the knitting of the tissues. A little clay,

cloth, or a leaf may be placed over the split in the stock when the

cleft graft is used, simply to keep out the soil. Otherwise there is

nothing more suitable or more favorable to the formation of a good

union that can be put around the graft than loose, moist soil. If the

soil is clayey, stiff or lumpy, it is necessary to surround the union

with loose soil or sand brought from outside the vineyard.



"It will usually be necessary to tie the grafts. A well-made cleft

graft often holds the scion with sufficient force to prevent its

displacement and no tying is necessary. Wherever there is any danger

of the graft moving, however, it should be tied. There is nothing

better for this purpose than ordinary raffia. The raffia should not be

bluestoned, as it will last long enough without and will be sure to

rot in a few weeks, and the trouble of cutting it will be avoided.

Cotton string or anything which will keep the graft in place for a few

weeks may also be used.



"As soon as the graft is made and tied, a stake should be driven and

the union covered with a little earth. The hilling up of the graft may

be left for a few hours, except in very hot, dry weather. Finally, the

whole graft should be covered with a broad hill of loose soil 2 inches

above the top of the scion.



"Field grafting should not be commenced as a rule, except in the

hottest and driest localities, before the middle of March. Before

that there is too much danger that heavy rains may keep the soil

soaked for several weeks--a condition very unfavorable to the

formation of good unions. In any case the grafting should not be done

while the soil is wet. Grafting may continue as long as the cuttings

can be kept dormant. It is difficult to graft successfully, however,

when the bark of the stock becomes loose, as it does soon after the

middle of April in most localities."



As in the East, it is necessary in California to remove suckers from

the roots and roots from the cions once or twice during the summer.

Suckers should not be allowed to overshade the graft, though it is

best not to remove them until danger of disturbing the graft is past.

The grafts should be staked and the vines looked after as recommended

for eastern conditions.




bottom, rye.]



Bench grafting.



The resistant vineyards of France and California are now started

almost entirely with bench-grafted vines. It has been learned in these

regions that a grafted vine, to be a permanent success, must have the

consorting parts perfectly united, and that the sooner the grafting is

done in the life of stock and cion the better the union. Cions of the

variety wanted are, therefore, grafted on resistant roots or resistant

cuttings in the workshop and then planted in the nursery. Bench

grafting has the advantage over field grafting in time gained and in

securing a fuller stand of vines.



Bench grafting really begins with the selection of cuttings, since

success largely depends on good cuttings of both stock and cion.

Cuttings are taken from strong healthy vines and are of medium size,

with short to medium joints. The best size is one-third of an inch in

diameter, that of stock and cion being the same since the two must

match exactly. The cutting-wood may be taken from the mother vines at

any time during the dormant season up to two weeks before buds swell

in the spring, and the cuttings can then be made as convenience

dictates, though meanwhile the wood must be kept cool and moist, which

is best done by covering them with moist but not wet soil or sand in a

cellar or cool shed. In California, the best results are obtained when

the grafting is done in February or March, though it may be begun

earlier and continued a month later.



Preparation of cuttings.



The stocks are cut into lengths of about ten inches, a gauge being

used to secure uniform length. The cut at the bottom is made through a

bud in such a way as to leave the diaphragm. The top cut is made as

near ten inches from the bottom as possible, leaving about one and

one-half inches above the top bud for convenience in grafting. The

stock is then disbudded, taking both visible and adventitious buds,

the latter indicated by woody enlargements, to keep down the number of

suckers.




the cleft-graft and the whip-graft.]



The cion should be made with but one bud, thereby gaining the

advantage of having every cion the same length so that all unions are

at the same distance below the surface of the ground in the nursery.

The cion is made with about two and one-half inches of internode below

the bud and one-half inch above, a sharp knife being the best tool for

making the cuts.



Stock and cion cuttings are now graded to exactly the same diameters,

this being necessary to secure perfection in the unions. Three

methods of uniting stock and cion are illustrated in Fig. 12. It

suffices to grade by the eye into three lots--large, small and

medium--but some nurserymen prefer to secure even greater accuracy by

the use of any one of several mechanical gauges. The methods of

uniting stock and cion may be described best by quoting Bioletti, from

whom most of the details already given have been summarized:[5]



Tongue grafting.



"When the stocks and scions are prepared and graded the grafter takes

a box of stocks and a box of the corresponding size of scions and

unites them. Each is cut at the same angle in such a way that when

placed together the cut surface of one exactly fits and covers the

whole of the cut surface of the other. The length of cut surface

should be from three to four times the diameter of the cutting, the

shorter cut for the larger sizes and the longer for the thinner. This

will correspond to an angle of from 14.5 to 19.5 degrees. The cut

should be made with a sliding movement of the knife. This will make

the cut more easily and more smoothly.



"The cut should be made with a single quick motion of the knife. If

the first cut is not satisfactory, a completely new one should be

made. There should be no paring of the cut, as this will make an

irregular or wavy surface and prevent the cuttings coming together

closely in all parts.



"The tongues are made with a slow, sliding motion of the knife. They

are commenced slightly above one-third of the distance from the sharp

end of the bevel and cut down until the tongue is just a trifle more

than one-third the length of the cut surface. The tongue should be

cut, not split. The knife should not follow the grain of the wood,

but should be slanted in such a way that the tongue will be about

one-half as thick as it would be if made by splitting. Before

withdrawing the knife it is bent over in order to open out the

tongue. This very much facilitates the placing together of stock and

scion.



"The stock and scion are now placed together and, if everything has

been done properly, there will be no cut surface visible and the

extremity of neither stock nor scion will project over the cut surface

of the other. It is much better that the points should not quite reach

the bottom of the cut surface than that they should overlap, as the

union will be more complete and the scions will be less liable to

throw out roots. If the points do overlap, the overlapping portion

should be cut off, as in the Champin grafts.



"A skillful grafter, by following the above-described method, will

make grafts most of which will hold together very firmly. Many of them

would be displaced, however, in subsequent operations, so that it is

necessary to tie them. This is done with raffia or waxed string. The

only object of the tying is to keep the stock and scion together until

they unite by the growth of their own tissues, so that the less

material used the better, provided this object is attained. For the

formation of healing tissue air is necessary, so that clay, wax,

tinfoil or anything that would exclude the air should not be used. The

tying material is passed twice around the point of the scion to hold

it down firmly, and then with one or two wide spirals it is carried to

the point of the stock, which is fastened firmly with two more turns

and the end of the string passed under the last turn. The less string

is used the more easily it is removed later in the nursery.



"Untreated raffia should be used for late grafts which are to be

planted directly out in the nursery, but if the grafts are to be

placed first in a callusing bed it is best to bluestone the raffia in

order to prevent rotting before the grafts are planted. This is done

by steeping the bundles of raffia in a three per cent solution of

bluestone for a few hours and then hanging them up to dry. Before

using, the raffia should be washed quickly in a stream of water in

order to remove the bluestone which has crystallized on the outside

and which might corrode the graft.



"Some grafters prefer waxed string for grafting. The string should be

strong enough to hold the graft, but thin enough to be broken by hand.

No. 18 knitting cotton is a good size. It is waxed by soaking the

balls in melted grafting wax for several hours. The string will absorb

the wax, and may then be placed on one side until needed. A good wax

for this purpose is made by melting together one part of tallow, two

parts of beeswax, and three parts of rosin."



Wire grafting.



"The merits claimed for this method are that it is more rapid,

requires less skill, and does away with the troublesome tying and

still more troublesome removal of the tying material. Practiced

grafters can obtain as large a percentage of No. 1 unions by this

method as by any other, and unpracticed grafters can do almost as well

as practiced. Another advantage of the method is that the scions have

less tendency to make roots than with the tongue graft.



"It consists essentially of the use of a short piece of galvanized

iron wire inserted in the pith of stock and scion for the purpose of

holding them together, thus replacing both tongues and raffia. It has

been objected that the iron would have a deleterious effect on the

tissues of the graft, corroding them, or causing them to decay. There

seems, however, no reason to expect any such result, and vines grafted

in this way have been bearing for years without showing any such

effect.



"The preparation and grading of stocks and scions are exactly the same

for this method as for the tongue graft.



"Stock and scion are cut at an angle of 45 degrees. A piece of

galvanized iron wire two inches long is then pushed one inch into the

firmest pith. This will usually be the pith of the stock, but it will

depend on the varieties being grafted. The scion is then pushed on to

the wire and pressed down until it is in contact with the stock. If

the cuttings have large pith it is better to use two pieces of wire,

one placed in the stock first and the other in the scion.



"The length of wire to use will vary with the size and firmness of the

cuttings, but 2 inches will usually be found most satisfactory. Wire

of No. 17 gauge is the most useful size."



Making bundles.



"If the grafts are to be planted out directly in the nursery, they may

be simply laid in boxes or trays, covered with damp sacks, and carried

out to be planted as soon as made. It is usually better, however, to

place them for several weeks in a callusing bed before planting. In

this case it is necessary for convenience of handling to tie them up

into bundles. No more than twenty grafts should be placed in a bundle,

and ten is better. If the bundles are too large there is danger of the

grafts in the middle becoming moldy or dry.



"A stand is very convenient. It consists of a piece of board 12

inches, on one end of which is nailed a cleat 6 inches by 4 inches and

under the other end a support of the same size. Two 4-inch wire nails

are driven through the board from below, 4 inches apart and 5 inches

from the cleat. Two other 4-inch nails are driven similarly at 1-1/2

inches from the other end. The grafts are laid on this stand with the

scions resting against the cleat, and are then tied with the two

pieces of bluestoned raffia that have previously been placed above

each pair of nails. This arrangement insures all the scions, and

therefore the unions, being at the same level, and puts both ties

below the union where they will not strain the graft. The tying is

more expeditious and less liable to disturb the unions than if the

bundles are made without a guide.



"A skillful grafter will make about one hundred tongue grafts on

cuttings per hour, or from sixty-five to seventy-five per hour if he

does the tying as well. Wire grafts can be made at the rate of two

hundred and fifty or more per hour, and by proper division of labor

where several grafters are employed this number can be easily

exceeded. These estimates do not include the preparation and grading

of the cuttings."



Grafting rooted cuttings.



The cion may be grafted on a stock rooted in the nursery the previous

season, much the same methods being used as with cuttings. This method

is employed to utilize cuttings too small to graft, the added sizes

attained in the nursery making them large enough, and in grafting on

stocks which root with difficulty, thus saving the making of grafts

which never grow. The stocks, in this method, are cut so that the

cions may be inserted as the original cutting and not as the new

growth. The roots, for convenience in handling, are cut back to an

inch or thereabouts in length.



The callusing bed.



If bench grafts are planted at once in the nursery, most of them fail.

They are, therefore, stratified in a callusing bed where moisture and

temperature can be controlled. Bioletti describes a callusing bed and

its use as follows:[6]



"This callusing bed is usually a pile of clean sand placed on the

south side of a wall or building and surrounded by a board partition

where there is no possibility of its becoming too wet by the flow of

water from a higher level or from an overhanging roof. It should be

protected, if necessary, by a surrounding ditch. It should be

furnished with a removable cover of canvas or boards to protect it

from rain and to enable the temperature to be controlled by the

admission or exclusion of the sun's rays. A water-proof wagon-cover,

black on one side and white on the other, is excellent for this

purpose.



"The bottom of the callusing bed is first covered with 2 or 3 inches

of sand. The bundles of grafts are then placed in a row along one end

of the bed, and sand well filled in around them. The bundles should be

placed in a slightly inclined position with the scions uppermost, and

the sand should be dry enough so that it sifts in between the grafts

in the bundle. The bundles of grafts are then covered up completely

with sand, leaving it at least 2 inches deep above the top of the

scion. Another row is then placed in the same manner until the bed is

full. Finally a layer of 2 or 3 inches of moss or straw is placed over

all.



"In the callusing bed we should endeavor to hasten and perfect the

union of stock and scion as much as possible while delaying the

starting of the buds and the emission of the roots. The latter

processes require more moisture than the formation of healing tissue,

therefore the sand should be kept comparatively dry. Between 5 and 10

per cent of water in the sand is sufficient. The purer the sand the

less water is necessary. There should be a little more moisture

present than in the sand used for keeping the cuttings over winter.

Too much moisture will stimulate the emission of roots and starting of

buds without aiding the callus formation.



"All the vital processes progress more rapidly when the cuttings are

kept warm. To delay them, therefore, we keep the sand cool, and to

hasten them we make it warm. In the beginning of the season and up to

the middle of March we keep the sand cool. This is done by keeping the

bed covered during the day when the sun is shining, and uncovering

occasionally at night when there is no fear of rain. If the

black-and-white wagon-cover is used, the white side should be placed

outward to reflect the heat. The temperature should be kept about 60 deg.

F. or lower.



"About the middle of March the temperature of the bed should be

raised. This is done by removing the cover during warm days and

carefully covering at night. If necessary the layer of moss or straw

should be removed on sunny days and then replaced. The temperature of

the sand at the level of the unions should be about 75 deg. F. during this

period. If the temperature rises higher than this, there will be a

more abundant production of callus, but it will be soft, easily

injured, and liable to decay.



"At the end of four weeks after warming the bed, the union should be

well cemented. The callus should not only have formed copiously around

the whole circumference of the wound, but it should have acquired a

certain amount of toughness due to the formation of fibrous tissue. It

should require a pull of several pounds to break the callus and

separate stock and scion. When the callus has acquired this quality

the grafts are in condition to be planted in the nursery, and may be

handled without danger. If taken from the bed while the callus is

still soft, many unions will be injured and the grafts will fail, or

unite only on one side.



"If left as long as this in the callusing bed most of the scion buds

will have started and formed white shoots. These shoots, however,

should not be more than 1/2 to 1 inch long. If they are longer the bed

has been kept too wet or too warm. Roots will also have started from

the stock, but these also should not be over 1/2 inch long. The grafts

should be handled as carefully as is practicable, but there is no

objection to breaking off any scion shoots or stock roots which have

grown too long. It is almost impossible to save them, and new ones

will start after the grafts are planted, and make a perfectly

satisfactory growth."



Care in the nursery.



The grafts are planted in the nursery, and are given much the same

care recommended for cuttings. They may be set in trenches made with

plow or spade; or they may be planted in very shallow trenches with a

dibble. After planting, the grafts are covered with an inch or two of

soil, thus forming a wide ridge in the nursery row with the union of

the grafts at the original level of the soil. Cultivation should begin

at once and be frequent enough to prevent the formation of a crust, in

order that the young shoots may not have difficulty in forcing their

way through the soil. Roots start on the cions sooner than on the

stock, the soil being warmer at the surface, and help sustain the

cions until the stocks are well rooted, at which time all roots

started on the cion are removed, and at the same time the tying

material is cut if it has not rotted. Suckers are removed as soon as

they show above ground. The grafts are dug as soon as the leaves fall

and the young vines become dormant, after which they are sorted in

three lots, according to size of top and root, and heeled-in in a cool

moist place until they are to be planted.



Nursery versus home-grown vines.



The verdict of all vineyardists is that it is better to buy

nursery-grown vines than to attempt to grow them. The high quality of

the vines which can be purchased and the reasonable purchase price

make it hardly worth while to try home-grown vines, especially since

considerable investment, experience and skill are required to grow

good vines.





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