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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.





Next: Pedigreed Grape Vines

Previous: Layering



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