GRAFTING
(Concluded)
“The part of a plant or tree above ground and the part under ground are
mutually dependent, the development of one implying a corresponding
development in the other. If there is a superabundance of foliage, the
roots will be unable to furnish it sufficient nourishment; on the other
hand, if the roots are unduly vigorous, there will be too much sap for
the foliage—an excess of nourishment which, there being no use for it,
will encumber the plant and be injurious to it. Hence if the trunk to
be grafted is strong it must have several grafts, in order that the
number of buds to be nourished may be in right proportion to the number
of nourishing roots.
“To this end the trunk is cut, not obliquely as for a single graft, but
horizontally. Then it is split all the way across, following a line
that passes through the central pith, and two grafts are implanted in
the cleft, one at each end. It is evident that not more than two can be
placed in the same cleft, because the bark of the graft must of
necessity come in contact with the bark of the stock to insure
inter-communication and coalescence between the sap-canals of the two.
If the size of the stock requires more than two grafts, instead of
splitting the trunk diametrically several times, it is preferable to
make lateral clefts which, leaving the center untouched, cause less
danger to the solidity of the stock.
“Recourse can also be had to the following method, in which no clefts
whatever are called for, clefts being difficult to cicatrize when the
wood is old. The grafts are cut like the mouthpiece of a flute; that is
to say, at the base half is taken off lengthwise while the other half
is left, but is whittled down, thinner and thinner toward the end, much
like a flute’s mouthpiece. Thus shaped, the grafts are inserted between
the wood and the bark of the stock, an operation facilitated by the
flow of sap in the spring, when the bark separates easily from the
wood. If there is danger of tearing the bark under the strain of the
graft acting as a wedge, a slight incision is made in the bark to give
it the play it needs. In this way the circumference of the stock
receives the number of grafts deemed necessary. It only remains now to
bind the whole securely and cover the wounds with mastic. This method
is called crown-grafting, because the grafts are arranged in a crown on
the circumference of the cross-section.
“Grafting by buds corresponds to that variety of slipping in which
buds, each one by itself on a small fragment of the branch, are set
into the ground. It consists in transplanting on the stock a simple bud
with the bit of bark that bears it. It is the method most commonly
employed. According to the time of year when the operation is
undertaken, the graft is called an active bud or a dormant bud. In the
first case the grafting is done in the spring, when nature is awaking
from her winter’s sleep, so that the eye or bud implanted in the stock
coalesces with it and very soon develops into a young shoot. In the
second instance the bud is set in place some time in July or August, at
the period of the autumnal sap, so that it lies dormant or, in other
words, remains stationary during the following autumn and winter, after
uniting with the stock.
“The implement here required is the grafting-knife, furnished at one
end with a very sharp blade, and at the other with a short spatula of
bone or very hard wood. The first thing to do is to remove the bud to
be transplanted. On a branch in which the sap is working we make with
the grafting-knife a transverse cut above the bud and another below;
then, holding the branch in one hand and the grafting-knife in the
other, as the picture shows, we remove the strip of bark lying between
these two cuts and delimited laterally by the line gg´g´´ and its
opposite, in figure F. This strip, which we call the shield, is shown
by itself in H. The leaf that sheltered the bud in its axil has been
removed, but the base of the stem of this leaf has been left and will
be useful later for taking hold of the shield and handling it more
conveniently. The shield must be cut away without any tearing and in
such a manner that no sap-wood is left clinging to the bark. The latter
must be perfectly intact, especially in its inner layers, the seat of
vital activities. Finally, the bud should have its proper complement of
young, greenish wood, which constitutes the germ, the very heart of the
bud. Should this germ be removed by unskilful manipulation, the bud
would have to be thrown away, for the graft would surely fail.
“The next step is to make a double incision in the bark in the shape of
a T, penetrating as far as the wood but without injuring it. With the
spatula of the grafting-knife the two lips of the wound are raised a
little while the bud with its shield is taken up by the piece of
leaf-stem attached to it and inserted between the bark and the wood.
All that now remains to be done is to draw the lips of the little wound
together and bind the whole with some sort of material sufficiently
pliant and elastic not to compress and finally strangle the bud as it
develops. A rush, a slender thong made of a long and flexible
grass-blade, or, better still, a piece of woolen yarn is well suited to
the purpose. But if despite all precautions the ligature should after a
while prove too tight on account of the swelling of the graft, it would
be necessary to loosen it without delay. As soon as the graft has
‘taken,’ as we say, the young shoots starting out on the stock are
gradually suppressed in the cautious manner prescribed for
cleft-grafting.
“When the stock is too small to receive a bud in the usual manner, the
following expedient is resorted to. From a shoot of about the same size
as the stock a rectangular strip of bark with bud attached is cut with
four incisions of the grafting-knife. This strip is immediately laid
upon the stock to serve as a pattern while the point of the knife is
passed all around it. In this way there is cut from the stock a strip
of bark having exactly the same shape and size as the pattern, which
latter is thereupon inserted in the vacant place and made fast there by
a ligature. This process may not inappropriately be called veneering.
“In flute-grafting the bark both above and below the bud is cut
transversely all around the stem, and then another cut is made
lengthwise between these two slashes. A cylinder of bark may thus be
peeled off in one piece. From the stock, which should match this
cylinder in size, a similar cylinder is removed and its place taken by
the other one bearing the bud we wish to transplant.”