_Time for Grafting Raisin-vines._--The best time for grafting
grapevines, as well as for grafting anything else, is when the stock on
which we graft has its sap in circulation, and when the scions or
cuttings which we are to insert in the stock are yet dormant. This time
occurs from the middle of January, when the sap first rises in the old
vine, and continues to March or even April, February and March being
generally the months best suited to the work. Grafting may also be done
in the fall of the year after the grape crop has been gathered, while
some growers have best succeeded still earlier, and advocate the month
of August as being the most favorable time for this process. The sap at
that time ceases flowing, and there is no danger of its being clogged.
Grapevines can be grafted at almost any time of the year at which the
weather is not too warm, as this will cause the cuttings to bud out
before they have joined the stock. If grafting on resistant stocks is
desired, the stocks, if small, must first be dug, and the grafting can
then be performed in the workshop any time between December and March,
the early winter months being preferable.
_Points to be Observed in Grafting._--The main object in grafting is to
properly join the scions and the stock. The point of junction should be
the cambium layer, or what is commonly called the inner bark. If a
cutting of a vine is cut off smoothly and placed in the ground, the
callus soon begins to form at the lower end. This callus, which is seen
to exude from the green layer between the hard wood and the bark, is fed
by the sap in the cutting descending through the cambium layer and
forming new cells at its free end. If this callus joins a similar callus
of the cambium or green layer of the stock, the two calluses unite and
form together a new vine, in which the top consists of the new scion and
the root of the old vine. The junction of the two is the place where the
cambium surface of the scion met the cambium of the stock. In the
scions, the cambium lies very close to the exterior layer of the
cutting, the bark here being very thin, while in the old stock the
cambium is situated many times deeper in, the outer layer or the bark
being very thick. It is not necessary that the cambium layers of the two
should meet or join all along the cut surface, and a few points of
contact and junction is sufficient, although it is better to have as
large a junction surface as possible. If the two cambium layers do not
meet, the scion will not grow, or, as it is called, take. The scions
must be dormant when being grafted, and, if their buds have begun to
swell, they will probably not take, or at least success is less certain.
In order to keep them dormant they should be cut early in winter, and
then be buried in cool and only slightly moist earth, either in a cellar
or on the north side of a house, where the sun and heat will not strike
them and cause them to start their buds. If the callus should form, or
even root, the callus and roots may be cut away without great injury to
the cuttings. If the cuttings are dry, they should be soaked for a few
hours in tepid water, and afterwards buried in moist sand. This
treatment is often useful for imported cuttings which have been injured
in transit. They often recover vigor wonderfully fast, and should never
be given up for lost as long as there is any green-colored cambium left,
in which the sap may again be brought into circulation.
_Various Methods of Grafting._--The general way to graft is to graft on
old stocks. Vines of one variety are thus changed into the variety we
wish to grow, and from which the scions are taken. The first step is to
dig away the soil from the vines down to the first roots, which should
be done by a separate gang of men. Next the stocks are sawed off
horizontally at the first roots, or say from four to six inches below
the surface of the soil. This should also be done by separate hands so
as to insure rapidity and skill in the work. Some grafters saw off the
stocks somewhat slanting, so as to cause them to shed the sap which
always exudes from the stump. Next in order comes the splitting of the
wood of the stock and the insertion of the grafts. This requires care
and skill, and should not be done by careless hands.
The splitting of the stock is done in several different ways, and to
accomplish it we can either use a knife and a wooden mallet or a
hand-saw. If the former is used, the knife must be sharp and thick, so
as to stand the blows of the mallet. Some growers even use a sharp
chisel. If a saw is the tool used,--and I prefer it every time,--the
edges of the old wood should afterwards be pared off smoothly with a
sharp knife, so as to leave no rough marks of the teeth of the saw. The
stock is split straight across, as in the cleft graft, and one scion is
then inserted at each end of the cleft on opposite sides of the stock;
or the stock is split on one side only, care being taken that the cleft
does not extend across the stump, and in this cleft a scion is carefully
fitted as before; or a wedge-shaped piece may be sawed out or cut out of
the stock, and of the size that can be fitted by a scion. It makes but
little difference what method is used, as with ordinary care and skill
the scions will take quite readily. Even if they should entirely fail,
the same stocks may be grafted over next fall or next year, as they keep
their vitality almost unimpaired for years after they are cut. It is
only necessary to saw them off until fresh wood is reached.
[Illustration: Simple Lateral Cleft Graft, 1_a._ Splitting the Trunk,
1_b._ The Scion, 1_c._ The Beveled End of the Latter, 1_d._ Scion and
Stock Joined.
2. Simple Transversal Cleft Graft with Two Scions. 3. Cleft Grafting
with a Cutting Graft. Champin Graft, or Graft on a Rooted Vine. 4_a._
Graft and Stock Before being Joined. 4_b._ The Same After being Joined.
All after Aimé Champin’s “Vine Grafting.”]
The next work is to insert the scions. They should never be longer than
sufficient to have one eye above the surface of the soil, two or three
eyes to the scion being generally enough. The cuttings are first cut in
sufficient lengths in the field, or on the spot, and there pared to fit
the cleft in the stock. If prepared in the house, they are apt to dry
out and become ruined. By keeping them in water they may be kept fresh,
but this greatly injures their quality. The best way is to bring the
cuttings out to the vineyard wrapped up in wet sacks, and to cut and
pare them on the spot where they are to be grafted. With a sharp knife
the two opposite sides of the scions are pared off tapering, but not
necessarily to a fine point. The scion is then fitted in the cleft, a
small wooden wedge being useful for holding the latter open while the
scion is fitted. If the stock closes tightly upon the graft, no tying is
required, but, if the grip of the stock is not sufficient, tying is
needed. Cotton cloth, manilla rope or anything that will hold the two
together will answer the purpose. The stocks and scions will both dry
slightly, and the tying should therefore be secure and tight.
A piece of bark of the vine is next placed over the cleft, so as to
prevent any soil from falling in the cleft, and very careful grafters
use a paste made of a mixture of two parts of adobe or clay and one part
of cowdung, for covering both the cleft and the sides of the grafts
outside of the tying. A stout stake is driven in the ground close to the
graft, and the two tied together in order that the graft may not give or
be disturbed in the least. The hole is next filled with soil, which
should be packed tightly and heaped above the scion, thus forming a
small mound above the ground all around the graft. The soil should not
be disturbed until the new shoots are well above the ground and have
begun to harden their wood, at which time the security of the graft is
fully assured. One or more of the grafts may be left growing for the
first year, and later on all except one graft are cut off so as to give
the vine only one trunk.
In grafting on resistant stocks, the latter generally being smaller then
old stocks, a different graft may be used, such as the whip graft. This
graft should be above or at least near the top of the ground in order to
prevent the scion from taking root, the latter’s roots not being
resistant to the phylloxera. Such grafts should be carefully covered
with the clay mixture, and soil should be heaped up over their tops. To
prevent the scions from drying out, their tops may also be covered with
grafting wax.
_Stocks and Their Influence._--The old stock has a decided influence on
the scion and the new vine. Which stock is the best on which to graft
the Muscat has not yet been determined, but we may presume that any
strong and healthy growing variety will answer our purpose. During the
first year, and also during the second year, in many instances the new
vine assumes a character half way between that of an old-stock variety
and that of the variety of the scions. Thus I have seen Muscats grafted
on Sultanas and Zinfandels which were almost identical with these
varieties. If I had not positively known that they were the tops
produced from Muscat scions, I would never have believed them to be
anything else than suckers from the old stocks. The leaves, berries and
branches of these Muscats were the first year exactly like Sultanas. The
berries of those grafted on black grapes were, however, in this
instance, not black but white, but I have heard of other instances in
which they were partially colored. Some vines, again, showed
characteristics of both varieties, the leaves generally being similar to
the old stock, while the grapes showed the characteristics of the
Muscats. This bastardity, however, wears off in a year or two, and
finally the vine assumes the full characteristics of the scion variety.
When this takes place it is evident that the sap of the scion or the top
of the vine has either changed the root, or through its quantity
overpowered the effects of the root-sap.
Muscats grafted on Malagas, Feher Szagos, Sultanas and Zinfandels all do
well in time, and in many instances bear even better than Muscats on
their own roots. Our experience in grafting the Muscat is, however,
limited, and we do not know with any certainty which roots are the most
favorable or the most unfavorable on which to graft the Muscat grape. I
have seen grafted Muscats on wine stocks which did not do well as
regards bearing, while the growth of the vines was rather vigorous.
These varieties mentioned above are, however, suitable stocks for Muscat
grafts. I learn from Mr. R. C. Kells of Yuba City that the late Dr. S.
R. Chandler of the same locality cleared the third year seventy-five
dollars per acre from Muscats grafted on Mission vines. This must be
considered as very successful, especially as I have heard of other
instances where similar grafts did not bear sufficiently the third year
to pay for the labor of caring for the vineyard work that year.