PROPAGATION OF THE PECAN.
The pecan tree is difficult of propagation by budding or grafting.
Skillful propagators are satisfied with seventy-five per cent. of living
buds or grafts, while very many have to be content with less. The
difficulty is due, in part, to lack of skill; in part to lack of
judgment in selecting good material with which to work; but in some
regions it is due to the attacks of the bud-worm, _Proteopteryx
deludana_, more than to anything else. The buds are eaten out and
destroyed by this insect at the time they start into growth. In certain
sections spring working of pecans has been abandoned entirely owing to
the destruction wrought by this pest. But notwithstanding all the
drawbacks, pecan trees can be, should be and are propagated in large
numbers by budding and grafting, and the seedling is becoming more and
more a thing of the past.
SEEDLING VS. GRAFTED TREES.
It is a fact worthy of note that the beginning of every tree-fruit
industry is marked by the use of seedling trees. In the later stages of
the development of the industry the seedling, owing to a more intimate
knowledge of its failings and shortcomings, gives way to the grafted[I]
tree. This stage has already been reached in pecan orcharding.
It has been stated that a certain percentage of pecans would produce
nuts identical with those of the parent tree. The author has yet to find
the first instance in which this was the case. This truth is borne out
by the observations of others.
In view of the fact just stated, if a planter desires to secure a
certain definite fixed variety of pecan, it can only be done by planting
grafted trees. Even though all the seedlings were of good size, yet the
variation in time of ripening, quality, prolificness, form and size
would be against them. Take a certain quantity of each of a number of
our largest pecans--Stuart, Van Deman, Centennial and Frotscher for
instance--mix them together, and under average circumstances the mixed
lot will sell for less money in the open market than the same varieties
and the same nuts would if marketed separately. Mixed nuts, no matter
how good the quality, cannot compete successfully in the market with a
single uniform sample of the same or nearly the same quality.
Grafted trees will come into bearing at an earlier age than seedlings.
In the case of seedlings it is very difficult to say when they will
begin to bear, while grafted trees of the more precocious varieties may
be expected to bear quite a little fruit in six or eight years from the
time of planting.
The great objection to grafted trees is the first cost, and yet, in the
face of that objection, it is best to plant grafted trees even if fewer
of them are planted. If grafted trees are out of the question, then
plant seedlings and top-work them. Grow the seedlings from nuts if
necessary; but to those who live in sections where pecans can be grown,
let me say, _plant pecan trees_; plant budded or grafted trees if you
can--but plant pecan trees.
PECAN STOCKS.
Nursery trees are propagated entirely on pecan stocks, and in the
present state of our knowledge, it is the best stock to use. It may be
that the pecan will grow and thrive as well on a number of different
species of hickory, but definite information bearing on this point is
lacking. _Hicoria tomentosa_, _H. alba_, and _H. aquatica_ have been
used for stocks in North Carolina, Florida, and other States, the pecan
being top-worked upon them. But for the present, at least, until our
experimental knowledge is farther advanced, the safest advice is to use
pecan stock only.
Too little attention on the part of propagators has been given to the
kind, source and quality of the seed used to raise stocks for
propagation work. The main object held in view in making a selection for
seed purposes is to get just as many nuts as possible in the pound. The
result of this policy is, that, without question, inferior seedlings are
often used for stock; they lack stamina and vigor. Frequently in a
nursery of budded or grafted stocks, or in a young pecan orchard, a wide
variation in the size and vigor of the trees can be noticed. No
satisfactory explanation has ever been offered, but there seems little
reason to doubt that it is due to the use of heterogenous lots of seed
for stock purposes. _The point must be emphasized, that greater care
should be exercised in the selection of the seed used in nursery work._
Nuts from rapid-growing, vigorous, healthy trees only should be used. It
is best to plant in spring only nuts which matured the previous autumn.
Preferably these nuts should be of fair or medium size for the variety
to give the young seedling a fair start in life.
As already pointed out in regard to pecan shade trees for more
northerly regions, so in the case of pecan nuts for use in raising
stocks in northern sections. It is best to secure nuts from trees near
the northern limits of nut production.
STORING AND PLANTING SEED NUTS.
If pecan nuts, intended for seed purposes, are stored and kept as nuts
ordinarily are kept, they become dried out. Before they will germinate
the following spring they must absorb all the moisture lost and
considerably more; in consequence of which they are slow in starting. If
too thoroughly dried out, many may fail to germinate.
To obviate this, and to insure better and more prompt germination, it is
best to keep the seed nuts in moist sand or clay during the winter
months. Procure a sufficient number of shallow boxes or trays; three
feet by one and a half feet by six or eight inches will answer nicely.
These are to be used in stratifying the nuts. The earth to be used
should preferably be good clean sand, free from organic matter, or, if
this cannot be secured, clay will answer. Place a layer of the earth
about one inch deep in the bottom of the boxes, then a single layer of
nuts, then a two-inch layer of earth, and so on in alternating layers
until the boxes are filled. These should then be slightly moistened and
set aside in a sheltered place and covered with pine straw, leaves or
straw.
In spring, when germination has just begun in the nuts and the tiny
sprouts are beginning to appear, they should be planted in rows. The
ground should be deeply plowed, well broken up, pulverized, and made
moderately rich. Ground which produced a heavy crop of cowpeas, velvet
beans or beggarweed the previous season is excellent for the purpose.
Farm-yard manure, well decomposed and plowed in the autumn previous, is
one of the best manures to use. The ground should be lined off in
perfectly straight rows four feet apart, running east and west, that,
the buds may be inserted on the north side. The nuts should be planted
four or five inches deep, depending upon their size and the character of
the soil. Large nuts should be planted deeper than small ones, and in
heavy soils nuts may be planted somewhat nearer the surface than in
light sandy ones. The rows may be opened with a small turning plow, or,
for lesser areas, with a shovel. Place the nuts, a foot apart, carefully
in the bottom of the furrow, cover with a hoe, roll the ground if the
weather is dry, and then scarify the surface with a weeder or a light
harrow to prevent evaporation of the soil moisture. Or the ground may be
mulched with pine-straw, grass, leaves or other suitable material. If no
mulch is applied, then the surface of the ground Should be cultivated
shallow from time to time.
Some propagators have adopted the plan, with good results, of planting
the nuts in the nursery rows, in late fall.
CULTIVATION OF NURSERY SEEDLINGS.
From the time the young shoots begin to appear above the surface
frequent shallow cultivation should be given. Once every ten days or two
weeks is not too often, and the ground should be broken to a depth of
one inch or so after every shower of rain. During dry weather more
frequent cultivation, once every week, will be well repaid in the
additional growth and vigor of the seedlings. A good commercial
fertilizer, analyzing 5 per cent. phosphoric acid, 6 per cent. potash
and 4 per cent. nitrogen, may be applied to advantage at the rate of
fifteen hundred or two thousand pounds per acre. By the following
autumn, the better seedlings will have ten or twelve inches of top, and
two and a half or three feet of taproot. The following spring some may
he whip-grafted at the crown, and by June, July and August of the same
year many of them should have attained sufficient size for budding.
Those which are not of sufficient size at this time can be worked the
following spring and summer.
[Illustration: PLATE IV. A Pecan Nursery.
_Photo by J. F. Jones._]
THE NECESSARY MATERIALS AND TOOLS.
The materials and tools used in grafting and budding are: a grafting
iron, a mallet, budding knives, grafting wax, strips of waxed cloth and
twine.
[Illustration: FIG. 17. Grafting Iron.]
Of grafting irons there are a number of different kinds, but one after
the general type shown in Fig. 17, works very well. It will be noticed
that the blade is curved at the corners, and the edge instead of being
straight is curved downward in the center. This type of blade in some
measure prevents the bruising of the bark when splitting the branch in
cleft-grafting. Such a grafting iron may be made by almost any
blacksmith. However, a good stout knife may be used instead.
[Illustration: FIG. 18. Common Budding Knife.]
For use in grafting, an ordinary budding knife, one of which is
illustrated in Fig. 18, is well nigh indispensable. No other knife is so
well adapted to making the smooth, sloping cuts on the scions.
[Illustration: White's Budding Tool.
Galbreath's Budding Tool.
Nelson's Budding Tool.
PLATE V.]
Some persons can insert annular and veneer shield buds rapidly and well
with nothing but an ordinary budding knife. In general, however, a
budding knife having two blades, placed parallel with a space of
three-quarters of an inch or an inch apart, is best. A very satisfactory
knife may be made by fastening the blades of two ordinary budding knives
on the sides of a piece of wood seven-eighths of an inch square and four
inches in length. The blades can be firmly held in place by means of
rivets and a piece of wire wound about the whole.
Three special budding knives, for use in pecan budding, have been
introduced, one by Mr. Herbert C. White, of DeWitt, Ga., one by Mr. D.
Galbreath, of New Orleans, La., and the other by Mr. Wm. Nelson, of New
Orleans, La. In these knives the blades are fixed seven-eighths of an
inch, one and one-eighth inch, and three-fourths of an inch apart,
respectively. These make it possible to cut the buds and the place where
they are to be inserted on the stock exactly the same size, an essential
point in pecan budding. They have not yet come into general use,
although well recommended by some who have used them. The White budding
tool is particularly well adapted for use in top-working trees.
A good grafting wax may be made according to a number of different
formulas. Either of the following will be found satisfactory:
{Resin 6 pounds.
I. {Beeswax 2 pounds.
{Linseed Oil 1 pound.
{Resin 4 pounds.
II.{Beeswax 1 pound.
{Linseed Oil 1 pint.
Break the resin and cut the beeswax into small pieces. Place in an iron
vessel, pour the oil over them and melt over a slow fire. Stir slightly
to insure their being well mixed together, pour out into a bucket of
cold water, grease the hands, and as soon as the mass is cool enough to
handle, pull until it becomes light yellow in color. The wax may be made
up in quantity and stored in greased tin or wooden boxes for future use.
To prepare waxed cloth, cut the cotton cloth into pieces of convenient
size, say eighteen inches square, dip them down into the melted wax,
remove them with a couple of sticks and stretch them out until cooled.
For use, the cloth may be torn into strips of desired width and wound
about a stick eighteen inches or so in length. Use a little grease to
prevent the grafting wax and grafting cloth from sticking to the hands.
For waxed twine, procure No. 18 knitting cotton and drop the balls into
the melted wax for a minute or two or until the wax penetrates them.
SELECTION OF SCIONS.
Great care should be exercised in the selection of scions for use in
budding and grafting. Much of the immediate success of the work depends
upon the character of the scions, while the health and longevity of the
future tree may be materially influenced by the kind of wood used in
propagating work.
The practice of taking scions and buds from young trees which have never
borne, or from nursery stuck, must be strongly condemned. They should be
cut only from thrifty, vigorous, prolific trees. Even trees of the same
variety differ in these things, and a thorough knowledge of what a tree
will do and has done is the only true guide in the selection of scions.
It is a well-known fact that desirable qualities can be reproduced and
perpetuated by grafting.
[Illustration: _From Bul. 57, Florida Exp. Sta._
FIG. 19. Scions: 1-3, Curtis; 4-6, Van Deman; 7-8, Stuart. 1. Poor
Scions--long, slender, pithy. 2,4,5,7,8. Scions from one year's growth.
3. Scion, partly one, partly two years old. 6. Scion with cut, back of
tip. 8. Scion which bore fruit at a.]
Grafts should be selected from well-matured branches of one year's
growth. Fig. 19, No. 1, shows an undesirable scion. The wood is angular,
small, the internodes long, and the pith large in proportion to the
diameter. Either terminal portions of twigs may be used or portions back
of the tip, but the buds should always be well developed, full and
plump--Fig. 19, Nos. 2 to 6. For this reason grafts should not be cut
from wood far back from the tip of the branch. As stated, twigs of the
previous season's growth are generally used, but scions composed partly
of two-year-old wood may be used, provided the growth is not too large.
Fig. 19, No. 3, shows one of these. Grafts are generally cut about five
or six inches long, and should be from one-quarter to three-eighths of
an inch in thickness.
It is best that the grafts be cut while still in a dormant state, and
inserted in the stock just before the growth starts. The scions may be
kept for a considerable length of time by placing them, loosely packed,
in damp moss or sawdust, in a box. The box should be covered over with
earth and the scions kept sufficiently moist to prevent drying out.
For bud sticks, well developed one-year-old branches, one-half to
seven-eighths of an inch in diameter, and on which the buds are well
formed, may be used. Such sticks frequently show three buds at a node,
and if some misfortune should overtake one or two of these, there is
still a chance of success, though the upper one being the strongest is
generally the one which starts, provided it is uninjured and the bud
takes. The degree of maturity of the bud is important, and care should
be exercised that only those which are plump, full and well developed,
are used. As soon as removed from the tree all bud sticks and grafts
should be wrapped in damp newspapers to prevent drying out.
TIME.
Grafts should be inserted in spring just before or at the time growth
starts. Buds may be inserted any time during the period when the bark
will slip readily. Last year's dormant buds may be inserted early in the
season, or buds of the current season's growth may be used during the
latter part of July and the month of August, at which time they have
become fully matured in the southernmost parts of the Gulf States. The
time may even be extended into September. Very many of these
late-inserted buds remain dormant during winter and begin growth in
spring.
BUDDING.
_Annular Budding._--A ring of bark about one inch in length is removed
from the stock. A bud stick of the same size is selected, and from it a
similar ring with a good bud on it is removed by cutting around the bud
stick and slitting down the back or side opposite the bud. This bud is
then placed in position on the stock. After the buds are in place, a
piece of stiff wrapping paper should be tied around the stock just above
the bud and allowed to flare out over the bud to protect it from the sun
and wind. Preferably all buds should be inserted on the north side.
[Illustration: _From Bul. 57, Florida Exp. Sta._
FIG. 20. Annular Budding. 1. Stock prepared for bud. 2. Bud. 3. Bud in
place and tied.]
Stocks from three-eighths to three-quarters of an inch may be worked by
this method.
_Veneer Shield-Budding. (Patch Budding)._ This method differs from the
last only in that the piece of bark removed from the stock and the piece
with the bud attached are not complete rings, but only parts. A
rectangular or even a triangular piece of bark is taken out of the
stock, a similar piece with a bud in its center taken from the bud
stick is fitted in its place and wrapped in the usual way.
[Illustration: From Bul. 57, Florida Exp. Sta.
FIG. 21. Veneer Shield-Budding.]
Mr. George W. Oliver, of the Bureau of Plant Industry, Washington, D.
C., has described[J] a modified method of veneer shield-budding, which
has given good satisfaction in his hands. Instead of removing the patch
from the stock, it is slit down the center from top to bottom and the
edges are lifted back, the buds inserted beneath and the side flaps are
then tied down over it. He has also found that dormant buds of last
year's growth give better results than buds of the current season.
The use of these buds has not, however, come into general use; first,
because of the large amount of wood which must be destroyed to secure
them; and second, because in those sections where bud-worms are
prevalent, their larvæ are to be found clustered about the buds until
quite late in the season and make their attack as soon as the bud starts
to grow.
Mr. E. W. Kirkpatrick,[K] McKinney, Texas, described a method
successfully used by him, as follows:
"We prepare the stock to receive the bud by cutting out a
section of bark and wood as shown in Fig. 22. The bud is cut
from the scion in the same way the cut on the stock is made. It
should be about the same length, width, thickness and shape of
the bark removed from the stock (see Fig. 22), so that the bud
will fit the stock. * * * * The bud should be firmly tied until
growth begins, usually about twenty-five days, when the string
should be cut and the stock also cut just above the bud. * * *
All shoots must be kept rubbed off so as to give the buds the
right of way. The small buds about the base of the scions or
those on the two-year-old wood are preferred. Where the buds
are small and in a cluster, several may be included in one set
and the thinning done after the growth starts."
[Illustration: FIG. 22. Chip Budding. Bud cut; Incision made; Bud in
place.]
GRAFTING.
_Cleft Grafting._ Having selected the branch for cleft grafting and the
point at which the scions are to be inserted, the branch should be
carefully and smoothly cut off. The limb is then split by using the
grafting iron. If rapid work is to be done, grafts should be prepared
beforehand and carried to the field, wrapped in damp paper. In preparing
the scion, a sloping cut should be made about one and one-half inches
long, cutting into the pith from a point one-half way up the cut down to
the lower end. On the opposite side, the cut should not be made to touch
the pith, but should be confined to woody tissue throughout its whole
length. The knife should have a keen, sharp edge. The cut should be
clean, smooth and straight, and the scion should be left wider on the
outer side. Start the cuts on each side of, and just at a bud, as shown
in Fig. 23. Having made the cleft, it is opened with the wedge on the
end of the grafting iron and the scion is placed in position. The
cambium layers should be in contact. Slip the scion well down until the
whole of the cut surface is within the cleft. If the stock is large
enough insert two scions. After inserting the scion it should be firmly
held in place by binding the stocks with strips of waxed cloth, after
which a covering of wax may be placed over the cloth. The cut end of the
stock should be covered, and if the scion be other than a terminal
shoot, its distal end should be waxed also.
[Illustration: Bul. 57, Fla. Exp. Sta.
FIG. 23. Cleft Grafting. 1. Scion. 2. Scion inserted ready for tying. 3.
Stock showing cleft.]
[Illustration: Bul. 57, Fla. Exp. Sta.
FIG. 24. Whip Grafting. 1. Stock showing cut. 2. Scion. 3. Stock and
Scion ready for bandage.]
_Whip Grafting._ Branches, which are to be worked by whip grafting,
should be less than one inch in diameter. The method is illustrated in
Fig. 24. A sloping cut, an inch and a half long, is made diagonally
across the stock. A corresponding cut is made on the scion, a tongue is
raised about the center of each cut by making another cut with the
budding knife held almost parallel to the sides of the wood. The tongue
is raised a little on both stock and scion and the two are shoved
together. They should be securely bound with a strip of waxed cloth, and
a layer of wax should be spread over the whole, covering up all the cut
surfaces to the exclusion of water, air and the germs of decay.
[Illustration: _Photo by J. F. Jones._
FIG. 25. One year Pecan in fruit. Unusual; due to bearing wood being
used as a scion.]
The scion and stock are preferably chosen of nearly the same size, but
a scion somewhat smaller than the stock may be used, in which case the
cambium layers along one side of the surfaces in contact should be
placed opposite each other, and the projecting portion of the stock
trimmed off.
AFTER-CARE.
In from ten days to three weeks, the buds should unite. They should be
examined, and if union--indicated by the full, plump condition of the
buds or the commencement of growth--has taken place, the wrappings
should be removed. If growth has started, the stock should be cut off or
lopped just above the insertion of the bud, in the case of budded trees.
From time to time the trees should be examined, and all sprouts which
might rob the bud of sap, thereby preventing its growth, should be
rubbed off.
FOOTNOTES:
[I] The term grafted, as here used, embraces budded trees as well.
[J] Bulletin 30, Bureau Plant Industry, U. S. Dept. Agr., 1902.
[K] Farm and Ranch, Dec. 3, 1904.