great deal has been said, and will be said, elsewhere, when the raffia
is rotten and breaks in the middle of tying a graft. It is the devil's
own stuff to carry when you don't carry it right. The right way to carry
it is to tuck one end of the bundle under one side of your belt, pass
the bundle behind your back and the other end under the other side of
your belt. Then the raffia never gets mixed up with scions, tools and
profanity and the end of a strand is as handy as the knives in your
belt. On the whole I do not know of any binding material as satisfactory
as raffia. It is stronger and easier to use when it is damp.
One of the great advances in the art of grafting is the use of melted
wax. I believe that we have to credit Mr. Jones for this. The use of
paraffine for grafting wax we owe to Dr. Morris. To him also we owe the
Merribrook melter which has added so much to the comfort and convenience
of grafting that it can be recommended as an outdoor sport for ladies. I
do not like the brush that Dr. Morris recommends but prefer a stiffer
one such as can be bought for ten cents.
Equipments vary with the individual and with the difference in the work
to be done. Mr. Slaughter carries into the nursery, when he is working
for Mr. Jones in the semi-tropical sun of Lancaster, a stool with
parasol attachment. Mr. Biederman of Arizona has the most elaborate
equipment which includes a table, planes, curved knives and gouges. Dr.
Morris carries a knapsack. I like an ordinary light market basket that
Mother Earth holds up for me when I'm not moving from place to place.
When in a tree I stuff my pockets with scions.
A saw is usually a necessity. For portability I prefer a curved one that
has a draw cut. It has also an aesthetic element and doesn't look like
a meat saw, which can't be said of Mr. Jones's saw that seduced Dr.
Morris from church. For heavy and steady work I much prefer a
carpenter's sharp hand saw. A two-edged saw is an abomination devised by
conscienceless manufacturers for the seduction of innocent amateurs.
For pruning shears I have a personal fancy for the French, hand-made
instrument, each one individual, a work of art and a potential legacy to
one's horticultural heir, if one doesn't let the village blacksmith
monkey with it, as I did with mine.
On some grafts it is desirable to use a bit of paper, either beneath or
outside of the raffia, to make waxing easier. For this I have found
scraps of Japanese paper napkin very adaptive to surfaces and absorptive
of wax.
On very heavy grafts Dr. Morris uses the Spanish windlass, as devised by
him, for which he carries sisal cord, wooden or metal meat skewers,
small staples and a mallet. He uses a chisel to cut slots in very thick
bark and planes for shaping heavy grafts.
I have tried fastening in grafts with a nail, using iron and brass nails
and bank pins. Mr. Jones has suggested cement covered nails. My
experience with iron nails is that they damage the scions. The use of
nails has not been fully worked out. They are almost essential in bridge
grafting apple trees. I think that just the right kind of a staple might
be a help with some kinds of grafts.
Paper bags, 2 pound size, are sometimes wanted, for protection from sun
or insects or to make the grafts conspicuous. Mr. Jones shades grafts
made close to the ground with a slip of paper.
For labels for immediate use the wooden ones, painted on one side and
with copper wire fastening, are satisfactory. Attach them by the
nurseryman's method, which it has taken me many years to recognize as
the right one, by twisting the _doubled_ wire around a convenient
object. Do not separate the wires which will probably permit the label
to flap in the wind and soon wear out the wires. I used to think that
the nurseryman's method was the result of hurry or laziness.
Copper labels, to be written on with a stylus, cost 1-1/2 or 2 cents
each, according to size. The smaller I consider preferable. I imagined
that these would solve the label problem. Picture my disappointment when
I found that many of them cracked, or broke off entirely near the
eyelet, from flapping in the wind. If they are to be used they must be
fastened so as not to move with the wind. Mr. Bixby has an excellent
label made on an aluminum strip printing machine. It has a hole in each
end and is fastened with a heavy copper wire. He uses two of these
labels on each tree. Dr. Morris sometimes uses a heavy wire stake to
which he fastens the labels. A good method of attaching labels, and one
that does away with the risk of girdling the graft or tree, is to fasten
the label to a staple driven into the tree. The matter of labels is a
troublesome one for they will get lost no matter what you do.
Other conveniences of equipment are a small whetstone, a small hammer,
matches, and some volatile oil, like citronella, lavender, wintergreen,
or other black fly and mosquito repellant. It is almost suicidal to slap
a mosquito on the back of your neck with a keen grafting knife in your
hand. A supply of parowax and alcohol for the lantern's sake should be
remembered.
_Technique_
If the stocks are vigorous and active, and the scions full of vitality,
I doubt if the technique is of chief importance, provided it is
ordinarily good. However, a good technique will increase the percentage
of success. One should have a variety of methods at command for varying
conditions of stocks and scions.
One may come as near 100% success in grafting hickories as one is able
and willing to observe all the known factors of success. I think that we
can say now that the factors of success in hickory grafting are known.
They are a vigorous and active stock, a scion of abundant vitality,
coaptation of the freshly cut cambium layers and prevention of
desiccation.
The stock and scion have already been considered. How is coadaptation
best obtained? One of the best methods, one that can be used in all
seasons and in most conditions of stock and scion, is the side graft,
the one that Mr. Jones uses in his nursery work. That is the best
argument for this graft. It is, perhaps, the simplest, and at the same
time one of the most difficult, of all grafts. The scion is cut wedge
shaped and pushed into a slanting incision in the side of the stock. Mr.
Jones's modified cleft graft is only a side graft made in the top of the
stock after cutting it off. The difficulty lies chiefly in cutting the
scion and the incision in the stock so that the fit will be perfectly
true. This requires practice.
The bark slot graft, as Dr. Morris calls it, I have used for several
years. It can be used only during the growing season when the bark will
slip. It is very successful, whether put in at the top of a cut off
stock, or inserted in the side of a limb or the trunk. It is not
convenient to use unless the scion is considerably smaller than the
stock. The scion is cut with a scarf, or bevel, on one side only. When
the slot is to be made in the top of a cut off stock two vertical cuts
are made through the bark, as far apart as the scion is wide, the tongue
of bark thus formed is raised slightly at the top, and the point of the
scion is inserted, cut surface toward the center of the tree, and pushed
down firmly into place. The superfluous part of the tongue of bark is
then cut off. By slightly undercutting the edges of the slot, and
slightly tapering it toward the bottom, the scion may be wedged, or
dovetailed, in place so as to be very firm. It is even possible to
dispense with tying, sometimes, but better not to do so.
When the slot is to be made in the side of a limb or trunk the same
procedure is followed except that it is necessary before making the slot
to remove a notch of bark, at right angles to the axis of the trunk, so
as to free the upper end of the tongue of bark.
The bark slot graft is the easiest of all and readily mastered once the
grafter learns to shape a true scion. It is much better than the old
bark graft where the bark of the stock is forced away from the wood
leaving considerable space to be filled or covered.
These two forms of graft, the side graft, of which Mr. Jones's modified
cleft graft is only a variation, as before stated, and the bark slot, in
its two variations as described, will meet all needs in topworking
hickory trees.
Finally, prevention of desiccation of the graft is obtained by waxing. I
have found Dr. Morris's method with melted paraffine satisfactory. The
addition of raw pine gum, as advocated by Dr. Morris is undoubtedly an
advantage under certain conditions, described by him, but I have not yet
used it. The melted parowax is applied to the whole graft and wrapping,
leaving no cut surface exposed and the whole scion being covered. If the
paraffine is at just the right temperature it will spread at a touch,
covering the surfaces without danger of scalding. It is much more
effective thus applied than if colder and daubed on. The thicker the
waxing the more likely to crack and separate. If the paraffine smokes it
is too hot. If it does not smoke, and is dexterously applied, I think we
can feel safely that it cannot be too hot. But if applied with a heavy
hand it may be too hot even at a temperature so low that it will not
spread.
_Season for Grafting_
According to Dr. Morris nut trees can be grafted successfully in any
month of the year. But practically I think that grafting will be limited
to that part of the year during which the cambium layer of the stock is
active. At other times of the year preservation of the vitality of the
scion will be too problematical, it seems to me, even if it is very
carefully waxed. However, I may be mistaken. At any rate grafting is not
very pleasant work out of doors in very cold weather. The success of
bench grafting would be an argument for the success of dormant season
grafting out of doors.
_After Care_
Without thoughtful after care the labor of topworking will almost
certainly be lost. There are many ways in which the grafts can be lost
but the two commonest are by being choked, or inhibited, by growth from
the stock, and by being blown out by the wind. All new growth from the
stock must be rigorously prevented. Grafts often make so heavy a growth
that, if not blown out by the wind, they will be dragged out by their
own weight. Consequently they must often be supported. When the grafts
are in, or near, the trunk of the stock, and not too high, the handiest
method of support is to cut a sapling of proper length, sharpen the
butt, stick this into the ground at the base of the stock, and tie it in
two places to the stock. When the grafts are too far out or too high for
this method laths or slats or sticks may be tied or nailed to the
branches. Support is likely to be even more necessary in the second
season when the growth is often astonishing.
Bud worms will sometimes destroy your graft just as it is starting, but
they are easily found if looked for. With my conditions the most harm by
insects is done by the night feeding beetles, which are particularly
exasperating as morning after morning you watch the progress of their
destructive work without ever seeing them. Bagging is the only
preventive and it pays to use bags when a particular graft is cherished.
_Is Topworking Hickories Worth While?_
Up to the present time it is the surest and easiest way, practically the
only way, of getting good results with the hickories, excepting the
pecan. The root systems of the native stocks are well established and
push the grafts rapidly. I have had a Siers hybrid grow 11 feet Straight
up in a season. A Taylor matured several nuts on the third season's
growth. A Terpenny had a crop the fourth year, the Griffin bears
annually since its fifth year, the Kirtland and Barnes since the sixth.
The Kentucky is a little slower. None of the hybrids have yet borne with
me but with others they have borne quite early. We can be sure that the
hickories will bear when top worked as soon as the average apple tree.
The size of the crop that any topworked hickory tree will bear will
depend on the size to which you have been able to grow the tree and the
habit of bearing of the particular variety. I think, also, that there is
good evidence to show that the size of the tree, the size of the nuts
and the size of the crop will depend largely on the amount of care and
the amount of plant food that is given the tree.
Two years ago I topworked a number of hickory trees for Mr. Patterson of
Wilkes-Barre, one of our members, and Mr. Patterson's foreman put in a
few grafts under my observation. This summer I went to Wilkes-Barre to
inspect my work. The foreman took me out into a field where he had done
a lot of grafting the year before and I found that he had had a little
better percentage of success than I had had. He had used the bark slot
graft for everything, even when the scions were almost as big as the
stocks. Before this I had thought that long experience was necessary for
successful grafting. Now I see that if you have good scions, a Morris
melter and a half hour of instructions, you will have all the essentials
for immediate success. Hickory grafting is easy now. But let no one be
contemptuous, for this ease has come only after many years of experiment
and countless failures by many men. The former difficulty in grafting
the hickory seems now like a mystery. The history of its evolution would
make a very pretty story for the nut grower.
NOTES ON MEDIATE AND IMMEDIATE GRAFTING AT ALL TIMES OF THE YEAR
_By Dr. R. T. Morris, Connecticut_
Any newly described fact which releases information on the subject of
tree grafting opens vistas of the new frontier in world agriculture.
Time was when men went from one country to another in search of fresh
top soil. That was when they did not know better. It was when their cogs
of habit turned their cogs of thought. They were engaged in raising
annual plants at a considerable expenditure of time, labor and expense.
They committed wastage of soluble plant foods (a variety of sin).
Malthus formulated a famous over-population fear-thought. It had basis
in his ignorance of the fact that steam was soon to become a factor in
the spreading of food supplies. Furthermore, he seemingly did not know
that when old top-soil frontiers had gone to the rear, new frontiers
would appear in the sub-soil. The tree digs deeper than the farmer ever
plowed.
After Malthus came hunger prophets who were ignorant of coming
possibilities of fleet transportation through the air. The caterpillar
tractor plunging into the tropical jungle will allow of the production
of a practically unlimited food supply. Famine in India, China, and
Russia is a social matter and unnecessary. Trees cure famine.
Within the past decade a number of thinkers on one end of the see-saw
have written heavily on the over-population question not knowing that
they and their birth control ideas were to be tossed into the air by
still heavier weight of fact on the other end of the see-saw.
The heavier weight of fact relates to the idea that famine does not
belong to tree food regions. It relates to the fact that tree foods can
supply all of the essentials of provender for men, livestock and fowls;
proteins, starches, fats and vitamines in delicious form. It relates to
the fact that tree foods come largely out of the sub-soil without
apparent diminution of fertility of the ground. The tree allows top-soil
bacteria and surface annual plants to manufacture plant food materials
and then deep roots take these materials to the leaves for elaboration
by sun chemistry.
Trees may be grown wherever crops of annual plants may be grown and
where annual plants may not be grown profitably. They do not require the
service of high cost labor for annual tillage of the soil. For example,
four large pecan trees or black walnut trees on an acre of ground
without tillage or fertilizer may average a thousand pounds of nut meats
annually for a century. How often is the market value and food value of
a thousand pounds of nut meats per acre equalled by crops from annual
plants which would require from 100 to 200 plowings and harrowings
during a hundred years of continuous cultivation leaving out the
question of expensive fertilizers and labor. Large populations live upon
dates, olives and figs. For trouble they have to look to religion.
Several centuries were required for the British farmers to raise the
wheat crop from six bushels to thirty bushels per acre. Things move
faster nowadays. It will not require so long a time to carry tree crops
from the seedling phase to the phase of grafted kinds with greater
productivity and quality. In the past the successful tree grafter was a
specially skilled man. Now almost anybody may graft almost any sort of
tree at almost any time of the year.
Aside from grafting, the hybridizing of nut trees, like that of cereal
grain plants, has become a scientific sport appealing to the play
instinct of man. When work becomes play in any field of human activity
progress goes by leaps and bounds. The recent advance in tree grafting
has amounted almost to a revolution rather than an evolution process.
Application of a few new grafting principles of great consequence is now
the order of the day. Old established grafting methods frequently ran
into failures when dealing with all but a few trees like the common
fruit bearing kinds.
The two chief obstacles to successful grafting were desiccation of the
graft and fungous or bacterial parasites which entered the land of milk
and honey where sap collected in graft wounds. Both of these dangers
have now been practically eliminated and it remains for us to extend the
season of grafting, carrying it away from a hurried procedure in busy
spring weeks.
The chief obstacle to this extension of the grafting season has been the
difficulty in finding the right sort of grafting wax or protective
material for covering the graft, buds and all, as well as the wound of
the stock. For covering the entire graft in order to avoid desiccation
grafting waxes had to be applied in melted form with a brush. They had
to be applied in melted form for filling interstices of wounds in which
sap might collect and ferment. These waxes had the effect of not
retaining their quality under greatly varying conditions of heat, cold
and moisture. The paraffin waxes which the author has preferred were
inclined to crack and to become separated from the graft and stock in
cold weather. Furthermore they would remelt and become useless in the
very hot sun of southern latitudes.
Experimentation for several seasons has resulted in the finding that raw
pine gum is miscible with the paraffins in almost all proportions
because of physical or chemical affinity. This gives to the wax an
elasticity and adhesiveness of such degree that we may now graft trees
in cold weather. Cohesiveness of molecules of the mixture is such that
remelting in the hot sun may not destroy the effectiveness of this
protective coating in hot weather.
Since the author has depended upon this mixture he has grafted peaches,
apples, hazels and hickories successfully in midwinter as well as in
midsummer. Many other kinds of trees have been grafted successfully out
of the so-called grafting season but these four kinds which represent
two of the "easiest grafters" and two of the "hardest grafters" will
suffice for purposes of illustration.
According to old-established idea trees may be grafted successfully only
from scions that have been cut when dormant and stored in proper
receptacles. This is what we may term "mediate grafting," a considerable
length of time intervening between cutting the scions and inserting the
grafts. On the other hand what we may call "immediate grafting" is the
taking of a scion from one tree and grafting it at once in a tree that
is to receive it. Mediate or immediate grafting may both be done at
almost any time of the year, winter or summer, spring or autumn.
When preparing the scion for immediate grafting in the spring or early
summer it is best to cut off all the leaves and herbaceous growth of the
year. We then depend upon latent buds situated in the older wood of the
scion. The latter may be one year or several years of age.
In midsummer when top buds have formed we may remove only the leaves,
allowing the growth of the year to remain and to serve for grafting
material.
In experiments with the apple for example it was found that mediate
grafts inserted on July 10th in the latitude of Stamford, Conn., began
to burst their buds five or six days later. Immediate grafts inserted at
the same time began to burst their buds about fifteen days later from
buds of the year and about twenty days later from latent buds in older
scion wood.
New shoots from these mediate apple grafts continued to grow as they do
in Spring grafting. Immediate apple grafts on the other hand put out
about six leaves from each bud and then came to a state of rest with the
formation of a new top bud. After about ten days of resting these new
top buds again burst forth and grew shoots like those of the mediate
grafts.
The philosophy of these phenomena would seem to include the idea that
the mediate summer grafts had contained a full supply of pabulum stored
up in the cambium layer. The immediate summer grafts, on the other hand,
had contained only a partial supply of pabulum, enough to allow them to
make six leaves and a top bud. After a few days of resting these shoots
with meager larder could then go forward with new food furnished by the
whole tree.
Mediate and immediate winter grafts were alike in their method of growth
in the spring. This would seem to confirm the idea that character of new
growth is dependent upon the relative quality of stored pabulum in the
cambium layer.
In experimental work it was noted that both mediate and immediate winter
grafts make a slower start in the spring than do the grafts inserted in
springtime. This is perhaps due to the formation of a protective corky
cell layer over wound surfaces. New granulation tissue would then find
some degree of mechanical obstacle in the presence of a corky cell layer
at first.
Herbaceous plants allow of grafting. We are familiar with the example of
the tomato plant grafted upon the potato plant, furnishing a crop of
tomatoes above and potatoes below.
It seemed to the author that the herbaceous growth of trees should be
grafted quite as readily. This seems to be not the case. A number of
experiments conducted with grafting of the herbaceous growth of trees in
advance of lignification has resulted wholly in failure with both soft
wood and hard wood trees.
The walnuts carried herbaceous bud grafts and scion grafts for a long
time however. These grafts sometimes remained quite green and promising
for a period of a month but lignification progressed in the stock
without extending to the scion. Speculation would introduce the idea
that lignification relates to a hormone influence proceeding from the
leaves of a tree and that the leafless scion does not send forth
hormones for stimulating the cells of the scion to the point of
furnishing enzymes for wood building.
Perhaps the most interesting part of new tree work relates to
experiments which are failures. Negative testimony is like the minor key
in music. There are many men who care to do only things that "cannot be
done." These are the ones who have made our progress in almost every
field of human activity.
STOCKS FOR HICKORIES
_Willard G. Bixby, Long Island_