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Title: Citrus propagation
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Title: Citrus propagation
Alternate Title: Bulletin 227 ; Florida Agricultural Experiment Station
Physical Description: Book
Language: English
Creator: Camp, A. F.
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville, Fla.
Publication Date: April, 1931
Copyright Date: 1931
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Bibliographic ID: UF00027156
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: aen4678 - LTUF
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i!


Bull tin 227 April, 1931

UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
Wilmon Newell, Director





CITRUS PROPAGATION






4
By A. F. CAMP


















f 07 -

















Bulletins will be sent free upon application to the
Agricultural Experiment Station
GAINESVILLE, FLORIDA









BOARD OF CONTROL
P. K. YONGE, Chairman, Pensacola RAYMER F. MAGUIRE, Orlando
A. H. BLENDING, Leesburg FRANK J. WIDEMAN, West Palm Beach
W. B. DAVIS, Perry J. T. DIAMOND, Secretary. Tallahassee

STATION EXECUTIVE STAFF
JOHN J. TIGERT, M.A., LL.D., President R. M. FULGHUM, B.S.A., Asst. Editor
WILMON NEWELL, D.Sc., Director IDA KEELING CRESAP, Librarian
H. HAROLD HUME, M.S., Asst. Dir., Re- RUBY NEWHALL, Secretary
search K. H. GRAHAM, Business Manager
S. T. FLEMING, A.B., Asst. Dir., Admin. RACHEL McQUARRIE, Accountant
J. FRANCIS COOPER, M.S.A., Editor

MAIN STATION-DEPARTMENTS AND INVESTIGATORS
AGRONOMY ECONOMICS. AGRICULTURAL
W. E. STOKES, M.S., Agronomist C. V. NOBLE, Ph.D., Agricultural Economist
W. A. LEUKEL, Ph.D., Associate BRUCE McKINLEY, A.B., B.S.A., Associate
G. E. RITCHEY, M.S.A., Assistant* M. A. BROOKER, M.SA., Assistant
FRED H. HULL, M.S., Assistant
J. D. WARNER, M.S., Assistant ECONOMICS, HOME
JOHN P. CAMP, M.S.A., Assistant OUIDA DAVIS ABBOTT, Ph.D., Head
ANIMAL HUSBANDRY L. W. GADDUM, Ph.D., Biochemist
C. F. AHMANN, Ph.D., Physiologist
A. L. SHEALY, D.V.M., Veterinarian in
Charge ENTOMOLOGY
E. F. THOMAS, D.V.M., Asst. Veterinarian WATSON A. M.. Entomologist
R. B. BECKER, Ph.D., Associate in Dairy A. N. TISSOT, M.S., Assistant
Husbandry. HE BRATLEY, M.S.A., Assistant
W. M. NEAL, Ph.D., Assistant in Animal H E BRATLEY, M.S.A Assistant
Nutrition L. nW. ZIEGLER, B.S., Assistant
C. R. DAWSON, B.S.A., Assistant Dairy HORTICULTURE
Investigations A. F. CAMP, Ph.D., Horticulturist
CHEMISTRY HAROLD MOWRY, B.S.A., Associate
R. W. RUPRECHT, Ph.D., Chemist M. R. ENSIGN, M.S., Assistant
R. M. BARNETTE, Ph.D., Associate A. L. STAHL, Ph.D., Assistant
C. E. BELL, M.S., Assistant G. H. BLACKMON, M.S.A., Pecan Culturist
J. M. COLEMAN, B.S., Assistant C. B. VAN CLEEF, M.S.A., Greenhouse
H. W. WINSOR, B.S.A., Assistant Foreman
H. W. JONES, B.S., Assistant PLANT PATHOLOGY
COTTON INVESTIGATIONS W. B. TISDALE, Ph.D., Plant Pathologist
E. F. GROSSMAN, M.A., Assistant G. F. WEBER, Ph.D., Associate
PAUL W. CALHOUN, B.S., Assistant A. H. EDDINS, Ph.D., Assistant
K. W. LOUCKS, M.S., Assistant
ERDMAN WEST, B.S., Mycologist

BRANCH STATION AND FIELD WORKERS
L. 0. GRATZ, Ph.D., Asso. Plant Pathologist in charge, Tobacco Exp. Sta. (Quincy)
R. R. KINCAID, M.S., Assistant Plant Pathologist (Quincy)
W. A. CARVER, Ph.D., Assistant, Cotton Investigations (Quincy)
RAYMOND M. CROWN, B.S.A., Field Asst., Cotton Investigations (Quincy)
JESSE REEVES, Farm Superintendent. Tobacco Experiment Station (Quincy)
J. H. JEFFERIES, Superintendent, Citrus Experiment Station (Lake Alfred)
GEO. D. RUEHLE, Ph.D., Assistant Plant Pathologist (Lake Alfred)
W. A. KUNTZ. A.M., Assistant Plant Pathologist (Lake Alfred)
B. R. FUDGE, Ph.D., Assistant Chemist (Lake Alfred)
W. L. THOMPSON, B.S., Assistant Entomologist (Lake Alfred)
R. V. ALLISON, Ph.D., Soils Specialist in charge Everglades Experiment Sta. (Belle Glade)
R. W. KIDDER, B.S., Foreman, Everglades Experiment Station (Belle Glade)
R. N. LOBDELL, M.S., Assistant Entomologist (Belle Glade)
F. D. STEVENS, B.S., Sugarcane Agronomist (.Belle Glade)
H. H. WEDGEWORTH, M.S., Associate Plant Pathologist (Belle Glade)
B. A. BOURNE, M.S., Associate Plant Physiologist (Belle Glade)
J. R. NELLER, Ph.D., Associate Biochemist (Belle Glade)
A. DAANE, Ph.D., Associate Agronomist (Belle Glade)
FRED YOUNT, Office Assistant (Belle Glade)
M. R. BEDSOLE, M.S.A., Assistant Chemist (Belle Glade)
A. N. BROOKS, Ph.D., Associate Plant Pathologist (Plant City)
R. E. NOLEN, M.S.A., Field Assistant in Plant Pathology (Plant City)
A. S. RHOADS, Ph.D., Associate Plant Pathologist (Cocoa)
C. M. TUCKER, Ph.D., Associate Plant Pathologist (Hastings)
H. S. WOLFE, Ph.D., Associate Horticulturist (Homestead)
L. R. TOY. B.S.A., Assistant Horticulturist (Homestead)
STACY O. HAWKINS, M.A., Field Assistant in Plant Pathology (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
FRED W. WALKER, Assistant Entomologist (Monticello)
D. A. SANDERS, D.V.M., Associate Veterinarian (West Palm Beach)
M. N. WALKER, Ph.D., Associate Plant Pathologist (Leesburg)
W. B. SHIPPY, Ph.D., Assistant Plant Pathologist (Leesburg)
C. C. GOFF, M.S., Assistant Entomologist (Leesburg)
J. W. WILSON, Ph.D., Assistant Entomologist (Pierson)
*In cooperation with U. S. Department of Agriculture.


















TABLE OF CONTENTS
PAGE

INTRODUCTION ................-.-......... ...............-.......... 5

ROOTSTOCKS ..............--------...... .-- .. .. .............. 5

Sour Orange ...... ...... ....-.........-.. .... .......... 6

Rough Lemon ........................... ......... ......... ......... .....- 6

Trifoliate Orange .............. .. ........... ... ......... ........... 8

Grapefruit ............. ........... .. ....................................... 9

Sweet Orange ....---................... -..................... 9

Miscellaneous ..... -....... .. .. .......... ... .. .............. 9

CITRUS SEEDS .--. ..... .. ...................... ......... .. -..-........ 10

THE SEEDBED ...................... ............. ............. .... ..... .. 13

BUDDING NURSERY STOCK ........................................ ......... 16

HANDLING BUDDED TREES ........................ ..................... 27

DIGGING NURSERY TREES -........................ ................... .. 28

PACKING NURSERY STOCK FOR SHIPMENT .......................... ............. 30

TOP-WORKING ---------..................... ............. ...................... 32

INARCHING .................................. .................... 41

ROOTING OF CUTTINGS ..----- ................ ..............-.................. 45

TRANSPLANTING LARGE CITRUS TREES ............................................ 47























































Fig. 2.-Field of budded trees. (Courtesy Glen St. Mary Nurseries.)










CITRUS PROPAGATION

By A. F. CAMP
The growing of citrus fruits in Florida began with the plant-
ing of seedling trees. As the industry developed the superiority
of the budded stock over the seedling tree became apparent and
led to the practical abandonment of the seedling method of prop-
agation. Fortunately the propagation of citrus by budding and
grafting is very easy and its practice has extended beyond the
nurseryman to the grove owner himself. Today many citrus
growers, and even many with only a few trees in their door-
yards, have acquired the skill necessary for the budding of nurs-
ery stock and the top-working of older trees.
The discussion of nursery practice given herein is based on
the best commercial practices of today together with knowledge
gained in experimental work. A number of procedures are
listed that are not in general commercial use but which have a
certain amount of interest to growers at large. In addition to
the discussion of propagation itself, some notes are included on
the choice of rootstocks, their adaptability and comparative
value. It should be remembered that there is still considerable
difference of opinion concerning the choice of rootstocks and
their relative merits. For this reason no attempt has been made
to give the last word on this interesting but complicated sub-
ject, but only to give what seems to be sound opinion based upon
our present knowledge.

ROOTSTOCKS
Probably no horticultural crop has as complicated a rootstock
problem as is found in the citrus industry in Florida. Several
factors combine to bring about this situation. The great vari-
ability of soils and the peculiar suitability of certain rootstocks
to certain soil conditions probably largely account for this situ-
ation, though the influence exerted by rootstocks on some vari-
eties is also a contributing factor.
There are at the present time two citrus rootstocks widely
used in this state, namely, sour orange and rough lemon. Sev-
eral others, including sweet orange, grapefruit, and Poncirus
trifoliata, are used to a lesser extent but in some cases have been
used quite extensively in the past. Recently the Cleopatra man-
darin has been developed as a rootstock and is now being tried








6 Florida Agricultural Experiment Station

extensively. A number of hybrids such as citranges, tangelos,
and citrangequats are also being used experimentally.
SOUR ORANGE
The sour orange (Citrus aurantium Linn.) was the first of
the citrus family introduced into Florida. After it was brought
here by the Spaniards it escaped from cultivation, and grew
in great thickets in the hammocks. It is well adapted to the
moist hammock soils and grows with such freedom as to lead
many people to believe that it is a native of the state. It also
grows well on moist flatwoods soils where the water table does
not come too close to the surface. It is extremely resistant to
root and crown diseases and particularly to foot rot, which is
one of the factors that has led to its great success on moist soils
where other species of citrus are severely attacked by this dis-
ease. The quality of fruit produced on the sour orange stock
is excellent and, in the opinion of many growers, is better than
that produced by any other stock. It has been demonstrated
to be a superior rootstock for Parson Brown oranges in the
northern portion of the citrus belt but is considered to be un-
satisfactory for satsumas, kumquats, limequats, and limes.
The sour orange is very resistant to cold and, to some extent,
conveys this characteristic to the scion, probably because it in-
duces a more intense dormancy during the winter months.
Nursery stock on sour orange has been observed to stand cold
weather better than stock in adjoining rows on rough lemon.
The chief difficulty with this stock lies in its inability to make
a tree at a satisfactory rate on the more sandy soils. This dif-
ficulty has led to the practical elimination of this rootstock on
such soils, since the young trees on this stock may require several
years to become sufficiently established to produce satisfactory
crops. On this account many groves have been planted with
trees on rough lemon rootstock on soils that were adapted to
sour orange, resulting in the production of a crop sooner than
would have been produced had sour orange rootstock been used.
It is also less satisfactory in the nursery than the rough lemon,
due to the fact that it does not make a tree as quickly or grow
quite so vigorously.
ROUGH LEMON
The rough lemon (Citrus limonia Osbeck) is a vigorous
grower, produces a tree very rapidly in the nursery, and brings








Bulletin 227, Citrus Propagation 7

grove trees to size and bearing quickly. It grows well on the
extremely light and sandy soils where sour orange will fail to
produce a tree in a reasonable time. It is not as resistant to foot
rot and similar diseases as sour orange, but is more resistant
than most of the other rootstocks. On sandy soils there is less
danger from foot rot and similar diseases than there is on the















S..
























Fig. 3.-Rough lemon fruits and foliage.







8 Florida Agricultural Experiment Station

heavier soils, and little difficulty is experienced with this trouble
in rough lemon roots on such soils.
There is a general opinion that it produces a quality of fruit
somewhat inferior to that produced by sour orange, the rind
being a little rougher and the texture a little coarser. There
is no question but that this attitude is accentuated considerably
by the fact that the rough lemon has been used extensively on
very sandy soils, which soils naturally tend to produce a'coarser
and drier fruit. There are several groves on rough- lemon stock
on heavier soils that have a reputation for the high quality of
fruit produced. In all cases these are groves of considerable
age, and observations would indicate that the quality of fruit
produced by trees budded on rough lemon stock improves as the
trees become older. The coarseness of fruit on young trees is
probably in part due to the very vigorous growth of the trees
when budded on this stock. The effect of the stock seems to be
less apparent in grapefruit budded on rough lemon and most ap-
parent in tangerines, Temple oranges, and early oranges. The
rough lemon seedlings are less resistant to cold than sour orange
seedlings and trees budded on rough lemon stock seem to flush
a little quicker with the advent of warm weather than do trees
budded on sour orange.
Generally speaking, the chief advantage possessed by the
rough lemon stock is the rapidity with which it will produce a
tree, particularly on light soil. It is probably not to be recom-
mended for the heavier soils upon which sour orange is a satis-
factory rootstock.
THE TRIFOLIATE ORANGE
The trifoliate orange (Poncirus trifoliata Raf.) is used chiefly
as the rootstock for satsuma oranges and kumquats. It is de-
ciduous and highly resistant to cold. The seedling trees of this
species are very thorny, and are relatively slow growers. The
addition of the evergreen top by budding, however, appears to
increase the vigor of the root system. In spite of this, however,
there is usually some stunting of the top. Outside of the north-
ern portion of the state where it is used extensively for satsumas
on account of the cold hazard it is very little used except as a
stock for kumquats, though some of the old groves have other
varieties budded on it. Generally speaking, it is probably much
better adapted to the northern section of Florida than to the
central and southern sections. Fruit from trees budded on this








Bulletin 227, Citrus Propagation 9

rootstock is usually of a very excellent quality and particularly
smooth. Such trees are usually quite precocious and bear while
younger than similar trees on other stocks.
GRAPEFRUIT
Grapefruit (Citrus paradisi Macf.) was used as a rootstock
to a considerable extent several years ago but is very little used
at present. Its use was probably the result of observations as
to the vigorous growth of seedling grapefruit trees. In many
cases on lighter soils it has proved unsatisfactory as a stock.
It is less cold-resistant than sour or sweet orange.
SWEET ORANGE
The early groves in this state were planted to seedling sweet
oranges (Citrus sinensis Osbeck) and these groves have been
among the most vigorous growers and producers. They are,
however, subject to foot rot and as the groves have become older
often there has been considerable difficulty in maintaining them
in a healthy condition. A number of groves of budded trees
have been planted in which this rootstock was used, and it is
found to produce a very excellent tree that grows vigorously
and produces a very fine quality of fruit. It is more cold resist-
ant than rough lemon or grapefruit and less resistant than sour
orange. It should never be used as a rootstock where the sour
orange will grow satisfactorily, as the danger from foot rot is
too great, and no advantages appear to be gained by using this
rootstock in preference to sour orange.
MISCELLANEOUS ROOTSTOCKS
A number of other rootstocks have been tried to some extent
but have not come into general use so far. The Cleopatra man-
darin has been widely recommended and tried during the last
few years and within a few years more it will be possible to gain
a fairly good idea from the existing plantings of its desirability.
It is a good grower, makes a good nursery tree, as to both union
and growth, and seems to be well adapted to the lighter soils.
It is hoped that it may prove to be better adapted to the pro-
duction of tangerines on light soils than is rough lemon.
Commercial lemon is frequently found as the rootstock of oc-
casional trees in groves presumably planted on rough lemon.
The seed in these cases probably were mixed accidentally with
the rough lemon seed, as it is not considered to be a desirable








10 Florida Agricultural Experiment Station

rootstock, due to its lack of disease resistance and the sort life
of trees budded on it.
At present a number of hybrids such as citranges and tange-
los are being tried as rootstocks, primarily in the hope of finding
a substitute for the trifoliate orange. A number of these hy-
brids exceed the trifoliate orange in vigor and make satisfactory
unions, but it will take some time to determine their suitability
in other respects.
CITRUS SEEDS

The extraction of sour orange seed is a considerable industry
in Florida, inasmuch as a great amount of seed is shipped to
Texas, Arizona, and California for use in the nurseries there.
The sour oranges are obtained largely from the wild thickets in
the hammocks and from scattered trees in commercial plantings
and remnants of commercial plantings.
The seeds are commonly obtained by cutting the fruits in
half and removing the seeds by hand or by using some sort of
power reamer similar to a juice extractor. Separation of the
seeds from the pulp is usually made in water, where the seeds
can be quite easily separated from other materials. The seed
are washed clean of the gelatinous matter that surrounds them
and are dried in the shade on cloth trays. After the seed have
been dried, they germinate much more, irregularly and very
much more slowly than fresh seed. Drying is necessary, how-
ever, in order to preserve the viability of the seed and it is only
in the case of local nurseries that fresh seed can be planted. Seed
should be planted as soon as possible after removal from the fruit
but where they have to be held for several months they can be
mixed with powdered charcoal. This latter precaution is not
necessary in the case of shipments of seed for use during the
current season unless the period between the extraction of the
seed and planting is unusually long.
Fig. 4 shows the seeds of some of the commonest species of
citrus. Most of the seeds have a white interior but, in the case
of the Mandarin group, the interior of the seed is tinted with
green. Each of the species has a fairly distinctive seed. A
pound of sour orange seed contains about 3,500 seeds and other
species of citrus more or less according to the size of the seeds.
Citrus seeds may produce more than one seedling per seed
through the development of extra embryos in the seed. This
condition is called polyembryony. From each seed there can









Bulletin 227, Citrus Propagation 11




"" SWET ORANGE-



O- 0UR ORANGE



GRAPLERUI.*



ROUGH LEJON


P. 'TIFOLIATA


'LEOPA'TRA TANGERIRD;


SI'-'RAIGE ,OR'_OR'


CXTAWGE RUSK


ST-iQRANCEQUAT


Fig. 4.-Seeds of various species of Citrus and Poncirus.

be produced only one seedling that is a result of pollination so
that the remaining seedlings can be considered in the same status
as cuttings or buds in that they will reproduce the parent tree.
This factor has probably played a considerable role in the de-
velopment of seedling groves in this state and would help to ac-
count for the uniform quality of fruit obtained in such groves.
Unfortunately, it is impossible to separate the seedlings that are
a result of pollination from the asexual seedlings in the seedbed,
unless the seeds are those of some of the hybrid citrus in which
there is a difference in leaf-shape in the two instances.












*41









-w-~ low Ar*






AA k
.~3-














WITS . .
w agar.bT+
-',.


Fig 5-N~aey eebe an vryyong eeligs.(Cures Gln t.May Nrsris.








Bulletin 227, Citrus Propagation 13

THE SEEDBED

The site of the seedbed should be on good soil that is well
drained and capable of producing first-class growth of the seed-
lings. It should be provided with irrigation, preferably of the
overhead type, and some nurserymen prefer to cover it with a
lath shade, though the latter is not necessary and the majority
of seedbeds are planted in the open. The lath shade has a ten-
dency to increase the amount of seedling diseases and makes
the seedbed difficult to handle from this standpoint.
A small amount of fertilizer is used in making up the seedbed.
This fertilizer should have a high percentage of nitrogen, prefer-
ably from organic materials. The fertilizer should be added
several weeks before the seed are planted and should be worked
thoroughly into the soil.
Where only a small seedbed is desired, the seeds are planted
in rows wide enough for hand cultivation, but where a large
number of seedlings is being raised the rows are laid out wide
enough for horse cultivation. The seeds are planted thickly in
the row and are covered with two to three inches of soil. Sour
orange, sweet orange, grapefruit, and rough lemon seeds are
planted after the danger of frost is over, as very young seedlings
are killed when frozen to the ground. Poncirus trifoliata seed-
lings are not completely killed by being frozen off, but sprout
up from below ground; consequently the seed can be planted
whenever they are ready.
After the seedlings have come up it is necessary to cultivate
sufficiently to keep down the weeds and to water enough to keep
the plants growing well but not so much as to cause damping-
off fungi to attack the seedlings. During the growing season
two or three applications of fertilizer having a high nitrogen
content should be made. Before the seedlings are removed from
the seedbed, cultivation and fertilization should be stopped to
allow the seedlings to harden up.
The number of days required for germination of citrus seeds
will depend upon the soil temperature and moisture and the
condition of the seed when planted. Experiments with fresh
seed have shown an optimum soil temperature for germination
around 90F. Near the optimum temperature fresh seeds will
sometimes germinate in two weeks but when the soil tempera-
ture is below 900F. a longer time is required for germination.
In this connection attention should be called to the fact that













-



















,1
.erne






























Fig. 6.-Nursery seedbed and seedlings almost ready to transplant to nursery row. (Courtesy Glen St. Mary Nurseries.)








Bulletin 227, Citrus Propagation 15





























Fig. 7.-Citrus nursery seedbed under shade. (Courtesy Glen St. Mary Nurseries.)
during the winter and spring the soil temperature is much lower
than that indicated as the optimum and the time required for
germination will be correspondingly longer. The seedlings,
however, are usually up in three weeks to a month in good
weather.
About one year from the September following the planting
of the seed, making about 18 months in the seedbed, the seed-
lings are transplanted to the nursery row for further growth and
budding. The seedlings can be removed by cutting the taproot
8 to 12 inches below the surface with a nursery spade, after
which the seedlings can be easily lifted. The seedbed should be
well watered just before the seedlings are removed. Many more
seedlings should be grown than will be required and all weak
seedlings should be discarded at this time. About twice as many
seedlings should be available at this time as it is intended to
plant, and the weakest 50% should be discarded.








16 Florida Agricultural Experiment Station

In planting seedbed stock in the nursery row the soil is usually
opened with a spade. Care should be practiced to prevent the
doubling up of roots and particularly the taproot when planting
this way. If necessary, prune back the roots before attempt-
ing to plant. Watering at the time of planting is highly desir-
able if the soil is even slightly dry.
The nursery rows are usually 3 to 4 feet apart and the trees
are planted about 12 inches apart in the row, the distances vary-
ing in different nurseries. Generally speaking, the rows should
be wide enough to permit of horse cultivation and the trees
should be far enough apart in the row to permit the free use
of a hoe between the trees. The trees are grown in the nursery
row for about one year before being budded. Budding is usually
done in the fall-September, October, or November.

BUDDING NURSERY STOCK

The standard method of propagating citrus nursery stock is
by budding. While the seedlings can be readily grafted by sev-
eral different methods, these are never used in practice because
budding is so much simpler, quicker, and more economical of
budwood than is any method of grafting. Citrus can be budded
whenever the bark will "slip", i. e., whenever it will separate
readily from the wood. This condition exists during most of
the spring, summer, and fall, but in nursery practice it is cus-
tomary to do practically all of the budding during the fall. Bud-
ding at this time is called dormant budding because the buds do
not start into growth until the following spring. When stock
is large enough to bud in the fall a delay until spring for bud-
ding will result in three to four weeks loss of growing time in
the budded tree.
Budding in citrus is accomplished by the insertion of a shield-
shaped bud into a "T" slot cut in the bark of the stock. The buds
are cut from wood about the size of a pencil or a little smaller,
which has outgrown its angular condition. In Fig. 9 are shown
two types of budwood, namely, the angled wood which is or-
dinarily considered unsuitable except for certain special types
of budding, and the round wood which is desirable. The bud-
wood should be selected from normal bearing trees of the variety
desired. The tree from which the budwood is selected should
bear satisfactory crops of fruit true to the varietal type. In
nursery practice buds are commonly taken from blocks of


































1-r.



























Fig. 8.-Citrus seedlingB in the nursery row ready to bud. -K








18 Florida Agricultural Experiment Station






























































Fig. 9.-Citrus budwood. The wood on the left is too angular; that on the right
is of better quality.







Bulletin 227, Citrus Propagation 19

nursery stock of the desired variety. Where the block records
are accurate and where the practice of obtaining new budding
material from bearing trees frequently is followed this practice
is not as bad as it would at first appear. A certain number of
off-type trees will appear but they will also appear in blocks
budded from bearing trees.
For convenience in budding, the budwood is usually cut into
pieces from 8 to 12 inches long, each piece carrying several buds.
The budwood should be of good normal growth, well rounded out
and hardened up sufficiently to handle well. As soon as the
budwood is cut from the tree it should be defoliated by cutting
the leaves off with a knife or pruning shears, leaving a piece
of the petiole attached to the wood. Where it is necessary to
hold the budwood until a later time for budding, the sticks can
be stored in cypress sawdust or in damp sphagnum moss in a
cool place. If stored in sawdust it will be necessary to repack
occasionally.
A knife having a blade of the very finest steel and with a
rounded end is necessary. The blade should be comparable to
razor steel and carefully ground and honed to a smooth, thin
edge. Many very careful workers prefer to finish sharpening
the knife with a strop similar to a razor strop. Unless the knife
is of very fine quality and very carefully sharpened, it is im-
possible to make smooth cuts and to open up the bark without
leaving loose shreds and other material to interfere with the
insertion of the bud. Standard budding knives are commonly
made with a bone handle with a flat, wedged end for opening up
the bark where necessary, but the handle is never used by
specialists in budding.
Budding tape for wrapping the buds is made from thin
bleached muslin put up in rolls 6 to 8 inches long and 1 to 2
inches in diameter. These are impregnated with a grafting wax
that will not harden. There are a large number of formulae
for the wax preparation but the one below, taken from Hume's
"Cultivation of Citrus Fruits", is considered very satisfactory
for use under Florida conditions: Resin, 1 pound; beeswax, 4
pounds; raw pine gum, 3 tablespoonfuls.
The grafting wax is heated over the fire until melted and the
rolls are immersed in it until thoroughly impregnated. The wax
must not be too hot during this procedure. If the rolls of cloth
are too large the wax will not penetrate readily and the diameter,
therefore, should be kept below 2 inches. To secure better pene-









20 Florida Agricultural Experiment Station






AV*-1


























































Fig. 10.-Initial steps in the budding process. A, making the vertical cut; the cutting
stroke is usually downward but may be made upward if desired. B, making the
cross cut at the bottom of the vertical slit; note tilt of knife blade. C, cutting the
bud shield from the bud stock. (Cf. Fig. 11.)
-4 -,




















1 _







Bulletin 227, Citrus Propagation 21

tration, many workers tear the muslin in squares about 36 inches
in dimension. These are folded up into smaller squares for ease
in handling prior to impregnation. These are immersed in the
melted wax and unfolded with sticks to make sure of even im-
pregnation. The sheets are then stretched on bamboo poles to
drain and dry. After the cloth is cool it can be torn off in strips
the proper width for use, as needed.
Any number of variations of this procedure have been sug-
gested or adopted by various budders, but it all amounts to a
matter of personal preference. A good grade of muslin, put
up in proper rolls and thoroughly impregnated with wax, can
be torn to any width desired, whereas tapes and other materials
made a definite width beforehand lack the flexibility in handling
of the above method of preparation. The cloth should be a good
grade of muslin, capable of withstanding considerable pull, and
the wax should be one that will retain a certain softness, and
not harden on exposure.
Budding in the nursery is usually carried out on seedling trees
from the size of a pencil up to an inch in diameter, but trees
1/2" to 3/4" caliper are most desirable; trees that are too small
should be discarded. The trunk of the seedling is pruned clean
of thorns and limbs, ahead of the budder, so as to save time.
With the knife grasped in the right hand with the edge of the
blade downward, a downward cut is made about an inch and
a half long (Fig. 10A). This is a vertical cut through the bark
but no farther into the wood than is necessary to be certain
that the bark has been completely cut. If desired, this cut can
be made upward instead of downward. The knife is now turned
horizontally and a cross-cut about half an inch long is made
across the bottom of the vertical cut, thus making an inverted
"T" (Fig. 10B). In making this cut, the back of the knife blade
is tilted slightly downward so that the cut is a little upward as
well as across the stock. At the finish of the cut, the knife blade
is tilted slightly upward and given a slight twist to open the bark
at the junction of the horizontal and vertical cuts.
The bud is now cut from a stick of budwood held as in Fig.
10C, with the basal end away from the operator. The cut is
toward the operator and is made as nearly as possible parallel
with the axis of the budwood, and with a slight rotating motion.
The knife is held with the blade almost parallel to the axis of
the budwood and the thumb of the knife hand used to steady the
budwood in making the cut. This will give a shield-shaped piece






22 Florida Agricultural Experiment Station





























F












Fig. 11.-The final steps in the budding process. D, inserting bud shield in stock: bul
is being held on knife blade. E, Bud shield in place in stock; note that it is en-
tirely within the flaps of bark. F, a closer view of the shield bud in place. G,
taping the bud; taping is started at the bottom in inverted "T" budding and at the
top in erect "T" budding. H, taping finished; end of tape is brought back on tape
wraps so that it will stick. (Cf. Fig. 10.)







Bulletin 227, Citrus Propagation 23

of bark and wood about 3/4 to 1 inch long with a smooth and
flat cut surface. The bud should not be scooped out. As the
cut is finished, the thumb retains the bud on the blade of the
budding knife and at the lower end of the shield. Using this
method of holding the bud, with thumb and knife blade, the
upper end of the bud is inserted in the stock as in Fig. 11D.
The bud shield when inserted is entirely beneath the bark and
should be pushed far up into the vertical cut (Figs. 11E and
11F).
Taping is started below the bud and the tape wrapped firmly
but not too tightly around the trunk of the tree up to above the
top of the vertical cut (Figs. 11G and 11H). As the wrapping
is finished the end of the tape should be brought back onto the
cloth, as this will make it adhere more firmly. For wrapping
buds it is usually found desirable to tear the cloth in about
three-quarter inch strips, but the size of the stock and other
conditions will influence this considerably. It is important that
the wrapping be sufficiently tight to prevent the entrance of
water into the wound and to hold the bud and the stock closely
together so that a callous growth will start and a union be
formed. After ten days to two weeks, the buds can be examined
and, if still green and showing callous formation indicating that
they have "taken", the tape can be removed.
The type of budding here illustrated is described as inverted
"T" incision. In California the erect "T" is used, that is, the
cross cut is made at the top of the vertical cut instead of at the
bottom as in the Florida method. It is claimed that the inverted
"T" method keeps out moisture better and allows, the bud to
"drain", though the real reason is probably to be found in cus-
tom, as either method will work satisfactorily. When the erect
"T" is used, the wrapping is started at the top, i. e., at the point
of intersection of the two cuts.
The distance of the bud from the ground must be determined
by the conditions under which the trees are to be used. Sweet
orange scions on sour orange stocks can be affected with foot rot
if water or mud stands above the bud union just as readily as
seedling sweet oranges can be attacked. Where the budded trees
are to be planted in moist locations the buds should be high above
the ground but when they are to be planted on drier lands the
bud may be within two or three inches of the ground to facilitate
protection against cold by banking.
When the bud starts to grow the seedling top is cut off smooth-








24 Florida Agricultural Experiment Station



























la




7
r%











r i -










s- A"' ~~PC
C~ i
T. '












Fig. 12.-"Lopped" seedling, showing bud that hs just "take".
Fi. 2-"ope" edln, hwig u ta hs ut tke"







Bulletin 227, Citrus Propagation 25

ly just above the bud, thus throwing the growth to the bud.
When the seedling is very large at the time of budding the top
is sometimes "lopped" when the bud starts, by cutting it par-
tially through. This helps to start the bud and at the same time
leaves some top to support the roots (Fig. 12). The cut should
be on the same side as the bud. After the bud shoot has grown
6 to 12 inches high, the old seedling top is entirely removed with
a pair of sharp clippers, making the cut close to the bud. Lop-
ping is seldom practiced in nurseries where normal seedlings
are being budded but is sometimes used where seedlings that
have remained too long in the nursery row are being worked.
As soon as the buds start to grow it will be necessary to put
a stake at each tree and to tie the shoot to the stake from time
to time with raffia or coarse string. The stakes may be of good
heart pine or cypress 3/4 to 1 inch square and 4 feet long, or they
may be of heavy galvanized wire. Many nurserymen using
wood stakes make it a practice to place the stake on the north
side of the scion to protect it from the north winds. The best
practice is to place the stake in the angle formed by the scion
and the stock. The stake is close to the scion, making training
easy, and the stake is kept out of the way of the cultivator. If
the stake is placed on the opposite side of the stock from the
bud, the scion will be bent in training. When the shoot is from
2 to 3 feet high, it is usually topped, thus starting the forma-
tion of a framework for the tree.
A large number of other methods of budding can be used
but are not ordinarily necessary in citrus. Some of these, such
as ring or patch budding, are particularly adapted to some
trees that are budded with considerable difficulty and which
will not respond readily to shield budding, but these methods
are not used in citrus. Some variations of the shield bud are
used in working stocks that are too hard or in utilizing budwood
that is too angled to permit of the cutting of satisfactory shields
of the usual type. Two of these methods are illustrated in Fig.
14. These two pictures-represent types of what is called side
budding and either of these methods will work sometimes on
stocks that are too hard for the usual method of shield budding.
Note in particular the shape of the bud shield with the bud eye
on one side of the shield instead of in the center. This type of
shield can be readily cut from very angular budwood. Except
for the shape of the bud shield and the method of making the
incision in the stock the procedure to be followed is the same as







26 Florida Agricultural Experiment Station

that followed in "T" or inverted "T" budding. Occasionally
with either of these types of side budding a small sprig of bud-
wood with 3 to 5 buds on it is substituted for a shield bud. This
type of procedure is frequently used in experimental work where
the wood available is too small for shields to be cut from it.



























Fig. 13.-Nursery trees staked and tied-wooden stakes.

In budding large blocks of nursery stock the pruner usually
cleans off the leaves, thorns, and limbs where the bud is to be
inserted, ahead of the budder. The budder has a tier working
with him who wraps the buds. Under such conditions a good
budder may put in as high as 1,500 or more buds in a day. In
nursery practice the tier always uses budding tape but where
small amounts of work are being done other methods of holding
the bud in place are sometimes used. The bud may be tied in
with raffia or string and the whole wound painted over with
melted paraffin and carnauba wax.







Bulletin 227, Citrus Propagation 27
























Fig. 14.-Side budding with curved incision on left and angled incision on right. Either
shield can be cut from angular budwood to better advantage than can the ordinary
shield.

In dormant budding it is sometimes necessary to protect the
bud from cold. This can be done by banking the trees with soil
after the wraps are removed. This is easily done by plowing a
furrow to each side of the row. This soil is removed after the
danger of frost is passed.

HANDLING BUDDED TREES

CARE DURING FIRST SEASON: CULTIVATION, FERTILIZING,
TIEING, TOPPING
Cultivation and fertilization of budded trees should be such
as to promote a thrifty growth. The nursery rows are culti-
vated so as to keep down weeds and grass. A horse-drawn
cultivator is used for cultivating the middles; the rows them-
selves are hoed out by hand. In the fall the cultivation is re-
duced so as to harden the trees up before frost. The amount and
type of fertilizer will depend greatly on the type of soil. A fer-
tilizer analyzing 4 to 5 percent nitrogen, 6 to 8 percent phos-
phoric acid, and 4 to 6 percent potash is suitable. Three appli-
cations of fertilizer per season should be made, the first just







28 Florida Agricultural Experiment Station

prior to the start of growth in the spring, the second in June
and the third in the latter part of August. The amounts will
vary from 500 to 1,500 pounds per acre per application, depend-
ing on the fertility of the soil. The applications may be made
broadcast and worked in with the cultivator but usually the first
is applied by "barring off" the rows (plowing a furrow away
from each side of the row with a small turning plow) and placing
the fertilizer in the furrow and covering it by plowing the soil
back into the furrow. Too much fertilization and cultivation
should be avoided as an excess tends to produce too rank and
soft a type of growth.
As pointed out previously, the scion must be tied to the stake
from time to time so that it will have a straight trunk. The
height at which it is to be topped to form the framework of the
tree will depend on the type of tree desired. Of late years the
tendency has been to the growing of low-headed trees and the
scions are usually topped at about 18 to 24 inches. In addition
to the work of training the scion the sprouts must be removed
from both stock and scion occasionally. When the tree has
developed a strong trunk the stake is removed so that it will not
be in the way in digging.
The budded trees are allowed to grow at least one year in the
nursery row before being planted in the grove. The grading
of nursery stock is usually done by caliper (i. e., the diameter of
the trunk two inches above the union is measured), and by age
of the trees from budding. Uirees for planting should preferably
caliper 5/8" or over after one year from budding. Two-year trees
should be larger. Trees that failed to make a satisfactory growth
the first year are commonly left for another year's growth. Many
nurserymen prefer to cut back such trees to the bud and make
an entirely new top the second year. Trees that are badly
stunted should be discarded.

DIGGING NURSERY TREES
Nursery trees are dug as ordered, and the selection of the
trees is based on the size desired to fill the order. In digging
nursery trees the foreman of the crew usually selects the trees
to be dug and prunes them back with long-handled shears to
a framework or a stub, according to instructions (Figs. 15 and
16C). The remaining leaves and twigs are cut off with a knife
or pruning shears and the lateral roots are cut off in a circle




















4Q

~ e ^ . . * ^ -- - -- ^ -- --------








N)
Fig. 1._Digging nursery trees. A, tree ready for digging. B, pruning back with loping shears preliminary to digging. (Cf. Figs. 16 and 17.) Q0







30 Florida Agricultural Experiment Station

around the tree by means of long-bladed nursery spades (Fig.
16D). A hole is then dug on one side of the tree so that the
spade can be driven under the tree at the proper depth to cut
the taproot (Fig. 17E). The tree is then "lifted" with the help
of the spade, and the roots are immediately covered to prevent
drying out (Figs. 17F and 17G). The trees may be loosened as
in Fig. 17E but have the roots still left in the soil until the truck
or wagon comes and then the trees can be quickly lifted and
placed under cover. IT IS VERY IMPORTANT THAT THE
ROOTS SHOULD NOT BE ALLOWED TO DRY OUT BE-
FORE PLANTING. This applies not only to the process of
digging but also to the hauling and handling of trees, particu-
larly when they are to be removed by truck or wagon directly
to the field where they are to be planted. The practice of
handling citrus nursery stock "bare rooted" is universal in
Florida. In California, however, the trees are "balled", i. e.,
dug with a ball of earth containing the roots and which is wrap-
ped with burlap. The difficulties attached to handling trees in
this way in the light Florida soils are obvious. Moreover, the
trees grow so readily when transplanted under Florida condi-
tions that this procedure is found to be unnecessary.

PACKING NURSERY STOCK FOR SHIPMENT

Nursery trees are packed in various ways for shipment by
freight, express, or mail. All of the methods, however, make use
of some sort of protection for the roots-such as moist sphag-
num moss or "shingletow" (sawdust from cypress shingle mills).
In Fig. 18A is shown a standard crate for the shipment of nurs-
ery trees. As shown in the figure, the crate is lying on its side
and it is placed in this position when the trees are being packed
in it. The 2" x 2" framing piece for the open side is removed
and the box lined with paper before the packing starts. A layer
of moss or shingletow is placed for the roots and excelsior is
used at the top of the box to protect the trunks against rubbing
and to keep the packing for the roots in place. The trees are
packed in tightly with alternate layers of packing material, and
finally covered with a layer of packing material and paper. The
framing piece is then nailed back in place and a piece of 1" x 3"
placed across the center of the open side and nailed to the sides
to help hold the trees in place. The side boards are then nailed
on and the box stood on end ready for receiving the burlap cover-
































Wk.-














Fig. 16.-Digging nursery trees. C, tree pruned back for digging. D, digging the tree. The man on the right is cutting the lateral roots with a
spade; the one on the left is cleaning off the leaves and twigs remaining after pruning. (Cf. Figs. 15 and 17.)







32 Florida Agricultural Experiment Station

ing to protect the tops of the trees (Fig. 18B). The tops of the
trees are now covered with burlap which is attached to the crate
by means of lath strips nailed to the top frame, and securely
sewed (Fig. 18C). The crates shown are usually 30" high but
the side dimensions may vary from 12" x 12" to much larger.
Smaller quantities of trees may be shipped in bales and three
types of bales are shown in Fig. 18D. These vary from a paper
covered bale for mail order shipments to coverings of corrugated
paper and wrapping paper or burlap for express shipments. In
all cases the trees are packed in the proper packing material in
much the same manner as described for the crates. In all cases
the packing must be done carefully to avoid drying out of the
trees while in transit. For local shipments shingletow is com-
monly used around the roots but trees to be shipped to distant
points are usually packed in sphagnum moss.

TOP-WORKING

It is often desirable or necessary to top-work grove trees be-
cause of cold damage or because it is desired to substitute a new
variety for an undesirable one. Top-working large trees, while
tedious, takes advantage of the root system already present
and brings a tree into production more quickly than can be done
by planting young trees. Frequently it is desired to work over
trees in yards so as to give additional varieties for home use and
this is sometimes done by budding or grafting more than one
variety on the same tree. Several methods may be used for top-
working trees but only three are ordinarily used. These are:
budding, bark grafting, and cleft grafting.
The budding of shoots or sprouts is commonly resorted to
when trees are frozen to the ground and sometimes when trees
are being top-worked for other reasons. Where large numbers
of trees must be worked, it is easier to let shoots grow from the
cut limbs and bud them in the usual manner than it is to cleft
or bark graft a large number of limbs. The use of this type of
budding usually results in a delay of a year in producing a top
but is often the easiest way to handle large numbers of trees.
Where small trees (under 5 or 6 years of age) are found to be
of an undesirable variety they are usually cut off at the ground
level and sprouts from the rootstock are budded, or bark graft-
ing is used on the stump (Fig. 19).
Citrus trees when cut back to the ground sprout readily and














































Fig. 17.-Digging nursery trees. E, cutting taproot of tree with a spade; note depth to which spade is thrust into soil. F, "lifting" a nursery
tree; the worker's right hand holds the handle of the spade and with his hand and knee he is using the spade to help pry the tree up. G, the
nursery tree lifted free of the soil; note the fine root system. (Cf. Figs. 15 and 16.)

C4








34 Florida Agricultural Experiment Station

the sprouts grow rapidly with the exception of trees budded on
Poncirus trifoliata, which commonly fail to send up sprouts
when the top is removed. The number of sprouts should be kept
within reason, two or three for small limbs or trunks and pro-
portionately more for larger limbs or trunks. After they have
grown for a season they can be budded as described for nursery
stock. Where stump sprouts are to be budded a clean cut should
be made across the stump before the sprouts have a chance to
appear, as an attempt to even up old stumps or to remove dead
trees from amongst a number of sprouts is very difficult and
usually results in damage to the sprouts. If small trees are to
be treated in this way the tops can be lopped with a saw and
staked to the ground until the sprouts are budded. This method
has the advantage of furnishing a top to feed the root system
throughout the period necessary to produce a new top.
When working large limbs budding can also be used directly
on the limb if the workman is careful. In case the bark is reas-
onably soft and pliable some form of shield budding can be used
as previously described. Often the curved or angled incision
will be found superior to the "T" for this purpose. When the
bark is thick and will not "work" without splitting it can be
shaved and scraped to remove the outer hard layers and the inner
bark left for "working". If the buds are slow to "take" a par-
tial girdling of the limb above the bud or cutting back the top
of the branch will help.
Bark grafting is commonly used in working over stumps and
large limbs. It is simple, quick, and efficient. Its chief difficulty
lies in a mechanical weakness of the union that may continue for
some years. Like cleft grafting it gains a year of time on sprout
budding. For this type of grafting the stump or limb is cut
off at a right angle to the axis and the cut surface smoothed up
with a knife. Small scions up to six or eight inches long are
given a long slanting cut at the butt end and the sharp end
shoved under the bark with the cut surface facing the wood of
the stump (Fig. 20A). Wherever possible a concave place in
the contour of the stump should be used and if the bark is at
all pliable the scion can usually be shoved under the bark easily.
Where the bark is hard it may be necessary to make a short
downward cut with the knife and to open the bark a little at
the top before the scion can be inserted. A brad or small nail
may be used to help hold the scion in place. The stump is taped









Bulletin 227, Citrus Propagation 35




































































Fig. 18.-Shipping nursery stock. A, shipping crate, with end and one side (up) left open
to facilitate packing. B, Nursery stock crated and ready for burlap covering over the
tops. C, crated for shipment. D, four types of packages for shipping citrus nursery
stock. In the background the crate, on the left the paper-wrapped parcel for mail
shipment, center corrugated paper and paper, and right burlap covering for express
shipment.








36 Florida Agricultural Experiment Station















-! I



























Fig. 19.-Budded sprouts from the rootstock of a tree which was cut off at the ground.
This is one method of top-working.

around so as to hold the scions firmly in place and the cut sur-
face of the stump covered with paraffin or grafting wax* to

*Hume gives the following formulae for grafting waxes:
"(1) Resin, 6 pounds; beeswax, 2 pounds; linseed oil, 1 pint.
"(2) Resin, 4 pounds; beeswax, 2 pounds; tallow, 1 pound.
"The directions for preparing them are briefly as follows:








Bulletin 227, Citrus Propagation 37














""^ -'-i s. x .. '-^9 ."

















Fig 20.-Bark grafting. A, scions in place; a brad driven through the scion into the
trunk will help to hold the scion in place. B,. bark graft taped and ready to be waxed.

exclude the air (Fig. 20B). Several scions can be inserted, the
number depending upon the size of the stump. This method is
very convenient for working seedlings that have grown too long

"Break the resin into small pieces, cut up the beeswax, and place the
two together in a suitable iron pot. Pour the linseed oil over them, or, in
case recipe No. 2 is used, place the tallow on top. Set the pot over a slow
fire and allow the materials to melt. Afterward remove from the fire,
pour into cold water, grease the hands, and pull until it is light colored.
"If a liquid wax is desired, take 1 pound of resin, 2 ounces of tallow,
melt them together and mix thoroughly. Remove from the fire, cool slight-
ly, and add slowly 6 ounces alcohol and 1 ounce spirits turpentine. Keep
tightly corked in a wide-mouthed bottle. Apply with a brush."
Paraffin is very convenient to use instead of grafting wax and a port-
able lamp or lantern is manufactured which will keep a small pot of it in
the melted condition. The ordinary paraffin is frequently of too low
a melting point for satisfactory use in the open in Florida. This difficulty
can be corrected by adding 3% to 5% of carnauba wax to the paraffin. For
application the paraffin should be just hot enough to keep it melted, if too
hot it will injure the tissues of the plant.








38 Florida Agricultural Experiment Station

in the nursery and trees frozen to the ground. Under such con-
ditions the new growth can be staked and saved from too much
mechanical stress until a strong union is established.
Cleft grafting is a standard method of top-working and the
results are excellent, but the work is slow and tedious. It has
one special advantage in that the work can be done when the
bark will not "slip". For this work a grafting iron is needed
with which to split the stub of the limb or trunk (Figs. 21A and
21B). The cut is made squarely across and smoothed up as for
bark grafting. It is then split longitudinally with the iron and
a mallet. Orange wood does not always split smoothly and in
careful work it is desirable to make a cut through the bark and
into the wood on each side of the stub with a knife, giving a
smooth cut where the scion is to be inserted. This can be easily
done by placing the edge of the knife as in Fig. 21A and hitting
it a sharp blow with a mallet. Care must be taken to get the
cuts on the opposite sides of stub and accurately in line if two
scions are to be used. The grafting knife is then placed across
the stub, lined up with the two initial cuts and the splitting is
accomplished with the aid of a mallet (Fig. 21B). The split is
then wedged open by the use of the wedged end of the mallet or
a wooden wedge cut for the purpose. The scions should be six
or eight inches long and cut with a budding knife to a long wedge
at the butt end (Fig. 21C). These wedges should be slightly
thicker on one side than on the other. The scions are inserted
in the split and the cambium of the scion and the cambium of
the stock carefully placed together with the wood of the scion
against the wood of the stock. The thick edge of the wedge
should be the one lined up with the cambium as this will bring
the pressure at the point where it is needed. After the scions
are in place the wedge is removed, the stub taped and the cut
end covered with grafting wax or paraffin (Fig. 21D).
This type of grafting gives the union a great deal of mechani-
cal strength from the start and is sometimes used in working
over large trees on this account. Frequently the pressure exert-
ed on the scion will be so great in large stubs as to tend to pinch
the scion off. Where this is likely to happen a wooden wedge
should be left in the split to help ease the pressure on the scion.
Success in any of the above methods lies in the careful carry-
ing out of certain basic principles. Once the cutting is started,
finish up as rapidly as possible so that the cut surfaces will not
dry out. Be sure that the cambium of the scion and the cambium








Bulletin 227, Citrus Propagation 39

of the stock are held firmly in contact. Seal the wound thorough-
ly with grafting wax or paraffin. Do the work when the tree
is in active growth; even cleft grafting is more successful under
these conditions. If these things are done carefully the work
will give good results.
























1P

"-dp Of



















Fig. 21.-Cleft grafting. A, splitting the stub down the sides; this gives a smooth cut
for insertion of scion. B, splitting the stub. C, inserting scions. D, scions inserted
and stub taped and ready for waxing.








40 Florida Agricultural Experiment Station

The top-working of large trees presents some perplexing
problems. When it is desired to top-work small trees it is ob-
viously easiest to cut the tree to the ground and start over in
making a top. The cutting of large trees in this way, however,
results in the loss of the large framework and seriously upsets
the functioning of the roots. Where it is not necessary to do
the work all at once part of the limbs can be cut back and bud-
ded or grafted and the new wood allowed to start before the
remainder of the limbs are cut back for working. In this way
there is a top at all times to support the root system and shade
the trunks and limbs. This eliminates the danger of sunburn-
ing. When this is done it is frequently difficult to remove the
old limbs after the scions are well started without breaking them
off and this may require considerable care. It is obviously the
surest method of getting good results, however. Where it is
necessary to do the work all at once the trunk and limbs should



.. ,41












'I02









Fig. 22.-Trees saved by inarching. A, Temple orange tree on rough lemon root inarched
with Cleopatra mandarin; the inarch at left was close to the ground and of a fine
type; fruit borne on limbs above the inarch showed favorable influence of new root
system. B, old seedling orange tree attacked by foot rot successfully inarched with
sour orange.







Bulletin 227, Citrus Propagation 41

be whitewashed to prevent sunburning, which is otherwise very
likely to occur.
The point at which the limbs are to be cut is difficult to de-
termine. The farther the cuts are made from the trunk the
quicker the tree will recover but the more limbs there will be
to work and to keep free from sprouts later. This point will
have to be determined by the worker.

INARCHING

Difficulties sometimes develop that make it necessary to give
a tree a new root system. This need occasionally is the result of
an attempt to grow a variety on an uncongenial rootstock but
more often the result of foot rot or some other disease that
girdles or partially girdles the trunk. It is possible under such
circumstances to inarch seedlings or sprouts into the trunk and
thus save the tree. This work is sometimes difficult and is not
usually attempted unless the tree to be saved is valuable. Where
the root system is sound and of a desirable type and sprouts can
be induced to grow, these are to be preferred. Where this is
not possible seedlings can be planted around the tree and after
they are established they may be inarched into the trunk.
Where the trouble is not caused by a disease, as in the case of
an undesirable rootstock, the inarching should be done as close
to the ground as possible (Fig. 22A), but where it is a matter













I. -




Fig. 23.-Inarching. A, seedling inserted in inverted "T" slot and bradded.
B, inarch tied and paraffined.







42 Florida Agricultural Experiment Station

of saving a tree attacked by foot rot the work should be done
well above the lesion (Fig. 22B). Foot rot is commonest on old
seedling trees and under such conditions sour orange seedlings
are to be preferred for inarching and sprouts from the sweet
orange root should not be used as they are susceptible to the

























4e
*11


A-




















Fig. 24.-Inarched seedling put in at an angle to the axis of trunk, a procedure
that is not recommended.








Bulletin 227, Citrus Propagation 43

disease. If the tree to be inarched is headed low, the seedlings
may be worked into the limbs instead of the trunk.
Inarching is accomplished by making an inverted "T" incision
in the trunk of the tree and opening the flaps of bark slightly
with the wedge on the end of the budding knife. The sprout or
seedling is then cut with a long slanting cut at such a height
that when it is inserted into the "T" slot the cut surface will be
entirely within the bark and in contact with the wood of the
trunk. The insertion is made by "springing" the stem of the





























3







Fig. 25.-Plants produced from rough lemon cutting (left) and seedling rough lemon
of same age (one year).








44 Florida Agricultural Experiment Station



























































Fig. 2.--Plant produced by rooting a leaf of rough lemon.







Bulletin 227, Citrus Propagation 45

seedling or sprout sufficiently that the cut tip of the seedling
can be inserted under the flaps of bark and the seedling is then
shoved upward until it is in the proper position (Fig. 23A). As
the stock tends to spring away from the trunk of the tree in most
instances it is necessary to secure it to the tree with a small nail
or brad. This should be driven in so that the cut surface of the
stock and the wood of the tree trunk are held tightly together.
The whole is then wrapped with budding tape, raffia or string
to help hold it in place and the wound sealed with grafting wax
or paraffin (Fig. 23B).
The work will have to be done when the bark will slip and
even then more or less difficulty will be experienced in working
the bark. If the work is done carefully, however, and the wound
thoroughly sealed, it will usually "take" and after several weeks
the wraps can be cut but the seal of wax or paraffin should not
be disturbed.
Variations of the above method have been employed but in
general most of these cause the wood of the stock and the wood
of the trunk or limb to be at a sharp angle to each other (Fig.
24) and the results do not seem to be as good as with the above
method. Observations indicate that where the stock and trunk
are nearly parallel the best results are obtained. This may be
the result of a more natural flow of sap in such unions.

ROOTING OF CUTTINGS

Cuttings of most species of citrus can be rooted if suitable
propagation equipment is available and care is used in the work.
So far, however, no practical application of this fact has been













FR. 27.-Electrically heated cutting bed (See Annual Report of the Florida Agricultural
Exp. Sta. for 1928, pp. 57-59).







46 Florida Agricultural Experiment Station

made in Florida. Lemon and particularly rough lemon cuttings
root more readily than cuttings of other species that have been
tried. Figure 25 shows a plant of rough lemon produced by root-
ing a cutting as compared with a seedling. In Fig. 26 is shown
a small rough lemon plant produced by placing a leaf .with peti-
ole only attached to it in the cutting box. Cuttings of other spe-
cies of commercial citrus do not seem to root as well as the lemon.
In propagating citrus by cuttings some sort of bottom heat
is required in the cutting box and the atmosphere surrounding
the cuttings should be very moist. An electrically heated cut-
ting bed such as is illustrated in Fig. 27 is very useful for this
work or the solar propagator illustrated in Fig. 28 and described
in Dept. Circular 310 of the U. S. Dept. of Agriculture can be
used. It will be found desirable to leave part of the leaves on
the cuttings when they are placed in the bed. Considerable time
is required for the development of a root system.
A modification of the rooting of cuttings is sometimes used
in producing a new root system on old trees that are almost
girdled by foot rot or other trouble. A frame about 8 or 10
feet square and a foot or more high is built around the base of
the tree and filled in with clay or a soil containing a large per-




















Fig. 28.-Solar propagating frame for rooting citrus cuttings.







Bulletin 227, Citrus Propagation 47

centage of clay. This soil should be kept moist during dry
weather. If the tree is still vigorous it will in time put out roots
above the girdle and eventually
develop a new root system suf-
ficient to support the tree. This
same system can be used in put-
ting a tree on its own root if the
rootstock on which it is budded
is not congenial. In doing this
the trunk is partially girdled at
the bud union and soil is packed
around it until a new root sys-
tem forms. Fig. 29 shows a
small tree treated in this way
with the resultant development
of a root system.
Good sized roots of most spe-
cies of citrus if cut off and the
cut end pulled to the surface of
the soil will start a top and oc- Fig. 29.-Young tree put on its own roots
by being girdled and having soil
casionally trees are produced in packed around the trunk.
this way. This procedure has had no commercial application
but may be used under special conditions.

TRANSPLANTING LARGE CITRUS TREES

Large citrus trees can be transplanted very easily if the prop-
er precautions are taken, and there is practically no danger of
failure. The trees should be dug with as little damage to the
root system as possible. The amount of root system to be trans-
planted will depend upon the facilities for moving the trees.
As soon as the tree is dug the roots should be protected from dry-
ing out by wet burlap or other covering and kept protected until
planted. The new hole should be large enough to easily contain
the entire root system and should be dug just before the tree is
planted so that it will not have a chance to dry out. If possible
the surface soil and subsoil should be kept separate and some
well decomposed compost and ground steamed bone meal should
be added to the soil as the tree is planted. Injured roots should
be pruned off. The soil should be placed about the roots so as
to leave them in normal position and not bunched up. Water







48 Florida Agricultural Experiment Station

should be added as the soil is filled in; the soil should be mad'
firm about the roots, and a heavy final watering given. The tree
should be given plenty of water until it is thoroughly established.
The methods of digging the trees vary considerably, but the
following method has been found very convenient. Dig a trench
around the tree 18 to 24 inches deep, depending on the size of
the tree, cutting all roots. This will cut practically all of the lat-
eral roots. From some point in the trench dig deeply under the
tree to cut the taproot at a level 2 feet or more below the bottom
of the trench. Then, by using a crane or by hand, loosen the tree
so that it can be lifted from the hole. The new hole is excavated
evenly to the depth of the trench used in removing the tree and
a post hole digger or shovel used to make a hole in the center
of it for the taproot. When the tree is let down into this hole
the lower lateral roots will rest on undisturbed soil so that there
will be less tendency for the tree to settle later. There is also
less disturbance of the subsoil than in the ordinary methods of
excavation.
Trees can be moved during the winter when they are fairly
dormant, in which case care will have to be used in keeping them
moist during the dry spring weather. Trees can also be moved
at the beginning of the summer rainy season and will usually
become established by winter.
The amount that the top will have to be cut back will depend
upon the extent of the root system moved and the care taken in
moving. If only a comparatively small root system is moved it
is well to cut the top back to a framework and protect the limbs
from sunburning with whitewash or some sort of shade. Where
large root systems are moved less cutting back of the limbs will
be required. Trees have been moved under favorable conditions
without cutting back of any kind.
Where it is desired to move large numbers of trees an auto-
mobile wrecking crane mounted on a truck is very convenient.
The arm of the crane can be attached to the trunk of the tree,
with the bark protected by padding. As soon as the digging
is completed the tree can be lifted and a tarpaulin or large bur-
lap covering wrapped around the roots and the tree moved
quickly to the new location. It is easy to back the truck up to
the new hole and let the tree down into it and hold it at the
proper level while the dirt is being filled in.





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