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U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY- Circular No. 46.
B. T. GALLOWAY, Chief of Bureau.
TIlE LDIITATION OF THE SATSUMA ORANGE
TO TRIFOLIATE- ORANGE STOCK.
BY
WALTER T. SWINGLE,
PHYSIOLOGIST IN CIIARGE OF CROP PHYSIOLOGY AND
BREEDING INVESTIGATIONS.
WASHINGTON: GOVERNMENT PRINTING OFFiCE: 1900
B. P. 1.- 531.
THE LIMITATION OF THE SATSUMA ORANGE TO
TRIFOLIATE- ORANGE STOCK. a
INTRODUCTION.
The Satsuma orange is a variety which has come to be widely
grown in the warmer parts of the Gulf States. Without entering
into a discussion as to the merits and demerits of this variety, it is
proposed in this circular to call attention to the fact that unlike most
commonly grown varieties it succeeds only when grafted on Trifoliateorange
stock and is a complete failure on the sour- orange stock upon
which almost all other citrus fruits can be grown successfully.
In view of the fact that large experimental and even commercial
plantings of the Satsuma orange are being made in nearly all of the
Gulf States and that Satsuma trees are being oiTered for sale on sourorange
stock, it is considered advisable to call attention to the certain
failure which will result from planting Satsuma oranges budded on
sour stock. . Fortunately a simple method has been discovered for
identifying with certainty Trifoliate stock, which makes it easy to
guard against the fradulent substitution of sour- orange or any other
stock for the Trifoliate.
HISTORY OF THE TRIFOLIATE ORANGE IN THIS COUNTRY.
Growers of citrus fruits in this country have long been accustomed
to use the sour orange and the sweet orange as stocks, while in recent
years the rough lemon and to a lesser extent the grapefruit have come
into use. These show widely dillerent adaptation to soil conditions,
as well as greatly varying powers of disease resistance.
Among the stocks which have come into prominence during the
past few dec:: tdes is the hardy Trifoliate orange of China and Japan.
a During the last few years there have been extensive plantings of the Satsuma
orange in the warmer parts of the Gulf States. Without entering into a discussion
as to the value of this variety and the prospects for growing and marketing it successfully
on a commercial scale, Mr. Swingle wishes to call attention in the present circular
to the unusually sharp limitations of this variety to a single stock- the Trifoliate
orange. It is believed to be desirable to warn all who desire to test the variety against
purchasing trees budded on the sour orange, a stock remarkably well adapted to almost
all other kinds of citrus fruits, but which Mr. Swingle finds to fail entirely for this
particular variety.
A simple method for distinguishing the Trifoliate orange from all other stocks is
pointed out, rendering it easy to protect purchasers of Satsuma oranges against the
substitution of sour- orange for Trifoliate stock.- B. T. GALLOWAY, Chief of Bureau.
~~ 3
LIMITATION OF SATSUMA ORANGE. 5
This was introduced into this country by the Department of Agriculture
in 1869 and was at first little more than a botanical curiosity.
It was soon found to be an excellent hedge plant in the South, and
even as far north as \ Vashington, D. C., and for many' years it was
grown for this purpose. The fact that it is able to withstand without
injury temperatures as low as zero Fahrenheit, or even lower, makes
it suitable for culture over nearly half the area of the United States.
Those forms of the Trifoliate orange which have fully developed
flowers are handsome ornamentals, especially when they blossom in
the spring and again when laden with fragrant yellow fruit in the
autumn. Unfortunately many of the Trifoliate orange trees grown
in this country do not develop their flowers perfectly, or, at least, not
all of their flowers, the petals being stunted and shortened by glandlike
growths on the edges near the base. The flowers are shown
natural size in Plat" e 1. A fruiting branch is shown in figure 1, and
fruits in cross section and in longitudinal section in figures 2 and 3.
FIG. 2.- Cross section of a fruit of the
Trifoliate orange.
( Natural size.)
FIG. 3.- Longitndinal section of a
frui t of the Trifoliate orange.
( Natural size.)
It would be very easy, however, to breed up a large- flowered race of
the Trifoliate orange that could be propagated very rapidly and
cheaply from the superabundant seeds that fill the fruits.
The Trifoliate orange has been used for ages in China and Japan as
a stock upon which to bud the cultivated citrus fruits, and about the
middle of the last century it was brought to notice in England as a
stock for the kumquat. This latter species itself was, however,
only a curiosity, and apparently very few experiments were made in
Europe with the Trifoliate orange as a stock for oranges, lemons, and
other common citrus fruits.
About a quarter of a century ago the Trifoliate orange began to be
used in this country as a stock for the Satsuma orange, as well as for
other citrus fruits. It was found that all grow well on this stock, and
that it had a tendency to force early and profuse bearing, at the
same time dwarfing the tree somewhat.
[ Cir. 46]
6 LIMITATION OF SATSUMA ORANGE.
Although the Trifoliate is naturally a small tree and of slow
growth, when used as a stock its growth is so stimulated that its
diameter always continues greater than that of the scion. This
disparity in size, while not sufficient to make the union a poor one,
makes it easy in walking through a grove of citrus fruits budded on
, this stock to detect the point of union of the scion with the stock
because of the abrupt increase in diameter of the latter. a
The Trifoliate- orange stock has one disadvantage in comparison
with sour- orange, sweet- orange, and other commonly used stocksit
does not sprout readily from the root if the top is killed by a
severe frost. For this reason varieties grafted on Trifoliate roots and
grown where there is danger of occasional severe fr6ezes should always
be earthed up a few inches above the point of insertion of the bud, so
that in case the top is killed by a severe freeze the budded variety can
be reproduced by sprouts issuing from that part of the trunk which
is protected by the earth. If this precaution is neglected there is
danger of orange trees grafted on Trifoliate stock being killed outright,
root b and branch, by an unusually severe winter.
THE KUMQUAT SUCCEEDS BEST ON TRIFOLIATE- ORANGE STOCK.
There are very few varieties of citrus fruits that do not succeed on
the Trifoliate stock, provided, always, the soil is adapted to the stock.
Some varieties succeed better on this stock than on any other. Perhaps
the most striking example of this is the kumquat, which is the
hardiest of the evergreen citrus fruits. On Trifoliate stock it bears
heavy crops of fruit while stili a mere bush.
On the other hand, the kumquat is not adapted for budding on sour��orange
stock, and such buds often fail to grow, or even die, after they
have started to push, something very rare among citrus fruits. c
THE SATSUMA ORANGE A FAILURE ON SOUR- ORANGE STOCK.
Another variety of citrus fruits that behaves very differently on
the various stocks is the Satsuma, a very early orange of the mandarin
class introduced from Japan, where it is known as the Unshiu. This
variety, which is the earliest and at the same time one of the hardiest
a This form of union wherein the stock slightly outgrows the scion has been noticed
also in the case of the loquat grafted on the quince growing at Eustis, Fla. In this
case, also, the variety so grafted began to bear when still very young and has borne
abundant crops since. It is interesting to note that in both of these cases we have a
large- leaved evergreen plant grafted on a small- leaved deciduous and not very closely
related species. The contrary union, where the scion outgrows decidedly the stock,
is apparently not satisfactory, the scion being likely to break off and being usually
short lived, even when it escapes being broken off.
b The Trifoliate root, strictly speaking, is not killed outright, but as it produces no
sprouts it soon dies from starvation.
c For these facts the writer is indebted to 1Ir. G. L. Tabor, of Glen St. :\ Iary, Fla.
[ Cir. 46]
eire. 46, Bureau of Plant Industry, U. S. Dept. of Agriculture. PLATE I.
A FLOWERING BRANCH OF THE TRIFOLIATE ORANGE, SHOWING THE FLOWER FULLY
EXPANDED BEFORE THE LEAVES ApPEAR. ( NATURAL SIZE.)
LIMITATION OF SATSUMA ORANGE. 7
of the oranges, a grows very well on sweet- orange stock- better, in
fact, than on the Trifoliate orange on most soils- but the fruit is of
decidedly inferior quality on the former stock, being coarse, dry, and
insipid, besides ripening later than on the Trifoliate stock.
On the sour orange the Satsuma is a complete failure, the growth
being so slow and stunted that it never becomes more than a dwarfed
bush. The fruit that is borne by this stunted top is of very inferior
quality. There is every evidence of a considerable degree of incompatibility
between the Satsuma and the sour orange. It is no exaggeration
to say that he who plants a Satsuma orange tree grafted on
sour stock might better bury a five- dollar bill and burn the tree,
which, if planted, will linger along for years, only to be finally dug up
as worthless. Inquiry among growers of Satsuma oranges in Florida,
Alabama, Mississippi, Louisiana, Texas, and northern Mexico has
failed to elicit a single instance of successful growth and satisfactory
fruiting of this variety budded on sour- orange stock. The writer
was stationed for five years in Florida investigating citrus fruits in
all parts of the State, and during that time he never saw a vigorous
Satsuma tree or any good crops of early- ripening fine- flavored Satsuma
oranges borne on trees budded on sour- orange stock.
THE SATSUMA ORANGE BEST ADApTED TO TRIFOLIATE- ORANGE
STOCK.
On the other hand, the Satsuma budded on the Trifoliate orange
produces fruits which ripen early and are of excellent quality, smooth
skinned, firm, and juicy. The trees budded on this stock are smaller
than those budded on sweet- orange stock, but they bear earlier and
fruit more profusely. They also ripen their fruits earlier in the
season and are decidedly hardier.
The Satsuma orange is the only one of the commonly grown citrus
fruits ( besides the kumquat) which shows such marked differences
in growth and character of fruit when budded on different stocks.
Since the Satsuma orange can succeed on but one stock, the Trifoliate
orange, it can be grown with hope of commercial success only
on soils to which the Trifoliate stock is adapted, namely, on fairly
rich, somewhat moist soils, preferably sandy soils with a clay subsoil.
It is almost impossible to successfully grow orange trees budded
upon Trifoliate stock on light, sandy soils such as make up the bulk
of the soil of southern Florida and parts of southern Texas.
a Growth ceases at an early period in autumn, and, when once the last growth has
hardened, the tree can endure a considerable spell of very warm weather without being
forced into growth. This high degree of winter dormancy is what renders the Satsuma
so well adapted for culture in the variable climate of the Gulf States. As to the quality
of. the fruit of the Satsuma, there are wide differences of opinion. This is due ill large
part to its greatly varying quality, depending on the stock upon which it is budded
and on the soil and climate of the locality where it is grown.
[ Clr. 46J
8 LIMITATION OF SATSUMA ORANGE.
H
FIG. 5.- Longitudinal section
of the pith of the
sour orange. Note the
absence of any thickwalled
cells. ( Magnified
56 diameters.)
( Drawn by Dr. Theo.
lIolm.)
HOW TO DISTINGUISH TRIFOLIATE FROM SOURORANGE
STOCK.
F lG. 4.- Longitudinal
section
of the pith of
the Trifoliate
orange, show ·
ing the thickwalled,
pitted
cells that make
up the imperfect
cross
plates. ( Magnified56
diameters.)
( Drawn
by Dr. Theo.
lIolm.)
In 1887, Prof. Otto Penzig, director of the botanic
garden at Genoa, Italy, published a very interesting
account of citrus fruits for the Department of Agriculture,
Industry, and Commerce
of the Italian Government. In the
course of his investigations of the
anatomy of the principal types
of citrus fruits, he discovered a
striking difference in the structure
of the pith of the Trifoliate orange
as compared with that of other
citrus fruits. b
If a section be made lengthwise
of a stem or twig of the Trifoliate
orange, the pith is found to con-tain
rows of cells arranged so as to
form more or less imperfect partitions somewhat
like the partitions in the pith of the walnut.
Such a section of the Trifoliate orange
showing the cross plates of thick- walled cells
in the pith is shown in figure 4 to be contrasted
with figure 5, showing the absence of any such
plates in the pith of the sour orange. A few of the thick- walled
cells which make up the imperfect longitudinal cross partitions of the
Trifoliate orange are shown under higher magnification in figure 6.
In case the soil is not adapted to the Trifoliate orange, there is
little hope of growing the Satsuma orange successfully unless some
new stock not as yet known is found adapted to this
variety and able to grow on light soils. As a last
resort, grapefruit, citrange, a or some other stock could
be tested, but it is useless to set out trees of this variety
grafted on sour- orange stocks.
a The citrange is a hardy citrus fruit originated by the Department of Agriculture
by crossing the common orange and the Trifoliate orange. Citranges grow more vigorously
than either parent, and some varieties can be reproduced practically unchanged
from the numerous seeds. Because of their vigor and their being half orange, citranges
can be expected to thrive in soils too light for the straight Trifoliate. As the
Satsuma orange grows rapidly on sweet- orange stock and fruits well on Trifoliate
stock, it would probably succeed on the citrange, a hybrid of these two stocks.
b Penzig, O. Studi botanici sugli agrumi e sulle piante affine, in Annali di Agricoltura,
1887, p. 137, pI. 13, fig. 6 ( Ministero di Agricoltfua, Industria e Commercio).
Rome, 1887.
[ Oir. 46]
LIMITATION OF SATSUMA ORANGE. 9
A longitudinal section of the pith of the sour orange is shown in
figure 5. It will be noted that there is an entire absence of Cross
partitions, and there are no thick walls to be seen. All of the ordinary
types of citrus fruits, including
the sour orange and all that are
ever used as stocks in this country,
have pith of this character without
any trace of cross partitions built up
out of thick- walled Gells.
These peculiar cells are of such a
striking character as to make it easy,
by using a low- power microscope, to
distinguish between Trifoliate and
sour orange stocks- in fact, to distinguish
Trifoliate- orange from any
other citrus stock- with absolute certainty.
To make such an examination
it is of course necessary to take FIG. 6.- A small group of thick- walled cells
from the pith of the Trifoliale orange. ( Mag-
OUt some of the pith of the stock. nified 372 diameters.) ( Drawn by Dr. Theo.
In the case of nursery stock this Holm.)
can even be done, if desired, without killing the plant, since a cut
extending half way through- necessary to take out the pith- will
soon heal up.
WARNING AGAINST THE PURCHASE OF SATSUMA ORANGES ON
SOUR- ORANGE STOCKS.
In spite of the fact that Satsuma oranges budded on sour- orang~
stock are known to be a total failure, some nurserymen have budded
them largely on this stock and are even offering them for sale on
the ground that the Trifoliate stock does Dot succeed on light, sandy
soil, whereas sour- orange stock does succeed in such situations. All
this is perfectly true, but no mention is made of the additional and
very important qualification that the Satsuma orange budded Oll
sour- orange stoek is perfectly worthless from a commercial point of
view on any soil.
In view of these facts, this occasion is taken to urge intending
purchasers of Satsuma oranges to insist that they be budded on
Trifoliate- orange stock. In no case should they be accepted on
sour- orange stock. If the experiment is to be made of growing
Satsuma oranges in a region where the soil is light, especially in
southern Florida and southern Texas, it may be worth while to experiment
with the Satsnma on certain other stocks, such as grapefruit
or seedling citrange, but there is little hope for financial success in
growing Satsuma oranges in such situations.
[ Clr. 46)
10 LIMITATION OF SATSUMA ORANGE.
In order to make it possible for orange growers to be sure that
they are getting plants grafted on Trifoliate- orange stock, the Department
of Agriculture will undertake temporarily to determine,
free of charge, whether or not nursery stock of citrus fruits is grafted
on Trifoliate- orange stock. It is hoped that this method will be
adopted by state horticultural inspectors and by state experiment
stations, as well as by growers themselves. It is the purpose of this
temporary offer of the Department to maJm known the possibility
of distinguishing readily whether or not the stock used is the Trifoliate
orange.
SUMMARY.
It is not the purpose of this circular to discuss the merits or demerits
of the Satsuma orange or to attempt to define the regions in which
it can be grown with reasonable hope of success.
The Satsuma orange is almost a complete failure on sour- orange
stock on any soil and in any climate, and succeeds well only when
budded on Trifoliate- orange stock. It can . be grown, but less successfully,
on sweet- orange, grapefruit, and perhaps rough- lemon
stocks.
The Satsuma orange, being limited to the Trifoliate- orange stock,
can be grown with reasonable hope of success only on soils to which
this stock is well adapted, namely, fairly rich, fairly heavy soils,
preferably with a clay subsoil.
Purchasers of Satsuma orange trees should insist that they be
grafted on Trifoliate- orange stock, ano to protect purchasers against
substitution of trees grafted on sour- orange stock the Department
of Agriculture will undertake for the present to determine whether
or not the stock is Trifoliate orange. .
Do not buy Satsuma oranges budded on sour- orange stock! If you
suspect substitution, send a sample to the Department of Agriculture
for determination.
Approved:
JAMES WILSON,
Secretary of Agricult1J. re.
WASHINGTON, D. C., December 6, 1909.
[ Cir. 46J o
