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UFLAC














LETTER OF TRAiNSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY, (
OFFICE OF THE CHIEF,
Washington, D. C., April 11, 1913.
SIR : Many requests are received at the Department of Agriculture
for information on the methods employed in growing oranges and
other citrus fruits in Florida and the Gulf States, and it is important
that the Department be able to supply the desired information as
fully as possible. In order to furnish this information in concise
form, Prof. P. H. Rolfs, Director of the Agricultural Experiment
Station of Florida, has revised Farmers' Bulletin 238, entitled "Citrus
Fruit Growing in the Gulf States," and has divided the material
contained in that publication into three parts, of which this paper
is the third, as follows: " Sites, Soils, and Varieties for Citrus
Groves in the Gulf States "; " Propagation of Citrus Trees in the
Gulf States "; " Culture, Fertilization, and Frost Protection of Citrus
Groves in the Gulf States." In this form the information will be
more available for distribution in the territory directly concerned and
will be of more service, it is believed, to prospective growers of
citrus fruits and to planters already engaged in this industry. I have
the honor to recommend that the paper be published as a Farmers'
Bulletin.
Respectfully, WM. A. TAYLOR,
Chief of Bureau.
Hon. D. F. HOUSTON,
Secretary of Agriculture.


























CONTENTS.

Page.
Introduction .......... ....... . ...5..... ... ......... ................ 5
Preparation of the land.................................... . . ............... 5
Setting out trees ................... ............ ........................... 6
Time and manner of setting out trees .................................... 6
Catch crjps .................................................. .............. 7
Pruning.............-............. ...- ......... ............................ 7
Fertilizers.............................................. ..... .............------- 8
Commercial fertilizers for Florida............................. ........... 8
Stable manure of doubtful utility..................................... 11
Injurious action of muck..........................-----..................... 12
Protection against cold ................ ........... ............-------.... 12
Protection by heat.---......... ---..... ............ ........... . ........... 12
Fuel oils...................................--------. ...------------..---------....... 13
Heaters ------------------------------------------------- 13
S torage tanks................................ ... .............. ............ 13
Storage tanks. - ----- -------------- ------ --------- 15
Cost of heating............................... ...................... 15
Wood fires.................--..................-----.....------....--...------- 16
Protection by irrigation...........................--..................... 17
Protection by sheds....................----............--.................. 17
Top-working.................................... ............................ 18
Crown-working............................................................. 19
542 3


\ I








Issued July 9, 1913.
U. S. DEPARTMENT OF AGRICULTURE.



FARMERS' BULLETIN 542.





CULTURE, FERTILIZATION, AND, FROST

PROTECTION OF CITRUS GROVES

IN THE GULF STATES.





BY

P. H. ROLFS,
Director of the Agricultural Experiment Station of Florida.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1913.




































ILLTJSTR ATIOINS.

Page.
FIG. 1. Crown-grafting an old orange stock................................... 18
2. Ruby orange bud, inserted May 21 on a sprout from an old sweet-orange
trunk, as it appeared on October 25............................... 19
3. Ruby orange crown graft, inserted March 1, as it appeared on October 23. 20
542


-i




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Citrus Canker Bulletins 538, 539, 542. 1913
ALL VOLUMES CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/AA00000206/00016
Finding Guide: A Guide to the Peter Henry Rolfs Collection
 Material Information
Title: Citrus Canker Bulletins 538, 539, 542. 1913
Series Title: Writings and Speeches 1891-1920
Physical Description: Unknown
Physical Location:
Box: 1
Divider: Articles, Speeches and Other Writings
Folder: Citrus Canker Bulletins 538, 539, 542. 1913
 Subjects
Subjects / Keywords: Agricultural extension work -- Florida.
Agriculture -- Florida -- Experimentation.
Agriculture -- Study and teaching -- Brazil -- Minas Gerais.
Agriculture -- Study and teaching -- Florida.
Citrus fruit industry -- Brazil.
Leprosy -- Research -- Brazil.
Minas Gerais (Brazil) -- Rural conditions.
Escola Superior de Agricultura e Veterinaria do Estado de Minas Gerais.
Florida Cooperative Extension Service.
University of Florida. Agricultural Experiment Station.
University of Florida. Herbarium.
 Record Information
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: AA00000206:00016

Table of Contents
    Culture, fertilization, and frost protection of citrus groves in the Gulf States
        Page A-1
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        Page A-20
    Sites, soils, and varieties for citrus groves in the Gulf States
        Page B-1
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        Page B-15
    Propagation of citrus trees in the Gulf States
        Page C-1
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        Page C-16
    Culture, fertilization, and frost protection of citrus groves in the Gulf States
        Page D-2
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        Page D-5
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        Page D-19
        Page D-20
Full Text



Issued July 9, 1913.

U. S. DEPARTMENT OF AGRICULTURE.



FARMERS' BULLETIN 542.





CULTURE, FERTILIZATION, AND, FROST

PROTECTION OF CITRUS GROVES

IN THE GULF STATES.





BY

P. H. ROLFS,
Director of the Agricultural Experiment Station of Florida.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1913.


A,













LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY,
OFFICE OF THE CHIEF,
Washington, D. C., April 11, 1913;
SIR : Many requests are received at the Department of Agriculture
for information on the methods employed in growing oranges and
other citrus fruits in Florida and the Gulf States, and it is important
that the Department be able to supply the desired information as
fully as possible. In order to furnish this information in concise
form, Prof. P. H. Rolfs, Director of the Agricultural Experiment
Station of Florida, has revised Farmers' Bulletin 238, entitled "Citrus
Fruit Growing in the Gulf States," and has divided the material
contained in that publication into three parts, of which this paper
is the third, as follows: Sites, Soils, and Varieties for Citrus
Groves in the Gulf States "; "Propagation of Citrus Trees in the
Gulf States "; Culture, Fertilization, and Frost Protection of Citrus
Groves in the Gulf States." In this form the information will be
more available for distribution in the territory directly concerned and
will be of more service, it is believed, to prospective growers of
citrus fruits and to planters already engaged in this industry. I have
the honor to recommend that the paper be published as a Farmers'
Bulletin.
Respectfully, WM. A. TAYLOR,
Chief of Bureau.
Hon. D. F. HouSTON,
Secretary of Agriculture.


























CONTENTS.

Page.
Introduction ..... ..... .... ..-- -- ------------------------.... ....... 5
Preparation of the land ................... .... ..... ................- 5
Setting out trees.. -------------....---- ......-.. ......... ................. 6
Time and manner of setting out trees........ ................. .......... 6
Catch crips ............. ...... ...... ...... ..... ... ...... ....... 7
Pruning.....--------------...........---- ....... ............................ 7
Fertilizers--- --------........- ................. .......- .. .............. 8
Commercial fertilizers for Florida .........................- ............- 8
Stable manure of doubtful utility -------------...-... .....--... .. .. 11
Injurious action of muck .............................................. 12
Protection against cold .........-......... ...-.......... ................ 12
Protection by heat .................................... ............. 12
Fuel oils ........................ .......... .....-. ..-......-... 13
Heaters ............... .......... ..... ........................ 13
Storage tanks.. : ................. ............................. 15
Cost of heating ....................... ............ .. ............... 15
Wood fires ..............-......................................... 16
Protection by irrigation ................................................ 17
Protection by sheds .................. ........ ................... ..... 17
Top-working ............................. ......-....................... 18
Crown-working............................................................. 19
542 3
































ILLUSTR NATIONS.

Page.
FIG. 1. Crown-grafting an old orange stock ................................... 18
2. Ruby orange bud, inserted May 21 on a sprout from an old sweet-orange
trunk, as it appeared on October 25..........-----------.................. 19
3. Ruby orange crown graft, inserted March 1, as it appeared on October 23. 20
542
4











B. P. I.-890.

CULTURE, FERTILIZATION, AND FROST PROTEC-

TION OF CITRUS GROVES IN THE GULF STATES.


INTRODUCTION.

The growing of citrus fruits, an industry which has attained vast
proportions in Florida, is receiving much attention in other Gulf
States. The purpose of this bulletin is to answer some of the many
inquiries constantly received by this Department and to act as a
general guide for prospective planters who need definite advice upon
questions of citrus-fruit growing. The information is necessarily of
a very general character, but the essential factors are presented in a
manner which, it is hoped, will enable planters to understand fully
the fundamental principles involved.1
PREPARATION OF THE LAND.
As a rule, the field chosen to be planted out to an orange grove is
land with a native growth upon it. Usually the land is covered with
forest trees. Various devices have been used for reducing the amount
of labor necessary to get rid of this native growth, but up to the
present time no substantial or decided progress has been made in
the methods of clearing land. The most of the work is done by main
strength and muscular labor. Where the native growth happens to
be some form of hard wood, it, is the usual practice to remove the
trees and stumps. Some advantage is frequently obtained by the use
of dynamite or other explosive in loosening the stumps. Where
the native growth is pine woods or palm trees, the necessity for
removing the stumps is not so great, though in the case of the former
the stumps are usually taken out. In cabbage-palmetto hammocks
some of the trees are left and used as nurse plants for a few years.
The most economical course is to remove all trees, shrubs, and
other forms of vegetation from the land and to clear it of all rocks
and any other debris that may be found. Then the land may be
broken up and put into a first-class state of tilth, which will permit
careful staking and planting.
SFor a discussion of other phases of this problem which can not be included here, since
to treat them adequately would unduly increase the size of this bulletin, see Farmers'
Bulletins 528, Sites, soils, and varieties for citrus groves in the Gulf States; 530, Prop-
agation of citrus trees in the Gulf States; and 172, Scale insects and mites on citrus
trees.
542






CULTURE OF CITRUS GROVES IN GULF STATES.


SETTING OUT TREES.

Usually the prospective orange grower buys trees from a nursery
and sets them out as soon as the field has been cleared, wishing, of
course, to get the trees on the land as soon as possible and to hasten
the time when he may be selling fruit. Sometimes this is by no means
the most profitable procedure. Land especially rich in organic matter
and heavily niatted with roots from the native growth would be
decidedly better for having -produced a crop or two of vegetables
before the grove is planted. If for any reason it is not desirable to
grow vegetables, a crop of weeds grown on it for a year would do
much to sweeten the land preparatory to receiving the trees. A
crop of cowpeas or velvet beans would be preferable, however.
The number of trees to be set out to the acre depends on the variety
selected and the character of the land. Large-growing citrus trees,
such as pomelos and the Valencia Late and Hart sweet oranges,
should not be set closer than 100 to the acre, and on first-class soil
80 are enough. Smaller growing varieties, such as the mandarin
group of oranges and the limes, should not be set closer than 200 trees
to the acre. The character of the land will also need to be consid-
ered in setting out a grove. In a sandy.loam rich in organic matter,
especially in southern Florida, trees grow much more vigorously and
in consequence should be set farther apart. Forty-nine trees to the
acre, i. e., setting them 30 feet apart each way, is about as small a
number as one can afford to plant. In the heavy clay soils trees
grow less vigorously and may be set nearer, together.

TIME AND MANNER OF SETTING OUT TREES.
The time of setting out trees will depend on the location and the
conditions. In the West Indies and south Florida trees may be set
out at any time of the year when the land is ready and when there
is sufficient moisture to favor their growth. In central Florida, the
spring (February and March) is preferable. The same is true of
north Florida, Louisiana, and Mississippi. In the extreme northern'
portions of the citrus-growing section it is usually better to wait
until the danger of freezing weather is past. This will bring the
date up to about the latter part of February. In setting out trees
from the nursery, care should be taken to injure the roots as little
as possible. Where trees can be taken up with a considerable ball
of earth and transplanted in this way, they may be set out without
any apparent check in growth. This, however, is not usually prac-
ticable.
When the trees are taken up, the roots should be carefully pro-
tected by means of wet cloths or moist moss and the trees set in holes
542





CULTURE OF CITRUS GROVES IN GULF STATES.


already prepared for them. If the ground is not already very moist,
the addition of one or two pails of water will usually puddle the
roots and cause the trees to grow promptly. At the time of setting
out, the tops should be cut back to correspond closely to the condition
of the roots. Complete defoliation is also advisable. The favorite
size of tree to set out is one that has grown about 4 feet tall in the
nursery and has several branches. Such trees are usually about an
inch or an inch and a half in diameter at the crown.
CATCH CROPS.

As soon as the field has been set to a grove, cultivation may be
begun. The kind and amount of cultivation will be determined by
the character of the soil. Light, sandy soil should have shallow but
careful cultivation. Heavy clay soils need thorough and deep
working. Where there is an abundance of moisture supplied natur-
ally to the soil, other crops may be grown to advantage. Where
the soil is inclined to be dry and irrigation has to be practiced, inter-
cropping is of doubtful utility. During the winter, vegetables may
be planted and cultivated as in ordinary fields with decided advan-
tage to the orange trees, unless the land is too dry. Leguminous
cover crops may be planted as soon as the spring and summer rains
begin. When fall droughts occur the cover crops will have to be
removed to conserve the moisture of the soil. Cultivation should
then be resumed. If the soil is inclined to be sterile the cover crop
should be used as a mulch for the trees. If the ground is sufficiently
fertile to permit it, the cover crop can be utilized for hay.
PRUNING.
"To prune or not to prune; that is the question." At many of the
meetings of the horticultural societies the question of pruning has
been vigorously discussed. There are many good reasons for pruning
trees; on the other hand, there are reasons why trees should not be
pruned. The question, then, must be decided by each individual.
One point, however, has been very well settled, and that is that low-
headed trees are preferable. Twenty-five or thirty years ago it was
a common practice to have citrus trees trimmed high enough to permit
a man to drive a cultivator under the branches. The severe cold of
several winters has caused this custom to be very largely abandoned.
In the southern part of Florida, where there is no danger from frost,
it has been found that shading the ground by the limbs has been very
beneficial to the grove. Another important advantage in low-headed
trees is that the fruit may be gathered much more cheaply than from
tall trees.
542






CULTURE OF CITRUS GROVES IN GULF STATES.


Nearly all orange growers will agree that the pruning out of dead
and worthless branches is of benefit to the tree. The extent to which
sound wood is pruned out, however, varies with the notions of the
individual grower. Some of the most extensive and best growers in
Florida practice no pruning at all. Diseased branches should always
be cut out, removed from the orchard at once, and burned. Sprouts
that start from below the bud must be removed, and this should be
done as soon as possible. Water sprouts arising from the trunks and
larger branches should also be removed.
A citrus tree should be kept in a low, compact form, but violent
pruning, such as is often practiced in deciduous fruit orchards, is
not only unnecessary but often absolutely harmful. Systematic
pruning for special purposes is often necessary, but it must be done
by a well-directed effort or more harm than good will result.

FERTILIZERS.

Under the general heading of fertilizers may be considered ma-
terials which are employed to enrich the soil or cause it to produce
a heavier crop. Ordinarily the term fertilizers is restricted to
such as are considered commercial articles, while the term manure "
is applied to organic offal and refuse accumulating on the farm. In
some parts of the United States the term guano has been used
to designate commercial fertilizers. : Cover crops which are grown
on the land for the purpose of enriching the soil are frequently
called green manures."
The kind of fertilizer required to produce a heavy crop of oranges
varies greatly. In the West Indies, Mexico, Mississippi, Louisiana,
and California the general constitution of the soil is so variable that
no hard-and-fast rule can be given. In fact, in many cases it is doubt-
ful whether the desired results attend the application of any or all
the elements usually needed as plant food. While fertile soils produce
trees of vigorous growth which often bear large crops of fruit, the
possibilities are necessarily limited to what Nature will do; but in
soils where one or more of the elements of plant food are present in
insufficient quantity, the modeling of the fruit and the production of
excellent qualities are more completely under the control of the
skilled horticulturist.
COMMERCIAL FERTILIZERS FOR FLORIDA.
The kind and quantity of fertilizer necessary to produce a maxi-
mum crop of fine.fruit depend entirely upon the soil in which the tree
is growing. Many soils in the citrus regions contain an excess of all
the elements necessary for the production of citrus fruits. When fer-
542





CULTURE OF CITRUS GROVES IN GULF STATES.


tilizers are applied under such conditions no beneficial effect can be
noticed from their use. An orange tree planted in soil that contains
large quantities of the necessary elements usually produces large
fruit, but often of an indifferent character. Soils that are deficient in
nitrogen, potash, and phosphoric acid can usually have these supplied
from such sources and in such quantity as will produce fruit of the
desired texture and consistency. It therefore happens that the finest
and most delicious fruit is grown on rather sterile soil.
The entire piny woods of Florida may be said to be deficient in
each of the three important elements of plant food-nitrogen, potash,
and phosphoric acid. Soils are also found in which there is a defi-
ciency of lime, so that frequently an addition of this element will
prove of value. The hammock soils are usually sufficiently fertile to
produce at least one crop, or even a few crops of fruit, without the
addition of fertilizer. These, however, in time become depleted, and
the elements of plant food then need to be supplied by substances
from a commercial source.
In growing citrus fruits on soils that are deficient in all of the
three important elements of plant food, a fertilizer of the following
composition is desirable:
Per cent.
Ammonia----------------------------- ---------- 4
Potash ----------------------- ----- 10
Phosphoric acid (available) ------------------------ 6
For growing nursery stock or for trees not of a bearing age the
amount of potash in the formula may be reduced to 6 per cent, leaving
the two other ingredients in about the above proportions.
The quantity of this fertilizer to be applied per acre will depend
upon various conditions. About 15 or 20 pounds per year may be
applied to each tree capable of producing 10 boxes of fruit, the
quantity being decreased or increased from year to year, as results
indicate. Calculating this on the basis of 100 trees per acre, 1,500
pounds per acre per year would be used for young bearing trees.
Double this amount is very frequently applied, and sometimes three
times as much is used.
The following table gives approximately the amount of material
needed per acre for bearing trees to supply a quantity of fertilizer
equal in fertilizing constituents to 1,500 pounds of the foregoing
formula:
Pounds.
(1) Sulphate of ammonia -------- ------ 250
[Sulphate of potash, high grade ---------- 300
(2) Or sulphate of potash magnesia (low-grade sulphate of
Spotash) ----------------------------------------- 550
( jDissolved boneblack ------------- ------------ 550
(3[Or acid phosphate, 14 per cent available phosphoric acid-- 50
-1IS- -Bull. :-1'-'-1:, 2-.





CULTURE OF CITRUS GROVES IN GULF STATES.


In the case of nursery stock and growing trees, 2 per cent of the
ammonia may be derived from an organic source. This would require
approximately the following ingredients:
Pounds.
(1) Sulphate of ammonia--------------------------------- 125
(2) Dried blood----------------------------------- 100
Sulphate of potash, high grade --- ---_------------200
(3) Or sulphate of potash magnesia (low-grade sulphate of
I potash---------------------------- ---- 350
( Dissolved boneblack---------------- 550
(4Or acid phosphate, 14 per cent available phosphoric acid_ 850
If there is any tendency toward die-back the dried blood should be
omitted and the amount of sulphate of ammonia increased to 250
pounds. If a quick-acting fertilizer is wanted, nitrate of soda (100
pounds) may be employed in place of dried blood.
Citrus-fruit growers wishing to compound their own fertilizers
should give due regard to the substances from which the different
qualities are derived.
Organic ammonia, as found in cottonseed meal, dried blood, guano,
and the various stable manures, is likely to produce a soft, rapid
growth, and in certain sections, especially in Florida, its continued
use is almost certain to produce die-back.
Nitrate of soda is soon taken up by the trees, but is easily washed
out of the soil. Where it is used as the only source of nitrogen it
has to be repeated from four to eight times each year, varying with
the amount of rainfall and the character of soil.
Sulphate of ammonia is much slower in becoming available to the
trees and seems to be retained in the soil much more tenaciously than
nitrate of soda, so that it need not be applied oftener than two to
four times a year.
In the use of potash there is very little choice between, the low-
grade sulphate, which is also called the double salts of potash and
magnesia, and the high-grade sulphate of potash.
In selecting phosphates, preference is given to dissolved bone or
dissolved boneblack over dissolved rock phosphate, although some
experienced orange growers consider the phosphoric acid derived
from dissolved rock as good as that obtained from dissolved bone.
Thomas slag may be employed to good advantage, especially on soils
giving an acid reaction.
The ammonia is washed out of the soil in great quantities by fre-
quent and heavy rains. Potash is washed out to a less degree and
phosphoric acid only to a slight extent, while lime, or calcium, is lost
in large quantities. The quantity of these elements lost will vary
according to the nature of the soil and the amount of heavy rainfall
occurring. The ideal way of fertilizing would be to make an appli-
cation of phosphoric acid in the spring before the rainy season has
s42






CULTURE OF CITRUS GROVES IN GULF STATES.


begun; to make two applications of potash-one in the early spring
at the time of applying the phosphate and another in the fall after
the rainy season has passed; and to make four or more applications
of ammonia-one with each application of the potash and two or
more at equal intervals between, except during the dormant winter
season.
The following example will serve to illustrate the point: Let us
suppose that a grove needs 1,500 pounds of fertilizer per acre per year
of the normal formula, that is, 4 per cent ammonia, 10 per cent potash,
and 6 per cent phosphoric acid. In the spring, therefore, before the
rainy season has begun, we would apply the entire allowance of phos-
phoric acid, or 850 pounds of 14 per cent acid phosphate; one-half
the potash, or 150 pounds of high-grade sulphate of potash; and one-
fourth the ammonia, or 624 pounds of high-grade sulphate of
ammonia. These ingredients may be mixed and applied in the usual
way. Care must be exercised, however, since such a mixture is a
very concentrated fertilizer, and if applied in a narrow zone around
the tree inj ury may result when the weather conditions make possible
the too rapid assimilation of the chemicals ov when the nature of the
soil itself is such that the fertilizer is taken up too quickly.
For the fall application, 150 pounds of high-grade: sulphate of
potash should be mixed with- 62 pounds of high-grade sulphate of
ammonia. The remaining 125 pounds of sulphate of ammonia should
be evenly divided and applied as the conditions indicate. In this
way the amount of plant food that is contained in. 1,500- pounds of
fertilizer of standard formula would be applied during the year.
The proper regulation of the amount of ammonia to be applied
is the greatest difficulty in preparing a complete fertilizer formula.
The presence of this element in too large or too small quantities in
the soil or in the fertilizer appears to give more trouble than any
other ingredient. Groves are very frequently injured by large appli-
cations of ammonia. A very common practice is to make only two
applications a year of a complete fertilizer-one during the spring
and one during the fall. Other growers make three applications-
one during the early spring, one later in the spring, and another
during the fall.
STABLE MANURE OF DOUBTFUL UTILITY.1
The benefits of stable or barn manure, which is largely used by
many growers, are also very doubtful. The fruits produced by nitro-
gen from this source are usually large, -coarse, thick-skinned, and of
inferior flavor. If barn manure is used, however, each tree should
receive only a small quantity, and where it is the main element of
fertilization liberal dressings of potash should occasionally be applied
to counterbalance the nitrogenous fertilizer.
1See Yearbook, U. S. Department of Agriculture, for 1894, pp. 195 and 196,
54,






CULTURE OF CITRUS GROVES IN GULF STATES.


INJURIOUS ACTION OF MUCK.1

Some growers claim that since muck is largely decaying vegetable
matter it should be applied to the grove in large quantities, either
raw or composted with sulphate of potash, etc. While this has occa-
sionally given excellent results, its extensive use has often done
serious injury. In order to obtain a smooth, thin-skinned, juicy
fruit with few or no seeds, we must vary the fertilization which the
plant receives in its wild state. The tendency of all organic manures
rich in nitrogen is to stimulate large, sickly growth. Groves which
have had liberal dressings of muck are frequently much diseased;
their crops are light, the oranges coarse, thick-skinned, and sour, the
fruit drops prematurely, and the trees are often affected with die-
back. What has been said of muck applies to a greater or less extent
to the various forms of organic nitrogen used.
What has been said about the effect of muck and barn manure on
the quality of the fruit applies equally to the effects produced by
cottonseed meal, blood and bone, tankage, etc. In general, organic
fertilizers do not stimulate fruiting to the same extent as the mineral
fertilizers.
PROTECTION AGAINST COLD.
The disastrous freezes of 1894, 1895, and 1899 in Florida and those
of 1912 and 1913 in California have caused the orange grower to cast
about for some means of protection against a sudden cold wave.
Two general methods have been practiced: The first is that of
warming the air without providing shelter and the second is that
of providing a shed or shelter for the trees.
The methods of raising the temperature by means of fires, as de-
scribed in the following paragraphs, can not be relied on if the,
cold weather is accompanied by high winds or rainfall. In a por-
tion of Florida during the heavy freeze of 1899 not only a heavy
rainfall but heavy winds accompanied the cold. All attempts at
building fires were useless, and even if they could have been built
the wind would soon have carried the warm air out of the groves.
When a very moderate breeze is blowing and the temperature
falls only 4 or 5 degrees below the danger point, fires should be
increased on the windward side, perhaps doubled, at the expense of
those in the interior, but fires should not be extinguished in the
interior of the grove, merely reduced.
PROTECTION BY HEAT.
The burning of different kinds of fuel in an orchard for the
purpose of raising the temperature has been employed a great many
SSee Yearbook, U. S. Department of Agriculture, for 1894, pp. 195 and 196,
544






CULTURE O CITRUS GROVES IN GULF STATES.


times. The success attending the work varies under different cir-
cumstances and with different conditions.: V Whli. the drop in tem-
perature is accompanied by a heavy windstorm and rain or sleet,
it is almost impossible to accomplish anything in the way of orchard
heating. Fortunately, freezing weather in the citrus, regions is
usually accompanied by a rather still atmosphere and freedom from
rain or snow.
A great many.kinds of fuel have been employed for orchard heat-
ing. Wood was probably the first, and it is still employed to some
extent. Coal, coke, and fuel oil have all been used to a greater or less
extent. Each of these fuels may have special advantages over others
in some particular place. In general, it may be said that the fuel-oil
method has given, satisfaction more-frequently than all the others
combined. To discuss all of the methods fully is quite beyond the
purpose of this bulletin.
FUEL OILS.

This term includes a variety of materials known under many
different trade names. In general, they are the heavy residue left
after the lighter oils contained in the petroleum have been removed.
A fuel oil known as crude oil is said to contain a large quantity of
asphiltum, which becomes quite troublesome. The asphaltum re-
mains as a residue in the bottom of the heaters and interferes with
the heating when the fuel burns low.
HEATERS.
The varieties and styles of heaters offered by the trade are nearly
as numerous as the varieties of fuels. Usually the more complicated
in construction the heater is, the less efficient it becomes in its prac-
tical work in the orchard. Even a 10-pound lard pail, holding
more than a gallon of fuel oil, compares very favorably in efficiency
with the patented heaters, in some cases even proving superior to
them. The lard-pail type of heater, made from heavy sheet metal
and holding about 5 quarts of oil, can usually be purchased
from heater manufacturers at 10 or 12 cents apiece when ordered
in carload lots. In this type of heater the quantity of fuel used
and the heat given off decrease gradually as the supply in the heater
is consumed.
The lard-pail type of heater holding a gallon of fuel oil will burn
for 3j to 4 hours, varying with the kind of fuel oil used and weather
conditions, giving off about one-half as much heat toward the close
as at the beginning of the clhi, L. -When a soot arrester is used, the
quantity of fuel consumed in an hour is much reduced, but at the same
542






14 CULTURE OF CITRUS GROVES IN GULF STATES.

time a correspondingly smaller amount of heat is given off. There
are a number of heaters that hold a much larger quantity of fuel oil.
Most of these are so constructed, either by means of a soot arrester or
otherwise, that the quantity of oil burned can be regulated. Ordi-
narily these are to be preferred to the smaller type, since when freez-
ing weather occurs it. is usually of more than four hours' duration.
The minimum temperature is very likely to occur about sunrise.
Refilling in the dark is difficult and wasteful.
The type of heater with a sliding top to regulate the area of the
burning surface has worked quite satisfactorily. Roughly speaking,
44 square inches of free burning surface will consume a gallon of fuel
oil in four hours. It has been pretty clearly demonstrated by experi-
ment that it will require the same quantity of 6il to raise the tem-
perature 5 degrees in an orchard, whether few or many heaters are
used. When many heaters are used the temperature in the orchard
can be maintained much more'evenly. The number of burners needed
per acre to raise the temperature 5 degrees will vary greatly, accord-
ing to the favorable or unfavorable climatic conditions and the condi-
tion of the grove. A small grove of large trees closely planted and
surrounded by a dense hammock will pass unharmed through a freeze
of 250 F., while considerable damage would be done in a grove not so
protected. Likewise, the number of heaters required in the former
grove would be fewer than in an open grove where the trees are small
and only a few to the acre.
From 50 to 100 heaters and from 100 to 200 gallons of fuel oil per
acre for each night when heating is necessary is a reasonably safe
estimate in a grove 7 to 10 years old. This number of heaters and
quantity of fuel oil will probably keep the temperature'5 degrees
above the surrounding atmosphere if the wind is not blowing more
than 4 or 5 miles an hour. Ordinarily the heaters are distributed
evenly throughout the grove, placing one in every center between
four trees. This requires about as many heaters as there are trees
in the grove, and is a poor rule to follow absolutely, since a grove
of small trees planted far apart will not hold the heat as well as a
grove of large trees planted closely. Every grove owner will have
abundant latitude to use his own judgment as to the effect of the
exposure of his grove and the other elements that enter into the ques-
tion of orchard heating.
Every grove supplied with heaters should have in it a thermometer
that will sound an alarm when the temperature approaches the
danger point. Such an instrument can be obtained for from $7 to
$20 from instrument manufacturers and dealers. The thermometer
should be placed in that part of the grove in which the danger from
542






CULTURE OF CITRUS GROVES IN GULF STATES.


frost is greatest, and the wires should run to the house or central
office.
The danger point will vary with conditions. At blooming time
the danger point is highest and injury may then occur whether the
temperature goes down to 320 F. or not. Mature fruit is almost
certain to remain unharmed unless the minimum temperature falls
below 280 F. Trees in a fully dormant condition will remain un-
harmed at 240 F., but when full dormancy has passed the trees
become increasingly sensitive to cold. When in full growth, frost,
no matter at what temperature it occurs, will destroy the tender
tissues.
Every grove owner should be in direct telephone communication
with the United States Weather Bureau, in order to receive warn-
ings of probable frosts and freezes. All the important fruit-growing
sections receive this information regularly over long-distance tele-
phones.
STORAGE TANKS,
The fuel oil should be stored in a tank located preferably in the
grove. Where possible, it should be so placed as to allow the oil
to be siphoned directly into it from the car tank, and then from it
into the wagon tank. The storage tank should always be so located
as to enable one to run the fuel oil into the wagon tank by gravity.
Pumps work satisfactorily in warm weather, but are apt to be
troublesome during a cold spell. They also require extra labor, which
could be more advantageously employed in the grove. A break in
a pump will cause delay and may make the fuel inaccessible, thus
rendering the whole plant ineffective.
Fuel oil may be stored in a variety of receptacles, the least desirable
of which are barrels. Concrete tanks or cisterns with tops, such as
are constructed for holding water, will be found useful. The inner
surface should be finished with cement plaster and finally given two
or three coats of asphaltum paint. Steel water tanks are in common
use. Wooden tanks similar to water tanks, made of upright 2-inch
planks, are commonly used and seem to be thoroughly practicable.
Some grove owners have tanks such as are used on tank cars for
hauling fuel oil, but these would seem to be unnecessarily expensive.
COST OF HEATING.

The estimated cost of preparing to heat a 10-acre grove will vary
within certain limits. No two groves would be located exactly alike
as to the cost of heating. The distance from the railroad, number
of times to be fired, and variation in price of labor all come in as
variables.
542






CULTURE OF CITRUS GROVES IN GULF STATES.


The following table gives an approximate cost for a 10-acre grove:

500 to 1,000 heaters, at 40 cents ------- $200 to $400
One steel wagon tank ---------- --------------- 25 to 30
Torches and gasoline can for lighting --- ------- 10 to 12
Thermometers and installing-------------------- 12 to 25
3,000 to 6,000 gallons of fuel oil------------- 90 to 180
Storage- tank for fuel oil ------- 100 to 300
Total---------- --------------- 437 to 947

After the equipment has been installed the expense is compara-
tively light and includes mainly the annual depreciation, care of out-
fit, fuel oil burned, transfer to storage tank, and labor. The last
item will vary from year to year. When no firing is needed this item
will be comparatively light. At firing time it will require two or
three additional men to take care of 10 acres. An allowance of $6
to $10 for each night fired should be ample, including the cost of
distributing the fuel oil for the next charge. In extensive groves
and where large-size heaters are used, one man to 10 acres will be
sufficient to take care of the fires, but additional labor will be needed
to replenish the fuel.
WOOD FIRES.

In a wooded country the form of protection against cold afforded
by fires is cheap and at the same time very effective when a still
cold occurs. The wood is piled in the centers of the squares, vary-
ing in quantity from three or four to a half-dozen or a dozen sticks
of cord wood. When a freeze is predicted, the watchers notice the
thermometer and by the time the cold approaches within 2 or 3
degrees of the danger point, which is 280 F. for fruit and 240 F. for
foliage, fires are started in alternate squares. These will usually
heat the grove some 4 or 5 degrees. If the cold continues to increase,
all the piles of wood are started. It is of course necessary to have on
hand a reserve stock of fuel in such an emergency. Shortly after the
sun rises the next morning the temperature will usually have risen
again, so there will no longer be any danger to the fruit or trees. If
there is no favorable change in the weather, the cold on the second
night is quite likely to be more severe than on the first. Firing
then must be begun much earlier, and consequently a greater quan-
tity of wood will be needed.
Owing to the large amount of labor involved and the difficulty of
securing efficient help, this form of orchard heating has been largely
abandoned.
542






CULTURE OF CITRUS GROVES IN GULF STATES. 17
PROTECTION BY IRRIGATION.

In the citrus-growing sections the water that is freshly pumped
from the soil is quite warm, ranging from 500 to 74 F. When this
water is carried through a grove in irrigating ditches it gives off a
considerable amount of heat and has been used effectively in some
instances where the temperature has fallen but slightly below the
danger point.
Arrangements have also been made to throw this water into the air
from spray nozzles. This is somewhat more effective than when the
same quantity of water is carried through irrigating ditches, but can
not be relied upon as being sufficient during extremely cold spells.
During one cold wave the orchard of Mr. Theodore Mead, at Oviedo,
Fla., was protected in this way. During one night the temperature
fell considerably below the freezing point. The next morning the
trees were so heavily coated with ice that some of the branches broke.
The following summer the trees bore a crop of fruit.
The waters from artesian wells have also been used for the purpose
of warming citrus groves, this water being quite warm, running into
the sixties usually and as high as 740 F. in some wells. While this
use of water does some good and protects that portion of the grove
in the immediate vicinity of the large flow, the amount of heat given
off is small and the volume of water supplied is not considered large
enough to protect the grove during severe freezes.

PROTECTION BY SHEDS.

The most successful method of protecting citrus trees from
extremely cold weather is that of building a shed over the grove. At
first thought this would seem to be entirely too expensive and not at
all feasible, but the sheds have now been used long enough to demon-
strate fully that they are not only possible but practicable. There
are several modifications of the shed.
This method was successfully employed immediately after the great
freezes and was profitable while Florida oranges brought a high price.
Orange sheds now occur to a limited extent and only in regions
where great damage from cold formerly occurred. These sheds are
simple structures, having a flat roof or cover held up by posts. The
posts are properly braced and hold the cover from 12 to 16 feet above
the ground. Some of the movable tops are made solid, while those with
stationary tops are made of slats or laths so placed as to give either
a half or third shade.
542






J.H CULTURE OF CITRUS GROVES IN GULF STATES.

TOP-WORKING.
It sometimes happens that a grove is planted out to a variety that
does not prove prolific, or one that may be unprofitable to market.
In such a case it becomes necessary to abandon the grove or to top-
work the trees. With the trees in a healthy and vigorous condition
most or all of the top should be removed, only two or three vigorous
limbs being left.. Buds of the desired variety may be inserted into
the remaining limbs. This cutting away of most of the top causes
a heavy flow of sap into the smaller limbs which remain. In such
cases the buds will "take" where they would fail if the top of the
tree had not been vigorously cut back.
Another way of top-working is to cut away nearly all of the top
and then wait for sprouts to start. After the sprouts have reached a





lI,












FIG. L.-Crown-grafting an old orange stock: a, Base of scion, showing
slanting cut; b, method of inserting scion. (From Yearbook, U. S. De-
partment of Agriculture, for 1805.)

size of about half an inch in diameter they may be budded, and the
bud will take readily. When trees have been cut back severely, the
.bodies and the larger limbs should receive a heavy coat of whitewash
to protect them against sun scalding.
Before top-working, the orchardist should be well acquainted with
his ,-rove and soil. In a very large portion of Florida severe top-
pruning results in die-back unless proper fertilization and soil treat-
ment accompany the work.
In California and Louisiana it appears to be safe-to remove the
entire top and to work buds into the large limbs. For top-working,
the shield bud and sprig graft may be used to best advantage.
542






CULTURE OF CITRUS GROVES IN GULF STATES.


CROWN-WORKING.

At times it becomes desirable not to permit the body of the tree to
remain. In such cases it may be cut off at the ground line. Some
citrus trees, especially limes, resent treatment of this kind and fail
to grow after the top has been entirely cut off. The ordinary citrus
stock, however, is almost certain to sprout again.if treated in this
way. Large areas, 20 to 40 acres in extent, were sprouted in this
way after the great freezes
of 1894 and 1895 in Florida
without the loss of a single
healthy stump.
Trees that have been-cut
back in this way may be
crown-worked or crown-
grafted, as illustrated in
figure 1, the sprig being in-
serted in the portion of.the
crown that will take it miost
easily. By slipping the
scion into the prtiion of the
crown where the bark may
be raised without breaking,
the work may be done with-
out the use of wax or other
binding material. After
the scion has been inserted,
moist earth should be raked
over the crown and around,
the scion, covering them
until they have taken,"' FIG. 2.-Ruby orange bud, inserted May 21, on a
and then exposing the tips. sprout from an old sweet-orange trunk, as it
Where this work is done by appeared on October 25. (From Yearbook, U.. S.
Department of Agriculture, for 1895.)
experienced hands, only a
very small percentage of the crowns fail in taking one or more sprigs.
Those that fail to take may be worked again or left to produce sprouts
and then budded into these sprouts. By using three or four such
scions in a crown 4 or more inches in diameter and doing the work
during February or the early part of March the percentage of loss
sustained will not be very great.
'Another method of renewing such an orchard is to wait until the
sprouts have started from ihe crown or the main roots. After these
sprouts have reached a size.of half an inch or so in diameter, buds are
inserted as low down as practicable. In doing this, however, a con-
542







20 CULTURE OF CITRUS GROVES IN GULF STATES.

siderable loss of time will be sustained in waiting, first, for the
sprouts to start and then, again, in cutting them back to make the
buds sprout. The loss of time is strikingly illustrated by the two


Fio. 3.--Ruby o-range crown graft, inserted March 1, as it appeared on October 23.

nccompnnyirng figure- nwmade .from photographs (figs. 2 and 3).
Thii mniethnolf of budding sprouts, although it results in some loss.of
time, is nevertheless very commonly used by growers because of its
convenience.
-i'4








Issued May 16, 1913.

U. S. DEPARTMENT OF AGRICULTURE.



FARMERS' BULLETIN 538.






SITES, SOILS, AND VARIETIES FOR CITRUS

GROVES IN THE GULF STATES.







BY


P. H. ROLFS,
Director of the Agricultural Experiment Station of Florida.


S -


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1913.


---_. --___ -




t


I


a















LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY,
OFFICE OF THE CHIEF,
Washington, D. C., March 27, 1913.
SIR: Many requests are received at the Department of Agriculture
for information on the methods employed in growing oranges and
other citrus fruits in Florida and the other Gulf States, and it is
important that the department be able to supply the desired infor-
mation as fully as possible. In order to furnish this information in
concise form, Prof. P. H. Rolfs, Director of the Agricultural Experi-
ment Station of Florida, has revised Farmers' Bulletin 238, entitled
"Citrus Fruit Growing in the Gulf States," and has divided the mate-
rial contained in that publication into three parts, of which this paper
is the first, as follows: (1) "Sites, Soils, and Varieties for Citrus
Groves in the Gulf States," (2) "Propagation of Citrus Trees in the
Gulf States," and. (3) "Culture, Fertilization, and Frost Protection
of Citrus Groves in the Gulf States." In this form the information
will be more available for distribution in the territory directly con-
cerned and will be of more service, it is believed, to prospective fruit
growers and to planters already engaged in this industry. I have the
honor to recommend that the paper be published as a Farmers'
Bulletin.
Respectfully, WILLIAM A. TAYLOR,
Chief of Bureau.
Hon. D. F. HOUsTON,
Secretary of Agriculture.
876070-Bul. 538-13 3




LAJ


























OONTENTS.

Page.
Introduction.................-....- ..-- ........................- 7
Climate......--....-........-- ..---------..-------.. ------.---------------..- 7
Soil....--.................... - - - - -................. - 8
Site of the grove .....................-----------------------------. ..- 9
Distance from transportation lines ..----....---------------------------- 9
Character of the soil .................................-- - - - - 9
Drainage ...............- -.............---- ---------..- -----.---.----. 10
Natural frost protection ...... -.--------.------------------------- 11
Protection from high winds-...........- ..... -------------------------- 11
Rainfall.. ....... .....-............ ... ......- - ...........- ....... 11
Varieties......................................-- -------------------------- ------ 12
Florida.......-..... ...........----- --.............---------- ........ 13
Louisiana and Mississippi ...........................................------------------------ 14
Texas ..... ......... ..............- - - - - - -- ........... - - - 15
Texas------------------------------------------------------ 1
Porto Rico and the West Indies generally............----------------... 15
538 5




w-3J












B. P. I.-877.

SITES, SOILS, AND VARIETIES FOR CITRUS

GROVES IN THE GULF STATES.


INTRODUCTION.
The following pages contain brief and concise directions for the
choice of the proper sites, soils, and varieties for citrus orchards in
the Gulf States, being a revision of one part of the material formerly
published in Farmers' Bulletin 238. It has been the aim of the writer
to furnish information to meet the needs of many inquirers rather
than to prepare a complete treatise on the industry.
The growing of the finest citrus fruits is a horticultural accomplish-
ment not surpassed in any line of the art. There are very few agri-
cultural occupations that require an equal amount of judgment and
very few that give as remunerative a return for the mental outlay.
Everyone who is willing to pay the price, either in labor or in dollars,
can grow oranges and grapefruit, but only he who is so constituted as
S to derive pleasure from exercising his mental faculties to their fullest
extent can produce fruit of the finest quality. There is- a very long
series of conditions, from the choice of the site to the delivery of the
package of perfect fruit to the consumer, which must be met success-
fully. If any link in the chain is broken, first place can not be
attained. Good judgment must be exercised in the choice of the
stock, the bud, the soil, and the location of the crop, in the treatment
of fungous and insect diseases, in picking and packing the fruit, and
in selecting a market for its disposal."
CLIMATE.
In general it may be stated that in all regions in which the temper-
ature does not fall below 18 above zero nor rise above 1000 F., under
humid conditions, and where there is sufficient moisture, citrus fruits
may be produced. However, there are localities within these limita-
tions that can not be said to be good citrus-growing sections. In some
1These subjects can not all be discussed here, however, and the reader is therefore referred to the fol-
lowing Farmers' Bulletins: No. 539, entitled, "Propagation of citrus trees in the Gulf States;"
No. 542, entitled, "Culture, fertilization, and frost protection of citrus groves in the Gulf States;" and
No. 172, entitled, "Scale insects and mites on citrus trees."
538 7






8 SITES, SOILS, AND VARIETIES FOR CITRUS GROVES.

places, although the trees grow luxuriantly, heavy rainfalls occur at
the time when the fruits are maturing, making it impossible to gather
and market them. In others the conditions for vegetative growth are
so favorable that very little fruit sets. Regions that are excessively
dry may, however, be utilized for citrus culture when irrigation can be
practiced. The more nearly the northern limit of the citrus belt is
approached, the more sprightly and deliciously flavored the fruit be-
comes, some of the very best fruit being marketed from areas where
the trees are every winter in danger of being frozen.
The ideal humid climate for citrus growing is one in which the rain-
fall occurs after the fruit has been shipped and before the new crop
begins to ripen. The rainfall should not be excessive, certainly not
more than 50 to 70 inches annually, and the winter temperature should
not go below 260 to 270 F. of continued cold, though a lower temper-
ature may be withstood for an hour or more without killing the trees.
Orange trees in a thoroughly dormant condition can withstand a tem-
perature as low as 240 F., if this is not continued for more than a few
hours at a time. A very sharp turn to 180 F., even if for only a few
hours, will entirely defoliate trees in the most dormant condition,
while it is likely to kill the larger proportion of those in active growth.
Small trees under 8 to 10 feet high, with poorly protected trunks.
are very liable to be killed to the ground under these conditions.
Sometimes snow falls and remains on the trees for several hours with-
out seriously damaging orange trees, but this is of rare occurrence.
SOIL.
It will be shown under the heading "Varieties" that citrus trees are
exceedingly variable, and consequently will readily adapt themselves
to almost any kind of soil in which plants can grow. Varieties of
citrus grow upon the sticky, adobe soils of Mesopotamia, upon the
alluvial soils of the lower Mississippi, upon the fertile soils of the
West India Islands, upon the dry soils of Arizona and California, and
upon the almost sterile, sandy soils of Florida. There is probably no
other genus of fruit trees in which the species are so plastic as to adapt
themselves to almost every possible gradation of soil. It should not
be inferred, however, that every variety of the genus can be grown
upon all of these different kinds of soil, for it is absolutely necessary
to choose the particular variety which is adapted to any peculiar soil.
While the rich, alluvial soils produce citrus trees of rank growth
which often bear enormous crops of fruit, the finest and highest
priced fruits are produced upon the nearly sterile soils. In fertile
soils the plant food is seldom properly balanced or present in the
condition best suited for producing the finest fruits, nor is it possible
to influence the contents or quality of the fruit by applying different
538






SITES, SOILS, AND VARIETIES FOR CITRUS GROVES. 9

forms of chemical fertilizers. If, therefore, a field is normally suffi-
ciently fertile to produce a citrus crop for an indefinite number of
years, it is usually impossible to influence the quality of fruit markedly
by means of fertilizers. Upon soils which are nearly sterile, however,
trees may be started and fed with just such chemicals as will produce
the finest quality of fruit. It therefore happens that soils which
formerly were considered absolutely worthless for agricultural pur-
poses are now made to produce large crops of most excellent fruit.
SITE OF THE GROVE.
Immediately upon deciding to plant a grove the best site that can
be procured should be selected. A great many questions arise in
determining where a grove shall be located. A few of these are
discussed below.
DISTANCE FROM TRANSPORTATION LINES.
Since the profit accruing from a grove is the grower's ultimate
object, it becomes necessary to study the possibility of getting the
fruit into the market cheaply. Long hauls by wagon over rough
roads should be avoided wherever possible. Hauling by wagon is
expensive and, what is more important, it consumes much time at a
period when it is difficult to employ efficient labor.
The distance to which it is profitable to haul fruit will vary greatly.
Hard-surfaced, smooth roads are found in nearly every progressive
community. In some localities automobile trucks are employed for
taking fruit from the grove to the central packing house, making the
transfer charges low. The fruit is also less likely to be injured in
transit. Under such circumstances a distance of 10 miles might be
regarded as the maximum at which to start a grove. Under more
adverse conditions one should not attempt to put out a grove at a
greater distance from transportation facilities than 5 miles.
First-class citrus land can be purchased in nearly every favor-
able locality in Florida at prices ranging from $20 to $50 an acre.
When located adjacent to hard-surfaced roads the price will vary
from $40 to $100 or more an acre. Placing the average crop at 200
boxes per acre and the average cost of transferring the fruit from
distant groves at 5 cents a box, the hauling charges would constitute
a tax of $10 per year per acre against such property. This charge
would be for the hauling of the fruit alone, and would not include
the handicap in securing labor, hauling supplies, and fertilizers.
CHARACTER OF THE SOIL.
The variation of the soils in the West Indies and in Louisiana and
Mississippi is not so sharply marked as that in Florida. There are,
however, characteristic soils in each of these regions that are better
538






SITES, SOILS, AND VARIETIES FOR CITRUS GROVES.


than others. In all sections a soil must be chosen that is not under-
lain with a heavy substratum known as hardpan. The land should
be elevated sufficiently to permit free drainage and in the sections
where irrigation must be practiced should be so located that water
can be easily supplied.
In Florida the soil usually known as hammock land is preferable
for orange growing. This, however, is of limited extent and fre-
quently is so far removed from transportation lines that it is not
profitable to use it. The second grade is called piny woods land.
Groves properly located on this type of soil and managed by intelli-
gent superintendents frequently give the best returns. It is upon
this land that most of the orange groves are located. The cabbage
palmetto hammock, if sufficiently high to permit natural drainage,
also makes excellent land for citrus growing.
DRAINAGE.
In Florida the question of drainage is of paramount importance.
There is scarcely a large citrus grove in the State in which some sec-
tion is not injured from time to time for the want of thorough and
deep drainage. While the total annual rainfall is likely to vary
within rather narrow limits, its distribution throughout the year will
probably be exceedingly variable. The drainage system should be
so constructed as to provide for periods of excessive rainfall rather
than for the average of what might be expected. In choosing the
site of a grove, one should ascertain that it is possible to dispose of
the surplus water promptly. Groves have been situated near a lake
or other body of water or on some site where it was impossible to
dispose of the surplus water during a rainy period, and irreparable
damage has resulted, although at the time of the excessive rainfall no
iujury was apparent. As a general rule, the water table for Florida
should not rise higher than within 18 inches of the surface of the
soil. Other conditions being the same, the groves in which it is 10
feet or more to the water table suffer less during a severe drought
than those where the water table rises almost to the surface. A
fluctuating water table ismore objectionable than a constant one,
however, even when the latter occurs high in the soil.
Water standing in a grove for a few days is almost certain to prove
fatal, while water flowing through the grove for the same length of
time will only injure it. It takes years to grow a good grove, which
may be destroyed or ruined in a week.
The important points in drainage, then, are to be certain (1) that
there is no possibility of ever having standing water in the grove,
and (2) that the water table is as deep as possible in the soil; the
farther down the better.
538







SITES, SOILS, AND VARIETIES FOR CITRUS GROVES. 11
NATURAL FROST PROTECTION.
After determining that the desirable features specified are' to be
found in the location under consideration, it is very important to see
that the land is well protected from the occasional frosts which visit
the citrus-growing sections.' Frost protection is imparted by large
bodies of water, such as make possible citrus growing in Louisiana, in
Mississippi, and in Florida near the lakes in the central part of the
State, along the Indian River on the east coast, and on Tampa Bay.
In the West Indies and the southernmost part of Florida this factor
does not enter into consideration. In fact, it seems that those places
in the West Indies which are subjected to the lowest winter tempera-
ture produce citrus fruits of the highest excellence. The temperature
in the vicinity of Mandeville, Jamaica, is said to go as low as into the
fifties during winter nights, and yet this is probably the best citrus
fruit section on the island.
PROTECTION FROM HIGH WINDS.
A location chosen so as to combine all the qualifications already
mentioned may still be undesirable if it is exposed to the force of high
winds, which may occur in any portion of the country. It is quite
impossible to protect a grove against tropical hurricanes, but the more
common high winds of frequent occurrence must be considered. They
carry off the moisture and bring with them a dry, parching air which
is injurious to citrus trees, and they are also very likely to cause
"thorning" or to mutilate the fruit in other ways. Sometimes it
becomes necessary to erect artificial windbreaks for protecting a
grove not well located. These artificial windbreaks may later be
supplanted by some natural growth that can withstand the force of
the wind.
RAINFALL.

The amount of rainfall needed to produce a crop of citrus fruits
depends on various factors; prominent among them are character of
soil and humidity of atmosphere. Where there is a deficiency of mois-
ture it may be supplied by irrigation, but a superabundance of mois-
ture can be controlled only in a measure by drainage. In the humid
portions of the United States and in the rainy sections of the West
Indies heavy rainfalls frequently occur at the time when the fruit
should be marketed or when the trees should be dormant preparatory
to blooming. As these conditions can not be corrected, citrus orchards
should not be planted in regions where excessive fall or winter rains
are prevalent. This is especially true of the rainy side of most
islands in the West Indies group.
1 For a discussion of artificial frost protection, see Farmer's Bulletin 542, entitled "Culture, fertilization,
and frost protection of citrus groves in the Gulf States."
538







12 SITES, SOILS, AND VARIETIES FOR CITRUS GROVES.

VARIETIES.

The group of plants which is designated by the generic term "cit-
rus" is fairly well circumscribed, but when it comes to a segregation of
the different species and varieties scientists do not all agree. While it
may be of interest to the scientific plant breeder to know just what
the classification is, to the practical grower of fruits who wishes to
get a large return for his labor it makes very little difference whether
the product belongs to one variety or another. The results of the
various attempts to classify the plants which fall under the general
term "citrus" vary exceedingly, and differing opinions regarding
their scientific relations are held by scientific investigators. There
are therefore a number of different classifications. In Table I the
writer has adopted the classification worked out by Dr. Herbert J.
Webber in the Cyclopedia of American Horticulture.

TABLE I.-Botanical and horticultural classes of the genus Citrus.

Botanical species. Botanical varieties. Horticultural races. Horticultural varieties.

I. Trifoliate.... ............ .............................. Trifoliatas.
Sour.
amara..................... ................. Bittersweet.
Seville.
II. Aurantim........... brgamia.................. .................... Bergaot orange.
Valencia.
Pineapple.
(Also other varieties.)
Satsuma.
China (mandarin).
III. Nobilis....................................... The mandarin group...... Dancy (tangerine).
Oneco.
King.
Pernambuco.
Pomelo (grapefruit)....... Triumph.
IV. Decumana.................................... (Also other varieties.)
Paradise.
Shaddock................. Forbidden Fruit.
(Also other varieties.)
Nagami.
V. Japonica.... ............................ Kumquats................ Marumi.
(Also other varieties.)
Corsican.
genui ................. Citron.................... ange.
Also other varieties.)
Lisbon.
Villa Franca.
VI. Medica.............. lemon................... Lemon.................... Sicily.
Eureka.
(Also other varieties.)
Imperial.
acida.................... Lime...................... e an.
(Also other varieties.)


Expeieur ce has taught that no variety of citrus is preeminently
useful for all portions of the world where this fruit is grown. As an
illustration we have the Bahia, or Washington Navel orange, which
is preeminently adapted for California, but is of little value in Florida
538






SITES, SOILS, AND VARIETIES FOR CITRUS GROVES.


or the West Indies, where it produces only a small crop. Certain va-
rieties of pomelo have an exquisite flavor when fruited in Florida,
but are not of the same excellence when grown in California. The
Pineapple orange and the Indian River orange are among the finest
of fruits when grown in the sections where they originated, but when
produced in Jamaica they can not be said to have superior qualities.
It becomes necessary, therefore, to test the particular variety in
the section into which it is to be introduced. Some varieties are
excellent in places far removed- from one another, as is illustrated
by the Satsuma, or Oonshiu, an introduction from Japan, and the
Bahia orange, which was brought from Brazil by the United States
Department of Agriculture and is now so extensively grown in Cali-
fornia. The last-named variety produces fruit of excellent quality
when grown in Florida, but, as stated, is not prolific. Frequently the
most important varieties of citrus for any given locality are those
which have originated as seedlings in that section, or have arisen as
bud varieties. An illustration of a variety arising as a bud variation
is the Surprise navel, originating in Mr. E. S. Hubbard's grove at Fed-
eral Point, Fla., from buds received from California. Seedlings, as a
rule, "sport" or are exceedingly variable; they, however, come true
to seed within certain limitations. So far as known, a pomelo can not
originate from an orange seed, except where an orange flower is polli-
nated from a pomelo, and it is then not a true pomelo. Seedlings from
the mandarin group reproduce a typical mandarin fruit. Seedlings
from the sweet orange produce a typical sweet orange. Seedlings
from pomelos produce pomelos of varying qualities.
The total number of varieties of citrus fruits that have been cata-
logued and described would run up into the thousands. Nearly every
one has some peculiar merit for a particular locality. Out of the
many thousands a few selected ones are of general value, and can be
planted with safety over a considerable area. The following very
brief list gives some of the varieties for the localities mentioned:
Florida.-The Florida State Horticultural Society has divided the
State into four horticultural sections, known as western north Florida,
eastern north Florida, central Florida, and south Florida.
Western north Florida includes that.portion of the State lying west
of the Aucilla River.
The main reliance in the citrus crop for that region should be in
the Satsuma orange. Under special conditions this variety produces
a most palatable and otherwise excellent fruit. Near the Gulf of
Mexico, in frost-protected places, sweet. seedlings, the Pineapple,
Parson Brown, and other early-ripening varieties are planted in
small orchards and are doing well.
538






14 SITES, SOILS, AND VARIETIES FOR CITRUS GROVES.

Eastern north Florida includes "that part of the State between the
Aucilla River and a straight line drawn across the State from the
mouth of the St. Johns River to Cedar Keys."
The following citrus fruits are considered especially adapted for this
region: Of the sweet-orange group, the Pineapple, Parson Brown, and
Sweet Seville; of the tangerine group, the Satsuma; of the kumquat
group, the Marumi and Nagami.
Central Florida includes "that part of the State between the line
above referred to and the counties constituting south Florida."
Of the sweet-orange group well adapted to this section may be
mentioned the Pineapple, Centennial, Tardiff, Homosassa, Jaffa,
Majorca, and Parson Brown; of the mandarin group, the Satsuma,
China, Dancy, and King; of the pomelo group, the Standard, Duncan,
Excelsior, Hall, Marsh, and Royal.
Shaddocks and citrons are not grown as commercial fruits, and
Nagami is the leading variety of kumquat for this section.
South Florida includes the following counties: Brevard, St. Lucie,
Palm Beach, Lee, Dade, Monroe, De Soto, and Manatee.
The sweet oranges recommended for this section are the Hart,
Valencia Late, Homosassa, and Majorca; of the mandarin group, the
China, Dancy, and King; of the pomelo group, the Standard, Duncan,
Excelsior, Hall, Marsh, and Pernambuco.
Shaddocks are not grown commercially and are found only as
ornamentals or novelties. In the kumquat group the leading variety
is the Nagami. Citrons are grown only as occasional specimens, and
lemons are not grown extensively in Florida.
On the keys and the adjacent coast considerable quantities of limes
grow without cultivation and are apparently naturalized. The United
States Department of Agriculture has distributed various importa-
tions of limes in south Florida, and nearly all of these varieties do
very well. The peculiar demands of the market, however, are such
as to make extensive lime growing unprofitable. Nevertheless, very
high prices are paid for the limes which are gathered' from trees
occurring spontaneously on the coast and keys. This lime is gen-
erally spoken of as the Key lime. It is a very small fruit and intensely
acid and usually contains many seeds. This same lime when taken
to the mainland and put under cultivation produces a large fruit
with very thick, rough skin, approaching the lemon in size and appear-
ance. Limes of this size do not meet with ready sale.
Louisiana and Mississippi.-The citrus-growing section of Louisiana
and Mississippi closely borders the Gulf. In Mississippi it is near
Biloxi, and in Louisiana. it is south of New Orleans.
In these sections the common sweet orange grown is known as the
Creole. This, strictly speaking, is not a variety, but an asseuiblage
538







SITES, SOILS, AND VARIETIES FOR CITRUS GROVES. 15

of seedling oranges that have been cultivated in this region for some
time. Of the mandarin group the Satsuma and China are the leading
varieties. Of the pomelo group only a few are grown, these being
the earliest varieties, such as the Standard, Royal, and Triumph.
Texas.-Considerable activity in planting citrus fruits in the Gulf
region of Texas has occurred in recent years. The main reliance has
been placed in the Satsuma on Citrus trifoliata stock.
Porto Rico and the West Indies generally.-Citrus growing through-
out the West Indies is in a rather formative state. The efforts at
systematic work in this line have not been carried forward with the
same degree of vigor as in California and Florida. Nearly all the
varieties recommended for south Florida may be planted with more
or less confidence in this region. After years of experimenting
local varieties will doubtless develop which will prove better than
many of those now cultivated on these islands.
538
O







Issued June 21, 1913.

U. S. DEPARTMENT OF AGRICULTURE.


FARMERS' BULLETIN 539.





PROPAGATION OF CITRUS TREES

IN THE GULF STATES.






BY

P. H. ROLFS,
Director of the Agricultural Experiment Station
of Florida.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1913.









LETTER OF TRANSMITTAL.



U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY,
OFFICE OF THE CHIEF,
Washington, D. C., March 27, 1918.
SIR: Many requests are received at the United States Department of Agriculture for
information on the methods employed in growing oranges and other citrus fruits in
Florida and the other Gulf States, and it is important that the Department be able to sup-
ply the desired information as fully as possible. In order to furnish this information in
concise form, Prof. P. H. Rolfs, Director of the Agricultural Experiment Station of
Florida, has revised Farmers' Bulletin 238, entitled Citrus Fruit Growing in the Gulf
States," and has divided the material contained in that publication into three parts, of
which this paper is the second, as -follows: (1) Sites, Soils, and Varieties for Citrus
Fruit Growing in the Gulf States"; (2) "Propagation of Citrus Trees in the Gulf
States"; and (3) "Culture, Fertilization, and Frost Protection of Citrus Groves in the
Gulf States." In this form the information will be more available for distribution in
the territory directly concerned and will be of more service, it is believed, to prospective
citrus-fruit growers and to planters already engaged in this industry. I have the honor
to recommend that the paper be published as a Farmers' Bulletin.
Respectfully, .
WM. A. TAYLOR,
Chief of Bureau.
Hon. D. F. HOUsTON,
Secretary of Agriculture.





CONTENTS.

Page.
Introduction ------------------------------------------------------------ 3
The nursery ------------------------------------------------- 3
Suitable stocks for different sections_ ------------------- --- 3
Louisiana and Mississippi --------------------------------------- 3
Eastern north Florida ---------------------- -------- ------- 4
Central Florida -- ----- -------------------- 4
South Florida------------------------------------------------- 4
Selecting seeds ----------------------------------- ---- 5
Keeping seeds---- 5
Preparation of the seed bed -------------------- ---------. 6
Time of sowing ------------------------ ---------- 6.
Cultivation of the seed bed --------------- ---------------------- 7
Transplanting .. 7
Transplanting ------------------------------------------------------- 7
Preparation for the nursery------------------------------------- ----- 8
Cultivation of the nursery ---- ----------------------- 9
Seedling grove------------------ ----------------
Propagation by cuttings-- ----------- ---
Budding-------------- -------------------------------- ----- 1
Time of budding ------------------------------------ 10
Cutting buds ----------------------------------- -----------10
Selecting buds ------------------------------------------------------ 10
Materials for budding_------------------------------------------------ 11
How to bud---------------------------------------------------------- 12
Unwrapping the buds ------------------------------------------ -- 14
Forcing the buds ---------------------------------------- ---- 14
Growth of the buds --------------------------------- ------ 15
Dormant budding------------------------------------------------------ 16





ILLUSTRATIONS.

Page.

FIG. 1. Citrus nursery at Naomi, La ------------------------------------ 4
2. Sweet-orange twigs -------------------------------------------------- 11
3. Strip of budding cloth, showing method of removing surplus wax ------- --- 1
4. Shield or eye buds ------------------------------------------------- 12
5. Shield or eye budding -------1------ ------------------------- 13
6. Shield budding with angular wood ----------------------------1
7. Treatment of buds------------------------------------------
8. Diagrams illustrating methods of lopping nursery trees----------------- 1
9. Arrangement of stakes in a nursery ..-------------------------- --- 16
79800--Bull. 539-15
2












B. P. I.-878.

PROPAGATION OF CITRUS TREES IN THE

GULF STATES.


INTRODUCTION.
This bulletin is published to fulfill an urgent request from grow-
ers in the Gulf States for a brief description of the methods of
propagating citrus trees and of the most important nursery prac-
tices. It includes also a discussion of the choice of suitable stocks
for different regions. Because of the limited size of the publication
and in order to make it applicable to Florida and the other Gulf
States the questions have necessarily been treated in a very general
manner.1
THE NURSERY.
The nursery is the starting point of the citrus grove. It is there-
fore one of.the factors of greatest importance. No matter how well
the climate may be suited to the growing of fruit or how well the
grove may be cared for after it is planted, if improper selections
have been made in the matter of stock or of buds, disappointment is
just as certain as if improper selection had been made of the locality
in which to grow the fruit.

SUITABLE STOCKS FOR DIFFERENT SECTIONS.
Each of the principal citrus-growing regions of the United States
has a stock which is best adapted to its own peculiar conditions.
Even in the larger citrus-growing. regions the variations of soil are
such as to demand different kinds of stocks or buds.
Louisiana and Mississippi.-In Louisiana and Mississippi the soil is
a heavy clay, very fertile, and usually quite moist. Citru trifoliata,
or trifoliata, as it is commonly called, is preeminently the stock for
use in this section. Here it not only is a vigorous grower but also
imparts more or less of hardiness to the scion by becoming dormant
in the autumn, since the trifoliata is a deciduous species (fig. 1).
'For discussions of other phases of this industry, see Farmers' Bulletins 538, entitled
" Sites, Soils, and Varieties for Citrus Groves in the Gulf States"; 542, entitled "Cul-
ture, Fertilization, and Frost Protection of Citrus Groves in the Gulf States"; and
172, entitled Scale Insects and Mites on Citrus Trees." A Farmers' Bulletin on the
harvesting and marketing of citrus fruits is in preparation.
539 Q







4 PROPAGATION OF CITRUS TREES IN THE GULF STATES.

Eastern north Florida.-In the eastern part of north Florida the
trifoliata is also the best stock to use, for the reason given in the pre-
ceding paragraph. Much of this region is also a rather heavy, sandy
soil inclined to become clayey. In the deep, sandy portion of this
section some of the more rampant-growing stocks do equally as well
as or possibly better than the trifoliata, but they do not produce quite
so hardy a tree.
Central Florida.-Throughout central Florida the soil is inclined to
be sandy, but usually contains a considerable quantity of decaying
vegetable matter. On this soil the pomelo stock does best, although
it does not make quite so hardy a tree as the sour-orange stock.


FIG. 1-Citrus nursery at Naomi, La.: Trifoliata stock and mandarins to right; pomelos
to left. Buds of one summer's growth.
South Florida.-The rough lemon is preeminently the stock adapted
for use in south Florida. It is a rampant grower, able to live on soils
that are almost sterile for the other stocks mentioned, but is inclined
to produce a little more coarse fruit than the other stocks. In the
heavy soil of this section, especially that which is free from lime-
stone, the pomelo and sour orange may be used to good advantage.
These trees are somewhat slower in growth, but produce a more
smooth and velvety fruit and ripen more evenly. The lime seedlings
have also been used for stocks in this section. This makes a tree
rather sensitive to cold, and the earliest crops of the fruit are inclined
539






PROPAGATION OF CITRUS TREES IN THE GULF STATES.


to be somewhat rough and thick skinned. The greatest drawback,
however, from the nurseryman's point of view, is that the ordinary
operation that would make 90 per cent of the buds live in rough-
lemon stock would probably not give more than 50 per cent in the
lime stock. It is therefore used very little.

SELECTING SEEDS.
In selecting seeds from which to grow nursery stock, one should
choose well-matured specimens. It is a matter of indifference as to
the perfection or imperfection of the fruit from which the seed is
taken, but the seed should be plump and well filled and the fruits
taken from the most vigorous trees. This is true for all the varieties
that are to be used as stock. One is frequently able to secure a lot
of pomelo drops and culls and from these secure large numbers of
fine seeds.
There are various methods of obtaining seeds from the fruit.
Where fruit has been damaged and thrown out to rot, the seed may
be washed out from the rotting mass and the superfluous water dried
off. The seed may be separated fairly easily by using an ordinary
sieve with large openings and forcing the water on the seed by the
use of a force pump or from a tank.
After gathering these fruits they are cut into sections with a dull
knife and most of the seeds pressed out, and the cut sections are
thrown into a barrel and covered with water. In a short time this
mass will be sufficiently disintegrated to allow easy separation of the
remainder of the seed. Care must be taken, of course, not to let the
material remain in the water long enough to injure the seed. If the
barrel is placed in a warm location, in two or three days the seeds
will slip out easily, and they can then be separated from the pulp by
washing.
The seeds that are squeezed out by hand need no special washing.
They should be placed in the open in a shed to allow the superfluous
moisture to dry off and then are ready for preservation. Bonavia
says that in India the seeds "are well dried in the sun for two or
three days."
KEEPING SEEDS.
In the. northern sections of the citrus-growing regions the seed
must be kept for a considerable time before the ground is sufficiently
warm to receive it. After the superfluous moisture has dried from
the seeds, which will occur in the course of from one to three days,
they may then be preserved in dry sand. Where sand is not readily
obtained, a fairly dry clay, such as will break up readily but which
is not moist enough to pack, will be found useful. In this kind of
539







6 PROPAGATION OF CITRUS TREES IN T HE GULF STATES.

material the seeds of trifoliata have been shipped from Japan to
Florida and have retained their germinating qualities perfectly.
PREPARATION OF THE SEED BED.
Where only a few thousand seeds are to be planted they may be
germinated in boxes or trays. Taking a box which is about 8 or 10
inches deep, with its other dimensions of convenient size, 3 or 4 inches
of soil are placed in the bottom. The seed may then be sown on this
layer of soil and an inch more of soil placed over them. Over this
a layer of mulching, such as decayed leaves or sphagnum, or, in
fact, anything that will keep the soil from drying out, may be placed,
and in this the seed may be allowed to germinate and seedlings
grown. The mulching should be removed as soon as the seedlings
begin to come up.
The ordinary seed bed, or cold frame, as it is usually prepared by
gardeners, is also an excellent place to germinate the .seed and grow
seedlings. In planting in beds of this kind the rows should be made
6 inches or a foot apart and the seeds dropped at'the rate of one or
two dozen to each foot of row. The seedlings may be left there until
they have grown sufficiently large to be planted in the nursery.
For growing seedlings on a large scale, where hundreds of thou-
sands are to be grown, it becomes necessary to make a careful selec-
tion of the spot where the seeds are to be planted. A place that is
not in danger of being flooded or becoming too wet, and yet that will
remain constantly moist, should be chosen. This land should be
thoroughly broken up, plowed deep, especially if it is of a heavy or
clayey nature, the rows laid off from 2 to 4 feet apart, according to
conditions, and the rows then opened and a liberal application of
fertilizer made. If the site happens to be a clay soil it is well to
break the rows at least 10 inches deep. Fertilizer is then scattered
down the rows and worked in thoroughly by the usual farming im-
plements. From two weeks to a month after the seed bed has
been prepared in this way the seed may be sown. The furrows are
thrown open 5 inches deep and the seed scattered down the rows,
being sufficiently distributed to give each seed an inch or so of space.
The rows may be made from .4 to 8 inches wide, according to the
needs and conditions. The seeds are then covered about an inch
deep and the soil firmed about them. If drought follows the plant-
ing it may become necessary to resort to watering to keep the seed
from drying out.
TIME OF SOWING.
The best time to sow depends upon the location of the seed bed.
In southern Florida and the West Inidie- the seed may be sown as
early as December. In central and nortAern Florida, and in Louisi-
539






PROPAGATION OF CITRUS TREES IN THE GULF STATES.


ana; Mississippi, and California, it is better to wait until the soil has
warmed up sufficiently to induce rapid germination and active
growth. This time may be reached' anywhere from the first of
February until about the middle of March or later, varying in dif-
ferent seasons and in different localities.
CULTIVATION OF THE SEED BED.

The cultivation of the citrus seed bed is the same as that usually
given to seeds of garden crops. At first a light working, such as may
be done with a garden rake, will be most useful. A skillful laborer
may rake over a seed bed when the seedlings are coming through
the ground with entire safety to the small plants. This raking may
seem quite useless in many instances, but it is very important in that
it conserves the' soil moisture and breaks the crust if there is any
tendency to form a hard surface. The middles may be cultivated
with the usual shallow-going farm tools-a spring-tooth cultivator,
a special harrow, or a hand plow. Cultivation should be repeated
every week or ten days, and as the seedlings grow stronger the culti-
vation in the clay soils should be made deeper, until in midsummer
or early autumn it has reached the maximum depth of farm cultiva-
tion. On the sandy lands cultivation should never be more than 3 or
4 inches deep, for on such lands the soil is already sufficiently loose
and further stirring does not add to its productiveness.
TRANSPLANTING,
Under -favorable conditions the seedlings will have attained a
height of from 6 to 12 inches and the diameter of a small pencil by
autumn or by the next winter. The seedlings are then in good con-
dition for transplanting. The best time for transplanting is less
definite than that of sowing the seed. In the West Indies and south-
ern Florida transplanting may be done with good success any time
after the seedlings are of sufficient size, depending on the favorable
condition of the soil. In other citrus-growing regions transplant-
ing is done in the spring or early summer, whenever favorable cli-
matic conditions occur. Under some conditions seedlings are per-
mitted to remain in the seed bed for nearly two years.
In preparing for transplanting on a large scale the nurseryman
frequently uses a tree digger to run under the seedlings. This loosens
up the ground on both sides, and at the same time cuts most of the
taproots. The depth to which the tree digger should be run will
depend on the amount of root growth the seedlings have made. In
heavy soils transplanting is much facilitated by plowing a deep fur-
row on each side of the seedling row. A heavy spade may then be
inserted under the row, and the seedlings lifted without much dam-
539







8 PROPAGATION OF CITRUS TREES IN THE GULF STATES.

age to the root system. Some means for keeping the roots moist
after they have been removed from the ground should be provided.

PREPARATION FOR THE NURSERY.
The location of the nursery is of very considerable importance.
The land selected can usually be slightly more moist than such as
would ordinarily produce a good grove, but to be successful it should
not be subject to flooding, nor should it be subject to drying out dur-
ing severe droughts. The rows should be laid off from 4 to 6 feet
apart, thoroughly broken out to a considerable depth, say about 10
inches, and then prepared in the usual manner in which gardeners
prepare their land for vegetables.
Thoroughly rotted stable manure will be found an excellent ferti-
lizer in heavy clay soils. In the soils that are inclined to be sandy,
commercial fertilizers will be found of greater advantage. The
quantity of manure and fertilizer to be used will depend on the fer-
tility of the land to be planted. Upon the ordinary sandy soils
from 500 to 1,000 pounds will be found entirely sufficient for the
first application. On rich clay soils well-rotted stable, manure at
the rate of several loads to the acre will be found sufficient.
The rows should be prepared thoroughly and the land made ready
about a month before the probable time for setting out the nursery
stock. After the land has been prepared it will do no special harm
if one has to wait longer than was expected before a favorable time
for transplanting arrives.
When the time for transplanting arrives the seedlings may be
taken out of the seed beds and transplanted into the nursery rows in
various ways. The trees should be set about a foot apart in the row.
Many nurserymen prefer to use a thin spade for transplanting, run-
ning this into the ground, bending it over, and setting in the tree.
In this operation one man uses the spade while another man inserts
the tree. When the spade is withdrawn, each man presses a foot
near the tree and firms the soil tightly about it. In other cases the
nurseryman prefers to simply run a furrow or double furrow down
the row, set the tree firmly into position by hand, and then fill in the
soil with a plow.
In setting the seedlings they-should be placed so that the level of
the soil is approximately at the same height on the seedling as when
it grew in the seed bed. If the trees happen to be set an inch or
so lower it will be of no serious disadvantage. In this work of trans-
planting, all small and inferior seedlings should be thrown out, as
in all probability they will make only second or third rate nursery
stock and will prove to be poor trees in the grove. What is wanted
of nursery stock is a tree that has vigorous growth.
539






PROPAGATION OF CITRUS TREES IN THE GULF STATES.


CULTIVATION OF THE NURSERY.

The cultivation of the nursery may begin immediately after the
seedlings are set out. The cultivation at first need not be deep,
merely running over with the finishing tools to conserve the moisture
and l -:, the ground in good condition. .Where the soil is sandy the
cultivation at no time need be much more than this. In the heavy
clay soils it is important to break up the soil as deeply and thor-
oughly as possible. The length of time elapsing between repetitions
of cultivation will depend upon the condition of the soil. In all of
the work of cultivating citrus trees it should be remembered that
the det iruction of weeds is of secondary importance. Of course this
should never be neglected, but the real value of cultivating lies in the
fact that the soil is kept in a suitable condition of aeration. If a
heavy, beating rain falls immediately after cultivating, much of the
good effected by the work is lost, and consequently another cultivation
should be made as soon as the soil conditions will permit.

SEEDLING GROVE.

In the early history of the citrus industry main reliance was placed
on the propagation of trees from seed. Such trees, when grown to
fruiting age, are usually spoken of as seedlings. The use of seedling
groves has been almost entirely superseded by budded groves. At
the present time very fev seedling groves are being planted. If
one wishes to plant a seedling grove it is of the utmost importance
to make a careful selection of the tree from which the seeds are
taken. The parent tree should be a uniformly heavy cropper and
one that produces superior fruits of the kind desired. Even with
all of these precautions there is less certainty as to the quality and
quantity of fruit that will be produced than where budded trees are
planted.
Another disadvantage of planting seedling groves is that such trees
are later in coming into bearing than budded trees and as a rule are
of a more upright growth. The vigor of seedling trees is usually
greater than that of the ordinary budded grove, but this is practi-
cally the only strong argument in favor of a seedling grove.

PROPAGATING BY CUTTINGS.

Lemons, limes, pomelos, and other citrus species may be propa-
gated very readily from cuttings. The cuttings should be made
from fairly matured wood and at such time of the year as will give
considerable moisture to the soil and at the same time considerable
539







10 PROPAGATION OF CITRUi TREES IN THE GULF STATES.

warmth. While these cuttings have been employed for producing
nursery stock on which to bud they are not so satisfactory as seed-
lings. The growth is somewhat slower and not as straight. Root
cuttings from these various species may also be employed, but these
have the same disadvantages that are encountered with the use of
cuttings from the branch.
BUDDING.
There are various methods of propagating citrus trees-by bud-
ding, grafting, or inarching. While there are conditions under
which grafting becomes necessary and when inarching must be prac-
ticed to obtain the desired end, budding is preeminently the best
method of propagating citrus trees. The work is done so easily and
may be accomplished with such certainty of good results that graft-
ing and inarching as methods of increasing the stock of any particu-
lar variety must be considered obsolete.
The subject of budding was well covered by Dr. H. J. Webber
in his paper entitled "Methods of Propagating the Orange and
Other Citrus Fruits," which appeared in the Yearbook of the United
States Department of Agriculture for 1896, and as no important
improvements have been made since that date the following chapters,
with the exceptions of those on time of budding and on cutting buds,
are quoted without modification.

TIME OF BUDDING.
In regions where a more or less definite winter occurs, budding is
practiced either late in the autumn, about November or December,
and called dormant budding; or in the spring, after a vigorous growth
has started. Good citrus stock may be budded at almost any time of
the year, except during the winter in those sections where a decided
lowering of the temperature occurs. In general it may be said that
buds may be inserted at any time of the year when the bark of the
stock separates easily from the wood. This always indicates a, strong
flow of sap.
CUTTING BUDS.
Some experienced nurserymen prefer to cut the bud sticks and keep
these for a few days or several weeks before inserting the bud. It is
thought by them that a larger percentage of the buds will take under
these conditions.
SELECTING BUDS.
Bud wood should always be selected from fairly well-matured wood of the
current year's growth. Round sticks (or as nearly round as possible) should
be selected. The young growth of orange wood is at first angular, becoming
rounder as the twig matures. The basal portions of the young branches, which
are nearly or quite round (fig. 2, a), supply the best buds, with the exception
of the first two or three, which are usually somewhat imperfect and should be
539







PROPAGATION OF CITRUS TREES IN THE GULF STATES.


discarded. Where it is difficult to secure well-rounded wood, angular wood
which is not too soft (fig. 2, b) may be used. This, however, is not quite so
satisfactory. Thorny bud wood should never be used
when other wood can be obtained. Thorny trees are very
undesirable, and a careful selection of thornless bud
wood will soon result in thornless trees. The thorns
have been bred out of many of the best citir.l v.rieties.
and if nurserymen would exercise po:r'er :.a;re L iall the
desirable varieties could soon be rend-r'e thorniles.
After cutting, the leaves should be iiriiuel .off ,u.l the
twigs cut into sections of the desired length. To preserve.
the bud wood until needed the twigs should be tied up in
convenient-sized bundles, carefully labeled, and packed in
old sawdust in a box of suitable size. The box should a
then be closed and buried in sheltered gro:iul s \-era-l '
inches below the surface. In this way bud r......:i I:al ? ; e
preserved in good condition for from two to three months.
Dampened sphagnum, or peat moss, may be used instead
of sawdust, but in this case considerable care must be
exercised to get the moss properly dried. It must be
moist, but not wet, for if too wet The bud wood may mold.
The same caution applies also to sawdust. In this case
the proper degree of moisture can be secured by taking the
material from the interior of an old pile. Sawdust does
not lose its moisture readily and is the best material for FiI. 2.-Sweet-orange
twigs: a, Round
packing. Some simply bury the bud wood in the soil under twig f elct buds
shelter, digging down until the moist earth is reached.' b, angular twig of
buds. (From Year-
MATERIALS FOR BUDDING. book, U. S. Dept. of
Before beginning the operation of budding, material Agriculture, for
1896.)
S should be provided for wrapping the buds. For this pur-
pose cotton cord, yarn, strips of waxed cloth, etc., are used. The last named
has practically superseded all others in Florida, being more convenient and
giving better results than any other wrapping material. The strips are made
from strong muslin or calico. Before the cloth is torn
into strips it is folded into convenient size and dipped
b into a hot solution of wax made by melting together two
I parts of beeswax and one part of rosin. Several formulas
for making this wax are used, any one of which will
probably answer. The method described is known from
personal experience and observation to give good results.
FIG. 3. Strip of After saturating the cloth with the hot wax, all the super-
budding c lot fluous wax should be removed before the cloth cools. To
showing method of
removing surplus accomplish this quickly, hang the piece of cloth, folded in
wax. (From Year- convenient form before waxing, over a small, strong
book, U.. S. Dept. stick (fig. 3, a), which is held by an assistant. Then
of Agriculture, for take two similar sticks of wood, and holding them parallel
1896.)
on either side of the cloth (fig. 3, b), press them firmly
together and pull downward, squeezing out the superfluous hot wax. The cloth
should then be spread out until cool, after which it is ready to be torn into
strips of the desired size-that is, one-fourth to one-half inch wide and from

SThe clean, long sawdust from cypress shingles will make'an excellent packing mate-
rial.-P. H. R.
539








12 PROPAGATION OF CITRUS TRrEES IN THE GULP STATES.

10 to 12 inches long. The cloth may be torn: into strips before it is taken into
the field or it may simply be torn into convenient-sized pieces and afterwards
torn into strips in the field as desired for use. The latter is probably the most
convenient way.1
Using waxed cloth for wrapping, effectually excludes moisture, prevents the
bud from drying out, and the work can be done more quickly than with string,
as the strips.cover more surface and do not require tying, the wax serving to
hold the cloth firmly in place. It may there-
Ifore be recommended as far preferable to
any other wrapping material.2

HOW TO BUID.

Budding is a simple process, consisting in
inserting a bud of a desired variety under
the bark of the stock in such a way that
the freshly cut inner bark of the bud comes
in close contact with the layer of growing
wood (cambium) of the stock. The bark is
closed over the inserted bud and the stock
I wrapped with waxed cloth, as described, so
that the bud is firmly pressed against the
growing wood. If the operation is properly
performed, the tissue of the bud and stock
soon fuse together and the bud may be
forced to grow.
A In all varieties and stocks of citrus fruits
the process of budding is practically the
b c same, the method commonly employed being
that known as shield or eye budding (fig. 4).
The bud is inserted in the young stock near
FG. 4.-Shield or eye buds: a, the ground. Previous to the severe freezes
Method of cutting bud from round of the winter of 1894-95 the general prac-
twig; b, bud cut ready to insert; tice was to insert the buds 12 to 18 inches
c, face of bJd showing the cut above the ground, but since then the tendency
surface. (Fiom Yearbook, U. S.
Dept. of Agriculture, for 1896.) is to bud as near the surface of the soil as
possible, so that the trees may be readily
banked with the earth above the bud to protect against injury from freezes.
Most of the buds are now inserted from 2 to 6 inches above the soil. In sections
where foot-rot is abundant and sour-orange stock is used as a preventive meas-
ure the buds should be inserted from 12 to 18 inches above the soil, so that
the sweet-orange wood will be above the influence of the disease.
All leaves and limbs which would hinder the proper wrapping of the buds
should be cut away with a sharp budding knife. The use of sharp tools is the
secret of success. A vertical cut about 1J inches long is made at the point where

1The waxed cloth may be torn in strips half an inch wide and the length of the cloth
and wrapped into balls. In wrapping the balls each new piece added is slipped about
half an inch under the former piece. These balls make a very convenient method of
carrying the waxed cloth into the fleld.-P. H. R.
2The choice of wrapping material is an individual and a local affair. Some nursery-
men use only raffia and have nearly perfect success; other nurserymen use only cotton
wrapping twine and their buds take almost perfectly. They are located in the moister
sections, where buds are not likely to dry out.-P. H. R.
539







PROPAGATION OF CITRUS TREES IN THE GULF STATES. 13

the bud is to be inserted. At the base of this a horizontal cut is made, so that
the two cuts present the appearance of an inverted T (-), as shown in fig. 5, a.
The cuts should not be deep. The aim should be to merely cut through
the bark, but no injury will result if the cuts are rather deeper. The
lower edges of the bark are slightly raised with the end of the knife blade
(fig. 5, b) to facilitate the insertion of the bud. This may also be accomplished
by giving the knife an upward turn after making the horizontal cut. Now,
take a stick of bud wood in the left hand and cut out a bud, as illustrated in
fig. 4. Formerly the portion of the wood cut out with the bud was removed,
but experience has shown that this is entirely unnecessary. The upper end of
the bud is inserted under the slightly raised uends of the bark (fig. 5, c) and
gradually pushed upward until all portions of the cut face of the bud come in
contact with the wood of the stock (fig. 5, d). If in proper condition for bud-
ding, the bark of the stock readily -.'a r'a te. allowing the bud to be pushed









1 .1











a bc d
FIG. 5.-Shield or eye budding: a, Incision on stock; b, incision with lower ends of
bark raised for inserting the bud; c, bud partially inserted; d, bud inserted ready to
wrap; e, bud wrapped with waxed cloth. (From Yearbook, U. S. Dept. of Agriculture,
for 1896.)

upward into position. The bud is now ready to wrap. Take a strip of the
waxed cloth prepared as above, and beginning slightly below the horizontal cut
wrap tightly around the -stock over the bud in a spiral manner, each turn
slightly overlapping the previous one. The wax holds the cloth in place and
makes it possible to draw it very tight. henc the vertical incision has been
entirely covered, turn the end of the 4rtrip slightly downward over the wrapped
portion, to which it adheres more driuly than ic would to the bark, and no
tying will be necessary (fig. 5, c). It is. better to wrap from below upward, as
in this case each turn overlaps the other in the right direction to prevent water
running down the stem from entering. Nurserymen usually wrap over the bud,
covering it entirely. Some, following the practice commonly used with other
fruits, leave the eye of the bud exposed. This, however, is more troublesome
and does not succeed so well.
In some cases where bud wood of certain varieties is difficult to secure, it
may be desired to use buds from the young angular wood (fig. 2, b). This may
539








14 PROPAGATION OF CITRUS TREES IN THE GULF STATES.

be used with good results if the stock to be budded is growing rapidly and is
in a succulent condition. In this case the method of cutting and inserting the
bud is slightly different from that already described. In cutting the buds the
tli': k i- it ni rj,- slightly to one side, so that as the bud is cut off the eye lies on
one side in-te:id of in the center of the bud (fig. 6, a, b, and c). It is only by
cutting the bud in this way that the cut surface is made wide enough to hold
the bud firmly in position. For- inserting these buds an incision is made in
the bark, as shown in fig. 5, a. The bark is slightly raised on one side with the
point of the knife and the bud is slipped under in a lateral direction, the eye
remaining in the vertical slit
S*. (fig. 6, d). The bud is then
i wrapped as shown in fig. 5, e.

S.. UNWRAPPING THE BUDS.


FIG. 6.-Shield budding .i;th inL;.toa w
Cutting the bud; b6 bud ,oj, rea d-- to
c, bud showing cut face; d, bud inserted
on right side only being raised. (Fron
book, U. S. Dept. of Agriculture, for 1896


In from 10 to 12 days the
buds will have united with the
stock and may then be un-
wrapped. In early spring, when
the weather is cool and the
g r..w tL slow, the wrapping
should be left on from 15 to
20 days, while in the summer
when the weather is warm
and the growth rapid, 10 days
is usually a sufficient length
of time. However, it is im-
possible to say definitely how
d much time should elapse be-
fore the wrapping should be
removed, as the wood of the
stock should never be allowed
to grow over the buds. It
ood: a, -should not be removed until a
insert;
d, bark light grayish line of new tissue
SYear- can be seen forming around the
) edge of the incision made in
inserting the bud. A little ex-


perience will enable one to tell at what stage it is safe to unwrap. Under
ordinary conditions from 12 to 15 days will give good results, but in very dry
weather in the summer, when growth is slow, it may be necessary to leave the
wrapping on for a longer time. Some 10 days after budding an examination
should be made of a number of the buds, and if they are fofind to be well healed
on, the wrapping may be taken off; but if not, the wrapping should be replaced
and allowed to remain some time longer. If the wraps are allowed to remain
too long, the wood of the stock is likely to grow over the buds and greatly
hinder their pushing.
FORCING THE BUDS.
In order to force the buds to push uniformly after they have healed on, it is
necessary to severely check the growth of the stock. This is most commonly
accomplished in nursery trees by lopping the tops, as it is called, which is
usually done from 3 to 5 days after the wraps are removed from the buds.
The lopping is usually done with pruning scissors, the knife edge being placed
589







PROPAGATION OF CITRUS TREES IN THE GULF STATES.


about 2 inches above the bud and the stock cut two-thirds through. The top
is then bent over to one side and allowed to rest on the ground (fig. 7, a).
To provide for subsequent cultivation and attention it is necessary to use
some definite plan of budding and lopping in the nursery. Two methods most
commonly followed by Florida nurserymen are to lop the tops of two adjoining
rows -into the same center (fig. 8, a), keeping the alternate
centers free for cultivation, or to lop the tops of alternate rows
in different directions, one row in each center (fig. 8, b), and
place them near the rows. By the latter method a cultivator
may be run up one row and down the other, passing always
in the direction in which the tops are inclined so that the
branches will not interfere with the cultivator. Usually the old
tops are allowed to remain attached until the buds hban attained
a height of from 12 to 18 inches, after which they may 1..e .-ut off. b
Some nurserymen have
found: that the buds
make a larger growth
if tue old tops are
nllow.-d to, remain at-
ta.bJ-d through the sum-
r11r "t,! ;'ar ocut off in
pWLre-ul r. Itthisprac- FIG. 7.-Treatment of buds: a, Young tree lopped to
tice i ffllin -1d. two force bud; b, bud and supporting stake after "lop"
rw .,f th houd be as been removed. (From Yearbook, U. S. Dept. of
f tri should ultr.... for 1896.)
i'pped tI.'eether. The
ti-!-- thui- f..ri a dense shade or sort of mulch on the soil, keeping it moist
and preventing the weeds from growing. In this case it is also desirable
that the rows lopped together should be planted rather close (about 3 feet


V V

\/ \ \
a
FIG. 8.-Diagrams


40 0






b
illustrating methods of


lopping nursery trees: a, Lopping two rows
in one center, leaving alternate centers
free for cultivation; b, lopping alternate
rows in opposite directions. (From Year-
book, U. S. Dept. of Agriculture, for 9,..,


apart), for if this is not done the
weeds will grow up among the tops,
making it necessary to cut off the
latter when the buds are 1 foot to
18 inches high in order to keep the
weeds down. In the case of vigor-
ously growing stocks, like the rough
lemon, it is said to be very desirable
to leave the tops attached for some
time.
When the old tops are removed,
the portion remaining above the
bud should be cut off smooth and
close to the bud, so that it will
soon heal over without forming an
ugly scar (fig. 7, b). Some follow
the practice of coating the freshly


cut end with shellac, but others working on an extensive scale never do this.
It is seldom that any noticeable benefit is derived from the practice.

GROWTH OF THE BUDS.
The attachment of the rapidly growing bud is at first very weak and it is
necessary to strengthen it by tying to a stake (fig. 7, b). Some nurserymen
practice cutting the stock rather high in lopping, and support the buds for a
539








16 PROPAGATION OF CITRUS TREES IN THE GULF STATES.

funle by tying them to the remaining portion of the stock. The Iu.ijdl Ilib much
I,.- rer. however, when the stocks are cut very close in lopping, so that it is
h: irdl y desirable to depeudt upon this method of supporting the buds, as in
either case it is necessary later to supply the .ulpi..rtiug stakes. (See figs.
7 and 9.)
The development of the buds should be carefujlly watched during summer,
and they should be pruned in such a way as to produce a top of the desired
shape. In Florida, where a lown tree is desired, it is necessary to nip the tops
when thLe-v re 2 or 3 feet high] to induce branching. The buds w'hieh puiih ).:.w


FIG )..- Arrangmenr i.. stakes In a oirery Froa Yearl,.:.k, U. Dept .:.'f .\c ihrure,
for 1896.)

down on the stock or bud should- be rubbed off before they have grown to any
size, as their growth detracts from the development of the bud.

DORMANT BUDDING.
Putting in buds which are intended to remain dormant during the winter, or
dormant budding, as it is called, is usually done in October or November. The
process is exactly the same as described above, except that the tops are allowed
to remain standing until the following spring. They are lopped in the usual
manner the latter part of Ilbriiar., or just before the spring growth starts.
The advantage of dormant budding is to secure the first spring growth in the
bud, which is the largest growth i the year.
539






(Sb


Issued July 9, 1913.
U. S. DEPARTMENT OF AGRICULTURE.



FARMERS' BULLETIN 542.





CULTURE, FERTILIZATION, AND FROST

PROTECTION OF CITRUS GROVES

IN THE GULF STATES.





BY

P. H. ROLFS,
Director of the Agricultural Experiment Station of Florida.


WASHINGTON:
GOVERNMENT PRINTING OFFICE,































CONTENTS.


Page.
In troidu' tion ...... ......... ...- ........ .-- -------......... 5
Prepar.ritnr of tle land ......---- .... -..-. ----.--.---- ......... 5
Setting out trees ...............-..-... ---.--.-..- ..- .......-......-...- 6
Time and manner of setting out trees........... ........................ 6
Catch crops. ................. ..- ...... ..-...... .. .- .. .. .. .............. 7
Pruniiig......... ......... . . ........... ......... 7
Fertilizers.......... ... ..... ........ ................ 8
Fertilizers......------------------------------------------------------- 8
Commercial fertilizers for Florida -.......-----....... --- ..-- ..........
Stable manure of doubtful utility ..............-.... .......-...... 11
Tnjurious .i :ti:n ruiic .................. ........... .. .. ..... .. 12
T'rr~- Ii'i ..'i~l~ (-Id--------------------------------------------1
I -'rr, t n: ri'i:n ,.,.u. .tl coldl ................ .. .............. ....... 12
Pro:ter: li, u by be:.-t ........ ..... .. . ........ .... .. ... ---12
Fuel oils........ ........ ........ --... .. -- ------.... : ....... ..... 13
'Heaters ................... ......-................................ 13
Storage tanks ........ ------. ...--......-......... ....... .... 15
Cost of heating..............----------------------------------------...........-- 15
Wood fires.-....- ......................-........ ............... 16
Protection by irrigation ................................... ... 17
Protection by sheds ..................-............. ................. 17
Top-working..... .---.....--.......... ......... ........................... 18
Crown-working ............................-- ......-......... ............. 19
542 3


I






































ILLUSTRATIONS.

Page.
Ficr. 1 "'r.-i wn.rajfting an old orange stock ............-..........-.......... 18
Ri by ra nge bud, inserted May 21 on a sprout from an old sweet-orange
tri nl:r, is it appeared on October 25................-............... 19
: .i.r .:,:n agecrowngraft, insertedMarch 1, asitappearedon October 23. 20
542


















B. P. I.-890.

CULTURE, FERTILIZATION, AND FROST PROTEC-
TION OF CITRUS GROVES IN THE GULF STATES.


INTRODUCTION.

The growing of citrus fruits, an industry which has attained vast
proportions in Florida, is receiving much attention in other Gulf
States. The purpose of this bulletin is to answer some of the many
inquiries constantly received by this Department and to act as a
general guide for prospective planters who need definite advice upon
questions of citrus-fruit growing. The information is necessarily of
a very general character, but the essential factors are presented in a
manner which, it is hoped, will enable planters to understand fully
the fundamental principles involved.1
PREPARATION OF THE LAND.

As a rule, the field chosen to be planted out to an orange grove is
land with a native growth upon it. Usually the land is covered with
forest trees. Various devices have been used for reducing the amount
of labor necessary to get rid of this native growth, but up to the
present time no substantial or decided progress has been made in
the methods of clearing land. The most of the work is done by main
strength and muscular labor. Where the native growth happens to
be some form of hard wood, it is the usual practice to remove the
trees and stumps. Some advantage is frequently obtained by the use
of dynamite or other explosive in loosening the stumps. Where
the native growth is pine woods or palm trees, the necessity for
removing the sIilinp is not so great, though in the case of the former
the stumps are usually taken out. In cabbage-palmetto hammocks
some of the trees are left and used as nurse plants for a few years.
The most economical course is to remove all trees, shrubs, and
other forms of vegetation from the land and to clear it of all rocks
and any other debris that may be found. Then the land may be
broken up and put into a first-class state of tilth, which will permit
careful staking and planting.
1 For a discussion of other phases of this problem which can not be included here, since
to treat them adequately would unduly increase the size of this bulletin, see Farmers'
Bulletins 528, Sites, soils, and varieties for citrus groves in the Gulf States; 539, Prop-
agation of citrus trees in the Gulf States; and 172, Scale insects and mites on citrus
trees.










6 CULTURE OF CITRUS. GROVES IN GULF STATES.
SETTING OUT TREES.

Usually the prospective orange grower buys trees from a nursery
and sets them out as soon as the field has been cleared, wishing, of
course, to get the trees on the land as soon as possible and to hasten
the time when he may be selling fruit. Sometimes this is by no means
the most profitable procedure. Land especially rich in organic matter
and heavily matted with roots from the native growth would be
decidedly better for having produced a crop or two of vegetables
before the grove is planted. If for any reason it is not desirable to
grow vegetables, a crop of weeds grown on it for a year would do
much to sweeten the land preparatory to receiving the trees. A
crop of cowpeas or velvet beans would be preferable, however.
The number of trees to be set out to the acre depends on the variety
selected and the character of the land. Large-growing citrus trees,
such as pomelos and the Valencia Late and Hart sweet oranges,
should not be set closer than 100 to the acre, and on first-class soil
80 are enough. Smaller growing varieties, such as the mandarin
group of oranges and the limes, should not be set closer than 200 trees
to the acre. The character of the land will also need to be consid-
ered in setting out a grove. In a sandy loam rich in organic matter,
especially in southern Florida, trees grow much more vigorously and
in consequence should be set farther apart. Forty-nine trees to the
acre, i. e., setting them 30 feet apart each way, is about as small a
number as one can afford to plant. In.the heavy clay soils trees
grow less vigorously and may be set nearer together.
TIME AND MANNER OF SETTING OUT TREES.
The time of setting out trees will depend on the location and the
conditions. In the West Indies and south Florida trees may be set
out at any time of the year when the land is ready and when there
is sufficient moisture to favor their growth. In central Florida, the
spring (February and March) is preferable. The same is true of
north Florida, Louisiana, and Mississippi. In the extreme northern
portions of the citrus-growing section it is usually better to wait
until the danger of freezing weather is past, This will bring the
date up to about the latter part of February. In setting out trees
from the nursery, care should be taken to injure the roots as little
as possible. Where trees can be taken up with a considerable ball
of earth and transplanted in this way, they may be set out without
any apparent check in growth. This, however, is not usually prac-
ticable.
When the trees are taken up, the roots should be carefully pro-
tected by means of wet cloths or moist moss and the trees set in holes
542









OULTTURE OV CITRUS GROVES IN GULF STATES. 7

already prepared for them. If the ground is not already very moist,
the addition of one or two pails of water will usually puddle the
roots and cause the trees to grow promptly. At the time of setting
out, the tops should be cut back to correspond closely to the condition
of the roots. Complete defoliation is also advisable. The favorite
size of tree to set out is one that has grown about 4 feet tall in the
nursery and has several branches. Such trees are usually about an
inch or an inch and a half in diameter at the crown.
CATCH CROPS.

As soon as the field has been set to a grove, cultivation may be
begun. The kind and amount of cultivation will be determined by
the character of the soil. Light, sandy soil should have shallow but
careful cultivation. Heavy clay soils need thorough and deep
working. Where there is an abundance of moisture supplied natur-
ally to the soil, other crops may be grown to advantage. Where
the soil is inclined to be dry and irrigation has to be practiced, inter-
cropping is of doubtful utility. During the winter, vegetables may
be planted and cultivated as in ordinary fields with decided advan-
tage to the orange trees, unless the land is too dry. Leguminous
cover crops may be planted as soon as the spring 'and summer rains
begin. When fall droughts occur 'the cover crops will have to be
removed to conserve the moisture of the soil. Cultivation should
then be resumed. If the soil is inclined to be sterile the cover crop
should be used as a mulch for the trees. If the ground is sufficiently
fertile to permit it, the cover crop can be utilized for hay.
PRUNING.

"To prune or not to prune; that is the question." At many of the
meetings of the horticultural societies the question of pruning has
been vigorously discussed. There are many good reasons for pruning
trees; on the other hand, there are reasons why trees should not be
pruned. The question, then, must be decided by each individual.
One point, however, has been very well settled, and that is that low-
headed trees are preferable. Twenty-five or thirty years ago it was
a common practice to have citrus trees trimmed high enough to permit
a man to drive a cultivator under the branches. The severe cold of
several winters has caused this custom to be very largely abandoned.
In the southern part of Florida, where there is no danger from frost,
it has been found that shading the ground by the limbs has been very
beneficial to the grove. Another important advantage in low-headed
trees is that the fruit may be gathered much more cheaply than from
tall trees.
542






5



8 CULTURE OF CITRUS GROVES IN GULF STATES.

Nearly all orange growers will agree that the pruning out of dead
and worthless branches is of benefit to the tree. The extent, to which
sound wood is pruned out, however, varies with the notions of the
individual grower. Some of the most-extensive and best growers in
Florida practice no pruning at all. Diseased branches should always
be cut out, removed from the orchard at once, and burned. Sprouts
that start from below the bud must be removed, and this should be
done as soon as possible. Water sprouts arising from the trunks and
larger branches should also be removed.
A citrus tree should be kept in a low, compact form, but violent
pruning, such as is often practiced in deciduous fruit orchards, is
not only unnecessary but often absolutely harmful. Systematic
pruning for special purposes is often necessary, but it must be done
by a well-directed effort or more harm than good will result.
FERTILIZERS.

Under the general heading of fertilizers may be considered ma-
terials which are employed to enrich the soil or cause it to produce
a heavier crop. Ordinarily the term fertilizers" is restricted to
,such as are considered commercial articles, while the term manure "
is applied to organic offal and refuse accumulating on the farm. In
some parts of the United States the term guano has been used
to designate commercial fertilizers. Cover crops which are grown
on the land for the purpose of enriching the soil are frequently
called green manures."
The kind of fertilizer required to produce a heavy crop of oranges
varies greatly. In the West Indies, Mexico, Mississippi, Louisiana,
and California the general constitution of the soil is so variable that
no hard-and-fast rule can be given. In fact, in many cases it is doubt-
ful whether the desired results attend the application of any or all
the elements usually needed as plant food. While fertile soils produce
trees of vigorous growth which often bear large crops of fruit, the
possibilities are necessarily limited to what Nature will do; but in
soils where one or more of the elements of plant food are present in
insufficient quantity, the modeling of the fruit and the production of
excellent qualities are more completely under the control of the
skilled horticulturist.
COMMERCIAL FERTILIZERS FOR FLORIDA.
The kind and quantity of fertilizer necessary-to produce a maxi-
mum crop of fine fruit depend entirely upon the soil in which the tree
is,growing. Many soils in the citrus regions contain an excess of all
the elements necessary for the production of citrus fruits. When fer-
542










CULTURE OF CITRUS GROVES IN GULF STATES. 9-

tilizers are applied under such conditions no beneficial effect can be
noticed from their use. An orange tree planted in soil that contains
large quantities of the necessary elements usually produces large
fruit, but often of an indifferent character. Soils that are deficient in
nitrogen, potash, and phosphoric acid can usually have these supplied
from such sources and in such quantity as will produce fruit of the
desired texture and consistency. It therefore happens that the finest
and most delicious fruit is grown on rather sterile soil.
The entire piny woods of Florida may be said to be deficient in
each of the three important elements of plant food-nitrogen, potash,
and phosphoric acid. Soils are also found in which'there is a defi-
ciency of lime, so that frequently an addition of this element will
prove of value. The hammock soils are usually sufficiently fertile to
produce at least one crop, or even a few crops of fruit, without the
addition of fertilizer. These, however, in time become depleted, and
the elements of plant food then need to be supplied by substances
from a commercial source.
In growing citrus fruits on soils that are deficient in all of the
three important elements of plant food, a fertilizer of the following
composition is desirable:
Per cent.
Ammonia----------------- ------------
Potash ------------- --------------10
Phosphoric acid (available) --------------------------- 6
For growing nursery stock or for trees not of a bearing age the
amount of potash in the formula may be reduced to 6 per cent, leaving
the two other ingredients in about the above proportions.
The quantity of this fertilizer to be applied per acre will depend
upon various conditions. About 15 or 20 pounds per year may be
applied to each tree capable of producing 10 boxes of fruit, the
quantity being decreased or increased from year to year, as results
indicate. Calculating this on the basis of 100 trees per acre, 1,500
pounds per acre per year would be used for young bearing trees.
Double this amount is very frequently applied, and sometimes three
times as much is used.
The following table gives approximately the amount of material
needed per acre for bearing trees to supply a quantity of fertilizer
equal in fertilizing constituents to 1,500 pounds of the foregoing
formula:
Pounds.
(1) Sulphate of ammonia---------------------------- 250
Sulphate of potash, high grade ----- ------------- 300
(2)Or sulphate of potash magnesia (low-grade sulphate of
potash) ----------------------------------- ---- ..550
8jDissolved boneblack 5----------- ------------------550
''9Or acid phosphate, 14 per cent available phosphoric acid- 850
905780-Bull. 542-13---2



I










10 : TJLTURE OF CITRUS GROVES I1~ GtTLF STATES.

In the case of nursery stock and growing trees, 2 per cent of the
ammonia may be derived from an organic source. This would require
approximately the following ingredients:
Pounds.
(1) Sulphate of ammonia-------------------------- 125
(2) Dried blood------ ------------ ------ 100
Sulphate of potash, high grade--------------- 200
(3 Or sulphate of potash magnesia (low-grade sulphate of
potash ------------------------------- 350
(4 Dissolved boneblack ------------- ----------------- 550
SOr acid phosphate, 14 per cent available phosphoric acid_ 850
If there is any tendency toward die-back the dried blood should be
omitted and the amount of sulphate of ammonia increased to 250
pounds. If a quick-acting fertilizer is wanted, nitrate of soda (100
pounds) may be employed in place of dried blood.
Citrus-fruit growers wishing to compound their own fertilizers
should give due regard to the substances from which the different
qualities are derived.
Organic ammonia, as found in cottonseed meal, dried blood, guano,
and the various stable manures, is likely to produce a soft, rapid
growth, and in certain sections, especially in Florida, its continued
use is almost certain to produce die-back.
Nitrate of soda is soon taken up by the trees, but is easily washed
out of the soil. Where it is used as the only source of nitrogen it
has to be repeated from four to eight times each year, varying with
the amount of rainfall and the character of soil.
Sulphate of ammonia is much slower in becoming available to the
trees and seems to be retained in the soil much more tenaciously than
nitrate of soda, so that it need not be applied oftener than two to
four times a year.
In the use of potash there is very little choice between the low-
.grade sulphate, which is also called the double salts of potash and
magnesia, and the high-grade sulphate of potash.
In selecting phosphates, preference is given to dissolved bone or
dissolved boneblack over dissolved rock phosphate, although. some
experienced orange growers consider the phosphoric acid derived
from dissolved rock as good as that obtained from dissolved bone.
Thomas slag may be employed to good advantage, especially on soils
giving an acid reaction.
The ammonia is washed out.of the soil in great quantities by fre-
quent and heavy rains. Potash is washed out to a less degree and
phosphoric acid only to a slight extent, while lime, or calcium, is lost
in large quantities. The quantity of these elements lost will vary
according to the nature of the soil and the amount of heavy rainfall
occurring. The ideal way of fertilizing would be to make an appli-
cation of phosphoric acid in the spring before the rainy season has
542












CULTURE OF CITRUS GROVES IN GULF STATES. 11

begun; to make two applications of potash-one in the early spring
at the time of applying the phosphate and another in the fall after
the rainy season has passed; and to make four or more applications
of ammonia-one with'each application of the potash and two or
more at equal intervals between, except during the dormant winter
season.
The following example will serve to illustrate the point: Let us
suppose that a grove needs 1,500 pounds of fertilizer per acre per year
of the normal formula, that is, 4 per cent ammonia, 10 per cent potash,
and 6 per cent phosphoric acid. In the spring, therefore, before the
rainy season has begun, we would apply the entire allowance of phos-
phoric acid, or 850 pounds of 14 per cent acid phosphate; one-half
the potash, or 150 pounds of high-grade sulphate of potash; and one-
fourth the ammonia, or 624 pounds of high-grade sulphate of
ammonia. These ingredients may be mixed and applied in the usual
way. Care must be exercised, however, since such a mixture is a
very concentrated fertilizer, and if applied in a narrow zone around
the tree injury may result when the weather conditions make possible
the too rapid assimilation of the chemicals or when the nature of the
soil itself is such that the fertilizer is taken up too quickly.
For the fall application, 150 pounds of high-grade sulphate of
potash should be mixed with 62 pounds of high-grade sulphate of
ammonia. The remaining 125 pounds of sulphate of ammonia should
be evenly divided and applied as the conditions indicate. In this
way the amount of plant food that is contained in 1,500 pounds of
fertilizer of standard formula would be applied during the year.
The proper regulation of the amount of ammonia to be applied
is the greatest difficulty in preparing a complete fertilizer formula.
The presence of this element in too large or too small quantities in
the soil or in the fertilizer appears to give more trouble than any
other ingredient. Groves are very frequently injured by large appli-
cations of ammonia. A very common practice is to make only two
applications a year of a complete fertilizer-one during the spring
and one during the fall. Other growers make three applications-
one during the early spring, one later in the spring, and another
during the fall.
STABLE MANURE OF DOUBTFUL UTILITY.1
The benefits of stable or barn manure, which is largely used by
many growers, are also very doubtful. The fruits produced by nitro-
gen from this source are usually large, coarse, thick-skinned, and of
inferior flavor. If barn manure is used, however, each tree should
receive only a small quantity, and where it is the main element of
fertilization liberal dressings of potash should occasionally be applied
to counterbalance the nitrogenous fertilizer.
1 See Yearbook, U. S. Department of Agriculture, for 1894, pp. 195 and 196.
542




A.







12 CULTURE OF CITRUS GROVES IN GULF STATES.
INJURIOUS ACTION OF MUCK.1

Some growers claim that since muck is largely decaying vegetable
matter it should be applied to the grove in large quantities, either
raw or composted with sulphate of potash, etc. While this has occa-
sionally given excellent results, its extensive use has often done
serious injury. In order to obtain a smooth, thin-skinned, juicy
fruit with few or no seeds, we must vary the fertilization which the
plant receives in its wild state. The tendency of all organic manures
rich in nitrogen is to stimulate large, sickly growth. Groves which
have had liberal dressings of muck are frequently much diseased;
their crops are light, the oranges coarse, thick-skinned, and sour, the
fruit drops prematurely, and the trees are often affected with die-
back. What has been said of muck applies to a greater or less extent
to the various forms of organic nitrogen used.
What has been said about the effect of muck and barn manure on
the quality of the fruit applies equally to the effects produced by
cottonseed meal, blood and bone, tankage, etc. In general, organic
fertilizers do not stimulate fruiting to the same extent as the mineral
fertilizers.
PROTECTION AGAINST COLD.

The disastrous freezes of 1894, 1895, and 1899 in Florida and those
of 1912 and 1913 in California have caused the orange grower to cast
about for some means of protection against a sudden cold wave.
Two general methods have been practiced: The first is that of
warming the air without. providing shelter and the second is that
of providing a shed or shelter for the trees.
The methods of raising the temperature by means of fires, as de-
scribed in the following paragraphs, can not be relied on if the
cold weather is accompanied by high winds or rainfall. In a por-
tion of Florida during the heavy freeze of 1899 not only a heavy
rainfall but heavy winds accompanied the cold. All attempts at
building fires were useless, and even if they could have been built
the wind would soon have carried the warm air out of the groves.
When a very moderate breeze is blowing and the temperature
falls only 4 or 5 degrees below- the danger point, fires should be
increased on the windward side, perhaps doubled, at the expense of
those in the interior, but fires should not be extinguished in the
interior of the grove, merely reduced.
PROTECTION BY HEAT.

The burning of different kinds of fuel in an orchard for the
purpose of raising the temperature has been employed a great many
1 See Yearbook, U. S. Department of Agriculture, for 1894, pp. 195 and 196.
542












CULTURE OF CITRUS GROVES IN GULF STATES. 13

times. The success attending the work varies under different cir-
cumstances and with diffierein conditions. When the drop in tem-
perature is accompanied by a heavy windstorm and rain or sleet,
it is almost impossible to accomplish anything in the way of orchard
heating. Fortunately, freezing weather in the citrus regions is
usually accompanied by a rather still atmosphere and freedom from
rain or snow.
A great many. kinds of fuel have been employed, for orchard heat-
ing. Wood was probably the first, and it is still employed to some
extent. Coal, coke, and fuel oil have all been used to a greater or less
extent. Each of these fuels may have special advantages over others
in some particular place. In general, it may be said that the fuel-oil
method has given satisfaction more frequently than all the others
combined. To discuss all of the methods fully is quite beyond the
purpose of this bulletin.
FUEL OILS.
This term includes a variety of materials known under many
different trade names. In general, they are the heavy residue left
after the lighter oils contained in the petroleum have been removed.
A fuel oil known as crude oil is said to contain a large quantity of
asphaltum, which becomes quite troublesome. The asphaltum re-
mains as a. residue in the bottom of the heaters and interferes with
the heating when the fuel burns low.

HEATERS.
The varieties and styles of heaters offered by the trade are nearly
as numerous as the varieties of fuels. Usually the more complicated
in construction the heater is, the less efficient it becomes in its prac-
tical work in the orchard. Even a 10-pound lard pail, holding
more than a gallon of fuel oil, compares very favorably in efficiency
with the patented heaters, in some cases even proving superior to
them. The lard-pail type of heater, made from heavy sheet metal
and holding about 5 quarts of oil, can usually be purchased
from heater manufacturers at 10 or 12 cents apiece when ordered
in carload lots. In this type of heater the quantity of fuel used
and the heat given off decrease gradually as the supply in the heater
is consumed.
The lard-pail type of heater holding a gallon of fuel oil will burn
for 31 to 4 hours, varying with the kind of fuel oil used and weather
conditions, giving off about one-half as much-heat toward the close
as at the beginning of the charge. When a soot arrester is used, the
quantity of fuel consumed in an hour is much reduced, but at the same
542










14 CULTURE OF CITRUS GROVES IN GULF STATES:

time a correspondingly smaller amount of heat is given off. There
are a number of heaters that hold a much larger quantity of fuel oil.
Most of these are so constructed, either by means of a soot arrester or
otherwise, that the quantity of oil burned can be regulated. Ordi-
narily these are to be preferred to the smaller type, since when freez-
ing weather occurs it is usually of more than four hours' duration.
The minimum temperature is very likely to occur about sunrise.
Refilling in the dark is difficult and wasteful.
The type of heater with a sliding top to regulate the area of the
burning surface has worked quite satisfactorily. Roughly speaking,
44 square inches of free burning surface will consume a gallon of fuel
oil in four hours. It has been pretty clearly demonstrated by experi-
ment that it will require the same quantity of oil to raise the tem-
perature 5 degrees in an orchard, whether few or many heaters are
used. When many heaters are used the temperature in the orchard
can be maintained much more-evenly. The number of burners needed
per acre to raise the temperature 5 degrees will vary greatly, accord-
ing to the favorable or unfavorable climatic conditions and the condi-
tion of the grove. A small grove of large trees closely planted and
surrounded by a dense hammock will pass unharmed through a freeze
of 250 F., while considerable damage would be done in a grove not so
protected. Likewise, the number of heaters required in the former
grove would be fewer than in an open grove where the trees are small
and only a few to the acre.
From 50 to 100 heaters and from 100 to 200 gallons of fuel oil per
acre for each night when heating is necessary is a reasonably safe
estimate in a grove 7 to 10 years old. This number of heaters and
quantity of fuel oil will probably keep the temperature 5 degrees
above the surrounding atmosphere if the wind is not blowing more
than 4 or 5 miles an hour. Ordinarily the heaters are distributed
evenly throughout the grove, placing one in every center between
four trees. This requires about as many heaters as there are trees
in the grove, and is a poor rule to follow absolutely, since a grove
of small trees planted far apart will not hold the heat as well as a
grove of large trees planted closely. Every grove owner will have
abundant latitude to use his own judgment as to the effect of the
exposure of his grove and the other elements that enter into the ques-
tion of orchard heating.
Every grove supplied with heaters should have in it a thermometer
that will sound an alarm when the temperature approaches the
danger point. Such an instrument can be obtained for from $7 to
$20 from instrument manufacturers and dealers. The thermometer
should be placed in that part of the grove in which the.danger from
542











CULTURE OF CIIRUS GROVES IN I.ULF STATEs. 15

fro-t is greatest, and the wires should riun to the liouie or t-entrial
oIce.
The danger point will vairy with condition,. At Ihniiin- time
the danger point is highe-t andi injury mni then -cllT w\hlitlhN-r the
temperature goes down to :, F. o-Ir rnt. Matur., fruit i- almo-t
,:,-rt:in to remain unhanrmed uirle:-., thie miniiiiuiim iieiltelmpirat ret fall,
below 280 F< Trees in a fully dormaniit 'onrdilion will remain 1-
i:irrmed at 240 F., but when full d,'rrolin.:- lua pi--- ..l the trLe,-
Ieconme increasingly sen-:itive to cold. Whien in full riwth, fr'-t,
Ii.1 matter at what tenmperi-ture it .i.-i.i-., will lde-tr u tI tl.ender
tissues.
Every grove owner s ehIlil.l I:e in d:lir',:t telieplioe ',Irliinlnicaiition
witli-the United States Weatihe Bireai, in i.,rdeir to Ire.'i\-e wa:rn-I
ing- of probable frosts ani:l freez-e. All the inipoirt:iat triuit-growing
sections receive this in format ion r-eglarly ovei r l:ng-di.tarine tele-
phoines.
STORAGE TaNKS.
The fuel oil should ble -tored in a tank ,locat'dl prifr'.l.-lv in thie
.r-,ve. Where possible, it shioulil I- to I.. siphoned directly int-, it fri:m thle car tank. and thi-!! froni it
into the wagon tank. Th,- stira.ge tank ,-l. _uld alwnay.3 be so located
:s- t. enable one to run the fuel oil into the wagon tank by gravity.
Purmips work satisfactorily in warm weather, but are apt to be
troi blesome during a cold spell. They also require extra labor, which
could be more advantageously employed in the grove. A break in
a pui mp will cause delay and may make the fuel inaccessible, thus
rendering the whole plant ineffective.
Fuel oil may be stored in a variety of receptacles, the least desirable
of which are barrels. Concrete tanks or cisterns with tops, such as
ar. constructed for holding water, will be found useful. The inner
-.irface should be finished with cement plaster and finally given two
or three coats of asphaltum paint. Steel water tanks are in common
iie. Wooden tanks similar to water tanks, made of upright 2-inch
plainks, are cor',monl, y used and seem to be thoroughly practicable.
Some grove owners have tanks such as are used on tank cars for
SI a ruling fuel oil, but these would seem to be unnecessarily expensive.

COST OF HEATING.
The estimated cost of preparing to heat a 10-acre grove will vary
within certain limits. No two groves would be located exactly alike
as- to the cost of heating. The distance from the railroad, number
of times to be fired, and variation in price of labor all come in as
va riables.
542











16 CULTURE l0 CITRUS GROVES IN GULF STATES.

The following table gives an al:proxiii:e cost for a 10-acre grove:

500 to 1,000 heaters, at 40 cents----- -------- $200 to $400
One steel wagon tank ----------- -------- 25 to 30
Torches and gasoline can for lighting ---------- 10 to 12
Thermometers and installing ---- ----------- 12 to 25
3,000 to 6,000 gallons of fuel oil------------ 90 to 180
Storage tank for fuel oil----------------- 100 to 300
Total -- --- --------------------- 437 to 947

After the equipment has been installed the expense is compara-
tively light and includes mainly the annual depreciation, care of out-
fit, fuel oil burned, transfer to storage tank, and labor. The last
item will vary from year to year. When no firing is needed this item
will be comparatively light. At firing time it will require two or
three additional men to take care of 10 acres. An allowance of $6
to $10 for each night fired should be ample, including the cost of
distributing the fuel oil for the next charge. In extensive groves
and where large-size heaters are used, one man to 10 acres will be
sufficient to take care of the fires, but additional labor will be needed
to replenish the fuel.

WOOD FIRES.

In a wooded country the form of protection against cold afforded
by fires is cheap and at the same time very effective when a still
cold occurs. The wood is piled in the centers of the squares, vary-
ing in quantity from three or four to a half-dozen or a dozen sticks
of cord wood. When a freeze is predicted, the watchers notice the
thermometer and by the time the cold approaches within 2 or 3
degrees of the danger point, which is 28 F. for fruit and 240 F. for
foliage, fires are started in alternate squares. These will- usually
heat the grove some 4 or 5 degrees. If the cold continues to increase,
all the piles of wood are started. It is of course necessary to have on
hand a reserve stock of fuel in such an emergency. Shortly after the
sun .rises the nyt morning the temperature will usually have risen
again, so there will no longer be any danger to the fruit or trees. If
there is no favorable change in the weather, the cold on the second
night is quite likely to be more severe than on the first. Firing
then must be begun much earlier, and consequently a greater quan-
tity of wood will be needed.
Owing to the large amount of labor involved and the difficulty of
securing efficient help, this form of orchard heating has been largely
abandoned.
542











CULTURE OF CITRUS GROVES IN GULF STATES. 17

PROTECTION BY IRRIGATION.

In the citrus-growing sections the water that is freshly pumped
from the soil is quite warm, ranging from 500 to 740 F. When this
water is carried through a grove in irrigating ditches it gives off a
considerable amount of heat and has been used effectively in some
instances where the temperature has fallen but slightly below the
danger point.
Arrangements have also been made to throw this water into the air
from spray nozzles. This is somewhat more effective than when the
same quantity of water is carried through irrigating ditches, but can
not be relied upon as being sufficient during extremely cold spells.
During one cold wave the orchard of Mr. Theodore Mead, at Oviedo,
Fla., was protected in this way. During one night the temperature
fell considerably below the -freezing point. The next morning the
trees were so heavily coated with ice that some of the branches broke.
The following summer the trees bore a crop of fruit.
The waters from artesian wells have also been used for the purpose
of warming citrus groves, this water being quite warm, running into
the sixties usually and as high as 740 F. in some wells. While this
use of water does some good and protects that portion of the grove
in the immediate vicinity of the large flow, the amount of heat given
off is small and the volume of water supplied is not considered large
enough to protect the grove during severe freezes.
PROTECTION BY SHEDS.

The most successful method of protecting citrus trees from
extremely cold weather is that of building a shed over the grove. At
first thought this would seem to be entirely too expensive and not at
all feasible, but the sheds have now been used long enough to demon-
strate fully that they are not only possible but practicable. There
are several modifications of the shed.
This method was successfully employed immediately after the great
freezes and was profitable while Florida oranges brought a high price.
Orange sheds now occur to a limited extent and only in regions
where great damage from cold formerly occurred. These sheds are
simple structures, having a flat roof or cover held up by posts. The
posts are properly braced and hold the cover from 12 to 16 feet above
the ground. Some of the movabletops are made solid, while those with
stationary tops are made of slats or laths so placed as to give either
a half or third shade.
542










18 CULTURE OF CITRUS GROVES IN GULF STATES.
TOP-WORKING.
It sometimes happens that a grove is planted out to a variety that
does not prove prolific, or one that may be unprofitable to market.
In such a case it becomes necessary to abandon the grove or to top-
-work the trees. With the trees in a healthy and vigorous condition
most or all of the top should be removed, only two or three vigorous
limbs being left. Buds of the desired variety may be inserted into
the remaining limbs. This cutting away of most of the top causes
a heavy flow of sap into the smaller limbs which remain. In such
cases the buds will "take" where they would fail if the top of the
tree had not been vigorously cut back.
Another way of top-working is to cut away nearly all of the top
and then wait for sprouts to start. After the sprouts have reached a









S4 '
f l i,, i I , ,- 7


$Y .Q ,



FIG. 1.-Crown-grafting an old orange stock: a, Base of scion, showing
slanting cut; b, method of inserting scion. (From Yearbook, U. S. De-
partment of Agriculture, for 1895.)
size of about half an inch in diameter they may be budded, and the
bud will take readily. When trees have been cut back severely, the
bodies and the larger limbs should receive a heavy coat of whitewash
to protect them against sun scalding.
Before top-working, the orchardist should be well acquainted with
his grove and soil. In a very large portion of Florida severe top-
pruning results in die-back unless proper fertilization and soil treat-
ment accompany the work.
In California and Louisiana it appears to be safe to remove the
entire top and to work buds into the large limbs. For top-working,
the shield bud and sprig graft may be used to best advantage.
542










CULTURE OF CITRUS GROVES IN GULF STATES. 19

CROWN-WORKING.

At times it becomes desirable not to permit the body of the tree to
remain. In such cases it may be cut off at the ground line. Some
citrus trees, especially limes, resent treatment of this kind and fail
to grow after the top has been entirely cut off. The ordinary citrus
stock, however, is almost certain to sprout again if treated in this
way. Large areas, 20 to 40 acres in extent, were sprouted in this
way after the great freezes
of 1894 and 1895 in Florida
without the loss of a single
healthy stump.
Trees that have been cut
back in this way may be
crown-worked or crown-
grafted, as illustrated in
figure 1, the sprig being in-
serted in the portion of the
crown that will take it most
easily. By slipping the
scion into the portion of the
crown where the bark may
be raised without breaking,
the work maybe done with-
out the use of wax or other
binding material. After
thescion has been inserted,
moist earth should be raked
over the crown and around
the scion,. covering them
until they have* "taken," FIG. 2.-Ruby orange bud, inserted May 21, on a
and then exposing the tips. sprout from an old sweet-orange trunk, as it
Where this work is done by appeared on October 25. (From Yearbook, U. S.
Department of Agriculture, for 1895.)
experienced hands, only a
very small percentage of the crowns fail in taking one or more sprigs.
Those that fail to take may be worked again or left to 'produce sprouts
and then budded into these sprouts. By using three or four such
scions in a crown 4 or more inches in diameter and doing the work
during February or the early part of March the percentage of loss
sustained will not be very great.
Another method of renewing such an orchard is to wait until the
sprouts have started from the crown or the main roots. After these
sprouts-have reached a size of half an inch or so in diameter, buds are
inserted as low down as practicable. In doing this, however, a con-
542




C ,*


20 CULTURE OF CITRUS GROVES IN GULF STATES.
siderable loss of time will be sustained in waiting, first, for the
sprouts to start and then, again, in cutting them back to make the
buds sprout. The loss of time is strikingly illustrated by the two


FIG. 3.-Ruby orange crown graft, inserted March 1, as it appeared on October 23.
accompanying figures made from .photographs (figs. 2 and 3).
This method of budding sprouts, although it results in some loss of
time, is nevertheless very commonly used by growers because of its
convenience.
542


k.


j