• TABLE OF CONTENTS
HIDE
 Title Page
 Table of Contents
 Table 1: Avocado plantings in Florida...
 Introduction
 History
 Distribution of avocados in...
 Uses of the avocado
 Botany of the avocado
 Varieties cultivated commercially...
 Hardiness to cold
 Pollination and interplanting
 Analyses of avocado fruits
 Propagation
 Grove management
 The crop
 Diseases
 Insects and other pests
 Reference
 Checklist of avocado varieties...






Group Title: Bulletin - Agricultural Experiment Station - no. 272
Title: Avocado production in Florida
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00028146/00001
 Material Information
Title: Avocado production in Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 96 p. : ill., charts ; 23 cm.
Language: English
Creator: Wolfe, Herbert S ( Herbert Snow )
Toy, L. R
Stahl, Arthur L
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1934
 Subjects
Subject: Avocado -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 95-96).
Statement of Responsibility: by H.S. Wolfe, L.R. Toy, Arthur L. Stahl.
General Note: Cover title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00028146
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 18207194

Table of Contents
    Title Page
        Page 1
        Page 2
    Table of Contents
        Page 3
    Table 1: Avocado plantings in Florida by counties (as of July 1, 1945)
        Page 4
    Introduction
        Page 5
    History
        Page 6
        Page 7
    Distribution of avocados in Florida
        Page 8
        Page 9
        Page 10
        Page 11
    Uses of the avocado
        Page 12
    Botany of the avocado
        Page 13
        Page 14
        Page 15
        Page 16
    Varieties cultivated commercially in Florida
        Page 17
        West Indian varieties
            Page 18
            Page 19
            Page 20
        Guatemalan varieties
            Page 21
            Page 22
            Page 23
            Page 24
        Mexican varieties
            Page 25
            Page 26
            Page 27
            Page 28
            Page 29
            Page 30
            Page 31
    Hardiness to cold
        Page 32
    Pollination and interplanting
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
    Analyses of avocado fruits
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
    Propagation
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
    Grove management
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
    The crop
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
    Diseases
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
    Insects and other pests
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
    Reference
        Page 91
        Page 92
        Page 93
    Checklist of avocado varieties in Florida
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
        Page 99
        Page 100
        Page 101
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
        Page 107
Full Text



Bulletin 129 March, 1946
(A revision of Extension Bulletin 112 and Experiment Station Bulletin 272)

'COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
AGRICULTURAL EXTENSION SERVICE, UNIVERSITY OF FLORIDA
FLORIDA STATE COLLEGE FOR WOMEN
AND UNITED STATES DEPARTMENT OF AGRICULTURE
COOPERATING
A. P. SPENCER. Director



AVOCADO PRODUCTION

IN FLORIDA

By
H. S. WOLFE, L. R. TOY and A. L. STAHL
Revised by H. S. WOLFE


Fig. 1.-Fruit of the Booth 8 variety.


Single copies free to Florida residents upon request to
AGRICULTURAL EXTENSION SERVICE
GAINESVILLE, FLORIDA










BOARD OF CONTROL

J. THOS. GURNEY, Chairman, Orlando M. L.' MERSHON, Miami
J. HENSON MARKHAM, Jacksonville N. B. JORDAN, Quincy
THOS. W. BRYANT,, Lakeland J. T. DIAMOND, Secretary, Tallahassee

STAFF, AGRICULTURAL EXTENSION SERVICE

JOHN J. TIGERT, M.A., LL.D., President of the University
H. HAROLD HUME, D.Sc., Provost for Agriculture
A. P. SPENCER, M.S., Director of Extension
MARSHALL O. WATKINS, B.S.A., Assistant to the Director

Agricultural Demonstration Work, Gainesville
J. FRANCIS COOPER, M.S.A., Editor1
CLYDE BEALE, A.B.J., Associate Editor'
JEFFERSON THOMAS, Assistant Editor1
RUBY NEWHALL, Administrative Manager'
W. T. NETTLES, B.S., District Agent
J. LEE SMITH, District Agent and Agronomist
E. F. DEBUSK, B.S., State Supervisor, Emergency Farm Labor
H. S. MCLENDON, B.A., Asst. State Supervisor, Emergency Farm Labor
HANS O. ANDERSEN, B.S.A., Asst. State Supervisor, EFL
P. L. PEADEN, M.A., Asst. State Supervisor, EFL
H. G. CLAYTON, M.S.A., Director, P. & M. Admin.
R. S. DENNIS, B.S.A., Assistant Director, P. & M. Admin.
R. W. BLACKLOCK, A.B., Boys' Club Agent
W. W. BASSETT, JR., B.S.A., Assistant Boys' Club Agent
A. L. SHEALY, D.V.M., Animal Industrialist'
HAMLIN L. BROWN, B.S., Dairy Husbandman
N. R. MEHRHOF, M.Agr., Poultry Husbandman'
WALTER J. SHEELY, B.S., Animal Husbandman
A. W. O'STEEN, B.S.A., Supervisor, Egg-Laying Test
L. T. NIELAND, Farm Forester
C. V. NOBLE, Ph.D., Agricultural Economist'
CHARLES M. HAMPSON, M.S., Agricultural Economist, Farm Management
D. E. TIMMONS, M.S.A., Economist in Marketing'
ZACH SAVAGE, M.S., Economist'
JOSEPH C. BEDSOLE, B.S.A., Assistant in Land-Use Planning'
K. S. MCMULLEN, B.S.A., Soil Conservationist
JOHN M. JOHNSON, B.S.A., Agricultural Engineer

Home Demonstration Work, Tallahassee
MARY E. KEOWN, M.S., State Agent
RUBY MCDAVID, District Agent
ETHYL HOLLOWAY, B.S., District Agent
MRS. EDITH Y. BARRUS, District Agent
ANNA MAE SIKES, M.S., Specialist in Nutrition
VIRGINIA P. MOORE, Home Improvement Agent
ISABELLE S. THURSBY, Specialist in Food Conservation
JOYCE BEVIS, M.A., Clothing Specialist

Negro Extension Work, Tallahassee
A. A. TURNER, Local District Agent
FLOY BRITT, B.S.H.E., Local District Agent
1 Part-time.
2 On leave.
















CONTENTS
Page

Introduction ..................................................... ........ 5

H history .................... ............ ............. ... ....... ........... ....... 6

Distribution of Avocados in Florida ................ ................. .. ............ 8

Uses of the Avocado ......................................................... 12

Botany of the Avocado .......................... .................... 13

Varieties Cultivated Commercially in Florida ............. ..... ............ .... 17

W est Indian Varieties ..... .............. ..... 18

Guatemalan Varieties ..................... ...... .................. ..... 21

Mexican Varieties ....... ....- -..-....- 25

Inter-Racial Hybrids ..... ............... .. ... ............. .......... 25

H ardiness to Cold ...................................... ..... ... ................ 32

Pollination and Interplanting .................... .... ...... ... .. .................. 33

Analyses of Avocado Fruits ............... ......................... ..... 42

Propagation .......................... ..................... ... ........ ............... 48

Grove Management ..................... ......... .... ....... .... ................ 59

The Crop .................... ............... .. ... ................ ........ 74

D diseases .............. ..... ......... ............... ... ...................... 79

Insects and Other Pests .................................... ......... 85

Literature Cited ................... ............ ..................... 91

Check List of Avocado Varieties in Florida ............................ ........... 94























TABLE 1.-AVOCADO PLANTINGS IN FLORIDA BY COUNTIES.
(As of July 1, 1945)

County Number of Avocado Trees
S Bearing I Non-bearing I Total


Brevard ..........................
Broward .............................
Charlotte ....................
Collier .................................
Dade ..................................
Glades ................................
Hendry ...........................
Highlands ...................
Hillsborough ...................
Lee "................................-...
Manatee ....... .................
Martin ..............................
Orange .............................
Palm Beach ........................
Pinellas ...............................
Polk .......................... ........
St. Lucie .............................

Total ...................


1,200
5,000


150,000

14,000
3,000
2,500
2,000
2,500
800
3,500
6,000
7,000
1,500


300
2,000

80,000

8,000
500
500
500
1,000
200
1,500
1,000
500
500


1,500
7,000
500
400
230,000
150
250
22,000
3,500
3,000
2,500
3.500
1,000
5,000
7,000
7,500
2,000

296,800









AVOCADO PRODUCTION IN FLORIDA
By
H. S. WOLFE, L. R. TOY and A. L. STAHL1
Revised by H. S. WOLFE

The most distinctive horticultural industry of the southern
half of Florida is the growing of avocados. Nowhere else in the
United States, except in southern California, can avocados be
produced commercially, and the Florida industry is much older
than the California one. In Dade County avocados have been
of increasing commercial importance for nearly a half century,
while in other parts of the state avocados have been grown
for shorter periods. In spite of the many years of commercial
culture, there is still a great deal to be learned about the avocado
and its requirements. Though numerous seedlings have been
named and propagated as varieties, there is still no general
agreement as to satisfactory varieties for Florida.
The avocado has been for centuries the great food crop of
Central America and adjacent territory, where it is indigenous.
Hitherto it has been considered a luxury crop in the United States,
and only a very small percentage of the population is acquainted
with it. The day of phenomenal prices for avocados as rare
exotic fruits has passed. Instead of thinking of prices of a
dollar or more apiece, the grower must think in terms of 5, 10
and 15 cents per pound. Sooner or later the avocado will take
its place as a real food crop in this country.
The consumption of avocados is already quite large, consider-
ing the small number of consumers familiar with it. From
40,000,000 to 50,000,000 pounds are consumed annually in this
country. Of this amount, Florida produces about 10 percent,
California about 70 percent, and Cuba the remaining 20 percent.
Since the California crop is mostly marketed during the winter
and spring, while the Cuban crop is marketed during the same
season as the Florida crop-summer and fall-the tremendous
importation of Cuban seedling fruit is the most serious obstacle
which the Florida grower has faced in his progress toward
prosperity. Increasingly, the Florida avocado grower has turned
his attention to varieties which mature in late fall and winter.
1Wolfe: formerly Horticulturist in Charge, Sub-Tropical Experiment
Station, now Head, Department of Horticulture, College of Agriculture;
Toy: formerly Assistant Horticulturist, Sub-Tropical Experiment Station;
Stahl: Associate Horticulturist, Florida Experiment Station.







Florida Cooperative Extension


In view of these considerations, it is increasingly important
for the Florida avocado grower to make every tree produce its
utmost. Unproductive varieties and unproductive trees within
the variety must be eliminated from the grove. Production costs
must be reduced to the minimum. The grower must concentrate
on the production of quality fruit, and this must include full con-
sideration for the appeal which the fruit makes to the consumer.
No finer quality avocados are produced anywhere than in Florida,
if they are allowed to mature properly before they are picked.
Many of the problems of avocado culture which confront the
grower are under intensive investigation at the Sub-Tropical
Experiment Station. Chemical analyses of avocado fruit have
also been carried out over several years at the Main Agricultural
Experiment Station in Gainesville.
In the preparation of this bulletin invaluable assistance has
been received from many individual growers, whose years of
practical experience have been drawn on freely. County agents
and nurseries have assisted in making the data contained herein
as complete and accurate as possible. Many of the photographs
were taken by Dr. A. F. Camp, S. J. Lynch and Harold Mowry,
of the staff of the Experiment Station. Dr. G. D. Ruehle and
J. R. Watson read the sections on diseases and insects, and very
kindly gave their advice on these subjects.

HISTORY
The avocado, like corn and tobacco, was unknown to the
European world until after Columbus made his voyages. Re-
search into the literature by Popenoe (16)2 shows that the
earliest written record of the avocado is found in an account
by Martin Fernandez de Encisco, in his "Suma de Geografia,"
published in 1519, describing a voyage made in 1510. The fruit
had been used for a very long time by the Indians of Central
America and adjacent portions of North and South America
before the Spaniards came, and an account written in 1653 by
Bernardo Cobo, a priest who had traveled widely in tropical
America, seems to indicate clearly that already at that time
the 3 present horticultural races were well differentiated.
The fruit was known to the Spanish conquistadores in Mexico
as "aguacate." Under this name in its correct form, "ahuacate,"
it is known in Mexico today, and this in turn is a variant of the

SItalic figures in parentheses refer to "Literature Cited," page 91.







Avocado Production in Florida


ancient Aztec name "ahuacatl." The accepted present English
-iame, avocado, is of course derived from the Spanish variant
of the old Aztec name.
Undoubtedly the avocado was introduced into Cuba and
Jamaica by the Spaniards soon after the Conquest, but they
must have introduced it into Florida long afterwards. Records
show the killing of "alligator pears" at St. Augustine in the very
cold winter of 1835, and these were undoubtedly West Indian
seedlings. The first recorded importation was by Henry Perrine
in 1833 and consisted of trees from Mexico for his grant of land
in Dade and Monroe counties. It is not known whether these
were of the Mexican or Guatemalan race, and the fate of the
plantation is also unknown. When the first permanent settlers
came to the Miami region in the middle of the last century, they
found only the West Indian seedlings growing wild in the ham-
mocks. By 1900 there were several groves of West Indian seed-
lings established near Miami for commercial production. Late
in the 1890's the first known successful budding of the avocado
was accomplished by a man named Smith living in Coconut Grove,
and in 1900 George B. Cellon began commercial propagation in
the first avocado nursery to be established. The first imported
budwood was of a Mexican variety, sent to P. H. Rolfs in 1902
by Wm. Chappelow, Monrovia, California, and named by Rolfs
for the owner when his budded tree fruited. However, until
about 1914 all commercial propagation in Florida was of selected
West Indian seedlings of local origin. The first commercial
planting of budded trees was 20 acres of Trapp set out by S. P.
Bliss near Miami in 1906. In 1911 J. S. Collins planted 100 acres
of Trapp on Miami Beach, and a few years later he had doubled
the acreage. In 1915, however, Collins had as large an acreage
as all the rest of Florida combined.
The fruiting in 1911-12 of the first Guatemalan varieties in
Florida, from seeds brought in by the U.S.D.A. in 1904-06,
created much interest in the possibility of extending greatly the
season of fruiting of avocados in Florida, since these fruited
during the spring months when formerly there had been no
avocados available. The Guatemalan seedlings were also much
hardier to cold than the West Indian ones, thus encouraging a
belief that avocados could be grown commercially over a large
part of the state by their use. In the fall of 1913 Cellon sent
to California for budwood and budded trees of Guatemalan vari-
eties. A year later Wilson Popenoe made selections of Guate-







Florida Cooperative Extension


malan and Mexican varieties in California and brought budwood
back to Florida, and in the same year O. F. Cook, also of the
U.S.D.A., made the first selections of budwood in Guatemala.
Popenoe made extended investigations of the avocado in Guate-
mala in 1916 and 1917, sending in budwood of many selected
trees, and in 1921 he did the same in Ecuador. There have been
no further importations.
Hawaii received avocado seedlings from Central America
before 1825, chiefly of the West Indian race but also some Guate-
malans. Introductions into many other countries have come in
recent years, and now avocados are cultivated in Algeria, Austra-
lia, the Canary Islands, southern France, Madagascar, Madeira,
Mauritius, New Zealand, Palestine, the Philippine Islands, Poly-
nesia, South Africa and southern Spain, as well as all over the
West Indies, Central America, Mexico and the northern half of
South America. Commercial plantings have been made on a
large scale in Brazil in recent years.

DISTRIBUTION OF AVOCADOS IN FLORIDA
Distribution Factors.-Of the various environmental factors
which limit the distribution of plants, temperature minimum is
the most important for the avocado. It is distinctly tropical and
sub-tropical in its requirements, and so occupies a narrowly
limited range in this country. Mature trees of the West Indian
race are killed by temperatures of 24 F. and injured considerably
at 270, while many Guatemalan varieties are not killed above 210
and some very hardy Mexican varieties endure less than 180.
Young trees have temperature minima a few degrees higher than
mature trees, and those in their first year cannot endure tempera-
tures within 6 or 7 degrees of what mature trees can stand.
Where the temperature is known to fall below the minimum
endured by the variety it is unwise to plant avocados of that
race, although they may grow and fruit well for several years
before a cold winter freezes them back.
Because of their sensitivity to cold it is especially important
that adequate air drainage be provided for avocados, particularly
in the Ridge section of Florida. Only the best situated land is
suitable for avocado culture, preferably a hillside with a lake at
the bottom. In southern Florida, where most of the avocados
are grown, this factor of air drainage plays a minor role, both
because of the very slight contours of the terrain and because
of higher average temperatures.







Avocado Production in Florida


The avocado is very catholic in respect to soils, being ap-
parently equally at home on the limerock of the Redlands, the
sand hills of the Ridge,; and the muck of the Lake region. It is
very intolerant, however, of standing water, and cannot endure
"wet feet" for more than a day or 2 at most. Consequently,
care must be taken to set the trees high in the low portions of a
grove, and to avoid planting in areas subject, to standing water
during the season of heavy rains. Where citrus trees endure
a week or 2 of overflow, the avocado usually is killed within
a couple of days. (See discussion on page 84 also.)
Like most other fruits, the avocado does not thrive where
exposed to strong winds. It is both possible and desirable to
plant a line or belt of trees as a windbreak, in places where there
is no natural protection from the winds, and so this factor can
hardly be considered as limiting avocado culture. The extreme
brittleness of the wood of the avocado is a sound reason for
giving plantings windbreak protection, but reduction of evapora-
tion loss during the dry seasons and prevention of bruising of
fruit by wind movements are even more important factors.
Nowhere in Florida is rainfall a limiting factor, unless per-
haps on some of the Keys. Trees growing at Key West have an
unhealthy appearance, but this is more probably due to leaf burn
by the salt spray than to water deficiency. The fruit is not hurt
by rains during ripening, and the flowering period is sufficiently
extended that the occasional rains at that season do not usually
affect adversely the setting of fruit.
Distribution by Counties.-In Table 1 (page 4) is shown the
distribution of avocado trees by counties in Florida, so far as it
has been possible to ascertain this. Several counties which have
less than 50 seedling trees have been omitted, since they do not
affect the commercial picture. The total number of avocado trees
in the state is about 300,000, and of these about 25,000 are in
dooryard plantings of a few trees each. The bulk of the trees
are set in grove form, and comprise about 3,500 acres in plant-
ings ranging from less than 1 acre to over 100 acres in size.
Over 5/6 of the total grove acreage is in southern Dade County,
where the climate is most suited to the avocado of any portion of
the state. There are a number of large groves in Highlands,
Pinellas and Polk counties. There have been repeated efforts
in the last 40 years to establish groves around the southeastern
shore of Lake Okeechobee, where the rapidity of growth is
phenomenal, but almost all of the plantings have been wiped







Florida Cooperative Extension


out by frost or high water. The Ridge section has expanded
its avocado plantings considerably in recent years, and consider-
able land is still available where air drainage is good enough to
permit avocado growing successfully. Southern Dade County
still has thousands of acres of potential avocado land.
Although there are occasional small groves scattered through
the remaining counties, most trees in those counties are in
dooryard plantings, especially in Tampa, Fort Myers, West Palm
Beach, Orlando and other cities. There are also scattered single
trees, mostly of the hardy Mexican race, in nearly every county
in the peninsula, even as far north as St. Augustine and Gaines-
ville.
The East Coast counties have about 250,000 trees, the West
Coast 17,000, and the Central counties about 31,000, in round
numbers. Of the total 300,000 trees, probably 8% are seedlings
and the other 92% are budded or grafted to some named variety.
About 30% of these budded trees are not yet in bearing, and
perhaps 40% are not old enough for full production. These
figures are of interest for comparison with California, which
now has about 15,000 acres with 75% in full bearing and 90%
in bearing, or about 1,275,000 trees with 1,200,000 in bearing,
of which perhaps 250,000 are not in full bearing.
Distribution by Varieties.-Since the first edition of this bul-
letin there has been no opportunity for making an accurate
census of plantings by varieties, and the figures given in the first
edition for Dade County groves are no longer valid.
On the basis of observation and with the help of estimates by
experienced growers, the situation in Dade County groves can be
approximated with a reasonable degree of accuracy, and Table 2
shows the changes in varieties which occurred in the area dur-
ing the 5 years from 1934-1939.
It will be noted that the Lula and the Booth 7 and 8 varieties
have increased greatly in number in the 5-year period, largely
at the expense of Winslowson, Collinson and Pollock. To a very
large extent the low-yielding latter varieties have been top-
worked to the former, or to other promising but still minor
varieties.
Outside of Dade County the Lula variety is even more promi-
nent, so that it is easily the leading variety in the state at
present. Waldin, Trapp, Taylor and the 2 Booth selections,
7 and 8, follow in order of importance for the state as a whole.








Avocado Production in Florida 11

TABLE 2.-DISTRIBUTION OF VARIETIES IN COMMERCIAL GROVES IN DADE
COUNTY IN 1934 AND 1939.

Varieties Percent of Total Trees
1934 1939

GROUP "A"

Collinson .... ............... 19.8 12:0
Fuchsia ......................... .......-. .... 2.9 4.0
Lula a ........ ............ ....... .. ..... ................ 8.0 15.0
M onroe ........ ..................... .....------------ .......-.. 0.9
Peterson ..........................------ --- ..--------- ......... 0.16 0.1
Pinelli .................................. .... ---- ... 0.6 0.6
Simmonds ................... ..- .. .......- ...... 1.4 1.4
Taft .... ............. .---... ---.. .....-. ..... 2.9 0.2
Taylor ........................... ...---4.1 6.0
W agner .. ............. ............... .......... 4.5 4.5
Waldin .............. ....--- --............ 14.1 14.3

Total "A" varieties .........................-----.---- 58.5 59.0

GROUP "B"

Booth 1 .. ..... -.. ............ .....---- .--- 0.7
Booth 7 and 8 ...............-...... ..-----... 0.4 10.0
Hickson ..... ......... ..................- .... 1.0
Itzamna ......-......... ..............---....... 0.25 0.3
Linda ........ ......... ..... ........ .......- 5.6 5.0
Pollock .......................................... .. 7.1 4.0
Schmidt ........... -.. --..- ................. 1.3 1.5
Trapp .............. ......... ...-...... ... ....... 8.8 9.5
Winslowson ......... .. ...................11.0 3.0

Total "B" varieties ..................................... ....... 34.5 35.0

Miscellaneous varieties and sedlings .................... 7.0 6.0

TOTALS -......-..---.......--- ------..- ..-- .. 100.0 100.0


The varietal census will probably be changed considerably
again after another 5- or 10-year period, as older varieties
prove less satisfactory than newer ones. However, the Trapp
and Waldin still dominate their respective seasons and Pollock
has not disappeared from the scene, although these are the
oldest commercial varieties. It is chiefly the Guatemalan vari-
eties or their hybrids with the West Indian which are being
discarded in favor of better hybrid types.
The Florida avocado industry is never likely to reach the con-
dition obtaining in California, because of climatic differences.







Florida Cooperative Extension


The Fuerte variety now constitutes over 75% of all plantings
in California, with no other single variety making up as much
as 7% of the total. Florida can have only about a 2 months'
harvesting season for any variety, and so needs a succession
of important varieties, maturing from June until March. The
need of constantly searching for new and better varieties is
imperative here because Florida can show no variety as satis-
factory, even in its own season, as the Fuerte has proven (with
its recognized faults) for California. In particular, Florida
needs a good early summer variety.

USES OF THE AVOCADO
The avocado has achieved fame mostly as a salad fruit, and
as such is widely used all over the United States, but it is a
nourishing food also. In its tropical home it is one of the most
important items of the daily diet of the natives during its
season of ripening. When the production in this country passes
the amount which can be consumed as a luxury fruit it may be
necessary to consider primarily the food value of the avocado.
As "the salad fruit of the tropics" and "aristocrat of fruits,"
the avocado is prized in salads for its delicate, nut-like flavor and
its smooth, buttery consistency. One of the most popular ways
of serving it in Florida is "on the half-shell," with the addition
of lime or lemon juice or of salt only. Because of its oil content
it need not be served with an oil dressing. The fruit is fre-
quently made an ingredient in salads of the Waldorf type, or
mixed with grapefruit or orange.
Mashed and seasoned, avocados are used as a sandwich filling,
or are spread on salted crackers, and in the tropics they are
often added to soups just before serving. Fully ripe fruit has
been utilized successfully in the manufacture of avocado ice
cream, and this offers some promise as an outlet for the disposal
of fruit unsalable by reason of appearance but of good quality.
Cooking detracts from both the flavor and the appearance of
the avocado, and so it cannot be preserved by canning. Fruit
preserved by quick-freezing processes often retains good ap-
pearance, but it has been tasteless. The extracted oil is suitable
for making soap and for other commercial uses, but it cannot
compete profitably with other vegetable oils of far cheaper pro-
duction. Cruess (5) and his co-workers in California have re-
ported that the ground pulp can be stored satisfactorily in glass







Avocado Production in Florida


containers at 150 F. or lower, and can be distributed for use in
making ice cream or for soda fountain and lunchroom use in
sandwich spreads and salads. The cost of this procedure is
still prohibitive commercially, although volume consumption
would make great changes in this. As production increases it
will become more and more necessary to take advantage of every
possible by-product usage to maintain a satisfactory price level
for fresh fruits.
The dietetic properties of the avocado are unusual, only the
olive being at all similar among fruits. Compared with the
dessert fruits, the avocado runs higher in ash and protein and
lower in sugars, besides being outstanding in fat content. There
is a great variation in this latter, the fat content of the fresh
pulp ranging from 3 to 30 percent. The high caloric value of
the avocado, together with the very low carbohydrate content,
renders it especially suited to diabetic cases.
Avocado fat has been found by Mattill (11) to be as digestible
as butterfat, although not at all similar in composition. Wea-
therby and his associates in California have confirmed Santos
(24, 40) as to the excellence of avocados as a source of vitamin
B and have further shown the vitamin A content to be good (42).
They reported (41) only traces of C, fair amounts of D and good
,amounts of E to be present. So far these tests have been made
only on the Fuerte variety, which is the commercial standard
in California, and the vitamin A content in particular is likely
to vary with the oil content of the variety.
Expressed oil of the avocado is very similar in chemical con-
stitution to olive oil, and is adapted to similar uses. Its high
cost makes its use in soap manufacture impracticable, but in
recent years there has developed in California a small com-
mercial utilization of avocado oil in cosmetic manufacture.
While the outlet thus afforded for utilization of cull avocados
must always be limited, nevertheless it is 1 more factor mak-
ing for the prosperity of the avocado industry.

BOTANY OF THE AVOCADO
Description.-The avocado is an evergreen tree with moder-
ately large, broad, leathery leaves, which vary in size from a
few inches to more than a foot in length. The wood is hard, but
coarse-grained, and quite brittle, so that the' tree is easily in-
jured in storms. Seedling trees are usually large and hand-






Florida Cooperative Extension


some, but the budded varieties range in form from low and
spreading to tall and slender (Fig. 2). The twigs are relatively
thick and the leaves are borne alternately upon them, some-
times tending to
be clustered at
the tip. The
leaves are in gen-
eral oval to lan-
ceolate or elliptic,
with the tips us-
ually acute but
sometimes obtuse
in a few varieties,
and the base cu-
neate. The mar-
gin is entire and
the venation dis-
tinct. Young
leaves and twigs
Share often finely
e pubescent, but at
maturity they
Fig. 2.-Taylor avocado tree, typical of the tall, maturity the
slender varieties. are always quite
smooth except in
1 small group of varieties. There is considerable varietal varia-
tion in glossiness and shade of green of avocado leaves, with
varieties of the Guatemalan race tending to be much darker
green than those of the West Indian group. Both leaves and
bark contain oil glands and mucilage glands.
The flowers are small, from half an inch to an inch across
when fully open, and of an inconspicuous greenish-yellow color.
They are produced in enormous numbers in large spreading
panicles from the tips of the branches, sometimes nearly cover-
ing the whole tree with a mantle of bloom. As is so often the
case in Nature, there is a prodigal wastage of flowers, only a
small fraction of a percent of them ever maturing into fruit.
The flowers are perfect, with calyx and corolla distinguishable
only by position (as in the lily) and usually referred to as outer
and inner perianth segments. There are 12 stamens, in 4 series
of whorls,,placed in double rank in front of each of the perianth
segments. Nine of these stamens are perfect and functional,
but the fourth or innermost series of 3, located opposite the







Avocado Production in Florida


inner perianth segments, has the stamens reduced to staminodia.
The perfect stamens each have 4 pollen chambers, which open
by uplifted flaps. In the outer 2 series these openings are
turned toward the center of the flower, but in the third series,
opposite the outer perianth segments, the openings are out-
wardly directed. The peculiar behavior of the stamens will be
discussed in the chapter on pollination. The staminodia secrete
nectar, as does also the double set of glands at the base of each
stamen of the third series.
The pistil consists of a single carpel, and the egg-shaped ovary
is surmounted by a slender style of equal length, bearing at its
summit a slightly expanded stigma. This stigma is constructed
as if the upper end of the style were slit open along 1 side and
turned inside out, and the stigmatic surface is continuous with
the lining of the stylar column down which the pollen tube grows.
All parts of the flower are more or less covered with fine hairs,
although there is some varietal specificity in the degree of
pubescence. The ovary contains a single pendant, anatropous
ovule with 2 integuments. The fruit is a berry and consists of
a single large seed, a thick, fleshy pulp, and a slin of thickness
and texture varying according to the variety. The shape of the
fruit is usually from pyriform to round, but is sometimes cucum-
ber or gourd-shaped. In weight the fruit may be anywhere
from a few ounces to a few pounds, depending on the variety.
The pulp is the edible portion of the fruit and when ripe it is
of the consistency of cool butter or ripe melon. This pulp varies
in color from almost white to golden-yellow, according to variety.
In the thin-skinned forms one can determine ripeness by external
pressure, but in the very thick-skinned varieties this cannot be
done. In such cases the "straw test" is useful. When the fruit
is nearly ripe the stem is easily pulled out of the fruit, and a
straw or toothpick can easily be pushed through this opening
and down through the pulp to the seed, when the fruit is ripe
enough for eating. The pulp contains a considerable amount of
vegetable oil or fat, varying from 3 to 30 percent in different
varieties. The matured seed has 2 parchment-like coats and 2
large hemispherical cotyledons stored with nourishment for the
small embryo which they enclose. This embryo is at the end
of the seed farthest from the stem, but is directed toward it.
Usually the seeds are not considered palatable, but goats are
said to eat them, and in Puerto Rico there have been attempts
to use the ground seeds like cottonseed meal for cattle feed.






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Relationships.-The avocado belongs to the genus Persea
Gaertn., of the Lauraceae or Laurel family. To this family
belong also the true laurel, with which victors in the ancient
Olympic games were crowned, the sassafras, camphor and cinna-
mon trees, and the native red-bay, shore-bay and swamp-bay
of southern Florida. The avocado is Persea americana Miller
(P., gratissima Gaertn.), native to Central America and adja-
cent portions of North and South America. Popenoe (17) re-
ports having found wild forms of the avocado (P. americana)
in Costa Rica, Honduras and Mexico.
Races.-For horticultural purposes it is sufficiently accurate
and far more convenient to consider that there is only a single
species of avocado, with 3 well marked races-West Indian,
Guatemalan and Mexican. But there are technical reasons for
separating the last of these races as a distinct botanical variety,
P. americana var. drymifolia Mez. Formerly this variety was
considered as a distinct species, but Popenoe (17) has found
that the wild prototype from the highlands of Costa Rica and
Honduras possesses both the anise odor in the leaves charac-
teristic of the Mexican race and the leathery skin of the West
Indian race, so that the supposed species distinction is no longer
valid. The 3 horticultural races are easily distinguished in
cultivated varieties, in accordance with the following key:
1. Leaves anise-scented when crushed; fruit small, with skin
rarely more than 1/32" thick.................................Mexican
1. Leaves not anise-scented; fruit large or else very thick-
skinned, always more than 1/32" thick.............................(2)
2. Fruit summer and fall ripening; skin leathery, about 1/16"
thick.......................... ........ ........... West Indian
2. Fruit winter and spring ripening; skin thick and woody,
from 1/16" to 1/4" thick................................Guatemalan

This scheme of differentiation is becoming constantly less
useful because of the increasing number of hybrid varieties be-
ing cultivated. Since these combine characters of 2 races, it
is impossible to distinguish them by any racial key.
The West Indian race is native to the lowlands of Central
and South America, and was introduced into the West Indies
by the early Spaniards. Trees of this race are the most sensitive
to cold. The skin of the fruit is always smooth and leathery,
and in green-skinned varieties is always a yellowish-green
rather than a dark green. The seed is comparatively large






Avocado Production in Florida


and often loose in the cavity, the seed coats are usually sep-
arated, and the cotyledons are rough on the surface. The fruit
stems are short.
The Guatemalan race is native to the highlands of Central
America and was unknown in Florida until after 1900. Although
native to Ecuador, Nicaragua and Mexico also, most of the im-
portations of seeds and scions have been from Guatemala, and
hence the race name. The trees are much more cold-resistant
than those of the West Indian race, and the newly flushed foliage
is more frequently reddish or bronze in color, instead of green.
The skin of the fruit is always thick and woody and usually
decidedly rough. In green-fruited varieties, usually the green
is a dark shade. The seed usually is small and fits tightly in the
cavity, the seed coats adhere closely to each other and to the
seed, and the cotyledon surfaces are smooth. The fruit usually
is borne on long fruit stems.
The Mexican race is native to the highlands of Mexico and of
the whole Andean cordillera as far as Chile. Leaves and young
fruit possess a characteristic odor of anise when crushed. The
fruit is smaller than that of the other races, rarely exceeding
1 pound and in most varieties averaging 8 ounces. The skin
is nearly always quite thin and smooth. The seed is com-
paratively large, the seed coats are thin and either separated
or adhering to the cotyledons and the surface of the cotyledons
is smooth.

VARIETIES CULTIVATED COMMERCIALLY IN FLORIDA
Of the many varieties that have been named and propagated
at some time during the past 45 years, only a few have continued
in favor and are now found in commercial plantings. The present
section will describe only the varieties commercially planted
and considered important in Florida. Many others are still
being grown on a larger or smaller scale, but are of little or no
commercial importance and these will all be found in a Check
List of Florida Avocado Varieties at the end of this bulletin.
Even after 35 years of commercial avocado culture in Florida
there is no 1 variety or set of varieties that is wholly satis-
factory. Each has some faults and each will be replaced by
some more desirable new variety eventually. General recom-
mendations for the 3 commercial avocado areas are as follows:







Florida Cooperative Extension


Lower East Coast-Waldin, Lula, Booth 7 and 8, Hickson,
Taylor, Itzamna.
Ridge -Waldin, Lula, Collinson, Booth 7 and 8,
Taylor, Nabal.
West Coast -Lula, Collinson, Booth 7 and 8, Taylor,
(Winter Mexican), Itzamna.

Season of fruit maturity in any variety varies somewhat
with the locality, with the time of fruit setting, and with the
weather during fruit development. Consequently, only an ap-
proximate season of maturity can be given. This variation is
not over 2 weeks, however, from one year to another, and the
approximate season of about 8 weeks which is given under each
variety should include the variations.
The figures given under each variety for the oil content in-
dicate, wherever known, the normal average values for the
beginning and end of the given season of maturity. This oil
content is the value obtained by ether extraction of the fresh
pulp. Where there are no data as to seasonal range, the oil
content value is the average of a number of analyses of mature
fruits. The oil content for any given date may be higher or
lower by a small amount from one year to another, this varia-
tion being about 2 percent for Guatemalan and hybrid varieties
and 1 percent for the West Indian ones.
The pack indicated is that of the standard avocado lug.

WEST INDIAN VARIETIES
Fuchsia (Fuchs).-Originated on the place of C. T. Fuchs, Sr.,
Homestead, Florida, from a seed of unknown origin planted
about 1910. Fruited first in 1916. Propagated commercially
since 1926. Fruit pyriform to oblong, occasionally necked, of
medium size, 10-18 oz. Pack 14-20. Skin smooth, light green.
Flesh light greenish-yellow, of good flavor. Seed medium size,
loose in the large cavity. Oil content 4 to 6 percent. Season
from late June to August. The variety is thrifty, prolific and
precocious, but does not have good quality until late July and
does not ship well then. While still shipped earlier than any
other commercial variety, it is not recommended for planting.
Pollock.-Originated on the place of H. S. Pollock, Miami,
Florida, some time prior to 1896, in a seedling plantation. Propa-
gated commercially in 1901. Fruit oblong to pyriform, very
large, 30-50 oz., but sometimes up to 5 pounds. Pack 8-12. Skin
smooth, light glossy green. Flesh a rich yellow, blending with







Avocado Production in Florida


green near the skin, of excellent quality. Seed large, often
loose in the cavity. Oil content 3 to 5 percent. Season July 15
to September 1. For 25 years this was the leading early avocado
in Florida. Although a vigorous grower, the tree is a shy
bearer. As the season of bloom is very early, it is possible
that injury to the bloom by low temperatures may sometimes
be a factor in its poor bearing. Although too large for general *
market purposes, the fruit has usually commanded a good price
because of its fine quality and early season. It is no longer
recommended for commercial planting and has been extensively
topworked to other varieties. Topworking half of the tree, or
every other row, to Lula, has given some growers satisfactory
yields.


Fig. 3.-Fruit of the Fuchsia variety.


Trapp.-Originated on the place of H. A. Trapp, Coconut
Grove, Florida, about 1894, and fruited first in 1898. Propagated
commercially in 1901. Fruit roundish-ovate or slightly pyri-
form, medium to large size, 12-24 oz. Pack 10-20. Skin smooth,







Florida Cooperative Extension


light to yellowish green. Flesh golden yellow, becoming pale
green next the skin, of excellent flavor. Seed large, often loose
in the cavity. Oil content 3 to 6 percent. Season September 1
to November 1. The tree is a comparatively weak grower and
is rather susceptible to injury from insects and fungi. Some-
times it puts out such a tremendous quantity of bloom that it
suffers a setback and carries little or no fruit to maturity. In
spite of these defects the Trapp was the dominant variety in
Florida for more than 25 years. Originally it was popular be-
cause of its late season, it having been considered as a December-
maturing fruit, but its consistent bearing of good crops, its fine
shipping habit and the splendid quality of the fruit more than
offset its defects even after later-maturing varieties came into
cultivation. It is no longer recommended for planting, however.



















Fig. 4.-Fruit of the Waldin variety.

Waldin.-Originated on the place of B. A. Waldin, Homestead,
Florida, from a seed planted in 1909. Fruited first in 1913.
Propagated commercially in 1917. Fruit oblong to oval, with
a characteristic flattening on 1 side at the blossom end, medium
to large size, 14-28 oz. Pack 10-18. Skin smooth, pale green
to greenish yellow. Flesh pale to greenish-yellow, of good flavor.
Seed medium to large, fairly tight in cavity. Oil content 6 to 10
percent. Season October 1 to December 1. The tree is preco-
cious, productive and hardier than most varieties of its race.







Avocado Production in Florida


There is a marked tendency toward bearing the fruit in clusters,
and such fruit is usually small and sunburned. Careful attention
to thinning should be given, to encourage normal fruit develop-
ment. In spite of the tendency to overbearing, and consequent
dieback of limbs, this variety has held its own fairly well and
is still recommended for southern Florida and the Ridge section.
























Fig. 5.-Fruit of the Itzamna variety.

GUATEMALAN VARIETIES
Itzamna.-Introduced as budwood from Guatemala by F. W.
Popenoe for the U. S. Department of Agriculture in 1916, this
variety fruited first at the Plant Introduction Garden in Miami
in 1918. It was not distributed until 1923 and has been com-
mercially propagated since then. Fruit oblong-pyriform with
a slight offset of the stem, medium large, 14-18 oz. Pack 14-18.
Skin rough-pebbled, dark green. Flesh yellow, of very good
flavor. Oil content 11 percent. Seed small and tight. Season
March 15 to May 15. While this variety has not yet been ex-
tensively planted in Florida it has been included in this list







Florida Cooperative Extension


because of its very late season of maturity, although some re-
ports of poor yields have been received. Fruit often hangs on
the tree through May. The variety is recommended for southern
Florida and the West Coast only because of its very late season.






















Fig. 6.-Fruit of the Linda variety.

Linda.-Introduced as budwood from Guatemala by E. E.
Knight, Yorba Linda, California, in 1914. Propagated commer-
cially in Florida in 1917 and fruited first in 1920. Fruit elliptical,
very large, 20-40 oz. Pack 8-12. Skin roughened, overcast with
dull purple at maturity. Flesh yellow, of excellent flavor. Seed
small and tight. Oil content 10 to 14 percent. Season December
15 to February 15. The tree is low and spreading in habit and
is often a good bearer, with the fruit well distributed and pro-
tected from injury by sun and wind. The fruit ships well, but
on account of its size and color it is discriminated against in
some markets. It has been more productive in the Ridge and
West Coast areas than in Dade County, but is not recommended
for future planting because of the large size and color of the
fruit.
Nabal.-Introduced as budwood from Guatemala by F. W.
Popenoe for the U. S. Department of Agriculture in 1917, this







Avocado Production in Florida


variety has been propagated commercially in California since
1927 but in Florida only since 1937. Fruit almost round, of
medium size, 16-24 oz. Pack 10-16. Skin nearly smooth, dark
green. Flesh yellow, of good flavor. Seed medium small, tight
in cavity. Oil content 10 to 15 percent. Season January and
February. Test plantings in southern Florida did not attract
favorable attention until recently and it has been little known
there. In very recent years the variety has fruited heavily
and consistently in the Ridge section and it is recommended
for that area chiefly, although it may be more widely planted
before long in Dade County.





















Fig. 7.-Fruit of the Nabal variety.

Schmidt. Introduced as budwood from Mexico by Carl
Schmidt for the West India Gardens, Altadena, California, in
1911 and fruited first in California in 1920. Propagated com-
mercially in Florida in 1922. Fruit pyriform, medium to large
size, 16-26 oz. Pack 10-16. Skin rough-pebbled, dark green.
Flesh light yellow, of very good flavor. Seed medium size, tight.
Oil content 12 to 16 percent. Season February 1 to April 1.
This variety has generally proven a weak grower and poor bearer
in Florida. It is not recommended for planting, but is more
satisfactory than any competitor for the season, especially when






Florida Cooperative Extension


topworked on vigorous old trees. It is as tender to cold as any
West Indian variety, while the fruit is easily hurt by frost and
does not keep in cold storage.


Fig. 8.-Fruit of the Taylor variety.


Taylor.-Originated from a seed of the Royal planted at the
U. S. Department of Agriculture Plant Introduction Garden,
Miami, Florida, in 1908. Fruited first in 1913. Propagated
commercially in 1914. Fruit obovate to pyriform, rarely necked,
small to medium size, 12-18 oz. Pack 14-20. Skin rough-
pebbled, dark green. Flesh light yellow, of very good flavor.
Seed medium size, tight. Oil content 13 to 17 percent. Season
December 1 to February 1. One of the first Guatemalan vari-
eties to be planted commercially, it is still popular. The tree
comes into bearing early, is vigorous in growth, and is the
hardiest to cold of all commercial varieties in Florida. Usually
it yields good crops of fruit, well distributed over the tree, but
occasional reports of poor bearing have been received. A more
frequent objection is the tall, slender habit of the tree, which
increases the time required for picking and spraying. In spite







Avocado Production in Florida


of this defect, the variety is recommended for planting in all
parts of Florida where avocados can be grown.
Wagner.-Originated from a seed of the Royal planted on the
C. F. Wagner place, Hollywood, California, in 1908, and fruited
first in 1913. Propagated commercially in Florida in 1916, where
it fruited first in 1918. Fruit rounded-obovate, small to medium
size, 10-16 oz. Pack 14-24. Skin slightly rough-pebbled, yellow-
ish to dark green. Flesh light yellow, of good flavor. Seed large,
tight. Oil content 16 to 20 percent. Season January 15 to
March 15. The tree has many resemblances in foliage and fruit
to its sister variety, Taylor, but is distinguished from it by the
lower growth habit of the tree, the rounder fruit and larger seed,
and the somewhat later season of maturity. The tree is some-
what weak in growth, although it bears heavily as a rule, and
the fruit is more subject to black-spot than is Taylor. It is
no longer recommended for planting.

MEXICAN VARIETIES
Up to the present there have been no large plantings of vari-
eties of this race in Florida. On the lower East Coast the West
Indian varieties are better adapted, and in the Ridge section
the Guatemalan and hybrid varieties seem better adapted. In
both sections the Mexican varieties show a tendency to uneven
ripening of individual fruits and a considerable susceptibility
to attack by anthracnose. In localities less favorably situated
with respect to cold the Mexican varieties offer some promise.
Although the fruit is small in most varieties there are some in
which the fruit is of fair size and good quality. Small test
plantings of several varieties should be made before setting
out an extensive acreage, in order to determine varietal suit-
ability. Little information can be given at present regarding
varieties suitable for planting in the colder parts of Florida.
Several have been fruited, but none can be recommended for
commercial planting yet.

INTER-RACIAL HYBRIDS
While there is no commercial variety which has resulted from
a known cross, there are a number of varieties which give evi-
dence in their fruit and vegetative characters of being the
product of pollination of flowers of 1 race by pollen from an-
other.







Florida Cooperative Extension


1. Guatemalan x West Indian hybrids originating in Florida
have attracted most attention. It has been noticed for many
years that where Guatemalan and West Indian varieties are
growing together seedlings from the former are likely to exhibit
characters of both races, whereas seedlings of the latter have
never been known to show any but West Indian characters. In
general the hybrids have shown what may be considered "hybrid
vigor," and have proven well adapted here. In season of ma-
turity and in oil content of fruit these hybrids are always nearer
the Guatemalan than the West Indian parent, but in general
they fill in the gap in season between the 2 races.


Fig. 9.-Fruit of the Bonita variety.


Bonita.-Originated in grove of C. Sartini, near Redlands,
Florida, from seed planted in 1925. Fruited first in 1932. Top-
worked in commercial groves since 1936, on small scale. Fruit
obovate, flattened somewhat on 1 side like Waldin, medium size,
16-24 oz. Skin green, slightly roughened, leathery. Seed med-
ium. Oil content 8-10 percent. Season December and January.







Avocado Production in Florida


Booth 7.-Originated in grove of Will Booth, Homestead,
Florida, as seedling of an unknown Guatemalan parent from
tree in mixed planting of Guatemalans and West Indians. Seed
planted in 1920. Fruited first in 1927. Propagated commercially
in 1935. Fruit rounded-obovate, medium size, 10-20 oz. Pack
12-24. Skin glossy, bright green, slightly pebbled, thick, woody.
Flesh light yellow. Seed medium tight. Oil content 10 to 14
percent. Season December 1 to January 15. This variety is
vigorous and prolific, producing attractive fruit of good size
and season, and is recommended for all Florida commercial avo-
cado areas.

















Fig. 10.-Fruit of the Booth 7 variety.

Booth 8.-Origin and history the same as Booth 7. Fruit
oblong-obovate, medium large, 14-28 oz. Pack 9-18. Skin rather
dull, medium green, slightly roughened, rather thick and woody.
Flesh light cream color. Seed medium large, tight. Oil content
8 to 12 percent. Season November 1 to December 15. Like
Booth 7, this vigorous and prolific variety is recommended for
all commercial plantings in Florida.
Booth 1.-Origin and history the same as Booth 7. Fruit
rounded-obovate, medium large, 16-24 oz. Pack 10-18. Skin
nearly smooth, glossy, dark green, medium thick and brittle.
Flesh light yellow. Seed large, loose in the cavity. Oil content
8 to 12 percent. Season December and January. A heavy bear-
ing variety, as topworked in several groves, but not recom-
mended because of the very large seed and rather poor quality.






Florida Cooperative Extension


Collinson.-Originated at the U. S. D. A. Plant Introduction
Garden, Miami, from a seed of the Collins planted in 1915.
Fruited first in 1920. Propagated commercially in 1922. Fruit
broadly obovoid to elliptical, large, 18-30 oz. Pack 10-14. Skin
leathery, smooth, dark green, usually glossy but sometimes dull.
Flesh creamy yellow, of very good flavor. Seed medium size,
usually tight. Oil content 10 to 16 percent. Season November
1 to January 1. This variety is exceptional in being unable to
produce pollen and hence entirely dependent on other varieties
for pollination. The tree is a rapid, vigorous grower, and the
large dark green leaves are resistant to scab, as is also the fruit.
The variety has not proven satisfactorily productive, and the
fruit sometimes turns black next to the seed when put in cold
storage. It is no longer recommended for commercial planting.


Fig. 11.-Fruit of the Hall variety.


Hall.-Originated on place of Willis Hall, Miami, as seedling
of unknown origin. Fruited first in 1937, propagated in 1938.
Fruit pyriform, 20-30 oz.; skin smooth, dark green, fairly thick;






Avocado Production in Florida


flesh deep yellow; seed medium large, tight in cavity. Oil con-
tent 12-16 percent. Season November and December. A very
handsome and fine quality fruit, apparently heavy bearing and
hardy to cold.




















Fig. 12.-Fruit of the Herman variety.

Herman.-Originated on place of W. F. Herman, Coconut
Grove, Florida, from seed of unknown origin planted in
1935. Fruited first in 1937, from topworking. Propagated
commercially in 1939. Fruit obovate, slightly flattened laterally
below, small size, 10-14 oz. Skin green, glossy smooth, rather
thin, pliable. Flesh yellow, seed small. Oil content 10-14 per-
cent. Season November 15 to January 15. This variety nas
proven fairly prolific and hardy to cold.
Hickson.-Originated in grove of J. R. Hickson, Naranja,
Florida, as a seedling of unknown parentage. Fruiting first
observed in 1932. Topworked in 1933 and since then in many
groves. Nursery propagation in 1938. Fruit obovate, medium
small, 16 to 20 oz. Pack 14-18. Skin green, slightly rough,
thick, brittle. Flesh light yellow. Seed small, tight. Oil con-
tent 8 to 10 percent. Season December and January. Heavy
bearing in alternate years, fruit hanging well in windstorms,
but lacking cold-resistance. This variety has been extensively






Florida Cooperative Extension


topworked in groves of the Redland area, and is now
used in new plantings also.


being


Fig. 13.-Fruit of the Hickson variety.


Simpson.-Originated in grove of Robt. Simpson, near
Richmond, Florida, as a sprout from the seedling stock of
a Collinson tree. Fruited first in 1925. Propagated com-
mercially in 1933. Fruit obovate-elliptical in shape, fairly large,
16-32 oz. Pack 8 to 16. Skin dull light green, slightly rugose,
medium thick and pliable. Flesh light yellow or light cream
color. Seed medium large, tight. Fat content 10 to 14 percent.
Season November 15 to January 1. Apparently heavy bearing,
and fruit well distributed.
New and Promising Hybrids.-Each year brings new hybrid
seedlings to the attention of growers, and registration of such
seedlings is warmly recommended. The Sub-Tropical Experi-
ment Station, Homestead, will supply forms. Of more than
casual interest seem the following, described at more length in
the Check-list: Avon, Choquette, Harris, Mitchell and Monroe.
2. Guatemalan x Mexican hybrids have been very satisfac-
tory in California, but the only 1 that has proven generally
desirable for Florida originated here, the Lula. This is also







Avocado Production in Florida 31

the only 1 whose parentage is known even on 1 side. Another
hybrid, called Winter Mexican, is planted on a small scale on
the West Coast. As might be expected, these hybrids are even
more hardy to cold than most of the Guatemalan varieties.




















Fig. 14.-Fruit of the Simpson variety.

Lula.-Originated on the place of George B. Cellon, Miami,
Florida, from a seed of the original Taft tree planted in 1915.
Fruited first in 1919. Propagated commercially in 1921. Fruit
pyriform or occasionally necked, medium large, 14-24 oz. Pack
12-18. Skin nearly smooth, light green. Flesh pale to greenish-
yellow, of very good flavor. Seed large but tight. Oil content
12 to 16 percent. Season November 15 to January 1. The
variety is precocious and very productive. The tree is a rapid
and thrifty grower and somewhat resembles Taylor in habit
and leaf, although the form is more spreading at the base.
Both the foliage and the fruit are highly susceptible to scab,
but this can be controlled by timely applications of spray. The
variety has proven very satisfactory both in the Ridge section
and on the lower East Coast, and it is recommended for planting
in both areas.
3. Mexican x West Indian hybrids have been developed by
W. E. Sexton, Vero Beach. The fruit are handsome and the
quality good, but the trees have proven very tender to cold







Florida Cooperative Extension


and the fruit mature in early fall when better varieties are
already established.


Fig. 15.-Fruit of the Lula variety.

HARDINESS TO COLD


Observations have been reported several times on the rela-
tive hardiness to cold of different avocado varieties grown in
Florida. While it is not possible to give definite limiting tempera-
tures for each variety, it is possible to rank them comparatively.
1. The group hardiest to cold includes Taylor, Lula and Win-
ter Mexican.
2. Next hardiest are Itzamna, Hall and Nabal, followed by
Booths 3, 7 and 8, and Wagner.
3. A third group comprises Collinson, Hickson, Linda and
Waldin.
4. Least hardy are most West Indians, such as Trapp, Pol-
lock and Fuchsia, the Guatemalan Schmidt and the hybrid
Winslowson.







Avocado Production in Florida


POLLINATION AND INTERPLANTING
Flower Behavior.-The avocado has perfect flowers, each
capable of producing pollen and of developing into a fruit. In
spite of this fact there is a pollination peculiarity which makes it
undesirable to plant solid blocks of single varieties. This pecu-
liarity is that the individual flowers do not shed pollen at the
time their stigmas are receptive to pollen, and that all the flowers
open on all the trees of any given variety are in the same condi-
tion at the same time. In every flower the stigma matures be-
fore the stamens, are ready to shed pollen, and when pollen is
shed later by that flower its stigma is no longer capable of being
pollinated. When the stigma is in a receptive condition the
stamens are all lying down flat on the perianth segments; when
pollen is being shed the 3 stamens of the inner series are erect
and clustered around the more or less withered stigma and the
other 6 stamens are partly upraised from their former recumbent
position. Thus the flower acts as if it were at first only female
and later only male, and every tree is first female and then male
in function. This is simultaneously true for all trees of any given
variety-a condition known as synchronous dichogamy, which
the avocado exhibits to a greater degree than any other plant
known. But when some varieties are acting as females others
may be acting as males; and when the former are shedding
pollen the latter may be receptive to pollen.
The basic principle was first announced by Nirody (14), who
came to Florida in the winter of 1921-22 to try breeding avocados.
He noted at once that flower opening and pollen shedding were
at different times of day for different varieties, but were at the
same time for all specimens of a given variety. Every day
throughout the blooming period a new set of flowers opened for
the first time on every tree, but in some varieties this occurred in
the morning and in some in the afternoon. If the flowers of a
tree opened for the first time in the morning and were receptive
to pollen, they did not shed pollen until afternoon. If a variety
opened its flowers to receive pollen for the first time in the after-
noon, pollen was shed by those flowers during the next forenoon;
and this daily alternation of being male and female he found to be
very regular all through the blooming season. Since the stigma
of the pistil was usually not receptive to pollen at the time when
that variety was shedding pollen, he pointed out that it was im-
possible for adequate pollination to take place in the case of most







34 Florida Cooperative Extension

varieties when planted in solid blocks. He advocated the inter-
planting of varieties which would each shed pollen when the
other was ready to receive it, and he drew up a brief list of such
reciprocating varieties.
The extensive and careful researches of Stout (31, 32), orig-
inally undertaken to see if cross-pollination rather than pollina-
tion in itself was needed by avocados for good fruiting, have
added very much to our knowledge of the peculiar flower be-
havior of avocados. Following up Nirody's work during the next
winter in California, he discovered that, while Nirody was correct
in principle, the phenomenon was even more complex than Nirody
had realized. Making observations about once an hour or less
often, Nirody had found that flowers which had their first open-
ing in the afternoon closed for the night and opened again next
morning to shed pollen. He reported also that those flowers
which had their first opening in the morning remained open all
day and shed their pollen that afternoon. Stout made observations
at more frequent intervals during the day on individual flowers
which he tagged, and discovered that every day there were 2 sets
of flowers opening on every tree. For the sake of simplification
he suggested that all varieties which opened for the first time in
the morning be grouped together in Class A, and those having
their first opening in the afternoon be grouped into Class B.

mohihg I afternoon Imo rnoing afternoon
CLE VARIETY kDW 789t01112123 456 78 3456789101121234-56
SXAXXXXX--- ---

AYLO XX-xxx xxx x x x x XXX A XX XAX ---X ------ .
TAYLOR 2 \\\\\\\\\\\


I X) .------ cLsed fi m xI




Fig. 16.-Blooming cycles of avocado flowers during 2 consecutive days.
---- -first or "female" opening of any flower-receptive to pollen.
- =second or "male" opening of any flower-no pollen being shed.
---- =second or "male" opening of any flower-pollen being shed.
xxx =period during which flower is closed again between first and
second openings.

On a tree of an A variety Stout found the flowers opening
for the first time at some hour of the morning, depending on the







Avocado Production in Florida


variety, as Nirody had reported. But all of these flowers closed
without shedding any pollen and at some time during the after-
noon another set of flowers opened and shed pollen. The first
set did not open for pollen shedding until afternoon of the second
day, and so every day on every A variety tree there opened in the
morning a fresh set of flowers to receive pollen and in the after-
noon a set to shed pollen which had opened previously on the
morning of the day before. In the case of the B varieties the cycle
was found to be as Nirody had reported, the same flowers opening
in the morning to shed pollen which had opened the previous
afternoon to receive it. In Fig. 16 is a graphic representation
of these flower-opening cycles for both A and B varieties while in
Fig. 17 is a summary of the normal midseason behavior of a num-
ber of varieties as respects the flower opening, adapted largely
from Nirody and Stout.


TAYLOR ~'"
WAGNER ..........
u TAFT ... .
O COLLI NSON -
WALDIN "_ ".
-I LULA .
S5MiAONDS _
oDUNEDIN ....
AI'uDONRL .. ..... ...

WN5LOWSON ........."
L F) TUERTE _.
t0 -TONNAGE --
I< POLLOCK -. ....... -
-J LINDA
-- INDA -- ...........-
) HARDEE -
T7iRAPP 4 4 I- -

Fig 17.-Normal daily bloom openings for various varieties of avocados.
--- =first or "female" opening of flowers-receptive to pollen.
-- =second or "male" opening of flowers-no pollen being shed.
---- =second or "male" opening of flowers-pollen being shed.







Florida Cooperative Extension


The list of reciprocating varieties given by Nirody was greatly
amplified by Stout, who noted also that the flower behavior of
any given variety was the same in California as Nirody had
found it in Florida. However, he found also many eccentricities
of flower behavior under California conditions, notably those
shbwn by some B varieties which might have flowers not opening
to shed pollen until the morning of the second day. The observa-
tion of Nirody that cool weather retards equally the hour of
flower opening for all varieties was confirmed, but Stout also
found that sudden changes of temperature and cloudiness may
cause great irregularity in flower behavior. This observation is
of especial interest and importance in view of the possibilities it
affords for overlapping of the periods of opening of different sets
of flowers on the same tree in cool, cloudy weather, so that some
pollination may occur between flowers on the same tree. Stout
pointed out further that, in the case of B varieties which open
very late in the afternoon, the stigma of the pistil may still be
receptive to pollen next morning, since it has had little exposure
during the afternoon to the drying effects of sun and wind. Such
varieties have a theoretical chance of being self-pollinating, and
this may explain the fruitfulness of the Trapp in solid plantings.
Clark (1, 2, 3) in 1923-26 also followed up Nirody's work by
California observations. He found that flower behavior in the
coastal region was commonly erratic, such as Stout had found in
the interior district to be the case only in bad weather, so that
there was normally an extensive overlapping of sets of flowers.
Under these conditions the Fuerte proved quite self-fruitful even
when tented by itself, but other varieties which apparently had an
equal amount of overlap were not very self-fruitful. The ques-
tion arose in Clark's mind as to whether varieties which normally
set fruit well to their own pollen might not be benefited by cross-
pollination, either in obtaining a larger set of fruit or in holding
better the fruit which was set. He made several experiments
with tented trees, introducing bees under the cheesecloth tents
which enclosed halves of 2 or more trees of reciprocating va-
rieties or half of a single tree. Only a few varieties were em-
ployed in these tests, most of the work being done with Fuerte
and Dickinson. In the case of the Fuerte there was no benefit
found from abundant cross-pollination from several reciprocating
varieties, but the Dickinson showed definite increase in fruit
setting as the result of cross-pollination. It should be noted that







Avocado Production in Florida


this latter variety showed little or no overlapping of different
sets of flowers, whereas Fuerte showed this in a high degree.
In 1925 Stout continued his studies in the Homestead area of
Florida, where Nirody had worked, and E. B. Savage of the U. S.
Department of Agriculture joined him in the investigations (34).
They established the normal cycles of a large number of varieties
and confirmed further the identity of flower behavior in both Cali-
fornia and Florida for any given variety. With the advance of
spring, the hours of opening and closing of flowers advanced uni-
formly for all varieties. Just as in California, sudden drops in
temperature caused great delays in the opening and closing of
flowers and often led to overlapping. The authors pointed out,
however, that, while such overlap seemed favorable to close-
pollination, conditions inducing it were unfavorable to pollina-
tion because insects were more sluggish and pollen and stigmas
were less able to function normally.
An interesting result of this investigation was the discovery
that Collinson was unable to produce any pollen at all. Later
studies by Robinson (18) showed that when tented alone with
bees this variety set no fruit whatever, confirming expectations.
No attempt was made by Stout and Savage to cross-pollinate
varieties, but single trees of several varieties were tented with
hives of bees to see how self-fruitful they were. Tented Trapp
trees had a set of fruit about like untented trees, while Linda,
Panchoy and Taft produced much less fruit under tents than out-
side them. It should be noted that whole trees were used in this
work, and not half trees as in Clark's, so that the same tree did
not serve for both control and pollination test. The results, how-
ever, seem sufficiently clear.
Stout visited Homestead again in the spring of 1932 to make
further observations and added a number of new varieties to the
lists of A and B groups (33). Working in conjunction with him,
Young (44) found that many avocado flowers have defective
pistils which probably could not set fruit to any pollination.
Studies of pollen tubes in pollinated pistils showed that very
few tubes ever reached the ovary, and gave rise to the question of
whether there are varietal differences in rate of pollen tube
growth so that some varieties may be better pollinators than
others.
Torres (35) has reported some interesting investigations of
compatability and self-fruitfulness. Using mostly varieties no
longer found in Florida but taken to the Philippines from Florida







Florida Cooperative Extension


originally, he made many reciprocal cross-pollinations and also
several close pollinations. Commodore and Miami were some-
what self-fruitful, whereas Pollock and Wester were not and
Cyrus was doubtfully so. Cyrus was effectively pollinated by
Commodore and Wester, but could not pollinate them apparently.
Wester pollen gave fair sets of fruit on all 6 reciprocal varieties
used with it, but none of these pollinated Wester except Tertoh
and possibly the Miami. The results are rather suggestive than
conclusive, but are further indications of the probability that
some varieties in our groves are better pollinators than others,
and that knowledge of the compatability of varieties for cross-
pollination might enable us to increase yields.
Skutch (25) has reported a few interesting observations on
seedling avocados in Panama. In a group of 8 trees he found
2 A and 2 B varieties, but the other 4 were conformable to
neither group, being highly erratic in flower behavior, often
having only a single flower opening and shedding pollen a few
hours after opening. The trees which showed regular behavior
set good crops, while those showing irregular flower behavior
set very little fruit. The explanation of these observations is
very uncertain. The many seedling trees which have been
examined in Florida have always been regular in flower behavior.
In connection with pollination problems, mention should be
made of the work of Van Elden, as reported by Hodgson (7). He
found in cytological studies of the avocado pistil that the embryo
sac was ready for fertilization at the first flower opening, and
that the egg had already been fertilized at the time of the second
opening, in some cases at least.
The following list contains the varieties likely to be found in
Florida grove. and also some promising new ones.

Class A Varieties Class B Varieties
Avon Ajax
Bonita Bitte
Booth 1 Blair
Choquette Booth 3, 5, 7, 8, 10
Collinred Eagle Rock
Collinred B Edmonds
Collinson Fuerte
Dunedin Gulfstream
Fuchsia Hall
Gottfried Hickson
Harris Itzamna
Herman Kilgore Special
Indian River Linda
Kay McDonald
Lindgren Major
Lula Marguerite







Avocado Production in Florida


Class A Varieties Class B Varieties
Marfield Nabal
Mitchell Nehrling
Monroe Nelson
Peterson Nirody
Pinelli Pollock
Simmonds Schmidt
Taylor Sexton
Wagner Simpson
Waldin Tonnage
Trapp
Vero
Winslowson
Winter Mexican

Hand Pollination.-Several workers have attempted to obtain
fruit from controlled hand crosses. Nirody (14) made several
thousand hand pollinations of a number of varieties and reported
a set of about 10 percent. However, only 2 fruit matured from
all of these laborious pollinations. One, a McDonald x Pollock
cross, has fruited and the name Nirody has been given it. It
has not proven very desirable for general planting. Stout (31)
made thousands of hand crosses in California in 1923 but obtained
a very low percentage of set; so far as is known no fruit matured
from these crosses. Savage (19) reported that he had obtained
successful results from hand crosses in 1916, but that the young
seedlings were killed by the 1917 freeze. In 1924 he made many
more hand pollinations and obtained a mature fruit from a Taft
x Winslowson cross. The seedling from this cross has not been
reported to have fruited yet.
In 1928 L. R. Toy made several hundred hand pollinations in
the Krome grove at Homestead and obtained 2 mature fruit to
the respective crosses Trapp x Lamat and Winslowson x Colla.
These did not prove to have desirable fruit characters. Edward
Simmonds, at the U. S. D. A. Plant Introduction Garden in
Miami, reported a Trapp x Collason cross in 1921 to the seed-
ling of which was given the name Trappson. This fruited in 1924
and resembled Trapp very closely.
Torres (35) reported from 3 to 7 percent set of fruit from
certain hand pollinations in 1931, in cases where from 300 to 600
flowers were pollinated. The highest percentage set recorded in
his tests was 15.4 percent, but only 13 flowers were pollinated.
Sets of around 10 percent were obtained from pollination of
about 50 flowers, which is still probably too small a number to be
adequate. No record is given of whether any fruit matured from
these hand pollinations.







Florida Cooperative Extension


It will be seen that many thousand hand pollinations by several
investigators have produced a scant half dozen new hybrids of
definitely known orgin, so that controlled crosses by hand polli-
nation are not a promising field of activity in avocados.
Insects and Pollination.-A number of insects are helpful in
pollinating the avocado and this is fortunate, since the pollen
must normally be transferred from 1 tree to another, often at a
distance. Various flies and wasps are the carriers of pollen in the
native haunts of the avocado, and a number of flies and other in-
sects have been observed at work in Florida avocado groves.
Bees are very fond of avocado nectar. Probably hives of bees in
the avocado grove would assist in obtaining a set of fruit, but no
investigations have been made on this point as yet. The bees
do not tend to fly from tree to tree so much as from hive to tree
and return, whereas the wild insect pollen carriers visit from
tree to tree. Good crops are set consistently in groves consider-
able distances from any bees, but it is quite possible that a hive
of bees per acre, with 5 set in the middle of each 5-acre tract,
would materially increase production. There are few large
groves planted uniformly enough to make possible testing of this
theory in a conclusive way.
Interplanting Observations.-Because of the impossibility of
getting a reasonable percentage of fruit from hand pollinations,
and because of the length of time and amount of equipment re-
quired for extensive tenting of reciprocal varieties, few data
are available on the compatibility of different varieties for polli-
nation. Some observations have been reported on the general
need of interplanting to provide pollination by reciprocal va-
rieties, but they are few and somewhat conflicting.
Clark (3) reported no benefit to either variety when Fuerte
and Challenge, Fuerte and Blakeman, Fuerte and Spinks, or
Tingley and Harman were top-worked together, although these
pairs are all reciprocal in flower behavior and abundant insect
activity was manifest. Likewise a test made by Mrs. W. J.
Krome at Homestead in 1932, when Linda and Taft were tented
together with a hive of bees at 1 end of the tent, indicated no
mutual benefit as compared with untented trees.
Robinson and Savage (19) reported observations in Florida,
at Terra Ceia and at Lake Eloise, of marked increase in yields
when a reciprocating variety was provided. This was true of a
solid block of Fuertes which had been unfruitful for several
years. In this case it was reported that when Spinks trees came







Avocado Production in Florida


into flower on 1 side of the Fuerte planting, there was a definite
gradation in Fuerte crop-setting, it being highest next to the
Spinks trees and diminishing steadily with distance from them.
A large number of Lula trees on the Ivey Properties, Lake
Placid, are in solid block planting except for 3 scattered trees
of reciprocating varieties. Careful observations over several
years, however, have shown no evidence of differential bearing
of these Lulas, corresponding either with the location of these
scattered interplants or with the adjacence of a neighboring block
of mixed varieties. In the Homestead district 2 solid 10-acre
plantings of Waldins, with Trapps adjoining on 1 side in each
case, are stated by the owners to have borne uniformly well
throughout the block. Another large block of Taylors planted
solidly is stated also to have fruited uniformly well, while the
authors have examined smaller blocks of Taylors several hun-
dred yards from any reciprocating variety in which every tree
bore heavily. Even blocks of Collinsons 5 to 10 rows deep have
apparently fruited well throughout the block without interplants.
Such observations by experienced growers have made many
of them skeptical of the need for interplanting reciprocating va-
rieties, in spite of the undoubted need for it as indicated by flower
studies. Consequently the Sub-Tropical Experiment Station has
endeavored to collect accurate data on this question by actual
counts of fruits of thousands of trees in various groves where A
and B varieties are growing close to or far from reciprocating
varieties. Comparisons are valid only when made on a given
variety under different conditions of interplanting in the same
grove and for the same season. It is hoped that such data may
afford a more solid basis for statements regarding the need of
interplanting than can be given by casual observations only.
TABLE 3.-AVERAGE NUMBER OF FRUIT PER TREE WITH DIFFERENT
INTERPLANTINGS.

Rows Distant from Nearest No.
Variety Reciprocating Variety of Trees
Averaged
1 2 ,3 | 4 5
Collinson* ................... 43 .... 36 30
Linda .................... 36 19 35 30 43 15
Taylor .............. ...... 58 55 59 40 43 7
Wagner ......................... 46 39 28 21 30 30
Waldin .................... 147 .... ... 123 30
Winslowson ........ ... 21 37 ... 14 .... 15

Interplanted with another variety of the same class.







Florida Cooperative Extension


Table 3 gives the results of a few of the fruit counts, where
given varieties could be found separated in the same grove by 1
or more rows from the nearest reciprocating variety.
In another grove the planting is almost entirely of A varieties,
with another grove of mixed A and B plantings adjacent to 1
end of the solid rows of the first grove. Counts were made of the
fruit on the 2 trees in each row nearest the mixed grove and of
the 2 farthest away. .The rows are 36 trees long. Results are
given in Table 4. The figures in parentheses after the variety
name indicate the number of trees whose fruit was averaged
for each count.
TABLE 4.-AVERAGE NUMBER OF FRUIT PER TREE ON OPPOSITE
SIDES OF GROVE.

Average Number of Fruit on Waldin (22) Wagner (8) Lula (34)

Nearest pair ...................................... 29 41 37
Farthest pair ............................. 7 31 50


From these and many other data obtained in fruit counts on
thousands of trees it seems clear that, while maximum yields
cannot be expected from solid plantings, nevertheless there is not
necessarily or clearly an advantage in having reciprocating va-
rieties closer than 3 or 4 rows. There seems also to be some
difference between varieties with respect to their ability to set
crops in more or less solid plantings. Waldin, Lula and Taylor
seem to be as well able to do this as is Trapp, while Wagner,
Wnslowson, Linda and Schmidt seem to have greater need of
interplanting and to show some correlation between the amount
of crop yield and the distance from reciprocating varieties. The
problem still requires for its solution, however, the keeping of
accurate yield records over a period of years.

ANALYSES OF AVOCADO FRUITS
During the past 20 years a great many analyses of fruits of a
large number of avocado varieties have been made. Results of
the very careful study of the changes taking place in the avocado
from early in its development until full maturity for the com-
mercially important varieties have been published (26). In
Tables 5 and 6 are given condensed results of determinations of
. fat, sugar, protein, ash and moisture content of 12 well known









TABLE 5.-CHARACTERISTICS OF WELL KNOWN FLORIDA AVOCADO VARIETIES.
(Averages of 10 to 100 mature fruits, Green Basis)*
--------i ,- -

Rank Variety Weight Variety % Variety % Variety Edible Variety %
(pounds) ISeed Skin Pulp 1 Ash

1 Linda 1.71 Linda 8.56 Pollock 9.42 Linda 77.72 Winslowson 1.23
2 Pollock 1.59 Simmonds 12.50 Trapp 9.53 Simmonds 77.22 Wagner 0.99
3 Winslowson 1.48 Schmidt 12.71 Waldin 10.13 Pollock 75.92 Collinson 0.96
4 Simmonds 1.39 Eagle Rock 14.67 Simmonds 10.71 Collinson 74.82 Linda 0.93
5 Eagle Rock 1.37 Pollock 14.68 Winslowson 10.72 Trapp 72.15 Lula 0.92
6 Collinson 1.37 Collinson 15.87 Collinson 10.94 Winslowson 72.12 Taylor 0.87
7 Waldin 0.99 Winslowson 17.17 Lula 12.60 Schmidt 71.84 Schmidt 0.86
8 Lula 0.94 Trapp 18.32 Wagner 12.86 Eagle Rock 71.03 Pollock 0.81
9 Trapp 0.93 Taylor 20.83 Linda 13.75 Waldin 65.57 Eagle Rock 0.80 3.
10 Schmidt 0.93 Wagner 22.91 Eagle Rock 14.30 Taylor 64.79 Simmonds 0.72
11 Wagner 0.72 Waldin 24.31 Taylor 14.37 Wagner 64.24 Waldin 0.70
12 Taylor 0.67 Lula 24.36 Schmidt 15.44 Lula 63.32 Trapp 0.64

Varieties ranked under each classification according to percentage composition.










TABLE 6.-COMPOSITION OF WELL KNOWN FLORIDA AVOCADO VARIETIES.
(Averages of 10 to 100 Mature Fruits)*


Variety


Variety


Simmonds
Eagle Rock
Winslowson
Lula
Trapp
Taylor


% \
Total |
Sugar Variety
(Greer
Basis)

1.92 Simmonds
1.85 Taylor
1.80 Eagle Rock
1.78 Lula
1.56 Trap'p
1.52 Winslowson


* Varieties ranked under each classification according to percentage composition.


Rank


1
2
3
4
5
6
7
8
9
10
11
12


%
Moisture


72.47
73.89
76.89
78.06
78.08
78.74
79.44
82.37
82.55
83.53
83.88
85.05


Wagner
Lula
Taylor
Eagle Rock
Winslowson
Linda
Collinson
Waldin
Schmidt
Trapp
Simmonds
Pollock


% Fat and Oil (Ether Extract)

Variety Green Variety Dry
Basis Basis

Wagner 18.77 Wagner 67.46
Lula 13.60 Linda 58.66
Winslowson 13.02 Winslowson 58.31
Taylor 12.81 Eagle Rock 55.12
Linda 12.32 Collinson 53.80
Eagle Rock 12.18 Taylor 53.38
Collinson 11.55 Lula 53.30
Schmidt 7.21 Schmidt 39.97
Simmonds I6.63 Simmonds 37.12
Waldin 6.34 Trapp 35.61
Trapp 5.91 Waldin 35.37
Pollock 4.77 Pollock 31.39
11 1


%
Protein
(Green
Basis)

1.71
1.40
1.34
1.21
0.90
0.86







Avocado Production in Florida 45

Florida varieties. These determinations were made on the fresh
pulp of mature avocados, are expressed in percentage composition
of this fresh pulp (except for figures giving fat content, ex-
pressed on the basis of dried pulp) and so represent the constitu-
tion of the avocado as consumed. The methods used in making
these analyses have been described fully in the publication re-
ferred to above (26). There are also given in these tables inter-
esting data on the proportions of the whole fruit which are skin,
seed and pulp. For ease of comparison the data of these tables
are presented graphically in Figures 18 and 19.

Io
SEED
8
70- SKIN


50--


30- PULP
20-



0 rr
I0 -






Fig. 18.-Proportion of seed, skin and pulp for standard varieties
of avocados. (See Table 5.)

There is considerable difference between the lowest and the
highest fat content shown in these tables, and there is no abso-
lute correlation between fat content and race. In general the
West Indian varieties show from 4 to 7 percent of fat, the Guate-
malan varieties from 10 to 13 percent, and the Mexican varieties
from 12 to 15 percent, but there are exceptions in all 3 races. It
is of interest to find that the same variety almost invariably
shows a fat content several percent higher in California analyses
than in Florida analyses, a condition undoubtedly due to climatic
conditions and to the difference in time required to reach ma-
turity. One variety, the Dorothea, has analyzed several points







Florida Cooperative Extension


higher in Florida, and the Linda, a comparatively late-maturing
variety in Florida, shows the same analysis in both states. The
other varieties mature in much shorter time in Florida than in
California, and studies of changes during fruit development have
shown there is a steady increase in fat content while the fruit
remains on the tree, even if it is allowed to hang until well past
the normal harvesting time for the variety.

fat content on dhy weight basic s

100 1 green weight basis
moisture content


0z tzi
U) L) MU
-J < 0 2- 0
6 < i < j
i ^~ -9 ,5 f
~ -- u in )-
I- UJIl C U) I) I i


Fig. 19.-Moisture and fat content of pulp of
of avocados. (See Table 6.)


standard varieties


Two very interesting phases of these developmental studies
may be mentioned'very briefly here, although the above bulletin
should be consulted for detailed analyses. Analyses for the
season 1930-31 showed consistently higher fat content for the
same date than the analyses for 1931-32. This difference was
about 2 percent for the varieties with comparatively high fat
contents, and about 1 percent for those with low fat contents.
The only exceptions were the Waldin, which was equally high
both seasons, and Pollock, which was higher in 1931-32 by 1
percent. This seasonal difference is doubtless the result of dif-
ference in time of setting fruit and hence in the length of de-







Avocado Production in Florida


velopment time during the 2 seasons. In this connection it may
be noted that Pollock blooms exceptionally early and may have
set fruit earlier in the same season when other varieties had a
late set.
It is impossible to make definite statements regarding the
cause of the differences noted,,but the fact of the seasonal varia-
tion in fat content is of importance and so is the small amount of
this variation. The variation shown in fat content of fruit grown
in different localities is much less for any given date than .the
variation on this date from 1 year to another, but is less than
10 percent of the total fat content of the fruit in either case.
The other point of interest is the finding that fruit stored
until soft showed consistently about 2 percent higher fat content
than fruit analyzed at once after picking on the same date. This
difference was rather uniform all through the season for all
varieties tested. In part it is due to loss of the water from the
fruit by evaporation, but this is not the only factor involved.
There is no correlation at all between high fat content and
good quality, as far as comparison of varieties is concerned. Two
of the finest varieties for eating are the Trapp and Pollock, both
low in fat. Collinson and Linda, almost equally esteemed, have
twice the fat content of the other 2. Some varieties low and
some high in this constituent are distinctly mediocre in palat-
ability. It is of some interest to note that high fat content is
almost always associated with high ash content, while there is
no relation between fat content and the amount of sugars or
protein contained in the fruit. Trapp and Simmonds are similar
in fat analysis, but the former runs comparatively low in sugar
and protein, while the latter runs high in both. There still re-
mains the necessity of correlating the fat content of the individ-
ual variety with its palatability, that we may have a satisfactory
basis for determining maturity. Since there is no necessary
connection between fat content and quality, we must find out the
time at which each variety acquires maximum quality, to make
possible the assigning of a definite fat content and time of year
for proper maturity.
These analyses may be more significant if we compare the
avocado with other well known fruits. The apple, banana, black-
berry, cherry, grape and mango have many similarities to the
avocado and 1 important dissimilarity. In content of water,
protein, ash and energy, these fruits are very similar to the






Florida Cooperative Extension


avocado, but they all have their energy derived chiefly from
sugars, while the avocado food energy is stored principally as fat.
The avocados of Florida range in water content from 72 to 85
percent, which compares well with the range of from 75 percent
for bananas to 85 percent for blackberries, and intermediate per-
centages for the other fruits. The protein of avocados constitutes
from 0.85 to 1.70 percent of the fresh pulp, while in the sweet
fruits it ranges from 0.3 percent in apples to 1.4 percent in
grapes. Florida avocados would seem to be comparatively rich in
proteins among fruits. The ash content is a measure of the min-
eral salts contained in the fruit. In avocado varieties it is from
0.65 to 1.25 percent, as compared with from 0.30 percent in apples
to 0.84 percent in bananas. Florida avocados are comparatively
high in mineral content, among energy-producing fruits.
The fat or oil content of Florida avocados makes up from 4
to 20 percent of the weight of the fresh pulp, comparing well
with the range of sugar content in the sweet fruits above listed,
from 6 percent in blackberries to 20 percent in bananas. The
energy value of fats, however, is more than twice that of carbo-
hydrates, so that avocados of a given fat content contain over
twice the calories contained in fruits showing an equal percent-
age of sugars. Thus our West Indian varieties compare in energy
content with apples, cherries, grapes and mangos, while our
Guatemalan varieties mostly exceed bananas in fuel value.
The sugar content of all avocado varieties is the lowest found
in any fruit of which we have analyses, and there is less variation
among the different varieties in this respect than is the case for
any other constituent of the fruit. The range is only from 1.5 to
2.0 percent. This range of values may be compared with the 0.2 .
to 1.4 percent of fat found in the sweet fruits, which produces an
amount of energy quite comparable to the energy of the avocado
sugar. This extremely low sugar content of avocados is a very
important feature of their constitution.

PROPAGATION
Nursery Practice.-As has been noted previously, the avocado
was propagated exclusively by seed until 40 years ago, and in
tropical countries that is still the usual method; but, as seedling
groves have great variability in quality and quantity of fruit pro-
duced by different trees, a method of vegetative propagation must
be employed to insure reproduction of any given variety. Cut-






Avocado Production in Florida


tings of avocado have proven difficult to root, although experi-
ments along this line have not been very extensive. Budding and
grafting are the methods of propagation employed for the avo-
cado by nurserymen in Florida. Inarching has never been em-
ployed here, although it is much used in the Philippines, where
Torres (36) recommends especially the tongue inarch.
Seeds of the West Indian race are imported in great quantity
from Cuba to provide nursery stocks, although seeds of any cull
fruit of any variety or race produced locally are also used. They
are viable for 2 or 3 weeks after being removed from the fruit,
if kept in a cool, dry place. Seeds planted in the early part of
the season, if from mature fruit, have the advantage of warm
weather to hasten their germination and growth. Very small
seeds should be discarded, even though of normal size for the
fruit from which they are taken, since the size of the seed indi-
cates the amount of food stored for the young seedling.
For box-grown trees in the slat-house, seed may be sprouted
in shallow beds of sawdust and transferred to boxes as soon as
they have sprouted, or may be planted at once in the boxes.
Seeds should be planted so that the end which was nearest the
stem of the fruit is up. In pointed seeds the point should be up.
Standard avocado boxes are usually made of /8" pecky cypress
and are 6" by 6" in cross-section and 12" deep. They are filled
with a sandy loam containing a light sprinkling of commercial
fertilizer. Good drainage and regular watering are essential to
successful growing of seedlings, and seeds are best covered not
more than half an inch.
Seeds may also be planted 18" apart in nursery rows in the
open when the soil is of sufficient depth and irrigation can be
provided, and the seedlings are then budded or grafted in the
nursery row. These rows should be 4 feet apart to allow for
cultivation. Young seedlings are more susceptible than older
trees to injury from low temperature, and some protection must
be given to stock grown in the open when damaging frosts or
freezes are experienced.
Until recent years the avocado was propagated in Florida
nurseries usually by shield-budding, the same method used in
citrus nurseries. This operation, however, requires much care
and experience for success, and even experienced citrus budders
are frequently unsuccessful in their first attempts at budding
the avocado. When the work is properly done a high percentage
of avocado buds unite with the stock. The most important fact-







Florida Cooperative Extension


ors are the condition of the budwood and that of the stock. Seed-
lings for budding should be kept in a thrifty growing condition,
and any unthrifty or weak seedlings should be discarded. Vigor-
ous seedlings should have reached budding size-3/16" to 1/4"
in diameter at the base-within 3 or 4 months after planting.
The best season for budding in Florida is from November through
March, preferably November and December. Budwood should
be selected from well matured terminal growth, preferably from
twigs which are just ready to put out a new flush of growth.
The wood should be sufficiently matured that it does not snap
readily on bending. The best buds are those which are plump
and show no sign of having started growth, although the termi-
nal bud shows this. Budsticks should be cut from healthy trees
which are known to bear satisfactory crops.
The bud is cut in the form of a shield from 1 to 112 inches
long, depending on the size of the stock. A very sharp, thin-
bladed knife should be used and the cut should be made with a
single smooth, sliding stroke. Most propagators carry a heavy
razor strop and renew the knife edge after cutting every 25 or 30
buds. The union depends largely upon close contact of the cam-
bium tissues of the bud and of the stock, and buds which have
been gouged out or cut with a rough contact surface have little
chance to unite properly. The cut in the stock, whenever the
bark slips readily, is made in the form of an inverted T, the cross
cut being slanted slightly upward. The bud should be inserted
immediately after it is cut, to avoid drying out of the tender cam-
bium, and should be allowed to complete the opening of the slit
by its own entrance. After insertion of the bud the stock is
wrapped with waxed cloth or raffia. Within 4 or 5 weeks the
wraps must be examined and removed or loosened if necessary
to prevent binding the stock. At this time the top of the seed-
ling stock should be pinched out to force the bud into develop-
ment. A few weeks later the stock may be cut off just above the
union and the cut surface covered with grafting wax or asphalt
paint. Stock sprouts which arise above or below the bud should
be pinched out. The bud should be inserted in the first few
inches above the ground level.
Grafting has largely superseded budding in Florida avocado
nurseries. The time required for producing a tree of planting
size is lessened considerably by grafting, and some varieties
difficult to bud-especially Taylor, Wagner and Simmonds-are
easily grafted. Also, it is much easier to find suitable graft






Avocado Production in Florida


scions than suitable budwood, and there is less danger of buds
being shed. Stocks of lead-pencil size may be grafted by whip-
grafting and even more slender ones by side-grafting. Terminal
scions or "tips" 2 to 21/ inches long are used and they should be
from the last matured growth just as it starts to flush. How-
ever, there is more latitude of choice possible in selecting twigs
more or less mature than there is in selecting budwood. The
buds and leaves along the lower part of the scion are cut off
closely so that the wraps will fit tightly. Either very thin waxed
cloth or rubber budding strips are used for wraps. The rubber
strips possess the advantage of giving adequate pressure and
exclusion of water without danger of injurious binding of the
tender stock and scion.


Fig. 20.-Interior of avocado nursery slat-house.
Side-grafting is the easier and more popular form of nursery
propagation. For this it is especially important that the tissues
of the stock shall not be too mature, since the scion is inserted
in the center of the stock. Seedlings suitable for grafting are
shown in Figs. 20 and 21A. The scion is cut with a long, wedge-




Florida Cooperative Extension


[~1


#1


4~i~:
I'
A~t~


Fig. 21.-Side-grafting avocados. A, Seedling suitable for grafting;
B, making the incision; C, scion inserted; D, the complete graft wrapped
with rubber band; E, complete graft after scion has started growth (left)
and the stock cut back (right).







Avocado Production in Florida


shaped lower end, and is inserted in a long, sloping cut made
diagonally down into the stock, as shown in Fig. 21B. It should
be inserted so that all of the cut portion is enclosed. After the
scion and stock have united the seedling top is treated as for
budded stocks. (Fig. 21 D and E.) In case of failure of the
graft to take, the stock may still be cleft-grafted lower down
(Fig. 22).


Fig. 22.-Cleft-grafting avocados. A, making the incision; B, scion
inserted; C, completed and wrapped graft.

Whip-grafting offers an even larger surface of contact for the
cambium layers of scion and stock than does side-grafting, but it
involves cutting off the top of the seedling stock at the time of
grafting, and in case of a failure of the graft it is necessary to
let a new top develop on the stock. It can be used successfully
for older stocks than can side-grafting.







Florida Cooperative Extension


Whether budwood or scions are being cut, it is very important
that the propagating material should not be allowed to dry out.
Budsticks can be held for a time by sealing the cut end in paraf-
fin and keeping the stick in slightly moist sphagnum or peat
moss. The more tender tip scions should be put at once into this
medium to keep them from wilting.
The young trees are fertilized with light applications of a fer-
tilizer high in ammonia and low in potash, such as 5-7-3 or 6-6-3.
Occasional applications of liquid manure also are beneficial. Trees
grown in boxes in slat-houses require no further attention until
they are large enough to plant, which will be at any time after the
new top has matured 1 or 2 flushes of growth. It is well to
harden young trees before setting out in the field by placing the
boxes outside the slat-house for a couple of weeks.
Rootstock.-It is customary in this state to use West Indian
seedlings as stocks on which to bud or graft the avocado. Seed-
lings of this race are generally vigorous, although there is some
variation in this respect. Seeds taken from fruit of Guatemalan
varieties growing near West Indian varieties usually make
thrifty seedlings also, perhaps due to "hybrid vigor." Some
Mexican seedlings are of exceptionally vigorous growth while
others are not at all so. Guatemalan seeds and scions appear
to succeed equally well on stocks of all 3 races but West Indian
varieties usually are unsuccessful on Mexican stock. Little ac-
curate information is available concerning racial and varietal
compatabilities of stock and scion, although doubtless certain
definite differences exist. How important these relations are
can be determined only by carefully planned investigations ex-
tending over many seasons. For the present, Cuban seedling
stocks, variable in vigor though they are, offer the most satis-
factory material for commercial propagation, but Guatemalan
stocks may confer slightly more cold resistance for plantings in
central Florida.
Top-Working.-As has been the case in many other fruit in-
dustries, the earlier plantings of avocados in Florida contained
many unproductive and inferior seedlings and many of the propa-
gated varieties have proved unsatisfactory after extended trial.
No consistent, organized interest has been maintained in the
study and standardization of varieties, and in consequence grow-
ers are now resorting to extensive top-working of the unsatis-
factory varieties and seedlings. No attempt should be made to
top-work trees in poor condition unless that condition is due to a







Avocado Production in Florida


temporary lack of fertilizer. It is more economical in the long
run to replace unhealthy trees with thrifty nursery trees than to
attempt to work them over.
It was formerly considered very difficult to graft avocado
trees of bearing age, and budding was the only method available
for top-working. A method of cleft-grafting, first suggested by
Krome (9) and amplified by Elliott (6), has given excellent suc-
cess in Florida when the work is done during the cooler season of
the year. December and January are the best months for graft-
ing in Florida but the process may be carried on until April, al-
though the percentage of success is likely to decrease steadily
as the season advances. Grafts have been made with success in
July but the chances of success are too small for this to be done
except in emergencies. Grafting is a more detailed and slower
process than budding and involves a greater outlay for equip-
ment, and so shield-budding is still employed in top-working by
some growers. It usually takes longer, however, to produce a
bearing tree by budding than by grafting, and so the latter
method has steadily gained favor (Fig. 25).
For cleft-grafting scions should be chosen from more mature
growth than is used for budwood, preferably from the second
or third flush back from the tip. They should have a diameter of
% inch or more and are preferably cut about 6 to 8 inches long.
The upper portion should have at least 2 plump, dormant buds,
and the lower half must be fairly straight. Trees to be grafted
are sawed off 1 to 4 feet above the ground, depending on the
diameter of the trunk. If several large limbs are present with
diameters of 3 inches or more, the cuts should be made on these
limbs a foot or more above their junction so that they form the
framework for the new tree. Some propagators prefer to leave
several "nurse" limbs but this is not essential to success. Ex-
periments in which 1/, 2/3 and all of the limbs have been removed
at the time of top-working have shown no striking differences
in results. The cleft is made'with a saw (Fig. 23A) and should
be 3 to 5 inches deep, according to the length of the scion. The
portion of the stump through which the cut is made should be
straight and free from knots at the sides of the cleft. A hard-
wood wedge is driven into this cleft until the trunk beneath the
cut begins to split (Fig. 23B). The sides of the cleft should be
pared thinly to remove sawdust and to make a smooth surface so
that the cambium layers of stock and scion fit snugly and make
close contact (Fig. 23C).

















94-CI -~


L~7~


Fig. 23.-Top-working avocados by cleft-grafting. A, making the cut;
B, opening the cleft; C, trimming the cleft; D, inserting the scions; E,
removing the wedge. (See Fig. 24 for final steps in the process.)





Avocado Production in Florida


The scions are trimmed to a wedge shape along the lower
portion (Fig. 23D), leaving them slightly thicker on the edge
which is to be on the outside of the cleft so that the cleft will
not be held open by the inner edge and the cambium layers pre-
vented from coming close together. A scion is placed in the cleft


P1*

p~'LL-


Fig. 24.-Final steps in top-working by cleft-grafting. F, painting the
scions and exposed stock surface; G, filling the cleft with grafting com-
pound; H, protecting the completed graft from sun and wind; I, putting
damp peat moss in the graft collar to keep the scions moist.






Florida Cooperative Extension


at each side (Fig. 23D) and fitted carefully into place so that the
cambium layers of scion and stock coincide as fully as possible.
In this connection it must be remembered that the bark of the
stock will be much thicker than that of the scion and that it is the
juncture of wood
and bark which
must be brought
in contact in both
Cases. When the
scions are tightly
fitted the wedge
is withdrawn en-
tirely in the case
of small stocks of
i less than 3 inches
diameter, leaving
the pressure of
the closing cleft
to hold the scions
in place (Fig.
23E). In large
stumps, however,
this pressure will
be too great for
the scions and
the wedge is
withdrawn only
far enough to in-
sure a tight hold-
ing of the scions
by the cleft. The
top of the wedge
may then be saw-
ed off flush with
the stump. To
prevent decay it
Fig. 25.-Scions 12 months after grafting. These is essential that
were on a very vigorous seedling stock. is essential that
all surfaces be
coated with a grafting compound (Fig. 24F) and the cleft filled
also (Fig. 24G). The scions also should be coated where they
are in the cleft. A strip of heavy paper is then tied around the
stub (Fig. 24H), projecting several inches above the top of the







Avocado Production in Florida


scions, and it is filled with a mixture of sand and peat moss, peat
moss alone, or dried leaves (Fig. 241). This may be watered
lightly at intervals to prevent drying out of the scions before they
have united with the stock. It is advisable also to bend a small
strip of paper as a cap over the open cylinder to give additional
protection against the sun, but holes for ventilation should be
made at the top and bottom of the cylinder also. These cylinders
may be left in place indefinitely, as they afford protection against
cold as well as against sun and wind.
The grafting compound commonly used in Florida is a mixture
of 4 parts beeswax and 1 part paraffin. Some prefer t.o add a
small piece of carnauba wax, about an inch in diameter, to each
pint of the above mixture in order to raise the melting point
somewhat. This is desirable especially when the work is done
in the warmer spring months but is not essential. Results equal
to those obtained with beeswax-paraffin mixture also have been
obtained by use of a proprietary asphalt emulsion (Tree-seal).
This is no more expensive and requires no heating.
The following tools and materials are required in top-working:
Carpenter's saw, adjustable pruning saw (known as California
saw), hand pruning shears, hardwood wedges, roll of heavy
building paper 15" wide, heavy twine, labels, pencil, whetstone,
mallet or hammer, very sharp thin-bladed knife, a mixture of
sand and peat moss, and the grafting compound. If the beeswax-
paraffin mixture is used there must be added a melter for the
wax. Patented wax melters are on the market and are well
worth their cost when much grafting is being done. Care should
be taken not to apply the wax too hot.

GROVE MANAGEMENT
Planting Distances.-Spacing of trees in the grove should be
governed somewhat by the varieties planted, by the type of soil,
and to some extent by the shape of the grove tract. Trees tend
to grow larger in rich soil than in poor, and should be spaced more
widely where known to grow larger. Likewise, some varieties
grow tall and slender and may be spaced closer than varieties
with a wide spreading habit of growth. On the whole, however,
it is unwise to adopt several spacings in the same grove, since, if
top-working to other varieties is desired, the close spacing of
originally slender trees may cause inconvenience.







Florida Cooperative Extension


Earliest avocado plantings in Florida were in places where there
was an abundance of soil, such as large potholes, and the seedling
trees grew quite large. Consequently, the first seedling and
budded groves were set with spacings of 30 feet between trees,
about 50 trees to the acre. As these matured it was realized
that such wide spacings were wasteful and many of these older
groves were later interplanted. The practice now is to plant
the trees about 20 feet apart and there is even a tendency to
plant more closely than this, 1 way. Where the trees are planted
close the ground is shaded more completely and this prevents
burning of the humus from the soil so rapidly, with resultant
benefit to the roots and to the water-holding capacity of the
soil. The avocado is native to lowland and highland forests
of the tropics, where partial shade, a carpet of fallen leaves, and
wind protection are present. The grower may well attempt to
duplicate such conditions so far as is consistent with economical
and efficient handling of the grove. Wider spacing, 30 feet or
so, should be allowed every 6 rows, to provide roadways through
the grove.
Preparation of Land for Planting.-In Dade County, where
is grown the bulk of Florida avocados, the soil is peculiar in con-
sisting of a more or less hard oolitic limestone containing numer-
ous pockets of sand or red clay. In the Redlands district the
oolite crops out all over the surface, so that only in potholes of
varying size is there any tillable soil. Farther north sand often
overlies the rock to a depth of from 2 inches to 2 feet. Early
plantings were made in deep sand or in potholes of soil, but it
was impossible to set out a grove in straight rows when only
potholes were employed. The next step was to dig shallow holes
in the rock where the tree should go and fill in around the
trees with surface soil. At yearly intervals the rock was chipped
farther back in a band just outside the root zone. Still later
the practice of blasting holes with dynamite came into vogue
and this is still a standard method.
The most satisfactory blasting practice is to use 3 charges
of 1 stick of dynamite each in holes drilled 24 inches deep and
spaced 26 inches apart as the apices of an equilateral triangle.
This breaks up the rock to a depth of 4 feet in a broad bowl, taper-
ing upward at the sides. The broken rock is cleaned out, some
fragments are replaced in the bottom of the cavity, and the hole
is filled again with surface soil. Two or 3 shovels full of







Avocado Production in Florida 61

well rotted animal manure should be thoroughly mixed with the
soil in each hole some weeks prior to planting.
The earlier groves were set among the stumps of the pine
forest which covered the ground, and these groves often bore
excellent crops, but grove cultural operations were difficult, and
so it has become the practice to clear and scarify the land. The
scarifiers break up the rock to a depth of 4 to 6 inches and leave
a surface layer of mingled rock and soil in which the roots can
spread and feed. It is usually necessary to scarify the land 4
times to get it into good condition.
In recent years an improvement in the process of scarification
has been widely adopted. First the land is cleared by use of a
specially developed form of bulldozer, which cuts just below the
ground level and lifts large pine trees out with ease. Then a
heavy triangular scarifier is mounted in place of the bulldozer
on the front of the huge track-type tractor, and the rock plowed
out by this scarifying plow is ground beneath the treads of the
tractor. Down the tree rows 1 way loose rock and soil are
scraped aside, and the process of plowing is repeated until a depth
of 18 inches of loose material is finally achieved down the tree
rows when the field is leveled, with 6" to 8" depth between rows.
No blasting is used in connection with this type of scarification.
On the deeper sandy soils of other areas the same method of
land preparation is followed for avocados as for citrus, except
that compost is mixed in the soil of the tree hole.
It is decidedly worthwhile, where possible, to prepare the
land a year in advance of planting and to grow a heavy cover
crop before planting. This gives opportunity for leaching of the
free lime resulting from breaking up the lime rock, as well as
increasing the organic content of the soil. An even better plan
is to crop the land to winter tomatoes, following these by a rank
cover crop growth during the summer, and then plant the trees
the following spring.
Time of Planting.-Avocados may be planted successfully in
Florida at any time of year, at least in the sections where com-
mercial culture is practiced, provided precautions are taken
against certain seasonal weather conditions which follow the
setting of the trees. Much more expense is entailed, however,
in setting out at some seasons than at others. The best season
for setting avocados is during the spring months, from early
April to early June. Temperatures at this season favor growth







Florida Cooperative Extension


and the amount of watering to be done is likely to be small.
The cost of watering newly planted trees becomes very great
when trees are planted during a dry season.
Trees set in September and October are likely to have good
weather conditions for getting established, since abundant rains
can be expected during these months and the temperatures are
no longer those of summer. The winter months which follow are
the driest of the year and watering must be done fairly regularly
all winter. Newly established trees are the most easily injured
by cold weather. The grower planning to set trees in late autumn
should be prepared to give them some protection from cold in
case of frost. In the central and northern parts of the state
avocados should be banked like citrus trees during the winter,
and fall planting is somewhat more hazardous in these areas.
Trees planted in mid-summer require more care in shading than
trees set in the fall or spring, but even in September shading
should be provided. Trees may be hardened before field planting
by placing them outside the nursery lath shed for a few weeks
with gradually decreasing water supply.
Interplanting and Variety Selection.-There is no evidence
at all so far regarding which reciprocating varieties are most
helpful mutually, and so the only general rule which can be given
is that formulated by Nirody: See that varieties are planted to-
gether which will provide pollen for each other at the time when
each is ready to receive pollen. Fortunately, however, the studies
of Stout enable us to simplify the application of the rule con-
siderably, for he has shown that almost any B variety sheds
pollen at a time of day suitable for almost any A variety to re-
ceive it, and it is only necessary to select varieties not too widely
separated in their season of bloom. Many B varieties can also
be pollinated by almost any A variety, but some of them open
too late in the afternoon for any A variety to be able to pollinate
them certainly. The normal season of bloom for a number of
varieties, as observed by the authors, is given in Fig. 26. It will
be noted that there are few varieties whose seasons are so widely
separated that they do not have a few days or weeks of simul-
taneous blooming, but it is better not to trust to brief periods of
common bloom. Early varieties ought to have early or mid-
season varieties as reciprocals, and late varieties should have
late or mid-season reciprocating varieties. The following classi-
fication may be of assistance:







Avocado Production in Florida


Early Blooming
Fuchsia
Fuerte
Gottfried
Pollock
Simmonds


Mid-season Blooming
Collinson
Lula
Tonnage
Tra'pp
Wagner
Waldin
Winslowson


Late Blooming
Booths 1, 7,and 8
Eagle Rock
Itzamna
Linda
McDonald
Schmidt
Taylor


APR


MAY


GOTTFRIED
FL ERTE
POLLOCK
SIMMOND$
FucHs IA
WINSLOWN _
TR APP
LULA
WALD IN _____
AGNER
COLLINSON _
TAYLOR
LINDA
5cHMIDT ___,D-__r .
ITZAMNA
BOOTH # 7
BOOTH #3
Fig. 26.-Normal blooming season for various varieties of avocados.

The method by which adequate pollination is to be assured in
planting a grove is not wholly established, but the considerable
data amassed at the Sub-Tropical Experiment Station show that
alternating several rows of 1 variety with an equal number of
1 from the reciprocating group provides quite adequate oppor-
tunities for pollination.
Table 7 offers a planting plan which is believed to be quite
satisfactory for assuring cross-pollination and yet offers the
maximum of convenience in grove handling. A wide middle is
left every 6 rows for a roadway, and the 3 rows on either side
of it are the same variety. Thus picking and spraying are done


-r-laM


MAR


FER







64 Florida Cooperative Extension

uniformly for any roadway, and yet reciprocating varieties are
never more than 3 rows from any tree. This scheme of planting
is recommended as quite practical.

TABLE 7.-A CONVENIENT GROVE PLANTING PLAN.


Table 8 suggests another planting scheme which is satis-
factory, both as to theoretical pollination assurance and as to
convenience of grove handling.
For those who are contemplating the planting of large acre-
ages it is urged strongly that they give careful consideration to
the opportunity afforded them for finding out whether some com-
binations of varieties give greater fruitfulness than others.
There may be compatibilities between certain avocado varieties,
such as are well known for apples and some other fruits, so that
1 variety is more satisfactory as a pollinator for certain other
varieties than another 1 is; or, more often, certain varieties may
be poor pollinators for some or all varieties.
The planter of a large acreage can plant in 5-acre units, using
only 2 varieties to the block and interplanting as in either Table
7 or Table 8. In a 40-acre tract he could make 8 such combina-







Avocado Production in Florida


tions, and with such large units of planting any difference in
pollination compatibility ought to be strikingly apparent in crop
yields. A few hundred acres planted judiciously would answer
positively all questions as to the varieties best suited for inter-
planting, and yet the grove owner would be taking no greater
risk in laying out plantings on this basis than he does at present
with any current method of planting.

TABLE 8.-ANOTHER GROVE PLANTING PLAN.


Planting.-On the limerock soils of Dade County the practice
is to set the trees higher than in other sections because of the
slow surface run-off in rainy weather. They are planted in a
mound so that the crown roots are about 6 inches above the
general ground level. In other areas the trees are set only
slightly above soil level. The improvised planting gauge shown
in Fig. 27 is made of light 1" x 11/2" wood and will be found very
useful by those not accustomed to this type of planting. When
boxed trees are being set the bottom of the box is removed and
the tree is set in place in line with the sighting stake. The soil
is packed firmly around it, the sides of the box are split with a







Florida Cooperative Extension


hatchet and pulled out, and the tree is watered well. Special care
must be taken to avoid leaving any air pockets in the soil about
the roots. A basin should be made about the tree to hold water
and should be mulched heavily with grass and weeds or sawdust
to prevent drying out and heating of the soil about the new roots.
This mulch should be pulled away, however, when there is dan-
ger of frost, unless the tree is to be covered as frost protection,
for young trees with a mulch, or with weeds growing around
the base, are more readily injured by frost than those around
which the soil is bare.


AM -,
944


Fig. 27.-Planting gauge in use.


Frequent waterings are necessary until the trees are estab-
lished and, if rainfall does not keep the trees adequately supplied,
water must be provided from barrels or tanks. Four gallons
of water per tree should be applied every 3 or 4 days during the
first 2 weeks, and every week for 2 or 3 months thereafter. One
inch of rain will probably give the tree the equivalent of this
amount. With a thick mulch the loss of water is less rapid than
in its absence, and these recommendations assume a fair amount
of mulch around the tree. By the end of 3 months the trees
should be able to take care of themselves, especially if well







Avocado Production in Florida


mulched, unless a long dry period is encountered during the first
year.
Shading of newly planted trees is desirable when plantings
are made at any season, but especially for summer plantings.
The most economical and convenient method of shading is to
drive stakes on the south, east and west sides of the tree, just
clearing the branch spread. A burlap feed or fertilizer sack
is split down 1 side and stretched in V-form around these 3
stakes, which should stand about 4 feet high. These shades
give some protection from wind as well as from sun.
Culture and Mulching.-On sandy soils clean cultivation is
usually given during the dry season, followed by cover crops in
the middles during the summer rainy season. On the limerock
soils of Dade County, however, such cultural practice is both
difficult and unwise. The usual practice is to permit a volunteer
growth of weeds and grasses to flourish throughout the rainy
season, mowing it at intervals to facilitate grove operations, and
keeping this growth mowed close during the drier winter and
spring. Where permanent cover crops can be established they
are handled in the same way. Dragging or disking the land need
never be done after the initial scarification, except as prepara-
tion for sowing cover crops and as fire protection. Because the
shallow soil necessitates the roots feeding near the surface, it
is unwise to drag a grove at all after the trees reach size enough
that the roots occupy the middles, although sometimes fire
hazards may make it advisable to drag a few rows.
Most Florida avocado soils are deficient in humus and some
practice should be followed which will add organic matter to
the soil. In some groves on both sand and limerock soils the
practice of permanent mulching is followed with excellent re-
sults. Grass and weeds growing in the row middles are piled
about the trees to shade the roots and conserve moisture, but
unless the middles are fertilized also for the definite purpose of
producing a heavy mulch it is rarely that enough material can
be produced in the grove itself. It is highly desirable to bring in
large quantities, of mulching materials from any available out-
side sources. Where this plan is followed the feeding roots grow
into and just beneath the mulch and as it decays more must be
added so that the roots will not be injured by exposure to drying
conditions. Mulching is of extreme importance in the growing of
avocados in warm, humid climates, and particularly so when the
soils are as light and shallow as are those of southern Florida.







Florida Cooperative Extension


Irrigation.-The avocado has leathery leaves which do not
indicate soil dryness as citrus leaves do by wilting. Nevertheless,
it needs abundant soil moisture for profitable growth and fruit-
ing. Except in areas where avocado culture is hazardous be-
cause of high water table, some provision should be made for
supplying the trees with water during the dry winter and spring
months. This is especially important during and for 3 months
immediately after blooming. Moderate drought in November
and December is likely to be beneficial, but drought following
the blooming period is sure to result in a poor set of fruit and a
heavy "June drop" when summer rains begin. Data are lacking
on which to base definite recommendations but experience sug-
gests that at least 2 acre-inches of water should be applied every
2 weeks during this period, unless rainfall supplies it. Various
methods of irrigation are in use, most of them supplyifig water
in spray form, although on the level, rocky soils of the Redlands
the flooding system is sometimes used.
Cover Crops.-Leguminous cover crops, or green manures,
are of particular value in that they may add nitrogen as well as
humus to the soil, and so reduce the cost of fertilizers. The
main factors to consider in a cover crop are (1) adaptability to
local conditions, (2) yield of green matter produced, and (3) ease
of handling the growth produced. A number of cover crops
satisfy these criteria well for the sandy soils of the central part
of the state, where they can be replanted each spring economic-
ally but, to date, no satisfactory permanent leguminous cover
crop has been found for Dade County, despite several years of
effort. Many cover crops make satisfactory tonnage but they
are either unable to compete with the volunteer cover crops after
the first season or they cannot be handled satisfactorily for grove
culture, and the nature of the soil makes it impossible to replant
annually.
Two species of crotalaria (Crotalaria spectabilis and C. striata)
have proven more satisfactory than any other cover crops. The
former is somewhat the more desirable. Bunch velvet beans,
cowpeas, beggarweed, soybeans and other crops may be grown
in sections where they produce satisfactory growth. No cover
crop makes a better growth on newly scarified pineland in the
Redlands district that Crotalaria spectabilis. The seed may be
sown at any time during the winter and allowed to germinate
with the spring rains. An application of 500 pounds per acre
of superphosphate soon after the seedlings appear is highly bene-







Avocado Production in Florida


ficial for this or any other cover crop on the limerock soil, but
on the sandy soils a complete fertilizer analyzing 4-8-3 or of
similar analysis should be applied in like amount.
Most cover crop seeds should not be sown until the spring
rains make germination sure. In preparing the ground harrow
or drag it thoroughly to kill as much as possible of the grass
and weeds. It is also advisable to sow a somewhat larger quan-
tity of seed than is generally recommended, because of the per-
sistence and rapidity of growth of volunteer weeds at this season.
The seed usually is sown broadcast and lightly harrowed in.
Where a winter tomato crop is planted in the row middles
the first season it should be followed by crotalaria or soybeans,
which will produce several tons of green matter. Crotalaria is able
to volunteer successfully year after year only if the ground is
dragged each spring to cover the seed and reduce weed compe-
tition. This dragging is not recommended after the first few
years because of the spread of the tree roots to the middles.
Natal grass offers the best permanent cover crop for southern
Dade County, and if given a good start and allowed a little plant
food it makes a good supply of mulch annually without having
the disagreeable features of some weeds.
Pruning.-No systematic pruning methods for the avocado
are generally followed. Trees which have been well cared for
and have never suffered a setback require little pruning. Some-
times, with certain varieties, small limbs which have carried a
very heavy crop are devitalized and these should be cut back to
strong healthy growth. Likewise, trees dying back from root
troubles may be greatly benefited by severe pruning, giving the
roots a chance to develop without heavy transpiration demand for
a season. Limbs resting on the ground should be removed if they
interfere with mowing and other cultural operations. Fruit on
such limbs is sometimes scarred and bruised and is more likely
to be eaten by rats and other animals. Some varieties, especially
Lula and Taylor, tend to grow very tall and these should be
pinched back periodically while young to encourage a more
spreading habit. Low, spreading trees are more economically
handled in spraying, pruning, picking and other cultural opera-
tions and are less liable to wind damage. Dead, broken or dis-
eased limbs should be removed, the cuts being made close to the
limbs from which these branches originate.
The best time to prune is in the dormant period of winter
after the fruit has been picked, if it matures in the fall or early







Florida Cooperative Extension


winter. All exposed surfaces should be painted with some pro-
tective material soon after the cuts are made. Carbolineum and
several commercial pruning paints having an asphalt base have
been found very satisfactory for this work. When cuts are left
unpainted, wood borers are sometimes found deep in the pith.
These insects gradually burrow downward and weaken the limb
to such an extent that it rarely recovers, and wood-decaying
fungi follow them.
Fertilization.-A scheme of fertilization of avocados has been
developed which differs from that used for citrus in the greater
quantities used, the higher percentage of nitrogen in the analysis,
and the derivation of a greater proportion of the nitrogen from
organic sources. The formulas used by different growers vary
considerably and good results have been obtained under widely
varying treatments, provided the quantity used was sufficient.
Animal and poultry manures are very beneficial to the avocado,
adding humus and bacteria to the soil besides being valuable as
fertilizers.
Experimental data are not available as a guide for all phases
of avocado fertilizing but some valuable information has been
obtained from research studies. Both this and the experience of
successful growers have been drawn on for the information pre-
sented here. Newly planted trees should receive about 1/ pound
per tree of a mixture analyzing approximately 5-7-3,3 the nitro-
gen being derived largely from organic materials. This applica-
tion is made about a month after planting and should be followed
at 60-day intervals by similar applications during the rest of the
year, the amount increasing gradually to 1 pound. In the second
year the same analysis is used but the applications should begin
with 1 pound in early spring and be made at 60-days intervals,
increasing gradually to 2 pounds per application by fall. In the
third and succeeding years 3 applications annually are made
of complete fertilizer, usually in February, June and October.
Experimental studies (43) have shown that a 4-5-5 analysis is
very satisfactory and that at least half of the nitrogen should be
from organic sources. No benefit has been shown from using
higher percentages of phosphoric acid and potash, or from vary-
ing the ratio during the year so as to increase potash and de-
crease nitrogen in the fall. The amounts applied will vary with
age and size of the trees, but as a rough guide it may be sug-

S5% nitrogen, 7% available phosphoric acid, 3% potash.







Avocado Production in Florida


gested that trees making vigorous growth can be given at each
application twice as many pounds of low-analysis fertilizer as the
tree is years of age. Thus a 4-year old tree would receive about
8 pounds of low-analysis fertilizer at each application. When
trees reach large size they cease to increase rapidly and a cor-
responding change in fertilizer schedule should be made.
Applications of nitrogen alone, intermediate to the regular
applications of mixed fertilizer, are very beneficial. Applying
1 to 3 pounds of sulfate of ammonia or nitrate of potash-soda per
tree 3 times a year at points halfway between the regular fertil-
izing has greatly increased yields in the Redlands area. Nitrate
of soda might be preferred for sandy soils.. The 3-pound applica-
tion would be made for quite large trees, with smaller amounts
for smaller trees, perhaps based on a rate of 10% of the pounds
applied at regular fertilizings.
The possibility of using the synthetic organic nitrogen fertil-
izers, such as urea and cyanamid, as the sole sources of nitrogen
is still under investigation. Undoubtedly they will require ap-
plication at more frequent intervals than the usual protein or-
ganic nitrogen sources and more care in distribution.
In the last few years the avocado has begun to exhibit symp-
toms of micro-nutrient element deficiencies. Definite proof has
been obtained of deficiency of zinc and copper in the case of cer-
tain avocado trees by Ruehle (20) and Ruehle and Lynch (23).
These symptoms are readily corrected by spraying with the
nutritional sprays used for citrus deficiencies. We can expect
these and perhaps other deficiencies to be more and more com-
mon in avocado groves as we supply less and less of the micro-
nutrient elements in the form of organic fertilizer materials,
but it should be easy to correct them as soon as observed.
The tolerance of the avocado tree to extreme conditions of
soil acidity and alkalinity has not been thoroughly investigated.
Where the soil is known to be far from average in reaction the
safer plan is to use, so far as possible, materials which will tend
to bring about a more nearly normal soil reaction. Sulfate of
ammonia and most of the organic ammoniates will aid in cor-
recting highly alkaline soils, while nitrate of soda, bone meal,
basic slag and lime tend to neutralize acid soils.
Under Florida conditions the avocado may receive large
amounts of nitrogenous fertilizer without apparent injury to the
tree. In common with most fruits, however, vigorous growth and
fruitfulness do not exist at the same time in the same tree. A







Florida Cooperative Extension


check in growth must take place before the tree will become
fruitful, and the drought and coolness of late fall and early
winter accomplish this usually.
Tree condition should be considered in determining the kind
and quantity of fertilizer to be used, and the mistake should not
be made of allowing trees to suffer for lack of sufficient fertilizer
for normal development. Undernourished trees produce fruit
which is sub-normal in size and pale in color and is generally
lacking in attractiveness. If considerable variation is apparent
in the grove the trees should be divided into 2 classes with re-
spect to condition of growth and fertilized accordingly.
Special attention must be given to the fertilization of trees
carrying heavy crops of fruit. If they are allowed to become un-
dernourished there is danger of shedding much of their foliage
and fruit when fertilizer again becomes available. A very heavy
bloom is also quite a drain on the resources of the tree and should
be compensated. When an unusually heavy crop has been set it
is well to make 1 or more light applications of nitrogen inter-
mediate to the regular ones. Kept in vigorous growing condi-
tion, with full foliage, the tree matures its fruit without injury
to itself and without sunburning and dwarfing of the fruit.
Trees which fail to set a crop need not be fertilized nearly so
heavily as those loaded with fruit, and need only be kept in good
healthy condition for the next year's crop.
Windbreaks.-Where avocados are grown commercially in
Florida winds are prevalent and cause more or less injury to tree
and crop. Occasional winds of hurricane force, because they
come at infrequent intervals, are not really so important as
ordinary sea breezes. During the dry season winds cause an
additional tax on the water-obtaining power of the tree by in-
creasing evaporation losses. The avocado leaf is stiff enough
that it never shows water deficit by wilting, as citrus leaves do,
but the rapid shedding of fruit when rain comes again, if not
before, shows that the deficit has been felt keenly. Windbreaks
reduce air movement and so lower evaporation loss. Wind injury
of fruits through rubbing against branches or against each
other is another factor of great importance. If bruised, a source
of entry for fungi is afforded, and if only scarred, the fruit is
spoiled in appearance. During high winds there is danger of
breakage of limbs heavily loaded with fruit. These mishaps are
greatly reduced by good windbreaks.
While a single row of windbreak trees affords some protec-







Avocado Production in Florida


tion, it is highly desirable to plant at least a double row in stag-
gered formation. The windbreak should extend clear around the
grove and when the grove is larger than 5 acres it is well to
separate each tract of 5 acres from the next by A single or
double line of windbreaks. The space sacrificed for windbreak
purposes will be a valuable investment in improved fruit. Where
the contour of the land is uneven, as in the Ridge section, open-
ings in the windbreaks should be left at 1 or more of the lowest
places to permit drainage of cold air out of the grove.
The selection of windbreak species should be based on the
following considerations: (1) Rate of growth, (2) ultimate size
reached, (3) resistance offered to wind, (4) toughness of
branches, (5) root habits, and (6) adaptation to soil and climate.
Some species of Ficus would, make excellent windbreaks were
it not for their undesirable root spread. Other trees are easily
broken up by the wind, or grow too slowly to be serviceable for
grove protection. No trees have shown themselves more satis-
factory as windbreaks in southern Florida than the Casuarinas.
There are 2 species commonly grown, the tall, slender Australian-
pine (Casuarina equisetifolia) and the shorter, thicker Brazilian-
oak (C. lepidophloia). Both species give very good protection
against wind, are rapid in growth, and become tall enough to be
effective windguards. Furthermore, they both have nitrogen-
fixing bacteria in their root nodules, as Mowry (12) has shown,
and so they enrich the soil somewhat. The second species tends
to produce root suckers on the limerock soil when the roots are
injured by dragging. It makes a lower and denser growth than
the other species, is hardier to cold, and is a better wind pro-
tection.
Other satisfactory windbreak species are the Australian silk-
oak (Grevillea robusta) in the Ridge section and the Jambolan
(Eugenia cumini) in Dade County. The species of Eucalyp-
tus have in general not made satisfactory windbreaks in Florida.
Many other trees are on trial for windbreaks at the Sub-Tropical
Experiment Station and elsewhere, but they have not been tried
sufficiently to be either recommended or rejected.
Rejuvenation of Neglected Groves.-Trees abandoned or neg-
lected for some time may be brought back to a fruitful condition
if reasonably sound in roots, trunk and larger limbs. Each tree
should be examined carefully and those which have become
stunted on account of being loose in the ground should be re-
placed with nursery trees. Drastic cutting back of tops and ap-







Florida Cooperative Extension


plication of mixed fertilizer such as is used on young trees are
the most important remedial measures. Trunk and limbs should
be examined for decayed places. Wherever the bark has been
broken wood-rotting fungi and borers are almost sure to enter.
Green avocado wood is comparatively soft and decays rapidly
and diseased areas must be treated before the decay has pene-
trated deeply. All diseased tissues should be cut away and the
exposed surfaces treated as described under "Pruning". It is
important that the cuts be made in such way that they will not
collect and hold water. If the decay has extended downward
inside farther than outside, a hole may be bored upward through
the bark and wood to the bottom of the pocket. A small open-
ing of this kind will provide drainage without the necessity of
weakening the trunk or limb by excessive cutting. The hole
may need to be opened again later if it has healed over before
the large wound has healed.
If insect pests or fungous diseases are present, control meas-
ures should be started as indicated in the discussion of these or-
ganisms. Top-working of unsatisfactory varieties in the planting
may be done as described under "Propagation". The grove
planting scheme can be revised, if necessary, to allow better
facilities for proper pollination by top-working or replacement
with nursery trees. In addition to these remedial measures the
grove should be mowed and mulched well. Subsequent care
should be. as for any other plantings, except that the trees
should not be allowed to carry a heavy crop for the first season.

THE CROP
Yields.-Seedling avocados as a rule come into bearing much
later than budded trees, from 5 to 7 years being required usually.
Budded trees frequently bear 1 or 2 fruits the year after being
planted and 1 or 2 precocious varieties may fruit in the nursery
row. Any fruit set the first and second years should be re-
Moved, but by the third year the budded tree should be able to
set and mature a crop of small size, and by the fourth year it
should carry a good crop safely.
Even in well fertilized groves the yield of a given variety may
vary tremendously from 1 season to the next, depending on
such factors as size of crop carried the previous year, conditions
during the blooming season, and rainfall and winds during fruit
development. Following the infrequent hurricanes or frosts







Avocado Production in Florida


trees on the lower East Coast may require several years to come
back into normal production. In other areas of the state freezes
may set the trees back severely at times.
Such heavy and consistent bearers as Trapp and Waldin can-
not be expected to produce more than 2 50-pound crates per sea-
son, as the average over a period of years, although occasionally
trees may produce over 10 crates. The average safe expectancy
for long-time production would be nearer 1 crate per tree. Lula,
Booth 8 and Booth 7 may be counted on for an average produc-
tion little lower than Trapp and Waldin, while Collinson, Fuchsia,
Linda, Taylor and Wagner are not quite so productive. Pollock
and Schmidt have not averaged over 1/2 bushel per tree in com-
mercial groves. Some unusually well cared for groves have
much exceeded these figures, but not the average grove.
Thinning.-Most varieties of avocados tend in greater or less
degree toward alternate bearing, i.e., a heavy crop 1 season is
followed by a light crop or none at all the next. While seemingly
'a natural tendency for the species, it is highly probable that
proper thinning of the crop would in large measure bring about
more regular bearing. A large portion of the crop is shed nat-
urally in separated periods of dropping fruit, but this varies
with the seasonal conditions and cannot be relied upon to relieve
an overburdened tree sufficiently. So far as is known no one
has ever practiced avocado thinning extensively, and so there
is no basis.of experience for, making suggestions. In the ab-
sence of such experience the following suggestions, are offered,
derived from experience with other fruits.
The best time for the first thinning is when the fruit is about
1 inch in diameter. Heavily laden trees and early maturing va-
rieties should receive attention first. The number of fruits to
be removed must be determined by the grower, and should be
governed by the condition of the particular tree and the ability
of the variety to carry heavy crops. All fruit which is badly
blemished, bruised or misshapen should be removed first, since
such fruit would be of little value even if the tree could mature
it, and the food and moisture which it would use may better go
to develop better quality fruit. Small branches carrying very
heavy loads of fruit should be relieved of much of it. Such
branches rarely are able to produce the normal amount of foliage
and the fruit is likely to be dwarfed and sunburned if not thinned
radically. -Six or 8 weeks later a check-up should be made and
additional fruit removed where necessary.







Florida Cooperative Extension


Picking.-Avocados should be picked with orange clippers,
cutting short stems to avoid stem punctures of other fruit. The
avocado is very susceptible to decay when the skin has been
broken, and careful handling at all times will prevent loss. For
reaching fruit in the top of tall trees a long bamboo picking pole
is used. To the end of the pole is attached a sharp-bladed hook
and below this is fastened a small canvas bag to catch the cut
fruit. The picker carries a galvanized iron picking bucket with
a layer of excelsior at the bottom to receive the fruit on transfer
from the picking pole receptacle, or to pick fruit into directly
by hand clipping, and these buckets have their contents in turn
placed in field crates well padded with some soft material on the
bottom and sides. In these padded field crates the fruit is de-
livered to the packing shed.
The most difficult phase of picking avocados is to know when
they are ready to pick. The season of maturity varies slightly
from year to year for each variety, according to time of bloom
and seasonal conditions during fruit growth, and so no calendar
date can be given for maturity of any variety. To create a mar-
ket and maintain the demand necessary for the profitable culture
of a little-known fruit such as the avocado, it is imperative that
the consumer be offered fruit which has attained its full flavor
and maturity. Due to the similarity in external appearance of
mature and immature fruits it is usually impossible for the
purchasers to differentiate between them, and the result is too
often disappointment and prejudice against the avocado.
Unlike some fruits, the avocado remains in perfect condition
on the tree for some time after reaching maturity, a few fruit
often hanging on for months, and never becomes soft enough on
the tree for eating. Before the first picking is made several
fruits should be laid aside for a week to see if they will soften
properly and possess the normal flavor of the variety. If the
samples taken become tough and rubbery and begin to shrivel
they have not yet reached the proper degree of maturity and
picking should be delayed until such a stage is reached. The
dropping of the first sound fruits when approximately full size
is usually taken as an indication that the fruit is mature. When
combined with the ripening test this affords a fairly dependable
determination of maturity, but care must be exercised to see that
the fruit has not dropped because of fungus infection of the stem.
Until such time as a relatively simple and accurate test of matur-







Avocado Production in Florida


ity can be standardized the ripening test should be used in de-
termining whether fruit is ready to pick and ship.
The picking and shipping of fruit which has reached the full-
est possible degree of maturity on the tree is not recommended,
but it is much preferable to shipping immature fruit. Such
exceptionally mature fruit, if graded carefully, may be marketed
successfully if shipped to consuming centers under refrigeration,
and its quality is splendid if the fruit is firm on arrival.
When the fruit is adjudged mature the first pickings from
the more heavily loaded limbs should consist of all but the very
small fruits. Unless this is done the loss of vitality occasioned by
the overcrop may induce a dying back of such branches and the
consequent loss of all the fruit borne on them. Of course, if the
fruit has been thinned judiciously this situation will not arise at
harvesting. From parts of the tree where the fruit is well dis-
tributed the practice should be followed of picking the largest
fruit each time.
Packing.-Florida avocados are packed for shipment in 2 kinds
of containers-the "vent" crate and the lug, mostly the latter.
The ventilated crate is the standard tomato crate and holds 40
pounds of fruit. The commonly used lug holds approximately
15 pounds of fruit and has inside dimensions as follows: Length
15", width 13", and depth 31/4", 38%" or 41/4", to allow for differ-
ent sizes of avocados. During the last few years there has been
increasing use of lugs made of corrugated paper. Formerly they
were made only of wood.
In packing avocados layers of excelsior or wood wool are placed
on all of the inside surfaces of the package, as well as between
the fruits, so that each fruit is "nested". (Fig. 28.) The bulge
pack used for citrus is quite impracticable for avocados, as they
have no resiliency and cannot withstand pressure without injury.
The use of tissue wraps for avocados is also undesirable, as
wrapped fruit tends to ripen too quickly. The pack, or number
of fruits per lug, varies with the variety and also within the
variety. The normal range for each commercial variety is given
under the varietal description.
Marketing.-In past years the bulk of the avocado crop moved
to market by express train and boat, mostly to Northern mar-
kets. New York, Chicago, Washington, Boston, St. Louis and
Cleveland received the largest shipments, in the order named.
In recent years, however, there has been a great increase in the
amount of fruit carried by refrigerated motor trucks and the







Florida Cooperative Extension


volume carried by trucks now far exceeds that carried by older
transport forms. The newer transportation vehicles have greatly
increased the range of distribution of avocados and have opened
many new markets all through the South and East. Bulk sales
to trucks at the packinghouse have become an important factor
in disposing of the crop also.


Fig. 28.-Avocados packed in excelsior for shipment.

The crop is marketed by some 10 to 12 shippers, for the most
part, ranging from growers who ship only what they produce to
shippers who grow nothing. No 1 of these marketing agencies
handles more than 15% of the crop.
Preference of consumers with regard to size, color and tex-
ture of fruit varies widely in different markets and with fluctuat-
ing price levels. Considerable experience in marketing avocados
and constant contact with principal markets are necessary to
obtain maximum returns. The general tendency of the trade,
however, seems to be toward fruit of small to medium size
(12, 14, 16 and 18 pack), green in color, and fairly smooth-
skinned or pebbled.
Storage.-It is sometimes desirable to put avocados in cold
storage to hold them in firm condition during a temporary mar-







Avocado Production in Florida


ket glut. Studies by Lynch and Stahl (10) have shown that
not only avocados of different races but also varieties of the
same race behave differently under cold storage. Table 9 shows
results of storage tests on 7 commercial varieties, stored at
different times throughout their season and at a wide range
of storage temperatures. Trapp was the most satisfactory
West Indian variety for holding in storage and Taylor the best
of the Guatemalan or hybrid varieties.
TABLE 9.-RESULTS OF STORING AVOCADO VARIETIES
AT VARIOUS TEMPERATURES.








Pollock ...... 42 21 3 3 17-19
Trapp .......... 42 21 4-6 2-5 18-20
Waldin ........ I Cold injury noted on skin even at 48 F. storage
Collinson .... 42-48 14 4-6 3-4 7-8
Booth 8 ...... 42 14 4-6 1-4 7-9
Lula ........... 37 28 3-6 2-3 20-24
Taylor ........ 37 28 4-6 2-3 23-26

Further investigation (27) has shown the importance of pre-
venting accumulation of carbon dioxide in the storage room.
Keeping the CO2 concentration below 3% has permitted longer
storage at all temperatures and reduced the development of
brown discoloration in the skin of the fruit. Studies of various
wrapping materials have shown that pliofilm has an unusual
ability to prolong the period of storage of avocados. Even when
held at 600 F. Lula and Taylor kept exceptionally ivell. It is
important in using this wrapping material that it should not be
twisted so tightly as to make an air-tight seal.

DISEASES
CERCOSPORA SPOT OR BLOTCH
Cercospora spot is the most important disease of the avocado
in Florida, no commercial variety being immune to it, and may
attack both foliage and fruit. Severe leaf infection rarely causes
defoliation. It is of economic importance chiefly as a fruit







Florida Cooperative Extension


disease. In itself the disease only spoils the appearance of the
fruit, as the spots do not penetrate the flesh, but the tissue
killed by the fungus and the cracks made in the rind afford
entrance for anthracnose and other decay organisms which
cause the ripening fruit to spoil. Different varieties vary con-
siderably in susceptibility to infection. Waldin, Taylor, Linda,
Wagner, Nabal and Booths 7 and 8 are very subject to attack,
while Trapp, Collinson and Fuchsia are moderately subject and
Pollock is only slightly susceptible.
The causal organism, Cercospora purpurea Cooke, does not
require a break in the skin to effect entrance and can attack
avocado fruit until nearly mature. Lesions on the fruit are
small, slightly sunken spots, irregular in shape and brown in
color. Individual spots are usually less than 1/8 inch across
but several may coalesce. The brown areas of sunken tissue
are dead and develop cracks and fissures. Characteristic gray-
ish spore-bearing tufts are always present during or just after
a period of wet weather. Stevens and Piper (30) have discussed
this disease in great detail.
Control.-This disease can readily be controlled by timely ap-
plication of copper sprays, as Stevens (28) first showed. Ex-
periments over many years in commercial groves have shown
that an application in early May followed by another in early
June gives effective control with varieties maturing in summer
and autumn. Both foliage and fruit should be well covered by
these sprays. In the case of winter-maturing varieties, a third
spray application in early July is desirable, directed chiefly to
covering the fruit. Ruehle (21) has investigated extensively
the effect of different copper sprays, and has found that while
4-4-100 bordeaux is satisfactory for groves where annual spray-
ing keeps the grove fairly free from disease, it is necessary to
use 6-6-100 bordeaux otherwise. Wettable cuprous oxide (83%)
at 11/2-100 is fully equal to 6-6-100 bordeaux, and at 1-100 is
equal to 4-4-100 bordeaux, while 4-100 copper compound A
(45%) and 6-100 basic copper sulfate (28%) are nearly equal
in effectiveness to the stronger bordeaux, with much less trouble
from scale insects in all cases because of less spray residue than
is left by bordeaux. It is important to add an efficient spreader
to the spray mixture unless the manufacturer has incorporated
1 in the spray material. Furthermore, it is desirable to spray
with an oil emulsion as soon as possible after fruit harvest to
control scales, which develop even with light residues.







Avocado Production in Florida


In addition to the regular fungicidal spray program, Stevens
and Piper (30) also recommend an application of spray in March
for control of fruit stem infections on varieties like Wagner,
with slender stems and late maturity. This spray decreases
summer drop in such varieties.

ANTHRACNOSE OR BLACK SPOT
The most conspicuous disease which avocado growers have to
combat is caused by the ubiquitous anthracnose fungus (Col-
letotrichum gloeosporioides Penz.). It is most commonly found
and is of most economic importance on the fruit, where it causes
"black spot". The organism is not able to penetrate the un-
broken skin of the avocado after it has reached the size of a
large pea, but Wardlaw et al (38) have shown that in Trinidad
latent infection is common in this fruit from infections estab-
lished in very early stages of growth. These latent infections
remain inactive until the fruit is mature, but develop rapidly in
the ripening fruit. However, these observations have not been
confirmed for Florida conditions.
Probably the most common means of anthracnose infections
in Florida avocado fruits is through breaks in the skin resulting
from blotch lesions or mechanical injuries. The organism forms
sunken black spots, usually nearly circular in outline and from
1/" to 1/2" in diameter. As the fruit ripens the infection spreads
rapidly into the softening flesh, causing decay which may involve
a large portion of fruit.
Control.-Where cercospora spot is controlled, there is little
or no trouble from black spot, and the control of both diseases
is accomplished by 1 program.

STEM-END ROT
Considerable loss of fruit occurs in transit from rots which
invade the fruit from the stem end and develop as the fruit
softens. Both Diplodia and Phomopsis, the common fungi caus-
ing stem-end rot in citrus, have been isolated from these rots.
The problem of their control is still under investigation and no
recommendations are at present possible.

SCAB
This disease, which is closely related to citrus scab, is second
only to cercospora spot in commercial importance, but avocado
varieties differ greatly in their susceptibility to it. Lula is the







Florida Cooperative Extension


most susceptible commercial variety; Fuchsia, Pollock, Booth 1,
Waldin, Itzamna, Linda and Collinson are quite resistant. The
scab organism (Sphaceloma perseae Jenkins) attacks the young
foliage and the fruit, but is rarely serious on the foliage except
in the nursery. The fruit of some varieties, however, may be
almost entirely of cull grade because of scabbiness. Spots on
the fruit are irregular in outline but often coalesce into a large
irregular area which gives the fruit a russetted appearance.
Practically the whole surface of the fruit may be affected in
some cases. The quality of the mature fruit is not in the least
affected by the disease, which is limited to the skin, but the
appearance is made very unattractive and in severe cases the
fruit may be deformed or dwarfed. On young twigs and leaves
the spots become corky in mature stages and cause considerable
distortion of the leaves.
Control.-The extensive studies on scab by Stevens have
shown that it can be controlled on the fruit by proper spraying
with 6-6-100 bordeaux, and Ruehle (22) has obtained equally
good control with 11/2-100 wettable cuprous oxide, which leaves
much less residue for scale protection. Spraying for cercospora
spot controls scab satisfactorily, except with very susceptible
varieties like Lula. Three additional applications are necessary
for this variety, as follows: (1) Just as the bloom buds begin
to open, usually late in January; (2) near the end of the main
bloom period, when the small fruits are just becoming visible;
(3) a month after (2). The first or delayed dormant spray may
be omitted if no old scab infections are visible on foliage and
scab has not been bad the past season, but application (2) should
be made in mid-bloom and (3) when all fruit has set. Moderately
susceptible varieties which start the season with many old
scabby leaves will need these 2 sprays also to clean them up.
Ruehle (22) has found that where some trees, usually suscept-
ible seedlings, have been left unsprayed, so that scab becomes
severe on them, adjacent sprayed trees may become infected
late in the season unless spraying is continued at monthly inter-
vals all summer. Obviously it is cheaper to spray these seedlings
with the commercial varieties, or to topwork them.
MINOR DISEASES
Among avocado diseases less frequently found and rarely
warranting the expense of spraying is powdery mildew (Oidium







Avocado Production in Florida


sp.). This is found more often in the nursery than in the grove,
and can be readily controlled by spraying with 6-6-100 bordeaux.
Sun-blotch is a virous disease which has caused considerable
trouble in California, but has been observed only a few times in
Florida. The first appearance, described in the first edition of
this bulletin (Exp. Sta. Bul. 272, 1934), was in a grove at Home-
stead, where in 1932 a scion of Carlsbad from California showed
typical symptoms on the fruit. The scion was destroyed
promptly. Stevens (29) has recently reported on another and
rather perplexing case where a whole row of trees was affected.
They had all been budded to Taft from a tree propagated from a
California scion, and were early topworked to other varieties.
The original Taft parent tree in Florida has never shown sun-
blotch, but all of the trees topworked on the Taft buds from this
tree developed the characteristic symptoms. These infected trees
were also destroyed. A third case from Dade County in 1933 on
a California scion of unknown origin is also recorded by Stevens,
and Ruehle (unpublished data) has noted 1 or 2 others. In all
cases the trees showing the virus have been destroyed.
The red alga spot (Cephaleuros virescens Kze.) sometimes at-
tacks the leaves of the avocado tree and needlessly alarms the
grower. The circular patches of reddish brown hairs on the
glossy green leaves are very prominent and may be observed on
a large number of leaves, but no permanent damage is known
ever to have been done. This organism is of economic import-
ance as a pest of some other fruits, but not of the avocado.
PHYSIOLOGICAL DISEASES
Several troubles affecting the avocado and finding expression
in an unhealthy or diseased appearance of the foliage appar-
ently are due wholly to conditions of environment and not to any
organism. Usually soil conditions are involved principally.
Little-leaf.-Principally on the calcareous soils of the East
Coast, a mottled or "frenched" condition of foliage has been
observed for years to develop occasionally during the long
winter dry season, but usually the symptoms have disappeared
with the coming of spring rains. In recent years these
symptoms have been increasingly severe, probably due to in-
creasing use of fertilizers derived almost wholly from inorganic
sources. At least, symptoms are less severe where organic mat-
ter is present in abundance and fertilizers contain a large portion
of nitrogen from organic sources. Ruehle (20) has shown that







Florida Cooperative Extension


it can be controlled by use of zinc sulfate, as can the analagous
frenching of citrus and rosette of pecan.
In mild cases the leaves show a mottled or frenched condition
(other causes may be responsible for similar foliage appear-
ance). In more severe cases the foliage size is markedly re-
duced, the leaves are curved and thickened, and the internodes
are shortened so that the leaves form a rosette. Use of 10-5-100
zinc sulfate-lime spray has given control of severe cases, while
a 5-21/2-100 spray seems adequate for correction of mild cases
or for maintenance. Spray applications are most efficient when
made just as a flush of growth is starting, and may be combined
with a fungicidal spray by adding the recommended amounts
of zinc and lime to 100 gallons of bordeaux mixture.
Tip-burn.-Another physiological disease which affects the
leaves of certain varieties of avocado, notably Taylor, is char-
acterized by a dying back of the tip for 1/3 to 1/ of the length
of the leaf, giving a scorched appearance. The disease usually
appears in the fall after the leaves are fully mature. No serious
results have been observed from such a condition, since affected
trees continue to grow and fruit well. Such leaves would nor-
mally soon be shed and replaced by new growth. There is no
reason to believe that spraying would have any preventive or
curative effect.
Fertilizer Burn.-Development of very small leaves may fol-
low application of large quantities of inorganic fertilizers to
trees with consequent injury to feeding roots. Injudicious ap-
plication of cyanamid also has caused serious foliage injury,
apparently the result of root injury also.
Die-Back.-Recently a die-back disease has been found affect-
ing young avocado trees on new land in the Ridge section. Ruehle
and Lynch (23) have presented evidence that this can be con-
trolled by application of copper sulfate, as for citrus die-back,
either as a spray or on the ground. The trouble does not appear
on trees sprayed for control of scab or black spot.
DECLINE
Trees which have endured a few days of water standing higher
than the crown roots are likely to die quickly, as if injured by
lightning. Formerly this was considered as resulting, from
suffocation of the roots by exclusion of oxygen. Studies in
California by Wager (37) suggested that it is chiefly due to soil
fungi, such as Phytophthora cinnamon, which are able to attack






Avocado Production in Florida


and rapidly kill avocado roots in poorly drained soils. These
observations have been confirmed in Florida, as also Wager's
finding that in soil free of these fungi avocado trees are not
injured by prolonged submergence of the soil. It appears also
that once these pathogens have thoroughly infested the soil they
may attack avocado roots even without flooding of the soil,
killing trees gradually. No control measures other than good
drainage are suggested at present.

INSECTS AND OTHER PESTS
Most of the work on avocado insects has been done by Moz-
nette, whose bulletin (13) was written in 1922. The reader may
refer to it for a more comprehensive discussion of the insect
pests. The bulletin on citrus insects by Watson (39) gives a full
discussion of methods of preparing various insect sprays, and
should be referred to for information on this matter. However,
it should be borne in mind that the avocado will be burned more
readily than citrus trees by oil and only highly refined, phyto-
nomic oils should be used.

DICTYOSPERMUM SCALE
In southern Florida this pest (Chrysomphalus dictyospermi
Morgan) is the most injurious insect attacking the avocado in
both nursery and grove. Varieties of the West Indian race are
preferred as hosts, but no variety has been found immune. In
the grove the scale is found on twigs, on young vigorous limbs,
and occasionally on foliage and fruit. Heavy infestations weaken
and often kill smaller branches. First indication of injury is
a cracked and darkened appearance of the green bark. Trees
already badly affected and unthrifty have the bark almost con-
cealed by the scales of this pest in the angles where small
branches leave the larger ones. Investigation has shown that
residue from bordeaux spray is a factor in getting this pest
started in groves.
The insects are more abundant in the summer and early fall,
when the trees are carrying a crop. Considerable damage may be
done at this season because the crop is already draining the
tree and the additional weakening may be more than the tree
can stand. The Trapp is more susceptible to serious injury than
any other variety, and heavily loaded trees may be badly at-
tacked while trees carrying little or no crop are uninjured. The







Florida Cooperative Extension


insects are sometimes found also along the fruit stem and at the
point where the stem is attached to the fruit, causing premature
dropping. The injury caused by this organism is through loss
of sap which it sucks from the young tissues. The scale cover-
ing is small (about 1/25 inch in diameter), brownish-gray, cir-
cular in outline and nipple-like. In the crawler stage the insect
is yellow.
Control.-Oil emulsions usually are effective in controlling the
dictyospermum scale if applied in sufficient strength. Using the
tank-mix phytonomic oils, it is safe to apply a 2% oil spray on
avocados and this will give positive control of this scale. Two
applications 3 weeks apart are necessary. Since infestations
are lightest in winter and the cooler weather of this season is
less conducive to spray burn, it is advisable to spray thoroughly
in December or January. If necessary to attempt control during
summer, spraying should be done in late afternoons or on cloudy
days. Use of the newer copper sprays which leave little residue
will greatly curtail the incidence of scale infestations.
The twice-stabbed ladybeetle (Chilocorus bivulnerus Muls.)
feeds upon the dictyospermum scale and has greatly aided in
keeping this pest in check, but it cannot be relied upon for com-
plete control.
PYRIFORM SCALE
This scale (Protopulvinaria pyriformis Ckll.) is not so destruc-
tive in Dade County as dictyospermum, but causes a marring of
the -fruit appearance due to the sooty-mold fungus which de-
velops in the honeydew secreted by this insect. In the northern
and central portions of the state it is a serious pest comparable
to dictyospermum in the south. It is found on the under surface
of leaves and occasionally on the fruit, where it attaches itself
and sucks the plant juices. The adult is pear-shaped, reddish-
brown with a white margin, and about 1/8 inch in length.
Control.-Spraying as recommended for dictyospermum scale
will give good control, using a 1% oil emulsion, but special care
must be taken to spray thoroughly the under side of the foliage.
AVOCADO WHITEFLY
This whitefly (Trialeurodes floridensis Q.) is smaller than any
of those attacking citrus, the adult being less than 1/25 inch in
length. The injury caused is very similar to that caused by pyri-
form scale. The body of the adult is lemon-yellow. In the pupal
(or resting) stage the insect may readily be identified by the







Avocado Production in Florida


yellow body covered by a thin transparent membrane, the cir-
cular shape, and the fringed margin.
Control.-Two applications of oil emulsion, the first in Novem-
ber and the second in February, will give satisfactory control.
The insect lives on the under side of the leaves and is more
abundant on the well protected and shaded parts of the tree.
The spray should, therefore, be directed particularly to these
parts. The papaya, guava, annona and a number of native plants
are hosts of this insect. When any of these are growing in or
near an avocado grove they should be sprayed or removed. Cer-
tain entomogenous fungi afford partial control of whitefly but
cannot be relied upon for complete control.
AVOCADO RED SPIDER
During warm, dry weather this "insect" (Paratetranychus
yothersi McG.) is often found in great numbers on avocado trees.
The mite is very small but its bright red color makes it easily
visible to the naked eye when it moves. It sucks the juices of
mature leaves, feeding on the upper surface only and causing the
foliage to assume a characteristic rusty-brown appearance. This
discoloration is first evident along each side of the midrib and
larger veins, but it widens as the mites extend their feeding area
until it finally covers the whole leaf. By this time the leaves
are badly devitalized and are soon shed. The grower should
be on the lookout for the first signs of injury during dry weather,
and should not wait for browned leaves to appear.
Control.-During summer usually no artificial control meas-
ures are necessary, as frequent heavy rains keep the red spider
in check. During the dry periods of winter and spring, and dur-
ing a prolonged period without rains in summer, it is necessary
to resort to dusting or spraying if the pests become numerous.
Thorough spraying with either oil emulsion or lime-sulfur, or
dusting with sulfur, will effect control. Lime-sulfur 1:60 may be
used safely in winter on bearing trees. While the fruit is still on
the tree it is better to dust or to spray with oil, as the lime-sulfur
is hard to remove from the fruit, but oil gives only temporary
checking. A second spraying or dusting should follow the first
in about 3 weeks to effect complete control. Rarely, a third is
needed. Where only a few trees are involved and these are
fairly low-headed a hand duster may be used effectively. Cam-
phor trees are a favorite host. Where they are present they offer
a steady source of these mites for attacking avocados.







Florida Cooperative Extension


/ AVOCADO LACE-BUG
This insect (Acysta perseae Heid.) occasionally may be found
infesting the under sides of leaves in winter, but more often in
the warmer, dry spring months. It prefers the West Indian
race, although no variety is known to be free from attack by it.
The lace-bug is a sucking insect, and pale spots appear on the
foliage wherever it feeds, due to the extraction of plant juices.
The insect may be recognized by the lace-like structure of its
wings and body.
Control.-Spraying with 1 part of nicotine sulfate (40%) in
900 parts of water gives good control. A spreader should be
added to the spray to make coverage more complete.

AVOCADO LEAF-ROLLER
During summer the avocado tree may be infested with the
larvae of a small gray moth (Gracilaria perseae Busck). These
larvae roll the leaves by drawing them inward from the margin.
They are chewing insects and when abundant give the foliage
a very ragged appearance. The actual damage, however, is
usually not sufficient to warrant spraying. Arsenate of lead at
the rate of 1 pound in 50 gallons of water gives satisfactory
control. If bordeaux spray is to be applied at the time the leaf-
roller is active the lead arsenate may be added to the bordeaux
mixture.
MIRIDS
In recent years avocado groves have occasionally suffered
serious crop injury from the attack of certain plant bugs known
as mirids, closely related to the tarnished plant bug. These
sucking insects attack the opening buds in great numbers and
cause much dropping of young fruit or development of mal-
formed fruit. They also cause some injury to leaves, which
look when fully opened as if many holes had been eaten in them.
Actually the leaf is attacked while still in the bud, but the punc-
ture made by the insect kills a very small area of leaf tissue,
and when the leaf expands these dead areas cannot grow and
so are left as holes.
If the infestation is observed promptly the insects may be
fairly well controlled by a strong spray of nicotine sulfate,
pyrethrum or rotenone. The insects usually disappear within
a few weeks after their first appearance, but may do great
damage in a short time in the blooming period. The adults are







Avocado Production in Florida


hard to kill and control measures are aimed at the young insects
or nymphs. All mirids are soft-bodied, rather small insects,
not over 1/4 inch long when adult. Two species have been identi-
fied in Florida avocado groves: Rhinacloa subpallicornis Knight
and Lygus fasciatus Reuter.
BLOSSOM ANOMALA
This beetle (Anomala undulata Mels.) occasionally appears in
great numbers at blooming time and devastates avocado bloom
spikes. It is a relative of the June-bug and looks somewhat like
a miniature edition of that insect. in brown and black. The in-
sects feed at night and drop to the ground in the morning to
spend the day under the top layer of soil. They play dead when
uncovered. Spraying with lead arsenate has not seemed to
have any detrimental effect on them, perhaps because the bloom
spikes are opening fresh buds constantly. A lighted lamp held
against a piece of galvanized iron with a pan of kerosene below
to catch the insects after they strike the shield and fall has
helped reduce infestations. The epidemic is transitory and
usually only a comparatively small number of trees are attacked.
BLOSSOM THRIPS
This little insect (Frankliniella cephalica Craw.) is pale yellow
in color and about 1/25 inch long. By depositing eggs in great
numbers in the flower bases they cause the flowers to be shed and
even more damage is done by feeding on stamens and other
flower parts. On the other hand, these thrips also force their
way into many flowers which have closed after their first open-
ing, and they may pollinate many flowers in their search for
food. Whether the damage done by feeding on flower parts is
greater than the benefit conferred by accomplishing pollinations
is a question that needs and deserves careful investigation.
LEAF-INFESTING THRIPS
This thrips (Heliothrips haemorrhoidalis Bouche) attacks the
upper surface of the leaves of the avocado in a way very much
like the red spider, but usually causes less severe injury. The
work of the 2 may be distinguished by the numerous minute
drops of blackish fluid left by the thrips, in addition to the
differences in their appearance. The thrips is dark brown and
has wings, while the bright red spider mite has no wings.







Florida Cooperative Extension


The red-banded thrips (Heliothrips rubrocinctus Giard.) is
sometimes found attacking avocado leaves.
Control.-Control of thrips is accomplished by spraying or
dusting with nicotine sulfate. If red spiders also are prevalent
it is best to spray in winter with lime-sulfur (1:60) containing
1 part of 40% nicotine sulfate in 900 parts of spray, or in the
fall while fruit hangs on, with oil emulsion containing the same
nicotine sulfate amount. As with red spider, it is important to
recognize the presence of this pest before the damage has pro-
ceeded so far as to injure the leaves seriously.

TENTWORM
This pest is the larva of an insect, and not a true worm, al-
though it is commonly so called. Like the leaf-roller, it is a
chewing insect, and sometimes it becomes so numerous as to re-
'quire control measures. The larvae spin a web about a cluster
of leaves during the winter and early spring months and feed
on the leaves until the pupal stage is reached.
Control.-Larvae have been found which were parasitized
by small white grubs, and in some cases almost complete control
has been effected by them. If spraying is necessary, lead arse-
nate may be used as for the leaf-roller.

BORERS
Newly planted groves should be carefully watched for infesta-
tion with borers or sawyers. These insects are sometimes found
infesting the pith or sapwood, having gained entrance through
stubs or other exposed surfaces of the trunk or branches. They
work their way downward, destroying all growth as they go,
and may eventually kill the tree. Even large trees are some-
times severely attacked.
Control.-Preventive measures consist in removing all dead
wood present and painting the cut surfaces with pruning paint
as previously recommended under "Pruning." If infestation is
found in trees, all infested branches should be removed and
burned and the cut ends of the branches treated as above.

MINOR INSECT PESTS
The following insects at times have become troublesome on
avocados, but are not likely to damage groves sufficiently to
warrant control measures.







Avocado Production in Florida


Florida red scale (Chrysomphalus aonidium L.) is a common
pest of citrus trees. It has been reported once as infesting
heavily an avocado tree of the Mexican race, and several times
has been found in mild infestations. If the insect adapts itself
to the avocado, control may be very difficult because of its re-
sistance to oil sprays. It is necessary to spray several times at
short intervals, since only the young scale can be killed by oil
spray.
Mealybug (Pseudococcus sp.) is sometimes found on avocado
foliage, especially under shaded conditions, but usually causes
slight injury. When infestations are troublesome in the slat-
house the insects may be washed off with a stiff spray from a
hose or scrubbed from the leaves with a suds of laundry or fish
oil soap.
Brown aphid (Toxoptera aurantiae Fonsc.) occasionally at-
tacks nursery trees, but the avocado is very little injured by
attacks of aphids, and even in the nursery it is not likely to
suffer seriously.
Cottony scale (Pulvinaria psidii Mask.) has been found a few
times infesting the avocado, but no serious effects have ever been
known to result, such as would warrant spraying.
RODENTS
Sometimes much fruit on the lower branches, and sometimes
even fruit higher up, is destroyed by rats or field mice. If the
cover crop is high in the grove while the fruit is maturing it
should be mowed if trouble from this source is expected, since
it affords a good hiding place for these rodents. Poisoned bait
may be used if necessary. Sweet potatoes cut into small pieces
and dusted with strychnine sulfate at the rate of 1 ounce per
peck give excellent results. Common soda and a pinch of table
salt are first dusted over the cut pieces and then the poison is
added.
LITERATURE CITED
1. CLARK, O. Avocado pollination and bees. Cal. Avoc. Asso. Rept.
1922-23: 57-62. 1923.
2. Avocado pollination tests. Cal. Avoc. Asso. Rept.
1923-24: 16-22. 1924.
3. CLARK, 0., and A. CLARK. Results of pollination and other experi-
ments on the avocado at Point Loma Homestead. Cal. Avoc. Asso.
Rept. 1925-26: 85-94. 1926.


91







92 Florida Cooperative Extension

4. CONDIT, I. History of the avocado in California, etc. Cal. Avoc. Asso.
Rept. 1916: 105-106. 1916.

5. CRUESS, W. V., and E. HARROLD. Investigations on the utilization of
cull avocados. Cal. Avoc. Asso. Rept. 1927: 34-38. 1928.

6. ELLIOTT, J. M. Practical pointers on budding and grafting avocados.
Cal. Avoc. Asso. Rept. 1922-23: 23-24. 1923.

7. HODGSON, R. W. The California avocado industry. Cal. Agr. Ext.
Serv. Cir. 43. 1930.

8. Observations on avocado production, etc. Cal. Avoc.
Asso. Rept. 1927: 89-98. 1927.

9. KROME, W. J. The Medora method of top-working avocados. Proc.
Fla. State Hort. Soc. 29: 149-151. 1916.

10. LYNCH, S. J., and A. L. STAHL. Studies in the cold storage of avocados.
Proc. Fla. State Hort. Soc. 52: 73-78. 1939.

11. MATTILL, H. A. Avocado digestibility. Cal. Avoc. Asso. Rept. 1916:
93-95. 1916.

12. MOWRY, H. Symbiotic nitrogen fixation in the genus Casuarina. Soil
Science 36: 409-424. 1933.

13. MOZNETTE, G. F. The avocado: Its insect enemies and how to combat
them. U.S.D.A. Farm. Bul. 1261. 1922.

14. NIRODY, B. S. Investigations in avocado breeding. Cal. Avoc. Asso.
Rept. 1921-22: 65-78. 1922.

15. POPENOE, W. Manual of tropical and sub-tropical fruits. Macmillan.
1920.

16. An -early account of the avocado. Cal. Avoc. Asso.
Rept. 1925-26: 83-85. 1926.

17. Wild avocados. Cal. Avoc. Asso. Rept. 1927: 51-54.
1927.

18. ROBINSON, T. R. Pollen sterility in the Collinson avocado. Jour.
Hered. 21: 35-38. 1930.

19. ROBINSON, T. R., and E. B. SAVAGE. Pollination of the avocado.
U.S.D.A. Dept. Circ. 387. 1926.

20. RUEHLE, G. D. Zinc deficiency of the avocado. Proc. Fla. State Hort.
Soc. 53: 150-152. 1940.

21. Cause and control of cercospora spot and anthracnose
of the avocado. Fla, Agr. Exp. Sta. Press Bul. 583. 1943.

22. -- Caue and control ol avocado scab. Fla. Agr. Exp.
Sta. Press Bul. 580. 1943.








Avocado Production in Florida 93

23. RUEHLE, G. D., and S. J. LYNCH. Copper sulfate as a corrective for
dieback, a new disease of the avocado. Proc. Fla. State Hort. Soc.
53: 152-154. 1940.

24. SANTOS, F. O. Some plant sources of vitamins B and C. Proc. Soc.
Exp. Biol. and Med. 19: 2-3. 1921.

25. SKUTCH, A. Observations on the flower behavior of the avocado in
Panama. Torreya 32: 85-94. 1932.

26. STAHL, A. L. Changes in the composition of Florida avocados in re-
lation to maturity. Fla. Agr. Exp. Sta. Bul. 259. 1933.

27. STAHL, A. L., in Rept. Fla. Agr. Exp. Sta. 1940, p. 89.

28. STEVENS, H. E. Avocado diseases. Fla. Agr. Exp. Sta. Bul. 161. 1922.

29. Avocado sun-blotch in Florida. Phytopath. 29: 537-541.
1939.

30. STEVENS, H. E., and R. B. PIPER. Avocado diseases in Florida.
U.S.D.A. Circ. 582. 1941.

31. STOUT, A. B. A study of cross-pollination of avocados in southern
California. Cal. Avoc. Asso. Rept. 1922-23: 29-45. 1923.

32. The flower mechanism of avocados with reference to
pollination and the production of fruit. Jour. N. Y. Bot. Gard.
25 1-7. 1924.

33. The pollination of avocados. Fla. Agr. Exp. Sta. Bul.
257. 1933.

34. STOUT, A. B., and E. B. SAVAGE. The flower behavior of avocados
with special reference to interplanting. Fla. State Hort. Soc. Proc.
38: 80-91. 1925.

35. TORRES, J. P. Some notes on avocado flowering. Phil. Jour. Agr. 7:
207-227. 1936.

36. Some notes on tongue-inarching of the avocado. Phil.
Jour. Agri. 10: 11-17. 1939.

37. WAGER, V. A. The dying-back of avocado trees in Southern California.
Cal. Avoc. Asso. Rept. 1940: 40-43. 1940.

38. WARDLAW, C. W., R. E. D. BAKER, and S. H. CROWDY. Latent infections
in tropical fruits. Trop. Agr. 16: 275-276. 1939.

39. WATSON, J. R. Citrus insects and their control. Fla. Agri. Ext. Serv.
Bul. 88. 1937.

40. WEATHERBY, L. S. Vitamin investigations of the avocado. Cal. Avoc.
Asso. Rept. 1928: 58-67. 1928.

41. Vitamins C, D and E. Cal. Avoc. Asso. Rept. 1930:
100-105. 1930.







Florida Cooperative Extension


42. WEATHERBY, L. S., J. E. YOUNTZ and R. V. WATSON. The vitamin A
content of avocados. Cal. Avoc. Asso. Rept. 1929: 54-57. 1929.
43. WOLFE, H. S., and S. J. LYNCH. Fertilizer studies with avocados.
Proc. Fla. State Hort. Soc. 53: 147-150. 1940.
44. YOUNG, T. W. Private Communication.

CHECKLIST OF AVOCADO VARIETIES IN FLORIDA
W-West Indian G-Guatemalan M-Mexican
I-formerly of commercial importance
II-formerly grown on small scale but of minor importance
III-never of any commercial value but propagated by commercial nurseries
formerly
IV-never propagated commercially but tested as specimen trees
V-no longer propagated in Florida
VI-obsolete, no longer grown in Florida
Varieties introduced by the U.S.D.A. have S.P.I. numbers given
AJAX (GxW) III
Another hybrid of the same origin as Booth 2, with fruit closely re-
sembling Collinson. Vigorous tree and heavy bearing. Dec. & Jan.
ALMA (GxW)
Originated on place of Heinrich Rohde, Sebring, Fla., in 1922 as a seed-
ling of unknown origin. Fruit rounded, 12-20 oz.; skin purple, thick,
rough; seed rather large. Quality very good. Oil content 20%.
Season January 15-March 15. While not recommended commercially,
this variety is of considerable interest for home planting as a late
winter variety because it has never been injured by cold at Sebring.
Certified 1944.
ANAHEIM (G) IV, VI
Introduced from California for trial about 1926.
ATLIXCO (G) II, V
Introduced from California about 1917 and planted on a small scale
in 1920-24. Fruit obovate-oblong, about 1 lb., mahogany-red when
mature, season Jan. & Feb. Nearly obsolete.
AUBURNDALE (W) IV Syn. Juliana
Originated on place of Capt. J. M. Burns, near Auburndale, as seed-
ling of Pollock, about 1925. Fruit obovate, about 2 lbs., glossy green
season November.
AVON (GxW)
Originated in grove of W. F. Ward, Avon Park, Florida, as one of
several hundred seedlings from Guatemalan trees with chance for
West Indian pollination. Evidently a hybrid. Seed planted in 1923.
Fruited first in 1927. Top-worked extensively in owner's grove in
1934. Fruit obovate, with obliquely flattened base, medium size,
12-20 oz. Pack 12-20. Skin slightly wrinkled, glossy medium green,
rather thin and pliable. Flesh light yellow. Seed rather large. Oil
content 9-14%. Season December and January. A very heavy bear-
ing variety as top-worked in the Ward grove, with good appearance of
fruit but handicapped by very large seed.








Avocado Production in Florida 95

BAKER (W) IV
Originated on Z. L. Baker place at Ojus, Florida, propagated about
1917, and then considered promising for late fall.
BALDWIN (W) IV, VI 12933
Originated on Baldwin place, Miami, and propagated somewhat from
1904-09. July and August season, green skin, 1 to 2 lbs., oblong.
BARKER (W) III, V
Originated at Bradenton, Florida, on grounds of Judge Barker, and
somewhat planted on the West Coast sinqe 1920 as home fruit. Fruit
large, resembling Pollock, maturing Oct.-Nov.
BENIK (G) JV, VI 44626
One of the Popenoe introductions from Guatemala in 1917 which has
proven satisfactory in California but not in Florida.
BITTE (W) III
Originated on place of Seymour Dane, Redlands, Florida, prior to
1912. Propagated in 1920 by topworking and since 1930 in commer-
cial nursery on very small scale. Fruit obovate, medium large size;
skin green, smooth, leathery; seed medium size, tight. Season October
and November. Heavy bearing, fruit ships well.
BLACKMAN (W) III, VI 26701
Originated on place of Rev. E. V. Blackman, Miami, and propagated
in 1907. Fruit round, 1% lb. weight, skin purple, season September
& October.
BLAIR (G)
Originated on place of J. R. Hickson, Naranja, Florida, from seed of
Taylor planted in 1926. Fruited in 1933, and topworked to small
extent in Redland groves since 1935. Nursery propagated in 1939.
Fruit obovate, medium size, closely resembling Lula, but not greatly
subject to scab. Season December and January. Bearing habit good.
BLAKEMAN (G) II, VI
Introduced from California in 1914 as one of most desirable for trial.
Fruited in 1918 and planted on small scale for 10 years. Fruit pyri-
form, 16-30 oz.; skin green, thick and woody, slightly rough; season
January.
BONITA (GxW) See Commercial Varieties.
BOOTH 1 (GxW) See Commercial Varieties.
BOOTH 2 (GxW) IV, V Syn. Acme
Originated in grove of Will Booth, Homestead, Florida, as a seedling
of unknown Guatemalan parent from tree in mixed planting of
Guatemalan and West Indian varieties. Seed planted in 1920; fruited
first in 1927. Fruit obovate-round, 1 lb. weight, green, season February
and March.
BOOTH 3 (GxW) III
Origin same as Booth 2. Fruit rounded-obovate, about 1% lb. weight;
skin dark, glossy green, nearly smooth, quite thick and woody. Season
January and February. Has good reputation for bearing.
BOOTH 5 (GxW) IV, V
Origin same as Booth 2. Fruit obovate, about 1 lb. weight, green,
season December.
BOOTH 7 (GxW) See Commercial Varieties.
BOOTH 8 (GxW) See Commercial Varieties








Florida Cooperative Extension


BUTLER (W) II, VI 26690
Originated at U.S.D.A. Plant Introduction Garden, Miami, from seed
sent by C. W. Butler, St. Petersburg, in 1904. Fruited in 1909 and
propagated somewhat from 1914-18. Fruit pyriform, 1% lb. weight,
skin green, season August and September.
CABNAL (G) IV, VI 44782
A Popenoe introduction from Guatemala in 1917.
CANTEL (G) IV, VI 44783
A Popenoe introduction from Guatemala in 1917, once a secondary
variety in California.
CARDINAL (W) VI
Originated in Florida prior to 1910, but nothing is known of its origin
and habits there. Introduced in California for trial in 1912 (?) and
so recorded in literature. Also introduced in 1914 from Florida to
Philippines, where now it is the most widely grown variety. Fruit
obovate, strongly necked; skin red, mottled with yellow. Season
September-October in Florida.
CARLSBAD (G) IV, VI
Introduced from California for trial in .1928.
CHABIL (G) IV, VI 45564
A Popenoe introduction from Guatemala in 1917.
CHALLENGE (G) III, VI
Introduced from California for trial about 1925.
CHISOY (G) IV, VI 43935
A Popenoe introduction from Guatemala in 1917.
CHOICE (G) IV, VI Syn. Stephens Choice
Introduced for trial about 1922 from California, where it was an im-
portant variety.
CHOQUETTE (GxW)
Originated on place of R. D. Choquette, Miami, from seed of unknown
origin planted in January 1929. Fruited first in 1934, propagated in
1939. Fruit oval, 30-40 oz., skin nearly smooth, glossy, dark green,
somewhat leathery; flesh thick, yellow; seed medium size, tight in
cavity. Oil content 13%. Season January to March. A handsome
fruit of good quality, with heavy bearing habit in alternate years,
which is of interest chiefly for home production. It seems fairly
resistant to disease. Certified 1942.
CHRISTMAS RED (W) III, VI
Originated at Palm Beach, Florida, as seedling of Trapp about 1910,
and propagated in 1916. Fruit oval, 1 lb., skin red-purple, season
November & December.
COBAN (G) IV, VI 43932
A Popenoe introduction from Guatemala in 1916.
COLLA (G) II, V 19058
Originated at U.S.D.A. Plant Introduction Garden, Miami, Florida,
from seed from Guatemala by G. N. Collins in 1906. One of first
Guatemalans to fruit in Florida. Fruit small, round, 8-12 oz. weight,
skin thick and woody, light green, season February and March. Has
not been propagated for 20 years but was a minor grove variety as
late as 1929, being hardy and prolific.
COLLASON (GxW) IV, VI
Seedling of Colla, originating at U.S.D.A. Plant Introduction Garden,
Miami, Florida.








Avocado Production in Florida


COLLINRED (GxW) II, V 62376
Originated at U.S.D.A. Plant Introduction Garden, Miami, from seed
of Collins planted in 1916. Fruited first in 1925 and distributed in
1928. Fruit obliquely obovate, with a stem often inserted obliquely,
medium-large size, 14-24 oz. Skin dark brownish purple at maturity,
smooth, fairly thick, rather granular. Season October and November.
COLLINRED SEEDLING B (GxW) Syn. Fairchild 106941
Originated at U.S.D.A. Plant Introduction Garden, Coconut Grove,
Florida, as seedling of Collinred. Seed planted 1925, fruited first
1930, propagated commercially 1934. Fruit oblong-obovate, slightly
flattened laterally at the distal end, medium large size, 16 to 30 oz.
Pack 8-16. Skin dull light green, often with deep maroon blush over
part or all of the fruit, smooth or slightly roughened by lenticel de-
velopment, thin but tough. Flesh light yellow. Seed medium large,
often loose in the cavity, with loose seed coats. Oil content 6-8%.
Season October. The fruits are often of great beauty, like red-
cheeked apples, but they do not hold up well in shipment and the
variety does not seem to have a future.
COLLINS (G) II, V 19080
Origin same as Colla. Fruit small, about 8-12 oz., obovate, dark
green with very rough and thick, woody skin. Season March and
April. An excellent quality fruit and grown on small scale until
about 1930, but not propagated since about 1926. A vigorous and
prolific variety, rather hardy to cold and holding fruit late in spring.
COLLINSON (GxW) See Commercial Variety List.
COLORADO (G) III, VI
Introduced from California for trial in 1916, but quickly abandoned.
COOK (G) IV, VI
Introduced in 1914 from Guatemala by O. F. Cook, U.S.D.A.
COURTRIGHT (M)
Originated on place of R. M. Courtright, Lakeland, Fla., from seed of
unknown origin planted about 1932. Two seeds were planted close
together and the resulting seedlings finally grew together at the base,
the other seedling being now named Van Kortryk. Fruited first in
1941. Fruit pyriform, 8-12 oz.; skin thin, purple; flesh yellow; seed
fairly large, loose in cavity. Oil content 15%. Season September and
October. Certified 1942.
CYRUS (W) III, VI Syn. St. Petersburg
Originated on place of Cyrus W. Butler, St. Petersburg,' Florida, prior
to 1890. Budwood sent to Philippines in 1907, where it attained some
importance. Propagated also by U.S.D.A. in 1907 at Miami and later
named St. Petersburg, but never of any importance under this name.
The parent tree of Butler. Fruit oblong-pyriform, small; skin greenish-
yellow, glossy, smooth, thin but leathery; seed medium size, loose.
Season September-October in Florida.
DADE (W) IV, VI 50968
Originated at U.S.D.A. Plant Introduction Garden, Miami, as seed-
ling of Trapp. Fruited in 1919 and distributed in 1920. Fruit nearly
round, green, 11/2 lb., season October-November.
DICKEY (G) III, VI
Introduced from California for trial about 1915, but never widely
propagated.
DICKINSON (G) II, VI
Introduced from California for trial in 1914, and fruited first in Florida
in 1921. Fruit round-obovoid, 12-18 oz., skin purple, rough, thick.
Season February & March. A minor variety for 10 years. Formerly
commercial in California.








98 Florida Cooperative Extension

DOROTHEA (GxM) IV, V
Introduced from California for trial about 1928.
DUNEDIN (GxW) III, V
Originated on grounds of L. B. Skinner, Dunedin, Florida, from seed
of Winslow planted in 1920. Fruited in 1925 and propagated com-
mercially in 1930 on very small scale. Fruit rounded obovate, 12-20
oz. weight; skin dull, light green, smooth and fairly thick. Seed
large, tight. Season December and January.
DUTTON (G) IV, V
Introduced from California for trial about 1928.
EAGLE ROCK (G) I, V
Originated on the Galloupe place, Eagle Rock, California, and called
Galloupe in that state. Introduced into Florida about 1920. Fruit
roundish-oblate, large, 20-32 oz. Pack 10-16. Skin rough-pebbled,
dark green. Flesh light to medium yellow, of very good flavor.
Seed medium large, tight. Oil content 10 to 14 percent. Season
January 1 to March 1. This variety was long considered satisfactory
in Central Florida after it went out of favor in Dade County, but is
no longer of commercial interest anywhere in the state. The fruit
quality is good and the season good for a home fruit, but the trees
have not been vigorous and bearing has been poor.
EDMONDS (GxW)
Originated on place of Tom Edmonds, near Homestead, Fla., about 1920
as seedling of unknown origin. Fruiting first observed in 1935. Fruit
oval, 24-36 oz.; skin smooth, green; seed rather small. Season
September and October. Flavor very good. Certified 1942.
ESTELLE (W) III, VI
Originated on place of H. H. Harrison, Fulford, Florida, from seed
planted in 1899 by J. T. Truitt, and propagated from 1912 for 10 years
for home use. Fruit pyriform, 12-24 oz. skin green, season late
June-July.
FAIRCHILD (See Collinred Seedling B)
FAMILY (W) III 12935
Originated at Miami, Florida, about 1897 on place later owned by
P. H. Rolfs, who selected it for propagation in 1904. Commercially
propagated on small scale for home use on West Coast for over 30
years. Fruit elongated-pyriform, 16-30 oz., skin purplish-red at ma-
turity. Season July to September.
FUCHSIA (W) Syn. Fuchs. See Commercial Varieties.
FUERTE (GxM) II, V
Introduced as budwood from Atlixco, Mexico, by Carl Schmidt for
the West India Gardens, Altadena, California, in 1911. Fruited first
in Florida in 1916 and propagated commercially in 1917. Fruit pyri-
form, 10-20 oz. Skin thick, slightly pebbled, dull green. Seed
medium size, tight. Oil content in Florida 13-17%. Season November
and December. The dominant avocado variety in California, it has
never been very satisfactory in Florida, although grown as a secondary
variety in the Ridge section for many years because of its hardiness
to cold. It is very subject to attack by scab and anthracnose, and
the fruit ripens unevenly.
FULFORD (W) IV, VI 26707
Originated on place of W. H. Fulford, Fulford, Florida, and first
propagated by U.S.D.A. Plant Introduction Garden, Miami, in 1908.
Distributed in 1916-17.







Avocado Production in Florida 99

GANTER (M) III, VI
Introduced from California for trial in 1914, propagated from 1917
to 1923 on a small scale for the cooler sections of the state. Fruit
oval, 6-10 oz., skin dark green, smooth, thin. Season July and August.
GARCIA (M) IV, VI
Introduced from California for trial about 1928.
GOTTFRIED (M) III 46337
Originated at U.S.D.A. Plant Introduction Garden, Miami, from seed
of Mexican seedling tree on place of Edward Gottfried, Key Largo,
Florida, planted in 1906. Fruited first in 1914 and distributed in
1918. Propagated commercially since 1920. Fruit pyriform, 12 to 20
oz., skin smooth, purplish-maroon when mature. Oil content 9-13%.
Season August and September. Very vigorous tree and quite hardy
to cold. An indifferent bearer on the lower East Coast but fairly
successful as a home fruit for the West Coast, for areas too cold for
West Indian varieties.
GRANDE (G) III, VI
Origin same as for Fuerte. Introduced from California for trial in
1916, and propagated in 1919. Soon discarded in favor of better
varieties in its season, December and January.
GULFSTREAM (GxW)
Originated on place of Geo. W. Smith, West Palm Beach, about 1934
as seedling of unknown origin. Fruited first 1940. Fruit obliquely
pyriform, 14-20 oz.; skin nearly smooth, glossy, bright green, somewhat
leathery but brittle; flesh bright yellow; seed rather large. Oil con-
tent 11%. Season November and December. Heavy bearing in alter-
nate years. Not disease resistant. Quality good. Certified 1944.
HADEN (W) III, VI
Originated on place of Capt. J. A. Haden, Coconut Grove, Florida, and
propagated from 1904-1910 on small scale.
HALL (GxW) See Commercial Varieties.
HARDEE (W) IV 26712
Originated on place of Capt. Thomas Hardee, Coconut Grove, Florida,
and first propagated in 1908. Fruit large, pyriform, red-purple at
maturity. Season August. Vigorous and prolific but never became
commercial. Still somewhat grown.
HARMAN (M) III, VI
Introduced from California in 1914, and propagated commercially
from 1917-1923. Fruit small, 6-10 oz., greenish-black at maturity,
season July-August.
HARRIS (G)
Originated at Homestead, Florida, from seed of Wagner planted in
1930. Fruited first 1933, propagated commercially 1938. Fruit
obovate, 14-18 oz., skin pebbled, medium green, fairly thick. Flesh
light yellow, with some trace of fibre but good quality. Seed medium
large, tight in cavity. Oil content 10-16%. Season December 15 to
February 15. The variety resembles Wagner greatly, but has thicker
flesh and smaller seed, and apparently is more thrifty.
HAWAII (W?) III, V
Introduced as budwood sent to A. A. Boggs, Miami, from Hawaii in
1903. Propagated commercially from 1921-1926. Fruit oblong-obovate,
20-30 oz., skin smooth, maroon-purple at maturity. Season June and
July. Leaves distinctly pubescent on lower sides.
HERMAN (GxW) See Commercial Varieties.
HICKSON (G) See Commercial Varieties.







Florida Cooperative Extension


HUNAPUH (G) IV, VI 44628
A Popenoe introduction from Guatemala in 1917.
INDIAN RIVER (MxW) IV
Originated in grove of W. E. Sexton, Vero Beach, Florida, as seed-
ling from Mexican variety in a mixed planting with West Indian
varieties. Seed planted 1927, fruited first 1931. Fruit oblong-obovate
to pyriform, 12-24 oz., skin dark green, slightly pebbled, thin. Season
October. Fruit handsome and flavor good, but trees not hardy to cold
and season too full already.
ISHIM (G) IV, VI 45562
A Popenoe introduction from Guatemala in 1917.
ISHKAL (G) IV, VI 43602
A Popenoe introduction from Guatemala in 1916.
ITZAMNA (G) 55736 See Commercial Varieties.
KANAN (G) IV, VI 45563
A Popenoe introduction from Guatemala in 1917.
KANOLA (G) IV, VI 43560
A Popenoe introduction from Guatemala in 1917.
KASHLAN (G) IV, VI 43934
A Popenoe introduction from Guatemala in 1916.
KAY (W) IV
Originated at Kay grove, Miami, in 1923. Fruit obovoid, 16-30 oz.,
skin green, smooth, pliable, yellowish. A good but shy bearing July
variety.
KAYAB (G) IV, VI 44681
A Popenoe introduction from Guatemala in 1917.
KEKCHI (G) IV, VI 44679
A Popenoe introduction from Guatemala in 1917.
KILGORE SPECIAL (GxM)xG?
Originated in grove of Barnard Kilgore, Clearwater, Florida, from
seed of Fuerte growing in mixed planting with West Indian and
Guatemalan varieties. Seed planted in 1927, first fruit in 1930. Propa-
gated extensively by Mr. Kilgore in 1936 and since then. Fruit
obovate, medium size, 12-18 oz. Skin green, smooth and leathery.
Flesh pale yellow. Seed medium. Flavor fair. Season December and
January. Heavy bearing, very early blooming, much less subject to
anthracnose than the parent Fuerte and about as hardy to cold.
KNIGHT (G) III, VI
Introduced from Guatemala in 1914 by E. E. Knight, Yorba Linda,
California. Sent to Florida in 1916, and propagated commercially
from 1917 to 1922. Fruited first there in 1920-21, and soon proved
unsatisfactory for Florida conditions, although a few trees were found
in commercial plantings as late as 1930.
LAMAT (G) III, VI 43476
Introduced by Popenoe from Guatemala in 1916 for the U.S.D.A.
Fruited first in Florida in 1920 and propagated for a few years in
a small way. Obsolete since 1930.
LINDA (G) See Commercial Varieties.
LINDGREN (GxW)
Originated on place of Mrs. Augusta Lindgren, Goulds, Florida, from
seed planted in 1928. Fruited first in 1932. Propagated on small
commercial scale in 1939. Fruit round-oval, medium size, 14-20 oz.




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