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Group Title: Bulletin Florida Dept. of Agriculture
Title: Tung oil industry in Florida
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Title: Tung oil industry in Florida
Series Title: Bulletin Florida Dept. of Agriculture
Physical Description: 41 p. : ill. ; 23 cm.
Language: English
Creator: Federal Writers' Project of the Work Projects Administration for the State of Florida
Publisher: Florida Dept. of Agriculture
Place of Publication: Tallahassee Fla
Publication Date: 1939
Edition: Rev.
Subject: Tung oil industry -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
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Statement of Responsibility: by Federal Writers' Project of Florida.
General Note: Title from cover.
General Note: "February, 1939"
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Full Text


Tung Oil Industry

in Florida
(Reviscd) y 5S

Federal Writers' Project of Florida

Department of Agriculture
Nathan Mayo, Commilsioner


February, 1939

Published by

NATHAN MAYO, Commissioner

Compiled by
W. T. Martin, Associate Editor
F. C. Harrington, Administrator
Florence S. Kerr, Assistant Administrator
Henry G. Alsberg, Director of Federal Writers' Project

Introduction ...................-.............-----....... ----. ....... 5
Tung Oil-Its Importance ................ ............................... 7
The Tree and Its Fruit.................-...... ................ ... 8
Expressing the Oil.................................................... ---- 9
Requirements of Soil and Climate.................-........................10
Hazards for the Inexperienced................................................15
Y ields ........................................................................... 15
F ire......................................................................................15
M marketing Expense..........................................................15
Diseases ........-........---------..... ------...... -----.. --16
Lack of Experienced Farmers..........................................16
Misinformation ............................----....................................16
Prospects of Tung Oil in Florida............................................19
Substitutes .........----------.-------- --.......... ------.......20
Tung Oil Domestic Price Trend......................................21
Yields of the Tung Grove................................................23
Planting and Maintenance Costs....................................26
Profits ................................................----------.........27
Chinese Competition?-- -------.............. ---.....--..........---27
Tung Oil and Linseed Oil...............................................30
Classification of Tung Grove Ownership................................30
Propagation ....................................----..........................................31
Preparation of Land....................................................32
Selecting the Stock............................................................32
Setting Out.. ............................ ..................................32
Cultivation ----...........................----- -----..... ----------33
Fertilization .....................................................................33
Harvesting and Marketing.. -----------........................ 36
Concerning Budding.........................................................36
Pruning .............................................................................37
Bronzing ................................. ................. ....................37
Frenching .........................................................................37
An Idea of Replants Necessary in the Tung Grove......37
Needs for Further Development of the Industry..................38
Economic Considerations of the South...----..........................38
Conclusion -.....................................-------------------.. 40
Reminder Briefs---...............................--------41
Reference Information................................................41


TUNG OIL is one of Florida's infant industries. Al-
though still a considerable distance from inclusion
among the State's important and successful enter-
prises, the development of commercial tung oil production
the past few years indicates a possible growth of this
venture into a profitable industry in localities best suited to
tung tree culture.
Production of tung oil in sections of Florida has largely
emerged from the chrysalis of blind experiment and has
begun to flutter its wings as an established business.
In contemplating the commercial production of tung oil,
however, caution should Le a byword to those inexperienced
in the nature and culture of this plant. As with any enter-
prise, to be profitable, tung oil production must be conducted
with intelligence and with the application of certain definite
principles and practices. The requirements in soils, drain-
age, climate, moisture, stock selection, fertilization, and
cultivation must be thoroughly understood for successful
propagation. Most of the failures have been due to faulty
practices or insufficient knowledge of fundamental condi-
tions. Many tung groves will turn out disappointments
because of the failure to appreciate these factors.

The tung tree is a native of China where it has grown
more or less wild for thousands of years. Known as the
"national tree of China," it flourishes best in that country
throughout the Yangtze Valley in latitudes between 25 and
34 degrees, north. Until recently the Chinese have supplied
the world exclusively with tung oil, using age-old, primitive
methods of harvesting and extraction.
Tung seeds were first brought to America in 1905 by the
United States Iepartment of Agriculture and planted in
Chico, California. A year later the seedlings were distri-
buted to state experiment stations and cooperators along a
belt similar in climatic conditions to those of China's tung
area and extending southeast from California to Florida.
In the period following, the Florida Agricultural Experi-
ment Station at Gainesville recorded excellent results in tung
tree propagation. Plantings in northern and north central

Florida indicated most favorable conditions in climate and
certain soil types for successful production and the first tung
oil to be extracted in the United States (2.2 gallons) came
from the seeds of a tree near Tallahassee. This tree was
the only one to survive of the five initial seedlings received
in 1906. It is still producing fruit.
Commercial plantings began in Alachua County in 1928,
spreading rapidly, until large plantings now exist in Alachua,
Levy, Clay, Jefferson, Okaloosa, Lake, and Polk counties
with smaller plantings in most of the central and north
Florida counties. The first modern tung nut crusher and
oil expressing plant in the world was put in operation
near Gainesville in 1928.

Tung Oil---
Its Importance

TIIE use of tung oil, or Chinawood oil, in a multitude
of industries, covers an increasingly wide and im-
portant range.
Its introduction into this country resulted in radical, if
not revolutionary, changes in the manufacture of varnishes
and other chief products of the paint industry. Until
then, all of the better varnishes and products with varnish
as an ingredient were manufactured from a basic combina-
tion of linseed oil and imported fossil gums that were rapid-
ly disappearing. In the manufacture of inferior varnishes
domestic rosin was used generally. The value of tung oil
to the paint industry was realized with the discovery that in
combination with rosin the resultant product was of such a
quality that it was possible to dispense with the imported
fossil gums.
When used in varnishes, tung oil tends to make the
product waterproof and reduces its liability to crack. It is
said that strictly waterproof varnish, as well as varnish
which will not turn white under exposure to water, cannot
be made without the use of tung oil. The oil is practically
unmatched for waterproofing and is also one of the best
"dryers" known.
Paints with tung oil give a much glossier finish than
ordinary paints, similar to enamel, and seem more resistant
to fungus attack. Research on the problem of substituting
tung oil for linseed oil in ordinary paints is resulting in its
increased use.
In addition to being a vital ingredient in the manufacture
of varnishes, paints, lacquers, enamels, fillers, etc., tung
oil is used extensively in the manufacture of linoleum, oil-
cloth, top dressings, and hundreds of other products. It is
also a valuable agent in waterproofing a great variety of
The oil is used as a dressing for leather and in the manu-
facture of soap. Fatty acids from it are utilized in mak-
ing lacquer or substitutes for shellac and, in combination
with rosin, waterproof or spar-varnish. With aluminum
oxide it is made into aluminum tungate which is used as
fireproofing and waterproofing numerous materials.


The waterproofing qualities of tung oil were utilized
centuries ago in China, where it is still used primarily for
this purpose. The Chinese use it for waterproofing masonry,
cloth, shoes, clothing, and paper, including paper umbrellas
and paper receptacles for liquids. Cruder grades of the oil
serve as the sole dressing for the Chinese boat or junk.
After the extraction of tung oil from the nuts, the residue
is burned and then mixed with a quantity of the oil to form
a paste for caulking boats. This residue is also used in the
manufacture of lampblack and Chinese ink, otherwise known
as "India ink."


The tung oil tree that is grown in this country, belongs
to the Spurge family and is botanically classified as Aleurites
fordi, known to the Chinaman as Tung-yu-shu.
The mature tung tree is about 30 or 35 feet high and
spreads in all directions equally. It is deciduous, dropping
its leaves in November and leafing out in March or early
April. The blossoms, appearing with or before the leaves,
are of two kinds-staminate and pistillate. Both types of
blossoms are borne on the same tree. Therefore, any tree
is self-pollinating.
In China the tree is said to have a life of from 30 to 50
years. There is no means of knowing how long it will live
in the Florida environment, but there is no reason to believe
that its length of life will be less than in China. Florida's
first planted tree, despite neglect and damage from fire, has
passed the quarter-century mark and is still producing.
The fruits, commonly but improperly called nuts, ripen
in October and November. When mature they drop from the
tree which obviates the necessity of picking and markedly
decreases harvesting costs. The appearance and shape
are somewhat like that of a small apple, the diameter being
from two to three inches and the color olive green. The
color becomes brown at maturity. Normally there are five
seeds in each fruit. The hull is tough and leathery and
becomes quite hard when thoroughly air-dried.
There are as yet no (generally) named varieties, although
several variations among seedlings trees are apparent.
These differences have to do mainly with the size and shape


of the fruit, variation in leaf shapes and blossom color, and
the number of individual fruits born at the twig end. The
last has led to the general designation of two types-single
and cluster. If cluster bearing proves an inherent char-
acteristic, as now appears to be the case, it will be advan-
tageous to plant this type so as to secure heaviest yields.


Tung oil yield is about one-third by weight from air-
dried seed and about one-fifth by weight from air-dried
whole fruits.
Before pressing, the oil in the seed is almost colorless,
the depth of color in the expressed oil depending in part on
the method used in extraction. American oil has a very
light amber or straw color and a very low acid content.
Both chemical and mixing tests have demonstrated the
superiority of the American product. Crude hand methods
and hollow-log processes, operated by hand and by awkward
manipulation of wedges, are used in China. It is said the
American method of extracting the oil results in a saving
great enough, over the crude Chinese method, to more than
pay for the cost of our extracting machinery and for the
extracting operation. The Chinese method, with its ac-
companying lack of efficiency, and a complicated system of
oil collection, results in an oil varying in degree of purity
and quality. Frequently it is greatly adulterated with in-
ferior oils.
There are three methods of oil extraction-namely, by
volatile solvent, by hydraulic press, and by screw press or
expelled. By comparative tests the expelled method has
proved best from standpoints of both economy and effi-
ciency. This is the method employed at Gainesville. The
oil-expressing operation is continuous and almost wholly
mechanical. The air-dried whole fruits are decorticated by
a combined huller-separator. The seeds are then conveyed
to a grinder which converts them into a coarse meal. This
meal is in turn fed into the expeller which by pressure ex-
tracts the oil. Further treatment of the oil, other than
settling, is not required; it is now ready for storage or im-
mediate use.
The pomace or seed cake, which is left when the oil is
extracted, contains about six per cent of ammonia and com-


pares favorably in analysis with castor pomace. This
material, therefore, has value as a fertilizer. The hulls can
be used to advantage for mulching purposes.
Two up-to-date oil-expressing plants in the Gainesville
area handle tung production for Florida, southern Georgia
and eastern Alabama. One is operated by the Benjamin
Moore Paint Co., New York, four miles west of Gainesville,
and the other by China Tung Oil, Inc., at Brooker, about 16
miles north of Gainesville. These mills have a performance
in oil extraction almost double that obtained by the ancient
methods employed by the Chinese.
Four other mills at present operate in the South; one
each at Cairo, Ga.; Picayune, Miss.; Bagalusa, La., and
Citronelle, Ala.


Because of the relatively short period of tung culture in
this country, a good deal still has to be learned of the tree's
adaptability to various soils and to climatic variations.
With climatic conditions apparently ideal, it is evident
the tree does not thrive on all soil types. It is too early to
attempt to define the best type of soil since all of the many
Florida soils have not been tested for adaptability but it
is known that best growth is obtained on soils which are
acid in reaction, which have plenty of moisture but are
thoroughly drained, and with no excessive amount of phos-
phate or lime. Alkaline soils seem to be fatal to tung
Most plantings in Florida are located on the higher soils
but thrifty trees are now growing on well-drained lower
lands not closely underlaid by heavy hardpan, and with a
sufficiently low water table. A high water level restricts
the growth of the roots downward. Poor drainage is prob-
ably more detrimental to tung tree growth than any other
Regarding fertility, the tung tree to a large extent
thrives in direct proportion to the richness of the soil on
which it is planted. The Norfolk is perhaps the soil series
on which tung trees are now most widely grown. Other


well-drained soils which have been planted to tung trees
include the Gainesville, Orangeburg, Tifton, Orlando, Green-
ville, Hernando and Susquehanna series. Deep sandy soils
and particularly coarse sands should be avoided.
*The Gainesville differs from the Norfolk in containing
particles of phosphate and limestone and is of a brown to a
reddish-brown color. The Hernando series is very similar
to Gainesville with considerable lime materials and under-
lying limestone. Groves on both Hernando and Gainesville
soils have frequently given considerable trouble due to
bronzing. The Orangeburg has a surface soil of gray to
almost black with a red to yellow subsoil. A red to brown-
ish-red surface soil and a red subsoil characterize the
Greenville series. The Tifton soils occur scatteringly in
the area west of the Suwannee River and are distinguished
by their pebbly iron concretions which are brown in color.
The Orlando soils occur largely in Orange and other south-
central counties and are closely related to Norfolk soils
but higher in organic matter.
Plantings have been made also on flatwoods soils in the
Blanton, Bladen, Coxville, Portsmouth, and Leon series.
These acid soils, usually high in organic matter content,
are suitable when they are sufficiently drained. The Bladen
series, with its soft, friable, dark gray surface soil and its
yellow to drab colored subsoil of sand with clay, seems well
adapted when adequately drained; the Coxville soils with a
reddish clay-mottled subsoil are very similar and are usually
a little better drained naturally. The Portsmouth series,
with its black to gray surface soil and light sand to sandy
clay subsoil, and the Blanton series with a gray surface soil
and a light yellow and white splotched sandy subsoil are also
used even if they are not as valuable as the Bladen series.
Even the Leon hardpan series has been planted when
adequate drainage is provided below the hardpan, which
usually occurs from one to three feet below the soil surface.
The roots of the tree appear to penetrate very effectively
through the hardpan when it is not too impervious and when
the drainage is established below it.
The question of whether or not the tung tree should be
planted on the naturally well-drained types of soil or on the
"flatwoods" type of soil may revolve itself into a question
of economics. If drainage of the latter may be effected at a
cost which is not prohibitive, it is possible that a significant


saving on the fertilizer costs may also be effected on these
types, due to their greater natural fertility. On the other
hand, with an adequate system of cover-cropping and a more
or less liberal use of commercial fertilizers, the culture of
tung trees on the well-drained soil types may be more profit-
able when drainage costs are considered. The question of
soil type evidently will be governed partially by local condi-
tions, and by the economic factor of the demand and supply
of the product-tung oil-which will control the price of
the commodity. (*The Tung Oil Tree, Bulletin No. 280,
Agricultural Experiment Station, Gainesville, Fla., 1935).
In the selection of soils for tung culture, Joseph C. Adder-
ley, author of American Tung Tree, says:
"The tung tree relies upon good drainage to a greater
extent than any other physical condition. The top surface
should be gently rolling or sloping and must provide a good
surface drainage. Avoid low, flat land, or land which may
be subject to overflow. It is also advisable to select land
which is not too sharply rolling and which may cause erosion
difficulties. Land that is moderately rolling may be success-
fully used for tung tree groves by means of contour planting
and terracing.
"Good air drainage is an important consideration in con-
nection with the selection of land for tung tree production.
High land is preferable to low land. It is a well-known fact
that cold air currents will follow valleys and the lower tem-
peratures are always present in the lowest spots. Air cur-
rents flow much like water and follow the same general con-
tours. A gently sloping or rolling surface of the land is
preferable. Low spots, and particularly low pockets, should
be avoided, as they always present the greatest possibility
of cold damage.
"A clay base subsoil is desirable for tung trees. Pre-
ferably the clay base should be of a loamy character which
will not form a hardpan. A clay base subsoil prevents the
leaching out of soil nutrients due to excessive rainfall and
makes for economy in the use of fertilizers. It also provides
a firm anchorage for the tree and permits it to resist wind
damage. The texture of the subsoil should be such as to
retard moisture, but nevertheless should provide for good
under-surface drainage.
"The ideal soil for tung trees consists of a top sandy
loam with high organic matter content. Such a surface


soil is more easily cultivated and kept clean than a heavy
top clay soil. The ideal subsoil consists of a clay or clayey
loam with a relatively high collodial content. The following
soil classifications have given excellent results for tung tree
growth and tung nut production: Orangeburg, Greenville,
Tifton, Ruston, Susquehanna, Norfolk, and other soil classi-
fications of similar characteristics."
In climate, as with many of her soils, Florida seems to be
especially favored in tung production. Although the largest
mature plantings are in this State, extensive tung acreages
exist in Mississippi with lesser acreages in the southern
parts of Georgia, Alabama, Louisiana, and in southeastern
Texas. The northern and southern limits for successful
culture are not definitely known. Minimum winter tempera-
tures will determine the northern boundary. Climatic re-
quirements apparently restrict plantings to the area from
Florida, west to eastern Texas, and approximately within
100 miles of the ocean or the Gulf.
From a report of the Farm Credit Administration (1935),
conflicting accounts were received as to the extent of winter
killing and frost damage to blossoms of existing groves in
the South. Because of the high percentage of trees outside
of Florida, not yet at commercial bearing age, and because
of the inherent variability in the period of dormancy of
trees, it was not possible at that date to determine accurately
the weather hazards in the various other areas of the South.
Several years' records of yields of mature commercial
groves will be necessary before these hazards can be de-
termined accurately.
At Gainesville mature trees and nursery stock have
undergone a temperature of 15 degrees F. without apparent
damage. Injury from freezing depends largely on the condi-
tion of the tree at the time. If in only a partially dormant
condition as, for instance, in fall or spring, damage might
result from low temperatures that would have no ill effect
on trees completely dormant. As the blossom season occurs
during the last week in March and the first week in April,
the trees at this time are susceptible to frost damage, which
will destroy the fruit. The northern boundary is therefore
limited to that area which is not frequently subjected to
frosts during this period.
Until sufficient plantings are made in southern Florida,
there is no way of determining the southern-most limits for


satisfactory growth. In the main, poor results have attend-
ed plantings in south Florida but in the majority of cases
it has been difficult to separate the effects of soil conditions
from the effects of climate. The tung tree, being decidu-
ous, seems to require a sufficient period of cold to cause the
leaves to drop and the trees to remain dormant over a certain
period of the winter.
According to Mr. Adderley, "the tung tree requires a full
three months' period of complete dormancy. During this
dormant period, the tree defoliates and is at rest. The
southern boundary is therefore limited to such areas as have
temperatures sufficiently and consistently low throughout
the months of December, January, and February to keep
the trees in a dormant condition. The range of desirable
temperature (Fahrenheit) during the winter season will be
from 30 degrees minimum to 70 degrees maximum and with
an average minimum of approximately 45 degrees and an
average maximum of approximately 60 degrees for the three
winter months .... in regions too far south a warm spell
during the winter months may cause the sap to rise and
if followed by freezing temperatures, injury to the tree
Apropos of the more or less exacting requirements of
both soil and climate, no doubt considerable sections of
Florida are unsuitable for successful tung culture. From
present indications the most propitious areas will be largely
confined to the ridge section of north and north-central
Florida. In addition to a variety of tested soils, a water
table low enough to keep the roots from reaching standing
water at any time is most desirable. In every instance the
task of not only analyzing but of drilling the soil should be
followed. Except to the initiates, surface indications are
not always dependable but often downright misleading.
At the Florida Chemurgic Conference held at Gaines-
ville, Feb., 1937, B. F. Williamson, of Gainesville, chairman
of the Florida section of the American Chemical Society,
made this interesting statement: "Looking over the whole
area (Florida) we find that some soils in the western area
are more fertile than some soils in the eastern area, where
tung oil is produced. In this connection the climatic condi-
tion must be taken into consideration. Records over 16
years have shown remarkable effect of climate. In the
western area crops have been seriously affected two out


of five years, whereas in the more protected locality in the
eastern area one out of 10 years."


In the 1935 Farm Credit Administration report present-
ing a study of the tung oil industry in the United States,
records were obtained of 2,045 acres of tung which already
had been abandoned and of an additional 1,635 acres likely
to be abandoned. The reasons given related to the import-
ant hazards which must be faced by the person entering the
business of producing tung oil. In addition to. the vital
factors of soils and climate, there is the matter of yields,
fire, marketing expense, diseases, lack of experienced farm-
ers, and misinformation:
Yields: Because of the limited amount of work which
has been done in selective breeding of trees, many of the
existing groves apparently have a high percentage of
"boarder" trees. Practically all of the existing trees are
seedlings. The history of most horticultural crops from
the seedling stage has been to establish desirable varieties
through the use of asexual methods of propagation in order
to insure continuance of a pure strain. The report suggests
that it is highly probable that the tung tree must be
developed along similar lines.
Fire: Tung trees are very sensitive to fire. Since much
of the land in the tung-growing area is burned over annually,
the danger of fire is one which the tung growers must con-
tinually guard against. This hazard, of course, is parti-
cularly great in groves which are not cultivated.
Marketing Expense: Distance to the nearest expression
plant is a major item. In 1935 there were only two expres-
sion mills in the United States. The average distance from
the farms surveyed to the nearest of these mills was 134
miles. In 1938, with the establishment of additional mills,
this is, of course, an exaggerated example but many growers
in the South are still faced with a relatively heavy market-
ing expense. In 1935 the carlot freight rate from Cairo,
approximately the center of tung production in Georgia,
to Gainesville was $4.80 per ton. The less-than-carlot rate
between these points was practically prohibitive, being
$11.80 per ton.


Diseases: Thus far the tung tree has been remarkably
free from pests and disease. The most serious troubles
have been from "bronzing," and "frenching," physiological
reactions apparently associated with soil conditions. (These
will be treated later). The tree is also attacked by nematode
root-knot, cottony cushion scale, and latania scale but prac-
tically negligible damage from these sources has been
Lack of Experienced Farmers: Because of the newness
of the industry, only a limited number of farmers have
had experience in production of tung oil. Consequently,
changes of ownership of tung groves are more likely to cause
failures because of mismanagement than is the case for well
established types of farming.
Misinformation: Glorified exaggeration of unscrupulous
promoters, picturing great production and sudden wealth,
presents another hazard to the inexperienced. Also, frequ-
ently attempts are made to dispose of tung groves not yet in
bearing and at unreasonable prices considering the initial
cost of the land and the limited investment so far repre-
sented. As with any new enterprise, the incipient tung
industry in this country has its share of individuals who
cast truth to the wind in the anticipation of quick profits.
With the best of selection, care and intelligent husbandry, a
commercially profitable crop will not be produced until at
least the fifth year after the trees are planted. Records
show that in the average instance any production in the
fourth year only serves to counteract the expense for that
Many fallacies also still exist in the business of tung
production. "The plantings and successful production of
tung oil," Mr. Adderley says in American Tung Tree, "is a
horticultural undertaking which requires the exercise of a
high degree of intelligence. There have been many failures
and disappointments in the past. Failures are always pres-
ent in new industries where a trial and error method is
necessary over a period of many years to determine and
establish proper methods and practice. In spite of the bitter
experiences of the past, many fallacies still continue to
persist .... The greatest of all horticultural heresies is the
theory that the tung tree, being originally a wild tree, will
grow and produce profitable crops with little or no cultiva-
tion or fertilization.


"Next to the fallacious theory of profitable crops from
uncultivated or unfertilized groves, more failures have re-
sulted from the fact that the prospective grower has been
unable to finance and cultivate his grove through the term
of years required to reach commercial production. The
result is an abandoned grove with dwarfed and stunted
trees which cannot be resurrected. Many such groves might
have been carried to the successful production stage, except
for the fact that the planter undertook to plant a greater
acreage than he could properly finance and care for."
In Tung Oil Culture, a special circular issued June, 1937,
by the National Paint, Varnish and Lacquer Association,
Inc., Washington, D. C., the following was published under
the caption, "Warning:"

The American Tung Oil Corporation was or-
ganized as an experimental unit, or field laboratory,
to demonstrate the possibilities of growing tung oil
in America, with the object of making us less de-
pendent upon foreign sources and of preventing
violent price fluctuations; to develop agricultural
information as to the best methods of growing tung
oil trees; to act as an experimental and educational
unit so that the information obtained could be
disseminated widely in order to encourage larger
and more successful planting of tung oil by others,
and to make available to such outside planters a
source of selected, multiple cluster type seed. The
Corporation was largely financed by members of
the National Paint, Varnish and Lacquer Associa-
tion, Inc.
The objects of the Corporation, as set forth
above, have apparently been accomplished, as evi-
denced by the fact that some 60,000 acres of tung
trees have now been planted by private interests,
in the Gulf Coast region of the United States.
and that technical information has been developed
to guide other planters. In 1935 the Corporation,
realizing that its own experimental groves were not
productive, sold its properties and discontinued
field experimental work. It is believed, however,
that the negative lessons provided by these groves
were of tremendous value in showing other planters
what to avoid in establishing successful groves.


It would appear, however, that there have been
organized a great number of tung oil corporations
and other Southern companies. Some of the adver-
tising regarding tung oil, which has appeared in
newspapers, would suggest that the promoters of
some of the corporations intend to sell stock or
other interests to the public. It has rarely been
pointed out in these advertisements that lands may
be purchased in certain sections at as low as $5
or $10 an acre in the uncleared state. Moreover, it
has not been pointed out that the cost of growing
young trees and transplanting them in grove for-
mation is very low. Such information obviously
should be brought to the attention of the public so
that investors would not be expected to purchase
groves at extremely high speculative prices. More-
over, the public should be warned that tung oil trees
will not grow on every type of land, and that it is
extremely important that well-drained land of the
right soil characteristics should be selected. A care-
ful soil survey by an expert should be made. Infor-
mation should also be obtained as to whether sub-
stantial yields of fruit have actually been produced
by grove plantings in the localities under considera-
tion. Even after the groves are planted, they
should receive careful cultivation and attention if
they are to produce good yields of fruit. The
planting of tung oil trees should be encouraged only
in such localities as are favorable. The more suc-
cessful results will doubtless attend the planting of
trees in good sized acreages under compentent man-
agement with the requisite corporate or personal
financial arrangements to carry the groves through
to production. Such undertakings should prefer-
ably not involve solicitation for subscription to
stock or land units.
The planting of small five or ten-acre groves
will probably not pay unless done individually by
farmers who may have small acreages of land upon
which the groves may be planted and used for
chicken runs or similar purposes. The planting
of large tracts of from 100 to 1,000 acres or more
would seem to be necessary if the overhead of car-
rying the groves through to production is to be
properly distributed in order to make the venture
more profitable.


The public should also be warned against state-
ments which set forth that great profits may be
made from tung oil. Such statements are usually
based on theoretical estimates of fruit yields. Es-
timates on individual trees rather than upon
groves are apt to be very misleading.
In conclusion, it would appear that tung oil pro-
duction in America has become established in cer-
tain selected areas and may rapidly grow, provided
every care is exercised to select good land, to take
care of the groves, and to finance the projects on
a logical basis without expecting the general inves-
tor to carry the burden.

The first commercial plantings of tung trees in the
United States were made in Florida in 1923, and amounted
to 140 acres. Since then plantings have increased to exten-
sive areas in certain sections of the State. It is difficult,
however, to give more than a rough estimate of the total
acreage under present cultivation.
In an address at the Farm Chemurgic Conference, Jack-
son, Miss., April, 1937, C. C. Concannon, Chief of the Chem-
urgic Division, Bureau of Foreign and Domestic Commerce,
U.S.D.C., gave the following estimates of existing tung oil
acreages in the various tung producing states: Florida,
17,525 acres; Georgia, 3,800 acres; Alabama, 800 acres;
Mississippi, 65,000 acres; Louisiana, 15,000 acres; and
Texas 1,000 acres-a total of 103,125 acres in the six South-
ern states. These figures were made after reviewing state-
ments and estimates from various official and private
Of this amount, some already had been abandoned and
Dr. Concannon predicted that half would never be commer-
cially successful. "Failure continues to arise from the selec-
tion of inappropriate or useless land; or, where the proper
conditions of soil and climate are met, it is all too often the
case that subsequent neglect occurs."
Because a number of older groves, once in partial produc-
tion are now out of production or have been abandoned, some
estimates of present Florida acreage run considerably below
that given above.


This would therefore indicate the gradual forging of a
new industry when intelligently planned and managed, as
well as the penalty of ignorance or neglect.
The first commercial yield of domestic tung oil was in
1932 when two tank cars (about 150,000 pounds of oil)
were shipped from Gainesville. In 1936 Florida was produc-
ing one-quarter of all the tung oil gown in the United States.
The total domestic output for that year was 2,000,000
pounds of oil. Florida's 1938 crop, which will be milled early
in 1939, is variously estimated from 800,000 to considerably
over 1,000,000 pounds of oil, and the country's entire pro-
duction at approximately 4,000,000 pounds. Florida's pres-
ent large proportion of domestic production is chiefly be-
cause of the greater age of many of her groves; the State's
many years of pioneering efforts must be remembered. By
far the greater number of trees in other states are not yet
at profitably bearing age. This is also true in Florida but
to a lesser extent.
The country's present tung oil production is less than
31/2 % of domestic requirements. In 1922 America imported
79,089,293 pounds of tung oil from China at a value of
$7,981,251. Since then, with the exception of one or two
years because of depression, the demand has increased
steadily, rising to 134,829,996 pounds of oil valued at $17,-
838,114 for the year 1936. The United States now utilizes
about 75% of all the tung oil exported from China. .Be-
cause of an ever-increasing variety of uses for the product,
some believe that American industries will eventually absorb
400,000,000 pounds of tung oil annually. Granting that
thousands of acres in the South have not yet come into bear-
ing, the ratio between domestic supply and demand promises
to be wide for a considerable time in the future.
Substitutes: The best marketing price for tung oil seems
to lie between 10 to 15 cents a pound. Lower prices deprive
the grower of profit, and higher prices discourage the use
of the oil in favor of substitutes. Difficulties experienced
in the past in securing ample supplies of oil and rising prices,
have caused large consumers to conduct extensive research
with a view of utilizing other oils and combinations as sub-
stitutes for tung oil. Some of these are combinations of
perilla, soybean, castor, and linseed oils. Synthetic resins
have also been developed which may reduce the use of tung
oil in process work. One of the latest developments is a


castor oil derivative. While this product may be used as a
replacement for tung oil, price and insufficient supplies of
the castor bean limit to a large extent its employment. Up
to the present, economic factors and quality of final product
considered, no satisfactory substitute has been found for
tung oil. (Note: The above paragraph in essence was
printed in Tung Oil, issued October, 1938, by the Chemical
Division of the United States Department of Commerce as a
brief synopsis of information).

Tung Oil Domestic Price Trend
(Nominal Price per Pound in Drums at New York City, given in

Month 1935 1936 1937 1938
January ................... ........... .097 .140 .148 .156
February .......................... .099 .148 .149 .156
March ............... ............. .137 .168 .154 .133
April .................. ............. .145 .187 .153 .125
May .............................. ..... 175 .187 .138 .116
June ................... ............. .178 .187 .130 .109
July ........................ ........ .153 .189 .129 .125
August ...................... .162 .165 .140 .142
September ............................ 267 .144 .205 .131
October ... ..... ........-..-- .299 .135 .227
November .............. ........ .183 .131 .161
December ....................... .158 .137 .146

1924 192 1921 1927 19 28
H L H L H L H L ,H L
January ........... s% $,21. 19 u ,1 )S ,14 ),111 .13 1,15H u,13 1 ,18 1,15
February .......... 9 17% ,14% .13 ,13% ,12% ,1 ,17 ,1 .17~ .4
March ............. .14 1 ,11 .13 ,12% 12 7 ,22 ,1 11 11
April ..................1 ,1 % ,13 ,U ,1% ,11 ,3 S 30 ,1 ,H14
May ................... 15 ,13 ,12 ,19 ,.l i .15 ,15 .1 ,
June ......... .........1 ,12 ,12 % 15 ,1 ,20 ,15% ,15 '
July ....... .......... 1 5 ,11I ,11 1 ,1 11 ,16 . 15 4 ,
August ...............1 .1 4 .1 ,i ,11 .1 1 .11 .17 .1 15
Septembr ...... 1 ,1. ,13% 13 % ,13 ,19 ,18 ,1 ,15 ,1 .4f
October ............. 1. ,15 ,13% ,11% ,17% ,11 ,11 .1 ,1 5 .1 5% I
November .........1 ,15% ,11 % .1,% ,16 .15 ,1 5 ,15 6 114 ~1 f
December ..,,,.....,,,l1 ,1 1 ,13 1 ,015 ,13% ,. 15 ,11 .1%, .1q ?l

IS0 ISO 1131 101 m0 | 0
H L l L H L H L H L H L
January ..,.........) 11. % 1.14 % 1 ,11% 1. ,01% 07.O 40% H.0 0,5% O
February ........... H.14 1% .1% .01 .0 % 0l *0l0% .0 11
March ................. 14 ,1 11 ,071 Ol ,01 % 0 m .07 ,0 i
April .................. 14% ,14i .11% .11 ,0% ,AOl ,01% ,0 % O 09
May ...................14 14% .11% ,10 ,01 7 0% *, N ,Oi ,06R ,0 m
June ................. 14 ,1 10 ,09% 1 O B% ,0% ,060i .H0% .0 X '
July .................. 14 ,14 ,09 ,09 ,07 .0~ 0 ,A0 ,096 ,7 m
August ............. 14, ,1( 09 .09 .0% .0l ,014 m ,0 ,08 ,01 i
Setember, ,,... 1 ,09 % 08. ,0 % *065 ,06 % ,Oi. ,018 ,0I%
October ............ .1 ,11 ,081 ,10 % 0 .i 06 Ol
November ........15 ,114 ,071 07 ,0O .06 ,0
December .,,...14~ ,13% 01 ,07 0 ,017 .0 ,06 .I05
Bulletin No, 11-Florida Department of Agrlculture-Augut 11


Yields of the Tung Grove: Owing to the variance in soil
conditions, seed selection, cultural attention and a number
of other circumstances, including weather, only a general
idea can be given as to what the tung grower may expect in
yields from his grove.
There is evident danger in using figures based on indi-
vidual trees as a guide in anticipating production from a
commercial grove. The following 13 year average of indi-
vidual yields from 10 trees belonging to the Agricultural
Experiment Station at Gainesville illustrate the inherent
variation in fruiting capacity of trees:
1922-84 average yield in pounds
Tree number of air-dried hulled seeds
1 ............................................. 17.6
2 ........................................... 39.8
3 .............................................. 4.8
4 ............................................ 13.8
5 .............................................. 4.7
6 .............................................. 34.1
7 ............................................. 11.9
8 ............................................. 25.1
9 .............................................. 67.3
10 .............................................. 7.7

Average.............. 22.7
These trees were planted in 1912. They were set in a
single row, 10 feet apart, and cultural treatment of all trees
was uniform. However the average yield per tree varied
from 4.7 pounds to 67.3 pounds of air-dried hulled fruit.
Analysis of the yields by individual years shows that the low
yielding tree was consistently low, and similarly that the
tree with a high average yield tended to produce relatively
high yields each year.
Over an eight-year period (ninth to 16th year) the trees
produced an annual average yield per tree of 22 pounds and
five ounces of hulled seed which is equivalent to almost one
gallon of oil. For the above period five of the trees pro-
duced 339 pounds of seed while the five trees of better bear-
ing capacity bore 1,443 pounds of seed. The trees were not
planted from selected stock.
The necessity of careful seed selection and the breeding
of inherently heavy-fruiting strains of trees is thus appar-


ent, especially when one realizes that otherwise a number
of years must elapse before light-fruiting trees become ap-
parent. Pioneers made little or no seed selection only to
find that possibly 40 per cent to 50 per cent of their trees
were "drones;" either barren, or with such low yields that
for any degree of profitable culture, it was necessary to re-
place them.
Because no acre plantings in this country have reached
full maturity, it is impossible to give data as to yields of
groves more than a few years older than bearing age.
The following information on yields was published in the
1935 Farm Credit Administration report:
Florida Georga and MIs., La., and
Foda Alabama Texas

1 year..... 4 550 0 5 188 0 9 2,945 0
2 year..... 6 918 0 18 667 .8 10 2,498 .6
3 year.... 13 1,916 34.3 24 772 20.4 5 2,477 .4
4 year.... 10 1,221 79.4 15 512 188.7 8 453 143.3
5 year... 3 101 188.7 7 164 110.0 6 276 252.4
6 year.... 2 345 277.4 2 17 411.8 1 200 270.0

The yields reported represent whole fruit actually har-
vested. However, it is believed that most of the growers
gathered the fruit if there was any significant quantity pro-
duced, so that these yields approximate closely the gross
It will be noted that the trees began to bear about the
third year and in general the yield increased with the age
of the trees, until at the age of six years, yields approxi-
mately 300 to 400 pounds of whole fruit per acre were ob-
tained. In these younger ages there appeared to be no
significant difference in yield depending on the area.
As there was such a limited number of groves over six
years of age, these were all grouped together irrespective of
area. There were seven farms represented in this group
having an average of 301 acres of tung between the ages of
seven to 11 years inclusive. The 1934 average yield of


whole fruit per acre on these farms was 343 pounds. It will
be noted that this yield falls far below the levels which have
been suggested for older groves by some of the disseminators
of tung oil information. On the other hand, it is very likely
that several of the earlier plantings were set on soils which
have proven poorly adapted to the sustained development of
the tree. The yields from such groves, therefore, would
not be likely to give a reliable indication of the yields which
might be obtained on older groves enjoying more favorable
Turning to a somewhat brighter side of the yield picture,
the five highest yields per acre on any of the cost groves
were as follows: 2,759 pounds, 2,632 pounds, 1,540 pounds,
1,167 pounds, and 1,067 pounds.
In order to determine how the yields in 1934 compared
with yields in previous years, the following tabulation was
Axr of Number :Nlhrr .AVrnmr yield of "holr fruit per nare (INm.)
K rove ot | I
March farnms I rr 19:3 1 12, ,1, 30 1929 192*S 1927

5 years 19 717 1W0 .R 12
6 5 562 279 77 34 22
7 3 354 272 64 25 173 6
8 3 359 322 270 58 304 79 43
9-10-11 3 1.322 285 207 53 311 81 123 59 22

This table indicates that insofar as yields were concerned,
the 1934 season was relatively favorable. It will also be
noted from the table that yields from the older groves were
relatively high in 1931 and relatively low in 1932 and 1933.
...... The explanation of the comparatively high yield in
1931 is a matter of surmise. It is probable, however, that
weather conditions in 1930 and 1931 had much to do with
it. In some sections of Florida there were frosts during the
bloom in 1932, which would at least partially account for
the low yield of that year. Dry weather and possible weak-
ening effect on the vitality of the trees through bearing the
relatively heavy 1931 crop may have been other contribut-
ing factors. The above table also clearly brings out the fail-
ure of the yields on some of the older plantings to increase
with the age of the groves. As previously suggested, un-


favorable soil conditions may in large measure account for
this result. (Some Results of a Study of the Tung Oil Indus-
try in the United States, FCA, Wash., D. C., 1935.)
Among outstanding instances of high yields, records are
available of one small commercial planting of nearly 200
trees to the acre that produced in its fifth year (sixth from
seed) an average of 3,531 pounds of air-dried whole fruit or
the equivalent of 74 gallons of oil per acre. B. F. William-
son reports instances where individual trees have produced
over 30 pounds of oil. He adds, "A small acreage planted in
1925 showed an average yield in 1929 and 1930 of a little
less than 700 pounds of oil an acre per year. Other plant-
ings have shown as high as 500 pounds to the acre, these
were 1924 and 1925 plantings and the yield records for
The National Paint, Varnish and Lacquer Association,
Inc., in its publication Tung Oil Culture, 1937, reports a
grove of five acres on higher land, well-drained and with a
chicken run affording organic fertilizer, which produced
7,646 pounds of air-dried whole fruit; an equivalent of 1,529
pounds per acre or 42 gallons of oil per acre. This publica-
tion warns, however, that such yields are exceptional and
should not be used in figuring yields to be obtained in com-
mercial practice on the ordinary run of groves. It states
that the tung oil industry is too young to predict estimates
as to the average yields which may be expected per acre in
tonnage or dollars and adds: "If the tung industry could
be sure of the average grove yielding as much as 50 gallons
of oil an acre, we would be satisfied."
The quantity of oil extracted from the dried seed varies.
Fertilization, cultivation, growing conditions, type of soil,
age of trees, etc., are responsible. Roughly, 100 pounds of
air-dried whole fruit will produce from 2 to 21/ gallons of
oil. Tung oil weighs approximately eight pounds to the
gallon. As will be remembered, the oil yield is approxi-
mately one-fifth by weight from air-dried whole fruit and
one-third by weight from air-dried hulled fruit; this is be-
fore the hard outer pellicle covering the seed is removed.
*Planting and Maintenance Costs: Values of land suited
to tung oil trees vary considerably due to location and size
of tracts involved. Clearing costs also differ greatly and de-
pend almost wholly on the type of vegetation growing on
the land. The number of trees planted per acre (plantings


range from 48 to 200) will have a large bearing on nursery
stock cost. In the effort to arrive at expense of planting
and maintenance it must be borne in mind that any figures
are subject to wide variations, because of the differences in
labor costs, methods of handling, grass and weed growth,
and other unforeseen factors, as well as acreage involved.
Usually large acreages can be maintained at less cost per
acre than small plantings.
The first year's expense may be divided approximately
as follows:
Nursery stock..........................$15.00 to $50.00 per acre
Clearing .................................. 8.00 to 40.00 per acre
Plowing, breaking .................... 2.50 to 5.00 per acre
Planting .................................. 4.00 to 6.50 per acre
Cultivation ............................... 5.00 to 10.00 per acre
Fertilizers and applying......... 4.00 to 6.00 per acre
No estimate is placed on the cost of the land used, inas-
much as land values vary greatly.
After the first year the fertilizer costs gradually in-
crease, but as the trees grow, cultivation costs in turn
gradually decrease. Since about 10 pounds of fertilizer is
the maximum quantity applied to mature trees, this ex-
pense will be but the cost of 700 to 1,200 pounds per acre,
plus the low cost of application. From $25 to $30 per acre
should cover fertilizer and labor costs on a mature planting.
Profits: The reader may see for himself how impossi-
ble it is to set forth in a publication of this kind definite
figures relating to profits. It is even impossible to say with
any degree of certainty what the average planter should ex-
pect by way of yield from his acres. But as regards profits,
figures compiled by the American Paint Journal show a
range in price of tung oil from January, 1919, through Sep-
tember, 1928, from 35 cents to nine cents per pound. Nat-
urally these were the prices for the Chinese oil. American
oil brings a higher price, being of a much higher quality.
But with these import prices as a basis, with perhaps 141/2
cents per pound a high average, the prospective planter can
probably do his own figuring, inasmuch as he should know
his own situation better than anyone else. (*Bulletin No.
11, Florida Department of Agriculture, 1935).
Chinese Competition? The -question frequently comes
up regarding the practicability of producing American tung


oil against the cheapness of Chinese labor and the almost
negligible expense of growing tung crops in China because
of the scanty cultivation given the half-wild trees of that
While labor in China is approximately only 15 cents a
day, an American press will do the work of 100 Chinamen.
Transportation in China is on human backs and costs a num-
ber of times more than transportation in this country. In
America, cultivation is largely by machinery. Three aver-
age tractors can cultivate 100 acres in a day and the number
of trees grown on an acre is considerably higher than in
China. Because of years of experiment, resulting in highly
scientific methods of selection and culture, the average tung
tree's production is also much higher.
In addition, tung oil produced in the United States, ac-
cording to definite analyses, is of a very high and satisfac-
tory quality. It has an excellent color and is much paler
and clearer than the imported product. In 1928, while still
highly in the experimental stage, a quantity of Florida
tung oil was distributed to about 80 domestic varnish manu-
facturers for varnish-making tests. All of the manufac-
turers reported the American oil superior. One maker re-
ported a slight improvement in the color of his finished
varnish; another, that the domestic oil gave faster body-
ing action in the kettle, producing a paler, clearer varnish
with a somewhat faster and harder drying film and with
hot water resistance, and another stated that the oil made
varnishes tougher and more elastic and with better water
Not only has the Chinese supply become increasingly
uncertain, but tung oil from China varies considerably in
quality. This is due largely to the crude milling methods
and the frequent opportunities of adulterating the product
on the way, which has been true since the time America
began importing tung oil from China. Comparatively, the
domestic oil is consistent in quality and with its high grav-
ity, high refractive index, low acidity, low heat test, and ex-
cellent color, is superior in every respect.
With a great variety of manufactured products at pres-
ent utilizing tung oil and with its constantly increasing use
in the manufacture of additional products, the oil has be-
come an economic necessity in the United States and it


would appear that overproduction in the tung industry is a
long way off. Practically all industrial countries of the
world, where indications suggest that tung trees can be
grown commercially, are experimenting in an effort to estab-
lish their own sources of supply.
"Assuming that in the near future the American pro-
duction of oil will cover the regular increase in the American
demand, then as the European demand increases it is likely
that China may meet it so long as prices remain high," ac-
cording to B. F. Williamson. "At the same time it is cer-
tain that there is a limit to the production of tung oil in
China, and there is no present indication of increased culti-
vation in China taking care of the increased demand. As
has been said, trees in China are not cultivated systematical-
ly and are commonly found on hillsides or in rocky situa-
tions and on the poorest of soils, unsuitable for ordinary
food crop cultivation.
"It has been said that the consumption of tung oil in
China greatly exceeds and may double the total export, but
all this reservoir of oil is certainly not available except at
good prices. It is evident that an increasing world demand
must encroach more and more on the stocks of material
normally reserved for domestic use in China with a conse-
quent upward tendency in price. The disturbed state of the
country can only accelerate this effect since one would ex-
pect supplies to shrink rather than expand. Under the best
conditions the difficulties in collecting the nuts, expressing
the oil by native methods, and transporting the oil from the
interior to the ports, are many; years of wars cannot have
made these difficulties any easier.
"In spite of the labor and the large percentage of waste
involved in the operations, tung oil is regarded as a most
profitable crop by the Chinese. In this very fact lies the
strongest argument for presuming that scientific cultivation
of the trees in plantations, with adequate machinery for
crushing and collecting the oil, is bound to succeed. The
systematic cultivation of the tung oil tree may well follow,
though on a smaller scale perhaps, the example of rubber.
Today it is a fact that rubber grown in its true home, the
Amazon basin, although there are countless trees available,
cannot be produced at the cost of plantation rubber, because
the method of ordered, scientific cultivation of the tree and


harvesting the product is more effective than the casual
collection of the jungle product."
Tung Oil and Linseed Oil: In the formulation of many
products in which linseed oil alone was formerly used,
blends of tung oil and linseed oil are now employed. This
practice, which is becoming general, indicates that in many
instances, tung oil has replaced linseed oil as a supplement-
ary material of distinctive properties. The greater recog-
hition of the necessity and value of quick drying finishing
materials in mass-production manufacturing has stimulated
interest in tung oil and has resulted in its more extensive
and more satisfactory application in varnish manufacture.
In this field linseed oil was formerly the predominant raw
material. Tung oil has been substituted in some other
cases, as it imparts to the finished product many desirable
characteristics which could not be obtained with linseed oil.
America imports $60,000,000 worth of linseed oil an-
nually besides $60,000,000 worth of linseed oil produced each
year from home-grown flax.
In considering the commercial production of tung oil,
Harold Mowry, of the Florida Agricultural Experiment Sta-
tion, says: "Greatest returns probably will be from large
acreages on low-priced suitable lands where overhead costs
are kept at a minimum. Plantings of a few acres apparently
would be best grown as a side crop and not as the chief
source of income. It appears that in locations adapted to
its growth, the tung tree offers a paying crop for a consid-
erable acreage that is now bringing no returns. Tung oil
has an advantage over many Florida grown products in that
it is not of a quickly perishable nature and in no way a com-
petitor of any other of the State's agricultural crops."

Those engaged in tung culture in the United States may
be divided into the following general classifications:
1. Paint and varnish manufacturers.
2. Persons receiving their major or total income from
3. Gentlemen farmers and business people whose major
income is from other sources than farming.
4. Lumber companies.
5. Promotional interests.


The first tung groves in this country were established in
Florida by paint and varnish interests, primarily to demon-
strate the possibilities of producing domestic tung oil com-
mercially with the idea of developing an independent supply
of the oil. The industry, therefore, received its first com-
mercial stimulus from the users of the oil.
Persons receiving their major or total income from farm-
ing have relatively small tung acreage. Reasons for plant-
ings have been various, including desire for experiment with
the new enterprise, possibility of improving the farm for
sale, or improved diversification toward self-sustenance or
profit. A comparatively recent group consists of small
landowners whose groves, as a supplementary crop, are
grouped in a vicinity where cooperative cultivation, super-
vision and harvesting are possible.
The gentlemen farmers and business people whose major
income is from other sources than farming, have fairly
large acreages set in some cases as a business proposition,
or as a hobby, and in other instances to increase the value
and desirability of their land holdings.
The plantings of the land companies, according to the
1935 report of the Farm Credit Administration, are prin-
cipally in Mississippi, Louisiana, and Texas. The report
states that the tung acreages of such owners are large
and that such concerns were generally motivated by a
desire to find some profitable utilization for the cut-over
pine lands common in the states mentioned.
The promotional interests are self-explanatory. This
group has done its full share in advertising the extreme
possibilities of the industry.


The present problems of tung oil are mainly cultural.
The matter of proper location embracing soil type, mois-
ture retention and drainage, climate, as well as the neces-
sity of correct stock selection, has been taken up in a gen-
eral sense to give the inexperienced a fair idea of the im-
portance of these factors. Reference information for de-
tailed and more scientific treatment is given at the con-
clusion of this bulletin.


The following additional subjects are also treated brief-
ly to serve as an initial guide:
Preparation of Land: Methods of preparing land for
planting tung trees, are practically the same as those used
in planting any farm crop. New land should be cleared
of all brush and stumps. Land which previously has
been in cultivation should be cover-cropped the season before
the trees are to be planted, unless such land has been well
maintained in humus and general fertility. This will in-
crease both the humus and nitrogen content of the soil
affording the trees a good start. Crotalaria, cowpeas,
velvet beans, beggarweed, are all good cover crops and
are usually planted during February or March. Such crops
are generally turned under in October or November. The
land to be planted should be thoroughly ploughed and then
disced or harrowed to compact the soil. On some types
of Florida soil there is an argument whether the cover
crop should be turned under at all, as the fertilizing value
might leach away during the winter months.
Selecting the Stock: Present tung plantings consist
almost entirely of seedling stock. Such stock, thoroughly
tested for prolificacy, can be obtained at reputable nur-
series. Seedlings are usually transplanted to the field
after a season's growth. Normally, year-old seedlings are
from three to seven feet in height. Growing seedlings
from seed is a subject apart and is treated upon in the
reference material. The nursery method apparently is
preferable to planting seeds directly in the field because of
the cost of cultivation and the reduced opportunity offered
for the elimination of undesirable seedlings.
Only the most vigorous seedlings, those showing a well
developed top and root system, should be selected. As
described, the production qualities of a tung tree in most
cases runs true to those of its parent. However, all trees
should be carefully followed up in future years and when
one fails to meet satisfactory standards, it should be elim-
Setting Out: Seedlings should be set out only during
the dormant period. This is generally during December,
January and February and when the trees are entirely
defoliated. The root system should be well protected and
kept moistened until set out. If the trees cannot be


planted shortly after received, they should be "heeled in"
with plenty of moist earth for coverage. Laying out the
land depends upon the number of trees to be set to the
acre and is treated at length in the reference material, as
well as the proper method of planting. At the time of
transplanting the trees should be cut back within 10 to 16
inches above the ground to over-balance the root system
against the upper structure, thus providing vigorous growth
and greater uniformity in the tree's development.
Cultivation: Cultivation should be sufficiently thorough
to keep down weed and grass growth and at the same time
shallow enough to leave the root system undisturbed. The
tung tree has a very shallow rooting habit. As soon as
the young tree has started to grow, a good method is to
cultivate the ground for a distance from four to six feet
on each side of the tree, hoeing around the tree to keep
the area clean and without risking injury to the trunk or
root system.
In many cases the middles can be inter-cropped, prefer-
ably with a legume such as peanuts, soya beans or cow
peas. This will help improve the soil and also provide some
measure of profitable production. A common practice is
to grow a cover crop during the summer months. These
crops are disced under before frost. As the trees mature
less cultivation is needed and eventually shade from the
foilage so reduces weed growth as to render intensive cul-
tivation under the trees unnecessary. While mulching of
young trees with weed and grass growth has proven very
good results, its chief disadvantage is the fire hazard.
Fertilization: Because of the wide diversification of
soils in character and fertility, a definite knowledge of
the chemical requirements of the land is necessary for the
correct fertilization of a tung grove. In American Tung
Tree, Mr. Adderley suggests the following:
"Owing to the rapid growth and heavy fruiting habits,
the tung tree makes great demands upon the soil. What
is taken from the soil must be restored, if soil fertility is
to be maintained and crop production is expected. Tung
trees cannot be grown to commercial advantage without
proper fertilization.
"Soils are often deficient in one or more of the prin-
cipal elements of available nutrition; namely, nitrogen,


phosphorus and potassium. The amount of tree growth
and'fruit yields produced are largely dependent upon these
three principal elements in proper balance and proportion.
There are many other mineral elements which the tree
requires, but the three named are required in greater quan-
"The growth of the tung tree and the fruit yields pro-
duced will give some indication as to the fertility or lack of
fertility in the soil. This indication, however, cannot de-
termine the element or elements which may be deficient
or absent. It is advisable to have the soil analyzed at
regular intervals, in order to definitely determine the
amount of available plant food and its character. Fer-
tilization by guess work invariably involves needless waste
and expense, and usually does not serve the best needs of
the tree. A soil analysis will determine exactly the ele-
ments of nutrition that are lacking and permit their most
economical replacement.
"Good results have been obtained from the use of mix-
tures of commercial fertilizer containing nitrogen, phos-
phoric acid and potash. A formula analyzing 5% nitro-
gen, 7% phosphoric acid, and 2% potash will generally
give good results during the first two or three years. It
is desirable to have the major supply of nitrogen from
organic sources.
"Whdn the tung tree reaches bearing age, it requires
an increased percentage of phosphoric acid and potash in
the fertilizer mixture. The following formula is recom-
mended for a four or five year old tree: 4% nitrogen,
8% phosphoric acid and 4% potash. Seven and eight year
old trees will require 5% nitrogen, 8% phosphoric acid and
6% potash.
"Tung trees should be given two applications of fertilizer
each year. The tree has two periods of intense activity
each season. The first period begins with the growing
season in early spring. The tree then blossoms, foliates.
and sets its fruit. During the mid-summer, there is an
intervening rest period, which occurs usually during the
month of July. The tree then sends out its new growth,
sets its buds for the following year, and fills its fruit.
"Fertilizers are applied to the best advantage at the
beginning of each of these two active periods. The first


application of fertilizer should be made at the time of the
first cultivation at the beginning of the growing season.
The second application of fertilizer is made during the
rest period in the month of July, which is just in advance
of the second period of activity.
"Unless the soil is exceedingly rich, it is considered good
practice to give the newly planted trees an application of
from one-half pound to one pound of fertilizer soon after
transplanting. From one pound to two pounds per tree
may be given in mid-summer. At the beginning of the
second year of growth, two pounds per tree may be used
for each application and from two pounds to three pounds
per tree may be used at each application during the third
year. Beginning with the fourth year, apply three pounds
or four pounds per tree at each application.
"Tung trees from eight to 10 years old in good bearing
should be given from five to six pounds of fertilizer at
each application. The rule is always to restore to the soil
a sufficient amount of chemical fertilizer to maintain a
proper soil balance, in order to assure continued produc-
tion and replace with like kind and amount the nutritive
elements which the tree has absorbed and used.
"Cover-cropping is highly recommended to provide and
maintain an adequate supply of humus and nitrogen in the
soil. A good legume, such as crotalaria, beggar weed, cow
peas, velvet beans or soya beans will serve this purpose.
Crotalaria is recommended because of its abundant growth
and high nitrogen producing value. Crotalaria Spectabilis
is the best growing variety and will reseed itself from year
to year.
"The press cake or residue remaining after the extrac-
tion of tung oil from the tung seed has been found to have
a high value as a fertilizer. It has a relatively high nitro-
gen content and in addition contains small amounts of phos-
phoric acid and potash. By the use of press cake as a
fertilizer, together with cover cropping, it will be possible
to maintain a balance in soil fertility by additions of phos-
phorus and potash. In this way, a lower cost of fertiliza-
tion may be secured.
"All animal manures are good fertilizers and should
be employed whenever available. Animal manures con-
tain a high ammonia nitrogen content which is quickly
converted to nitrate nitrogen and is then available for the


use of the tung tree. Chicken manure has been found to
give most excellent results. This form of fertilizer, in
addition to the usual elements found in other fertilizers,
has a zinc content. This zinc element contributes largely
to the health of the tung tree and to the availability of
other nutritive elements.
"Too rapid growth upon the part of the young tree is
inadvisable. It results in long, gangling branches which
are usually brittle and susceptible to wind damage. Such
trees are often unable to support the weight of a normal
nut crop. In such cases, it is advisable to add potash in
some available form. This will slow up the tree growth
and harden the wood."
Harvesting and Marketing: As the fruits mature they
fall to the ground and are gathered by hand. This is in
the latter part of October and the early part of November.
Gathering the nuts is largely a matter of convenience, ex-
cept that if they are allowed to remain on the ground after
the tree sheds its leaves the operation of recovery from
the leaves is more expensive and difficult.
The whole fruits should be stored where they are com-
pletely protected from moisture until they are thoroughly
dry. Hulls should not be removed because of possible
damage to the pellicle or seed coating and a consequent de-
crease in the quantity and price of the oil. If the nuts
are stored in sacks, the sacks should be arranged to permit
proper air circulation. When stored in bulk, they should
be placed on a dry floor with air circulation beneath and
turned with a shovel once or twice until dry.
The nuts may be marketed any time within six months
after they are dry. This offers the grower a possible op-
portunity to dispose of his crop at advantageous market
Concerning Budding: Although production traits are
generally transmitted from parent tree to seedlings, irreg-
ularities are frequent. For this reason growers are show-
ing increasing interest in asexual methods of propagation
or what is known as budding or grafting. According to
the Florida Agricultural Experiment Station, the absolute
value of these methods has not been established but it is
desirable that as many growers as possible experiment
along these lines. Some growers predict that future prop-


agation of the tung tree in this country will resolve into a
matter of budding entirely. A number of methods so far
tried out are described in Bulletin No. 280 of the above
Pruning: Except for the removal of dead, broken, or in-
terfering branches, pruning. of older trees is of negligible
advantage and tends to reduce the number of fruiting trees
with a consequent reduction in yield. Development in tree
character, however, is largely dependent upon a certain
amount of specialized pruning in the tree's initial period of
growth. This subject is also dealt with in the above bulletin
and in American Tung Tree.
Bronzing: Bronzing is a physiological disorder which
seriously affects tung trees on certain soils and in certain
localities. The name is suggested by the bronze coloring of
the leaves shortly after the affliction has passed out of its
initial stage. Without proper treatment the tree becomes
stunted and finally dies. Experiments carried on by the
Florida Agricultural Experiment Station since 1931 have
more or less definitely determined this condition to be the
result of certain chemical malnutrition which, in most cases,
can be corrected if treated in time. Bulletin No. 273, issued
by the station, treats the subject in detail.
Frenching: Another and quite different disorder to
bronzing has been found to occur in varying degree over a
widespread area. It is a type of partial chlorosis and
necrosis affecting tung tree foliage suggesting the word
"frenching." Observations made in a preliminary survey
in the spring of 1937 indicate that between five and 10
percent of commercial tung plantings evidence symptoms
to some extent. Data presented indicate that frenching
is not confined to any particular soil series or narrow range
of soil reaction, but is correlated with the exchangeable
manganese content of the soil. While experiments are still
far from complete, indications are that control can be ef-
fected by manganese sulfate treatment. A special bulletin
on the subject (No. 318) was issued by the Florida Agricul-
tural Experiment Station, Dec., 1937.
An Idea of Replants Necessary in the Tung Grovf: Dur-
ing the first three years of the tree's life in the groves
there will be some mortality. The number of trees lost will
depend upon climatic conditions, care at time of planting and


supervision of the grove. In one Florida grove the figures
ran from three to 22 percent, and a fair average might be
eight percent. The mortality after the third year should
drop to a very low figure.

B. F. Williamson

1. Further development of prolific bearing strains
through continued careful seed selection.
2. Further study of fertilizing.
3. Development of a portable huller.
(This will reduce the weight about 40 percent and
the bulk fully 50 percent. This would leave the hulls
near the grove where they could be put back around
the trees. Such a machine would help to develop
small plantings in new localities).
4. Continued study of better methods for extracting the
oil either by solvents or presses.
5. Fundamental research in the chemical composition of
tung oil and for byproducts from the inner and outer
Definite standards for American oil must be set. This
will reflect the high superior quality for American oil and
should justify a better price to the producer for his tung oil
seed at the mill. (From the condensed proceedings of the
Florida Chemurgic Conference, Gainesville, Feb., 1937).


The planting of tung trees has been suggested as a solu-
tion of many of the difficult agricultural problems of the
South. The outstanding position of cotton in the economic
life of many of the Southern states has resulted in marked
fluctuations in individual and general business prosperity
following closely trends in the cotton market. It is con-
tended that the addition of a new industrial crop will assist


in diversifying agricultural activity and thus may bring a
more balanced prosperity to that region.
Timber exploitations in the South far exceed replacement
reforestation and in certain states is rapidly exhausting this
important natural resource. The large and increasing acre-
age of cut-over timberland represents, at present, a consider-
able economic loss to the South. Therefore the problem of
a profitable utilization of these waste lands has been of ma-
terial concern to lumber companies and owners of such prop-
erty in the Gulf coastal region. Tung nuts have been visual-
ized as a potential crop for some such areas, and lumber
firms have played an important part in the encouragement
and development of tung tree plantings in Mississippi, Louis-
iana and Texas. If the tung tree satisfactorily solves this
problem, benefits will acrue not only to property owners,
workers, and all classes deriving income or sustenance from
the land, but to county and state treasuries as well, in the
form of increased tax returns.
Extensive plants of tung trees may lead to the develop-
ment of an extensive milling industry, a movement in keep-
ing with the trend toward industrialization now quite evi-
dent in the Southern states. Since tung oil, turpentine, and
rosin are essential raw materials in paint and varnish manu-
facture, certain leaders in the paint industry, as well as tung
tree planters, have visualized the commercial production of
tung oil in conjunction with the already well developed naval
stores industry of the South as an incentive to the extension
of paint and varnish manufacture in that region.
Forestry authorities in various states of the South have
recommended the growth of this tree in hilly or rolling
areas, where its long tap roots would serve as a protection
against excessive erosion and resultant exhaustion of the
soil. Such plantings may assist farmers in the more eco-
nomic use of their uncultivated land, since tung trees grow
satisfactorily on hillsides and on irregular plots of ground
which may be difficult to utilize for general farming. In
some localities a few plantings are being made along rail-
road tracks, highways and edges of fields, so that the trees
in addition to yielding nut crops, may be used instead of
posts for stringing wire fencing. The tung tree is beautiful
in bloom and may add greatly to the scenic inducements of
the South to attract tourists and vacationists.



The development of tung oil production in Florida into a
generally profitable, fundamentally sound and important in-
dustry, apparently covers a range of possibilities, one way
or the other, with success depending largely on the intelli-
gent employment of definite tung knowledge, and the appli-
cation of principles necessary to the success of any business.
Advantages for profitable culture would seem to be with
the large grower because of economy in maintenance, pur-
chasing, and usually the fact that the large grower has suf-
ficient capital to see him through to successful production.
The small grower, however, has certain advantages in his
favor. The farmer with limited income, as suggested, might
find in tung culture an opportunity for increased diversifica-
tion and profit provided, of course, his land and its location
is adaptable to tung production. With proper regard for
the land he may inter-crop among his tung plantings, thus
reducing the expense of the growing trees. In localities
with a number of small groves, the growers can probably
band together advantageously for cooperative supervision,
maintenance, purchasing and eventually marketing.
It must be remembered, however, that tung production
in this country is still considerably an experiment and that
most of the tung trees planted are nqt yet at bearing age.
Nevertheless there are several groves sufficiently aged to
indicate that a profitable yield will result where the neces-
sary requirements are complied with:
1. Suitable soil
2. Properly drained
3. Right Climate
4. Planted with properly selected seedlings and
given adequate cultivation and fertilization
In preparing this bulletin an effort has been made to
present as neutral a picture as possible to help the reader
form his own conclusions regarding the prospects of tung


Reminder Briefs:
1. Proper soil and location.
2. Careful selection of stock.
3. Cultivation and fertilization according to highest
known tung standards.
4. Enterprise well directed under competent super-
5. Painstakingly multiplying trees showing a high rate
of bearing over a period of years.
6. Planting of no greater acreage than can be carried
financially until commercial production-not less
than five years.

American Tung Tree, Propagation and Production., Joseph C. Adder-
ley, published by American Tung Oil Institute, Pensacola,
Fla., 1936.
Producing Tung Oil in Florida, Bulletin No. II, Florida Department of
Agriculture, Tallahassee. 1935,
The Tung Oil Tree, Bulletin No. 280, Florida Agricultural Experiment
Station, Gainesville, 1935.
A Preliminary Report on Zinc Sulphate as a Corrective for Bronzing
of Tung Trees, Bulletin No. 273, Florida Agricultural Experi-
ment Station, 1934.
A Preliminary Report on Frenching of Tung Trees, Bulletin No. 318,
Florida Agricultural Experiment Station. 1937.
Some Results of a Study of the Tung Oil Industry in the United
States, Farm Credit Administration, Washington, D. C., 1935.
Tung Oil Culture, Questions and Answers, National Paint, Varnish
and Laquer Association, Inc., Washington, D. C., 1937.
Tung Oil, Bulletin No. 133, Bureau of Foreign and Domestic Com-
merce, U. S. Department of Commerce, Washington, D. C., 1932.
Tung Oil, Synopsis of Information, Bureau of Foreign and Domestic
Commerce, U.S.D.C., Washington, D. C., 1938.

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