Annual Report of the Canal Zone Experiment Gardens, for the fiscal year...


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Annual Report of the Canal Zone Experiment Gardens, for the fiscal year...
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Canal Zone -- Experiment Gardens
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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Title Page
        Title Page 1
        Title Page 2
    Letter of transmittal
        Page 1
        Page 2
    Table of Contents
        Page 3
    List of Illustrations
        Page 4
        Page 5
        Page 6
    General statement
        Page 7
        Page 8
    Publications and improvements
        Page 9
        Page 10
        Page 10a
        Page 10b
        Page 11
        Page 12
        Page 12a
        Page 12b
        Page 13
        Page 14
        Page 15
        Page 16
        Page 16a
        Page 16b
        Page 17
        Page 18
        Page 18a
        Page 18b
        Page 19
        Page 20
        Page 21
        Page 20b
    Ethylene gas and fruit ripening
        Page 21
        Page 22
        Page 22a
        Page 22b
    Sugar cane
        Page 23
    Some insect problems
        Page 24
    The nurseries and the revolving fund
        Page 25
        Page 26
        Page 27
        Page 28
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text

c0O-5 -7



Canal Zone

Experiment Gardens*

For the Fiscal Year

* Succeeding the Canal Zone Plant Introduction Gardens.




For additional copies of this publication address The Panama Canal, Washiington, D. C.,
or Balboa Heights, Canal Zone.


Summit, C. Z., 7uly 16, 193o.

SIR: I have the honor to transmit herewith and to recommend for
publication, the Annual Report of the Canal Zone Experiment Gardens,
for the year ending June 30, 1930.
Mr. Roy R. WATSON,
Chief quartermaster,
Balboa Heights, Canal Zone.
Through Mr. J. H. K. HUMPHREY,
Assistant Chief Quartermaster.

Digitized by the Internet Archive
in 2013


General Statement-.......---- --------------------------.-----------------.------------------------- 7
Publications--...............------------- ----------------------- ------------------------- 9
Improvements--------------.-------------------------------------------------------------------------- 9
Irrigation System-.----------------------------------------------------------------------------. 9
Directing Signs----------- --------------------------------------------------------------------. 10
Road to Office....--------------------------------------.---------------.-------------.--------. 10
Road Repairs----------------------------------------------------------------------------------- 11
Entrance Gate------------------------------------------------------------------------------- 11
Fence----...............---......--------. ---- ----- ---------------....---------------.. 11
Office Repairs..--------------------------------.---------.--------------------.--------------- 11
Ditching..--------------.--------.................-..---.... ---------------------------..--------- 11
Vine Supports.....................--------------....--......-... .-----------------------. 11
Manure Spreader for the Fly Problem-------------------------------.. -----------.------. 12
Library Increments---------------------------------------------------------------------------- 12
Herbarium......----------------------------------------------------------- --------------------- 12
Citrus-..---. .......---...---- ---..--------- --....... --.---------.- ----------- --------......------........ 13
The Meyer Lemon---------------------------------.. -----------.......---------------......... 13
Pomelos or Grapefruit.-----------.............. ----.... ...---------------------------------...... .......... 16
Pummelos--------------------------.. ----------------------------------------..---------------.. 18
Oranges--------------------------.---------------------------------------------------.----------. 19
Treatment of Citrus Fruits.--.........--- -.-.----..... .-----------------------.. ............. 19
Ethylene Gas and Fruit Ripening.......---.-...-----------------------------.........----------. 21
Rice ---------------------------------------------------;-- ---------..-----.-----...................... 22
Sugar Cane------------------------------------------------... ..----....--... - --. ---------------..... 23
Some Insect Problems---------------------------------------....------......--------.-------- 24
Papaya Fruit Fly--.....--.------------...... .------.......--.-..--.....------------............ 24
A Wood-cutting Beetle ................-------------------------------------...----------......................... 24
The Nurseries and the Revolving Fund.................--........................................................... 25



PLATE I Gate at main entrance.
PLATE II Part of circle in road to office.
PLATE III The Meyer lemon.

PLATE V Figure
PL \'IE I' Fi,_ure
Fi Lure

PI.- rE V'II


The Marsh grapefurit.
The McCarty grapefruit.
The Duncan grapefruit.
The Kao Pan, a Siamese pummelo.
Aln unidentified orange received as "Valencia."
The Temple orange.
'The Pineapple orange.
Rice trial plots at harvest rime, sugar cane trial plots in back-


Three illustrations have been misplaced in the final setting up
of this publication. That shown as Plate IV, Fig. i, should bear
the title An unidentified orange-received as "Falencia." The title
of Plate VI, Fig. i, should read The Temple orange. The title of
Plate VI, Fig. 2, should be Marsh grapefruit.
Therefore on page 17, "Plate IV, Fig. C" should read Plate
VI, Fig 2. On page 19 the second sentence should read as fol-
lows: Plate IV, Fig i indicates the heavy bearing of an uniden-
tified variety of orange which came to the Gardens under the
name "Valencia" and similar productivity in the Temple variety
is shown in Plate VI, Fig. I.


Gate at main entrance.

p. 6-a.



In the Annual Report of the Canal Zone Plant Introduction Gardens
for 1929, it was mentioned in a footnote that the name of the Gardens
had been changed to Canal Zone Experiment Gardens. No explanation
was given at that time, but an announcement of the change and the
reasons for the same has been sent to all on the general mailing list.
The new name represents a slight change in organization, but the
functions and objectives of the institution remain the same, the new
designation being given to better represent the purposes being pursued
rather than to indicate any change in policy.
The objectives of the work as now carried on, were rather fully set
forth in the Annual Report for the fiscal year 1928. From time to time
new spheres of usefulness appear, or old ones are enlarged. During the
year just closed, the Gardens were honored with a visit from the repre-
sentatives of the Institute of Educational Research of Teachers' College
of Columbia University in connection with their survey of the schools
of the Panama Canal Zone, under the direction of Dr. N. L. Engelhardt.
Doctor Engelhardt laid emphasis upon the relationship of the Experiment
Gardens to educational problems in the Canal Zone.
A sphere in which the Gardens are now serving the United States, as a
whole, is that of supplying tropical plant material to conservatories and
to research workers as well as to those who are testing such cultures in
the most nearly tropical portions of the Union. The number of such
calls seem to be considerably on the increase.

The work that is being done here may be regarded as the laying of the
foundations of an institution which should become a great out-of-door
laboratory for scientific research in the problems concerning tropical
plants in relation to their environment of soil, climate, and other plant
and animal life. Such research is inevitable if the agriculture of this
Central American and tropical South American region is to progress.
Capital is ready to enter into such developments as soon as safe invest-
ments can be pointed out, secured by a knowledge of the conditions and
of the necessary technique. Such developments will benefit the United
States, not only by furnishing profitable investment for surplus capital,
but also in supplying tropical raw materials necessary in manufacture.
The relation of all of this to the income from the operation of the Panama
Canal need not be emphasized. It is patent to everybody that such
developments must be followed by increased tonnage in transit and
increased collections in tolls. The benefits that would accrue to Panama
and to the neighboring republics from such agricultural developments
are too obvious to require any elaboration. The Governor of the Canal
has pointed out the great benefits, in international relations, mutual
understanding and good will which might be expected to be brought
about by a university, located in the Canal Zone, and serving the
surrounding region. This may be regarded as an expansion of the
same thought which the Governor has had in mind in fostering the
development of plant research in the Canal Zone.
It would seem clear therefore that the same broad view of the signifi-
cance of the work that has been begun at Summit should be generally
recognized in the United States as well as here in the Canal Zone, and in
the entire surrounding region. The Congress of the United States has
made provision for such investigational work in Hawaii, Puerto Rico,
Guam, and the Virgin Islands. Although it is not designed to make the
Canal Zone an important agricultural country, the strategic importance
of its location with reference to the agricultural development of the
surrounding region and the relation of such development to the economics
of our own country should not escape the attention of the people of the
United States. With a vision of the importance of an agricultural
center here, The Panama Canal has begun this work and carried it on to
the extent of available funds. But the time seems to have come when
the project should be recognized as of national and international signifi-
To point out some of the needs that are outstanding, mention may
be made of the fact that there is, so far as we are aware, no soil specialist
in the public service anywhere in this region and no soils laboratory.
Likewise there is no plant pathologist to study the diseases of plants

or methods of combating them. Practically nothing is known of the
plant diseases here, except in so far as they are identical with those
found elsewhere, and no survey has been made to learn what diseases do
exist here. A botanist is much needed whose time could be devoted
exclusively to gaining a wider and more intimate knowledge of the wild
plants, many of which are of economic value, and also to gaining a
knowledge of the physiology of the cultivated plants. These are a few
of the outstanding needs, from the standpoint of plants and soils.


In addition to the Annual Report, there was published during the
year, the "Revised Catalogue of the Principal Plants at the Canal Zone
Plant Introduction Gardens." Mimeographed lists of "Plants for sale
at the Canal Zone Experiment Gardens" have been issued and distributed
locally and to correspondents in the neighboring Republics. This is
not sent out to the general mailing list in the United States and foreign
countries as most of the plants covered in this enumeration are intended
for use on the Isthmus or in nearby locations and can not easily be
shipped long distances by mail. A copy of this list will be mailed to
any botanic garden or experiment station, if requested.


The activities of the year have included rather more attention than
usual to certain improvements other than plantings.
The irrigation system.-Chief among these improvements is the
irrigation system, the pressing need for which was mentioned in the
Annual Report for 1928. A special allotment of approximately I$14,400
was set aside by the Governor of The Panama Canal for this purpose,
of which $7,200oo was made available for the fiscal year 1930, and the
balance for 1931. Estimates of the amount of water that will be
required at the Gardens were submitted by the Director, and the plans
were drawn up by the engineers of the Department of Operation and
Maintenance. The work of installation has been conducted by the
Municipal Division of the same department. The 36-inch main pipe-
line, which passes the west and lower side of the Gardens and conducts
water from the Chagres River to the Miraflores Filtration Plant, was
tapped with a 36-inch by io-inch T near the entrance to the Gardens.
The pump house was rebuilt and a new electrically operated single
stage pump with I2}-horsepower motor and capacity of 300 gallons
per minute, was installed. The main pipe line was laid parallel to the


general direction of the main road through the Gardens and leading
near to the upper boundary. This line consists of about 50 feet of
io-inch, 5oo feet of 8-inch, 1,oo000 feet of 6-inch, and i,ooo000 feet of 4-inch
and 3-inch pipe. Where necessary Ts and valves or plugs were installed
to provide for connecting the main distribution lines which are to be
laid during the coming year. The few distribution lines of the old
system were connected with the new main line so as to keep these in
service and distribute water where possible. By the careful conserva-
tion of the funds of the regular allotment for the operation of the
Gardens, it was possible to make some extensions of the distribution
lines, including the laying of a 3-inch pipe through a part of the avo-
cado orchard and the balance with a 2-inch pipe, which made it possible
for the first time to get any considerable volume of water to this
orchard. In some parts of the Gardens, water was conducted to the
points where it was most needed by the installation of 2-inch fire
hydrants and the use of condemned fire hose bought from the obsolete
storehouse. This was a great aid in emergency. Several hundred feet
of movable surface pipe, now much used in the Pacific Coast States,
was bought from the general operation funds. This was shifted from
place to place as needed. By all of these and other devices a much
larger quantity of water was applied than had been possible in any
previous year.
Directing signs.-Several signs have been erected for the guidance of
visitors who may be unfamiliar with the Gardens. In some instances
strangers who had come out from town in hired cars had been carried
on the highway far beyond the road that turns off to the Gardens. A
sign was put up at this junction to avoid repetition of such errors on the
part of chauffeurs. Another sign was put up at the entrance indicating
the directions to the office and to the nurseries and the Garden plantings.
A third was placed on the office building.
Road to office.-A suitable road leading to the office building has
always been greatly needed. The only approach has been along the
edgLe of the Panama Railroad right-of-way, and so close to the siding as
to be unsafe when freight cars were on the rails, as well as unsightly.
.-Also, it was impossible for large trucks to get through to the cars without
breaking the plants along this approach. A short piece of macadamized
road leading directly to the office has been constructed which will add
much to the convenience, the safety, and the appearance of the approach,
and which also (,pens up a vista through a part of the Gardens where
many interesting plants are brought into view, and where others will be
planted. Plate II shows a part of this little piece of road on which



y. ., l a ." ,. .. ..
*\:.' .- ' .. '-

I-T .
-,. , ... a


Part of circle in road to office.


plantings have not yet been completed. This road has been constructed
at only nominal cost because of the availability of waste material which
had to be cleared away from the floor of the nearby stone quarry, and was
therefore supplied and loaded without charge by the Municipal Division.
The hauling was done almost entirely by the regular transportation
facilities of the Gardens, and the work, except the rolling, was all
performed by the regular labor gangs. Technical advice was supplied
by the Municipal Engineering Division.
A short piece of concrete walk has been constructed leading from the
circle of the road to the office entrance.
Road repairs.-No other new roads have been built during the year,
but considerable repairing has been done on the old roads, including the
oiling and sanding of the driveway which circles toward the center of
the Gardens.
Entrance gate.-A new iron gate and reinforced concrete pillars,
designed by Mr. C. A. Black, has been erected by the Constructing
Quartermaster's Division to replace the old wooden gate which had
decayed and had been taken away some time ago. This strong and
substantial gate at the entrance, which is shown in Plate I, is very much
in keeping with the surroundings and adds greatly to the appearance
of the place, while it affords protection against intruders at hours when
the Gardens are not open to the public. The necessity for such pro-
tection has been brought forcibly to our attention on many occasions.
Fence.-A new fence with iron posts has been built leading from the
entrance gate to the south boundary where it joins the fences of the
Cattle Industry pastures; and also another from the entrance gate north-
ward to the office building. With another small gate which must be
built near the office to close the entrance into the mango orchard, these
fences will complete the much needed protection on the side next to the
highway and to the railroad station.
Office repairs.-The office has undergone some repairs during the year,
and a half of the interior has been repainted. Minor repairs have been
made on some of the sheds and other buildings. These necessary
improvements have been paid for out of the regular funds for operation.
Ditching.-Considerable ditching has been done in some parts of the
Gardens to take care of the excess of water during the rainy season.
This is very important as there are many places where nothing will
grow until this excess water is removed. So far only open ditches
have been attempted.
Vine supports.-Two galvanized iron pipe trellises have been built
for the support of many economic and ornamental vines. These are

plain pipe trellises set in concrete footings and connected with
ordinary wire at suitable distances for the support of the vines. Their
combined length is approximately 200 feet.
manure spreaderfor the fly problem.-Organic manures are absolutely
essential to the permanent success of the Gardens. Fortunately there
has been a liberal supply of these materials available, but it is necessary
so to use them as to avoid the breading of flies. Until this material is
well aged, it will breed flies if placed among our plantings by the usual
method of handling with forks. During the year just closed an attempt
has been made to solve this problem in part by the use of a farm manure
spreader. This machine can easily be operated, in many of the plantings,
and can be adjusted to spread even coarse material very thinly. It is
claimed to spread as thinly as four tons per acre. Although no exact
measurements of the area covered have been made, the spread appears
to be thin enough to render the material uninviting to flies as a breeding
place. The application can be repeated often enough to give a liberal
supply, as each application soon disappears either in rainy weather or
in the dry season.
Library incremen/s.-Through the kind cooperation of the officials of
the United States Department of Agriculture, the Gardens have received
many valuable departmental publications, including sets, as nearly
complete as possible, of the back numbers of the Experiment Stations
Record, the Journal of Agricultural Research, the bulletins of the
Technical series, Farmers bulletins, Year Books of the Department of
Agriculture, and others. The new numbers of all of these are being
received as issued. The older sets and the new numbers make exceed-
ingly valuable additions to the reference library and their receipt is
gratefully acknowledged. Publications are being received from several
agricultural experiment stations and botanic gardens in the United
States. Other publications have been received as exchanges from
botanic gardens and experiment stations in foreign countries. As funds
are available, new volumes are being added each year by purchase.
By all of these means a valuable working library is being built up.
Herbarium.-Under an arrangement entered into by the United States
National Museum and the Governor of The Panama Canal, relating
to the botanical investigations carried on in the Canal Zone by Mr.
Paul C. Standley, a very fine herbarium collection of 1,137 species of
plants, collected from this locatility and identified by Mr. Standley,
came into the possession of the Government of The Panama Canal during
the year and has been placed in the custody of the Experiment Gardens.
Through the generosity of Dr. Thomas Barbour, whose interest in the
Canal Zone is well know, six insect-proof metal cases were donated for


The Meyer lemon (synonyms, Hsien Yuang-Fragrant lemon-Chinese ornamental lemon).

the proper care and preservation of this collection. Our sincere thanks
are expressed to Doctor Barbour. The collection and the cases for its
preservation will greatly aid the work of the Gardens.


The year has afforded a very good opportunity for observation of the
citrus fruits, as the trees of most of the varieties have come into bearing
and produced a very good crop. Of course, too much confidence
should no be placed in the results of one year's performance, but those
who are interested in extending citrus plantings will be desirous of
securing such data as are available.


The most outstanding citrus fruit of the year has been a new lemon
(Plate III), named the MeyerI in honor of the late Mr. Frank Meyer,
who introduced it from China where it is known as the Hsien Yuanc,
or fragrant lemon. It is also called the Chinese ornamental lemon.
The latter designation would seem to be appropriate if it did not convey
the idea that the fruit is valuable only as an ornament, for it is one of the
most beautiful of all the varieties of lemons. Also this name is too long
and does not conform to the rules of pomological nomenclature. The
color of the fruit, whether ripened on the tree or by ordinary curing
methods or by the recent ethylene gas treatment, is a clear lemon yellow
of rather brighter hue than that of most commercial lemons. The rind
is smooth and up to the present time has shown no Verrucosis or seal),
although this disease is present but not prevalent in the Gardens.
It is thin and cures well, becoming quite leathery, although no long
distance shipping tests have been made to determine its resistance to
abrasions. The form of this fruit is somewhat less elonmated than in
most varieties, some specimens leing almost spherical with the nipple
practically absent. The juice is of excell,-nt quality and exceedinuly
abundant, as will be seen by reference to the tabulation prcscnitcI below.
The crop was heavy for trees in their first year of bearing.
Samples of the Meyer lemon were submitted to the General .lanagcr
of the Commissary, including lots of medium and of lar-c-sicl fruit,
cured and uncured in each case. The following tabulations (Tables 1
and 2) were submitted by the manager as the result of analycs made
by the chemist:
McKtve. RRlanl, 19'26. Chincese D\ Meyer Lemon Intri, IU... U 1. 1) apartment of
Agriculture Yearbook, 1926. 218-221.



Sample. Weight. Pulp. Rind. Seeds. Juice. Juice.

Grams. Per cent. Per cent. Per cent. Per cent. cc.
States................................... 124 23.0 36.4 0.4 40.2 48
129 22.4 36.8 0.3 40.5 50
119 19.3 36.9 0.3 43.3 49
131 23.5 36.7 0.5 39.3 49
122 21.7 33.7 0.5 44.1 51
107 25.8 29.6 .......... 44.6 45
States, average........................ 122 22.6 35.0 0.4 42.0 49
Meyer, Lot 1, large size, uncured............. 307 21.7 25.1 1.1 52.1 154
331 21.6 19.3 1.1 58.0 186
Me.vcer, Lot 1, large size uncured, average 319 21.7 22.2 1.1 55.0 170
Mcver. Lot 2, medium size, uncured.......... 236 21.5 21.3 1.1 56.1 127
243 20.2 19.8 0.9 59.1 137
Meyer, Lot 2, average ................ 239.5 20.8 20.6 1.0 57.6 132
Meyer, Lot 3, large, cured................... 194 19.9 11.9 1.4 66.8 123
217 19.3 17.9 1.4 61.4 127
Meyer, Lot 3, avcrage. ............... 205.5 19.6 14.9 1.4 64.1 125
M'cer, Lot 4, medium, cured............... 149 19.6 13.8 0.8 65.8 94
143 21.5 10.8 1.2 66.5 90
Meyer, Lot 4, average................. 146 20.6 12.3 1.0 66.1 92
Lemons from Messina, Italy................ 116 20.2 43.9 2.6 33.3 36
124 19.5 39.2 3.9 37.4 44
119 19.7 39.3 4.1 36.9 42
104 21.7 30.5 3.3 44.5 44
102 22.4 34.3 5.5 37.8 37
105 22.3 39.1 3.7 34.9 35
Italian, average ...................... 111 21.0 37.7 3.8 37.5 40


Rotation Acidity
Sample. Sp. Gr. 26 C as citric Sucrose Invert Total
200, 4' C. 200 mm. ov acid. sugar. sugars.

Per cent. Per cent. Per cent. Per cent.
states .................................. 1.0367 -0.36 6.28 0.26 1.50 1.76
M.yrr, Lot l ............................ 1.0255 +0.31 3.94 0.14 1.89 2.03
Meyer, Lot 2 ............................ 1.0295 -0.99 4.82 0.21 1.67 1.88
MIryer. Lot 3 ............................ 1.0288 -0.93 4.84 0.13 1.67 1.80
Meyer, Lot 4............................ 1.0307 -0.92 5.16 0.09 1.78 1.87
Italian .................................. 1.0407 0.00 7.67 0.15 1.06 1.21

These comparative analyses of lemons from the United States and
from Italy seem to indicate that the Meyer variety, from China, as
grown at the Canal Zone Experiment Gardens, were superior to the
imported lemons, in all respects covered by the analyses except that the
juice contained a slightly lower percentage of citric acid. Taking the
Meyer Lot 4, medium size and cured as the most comparable, the tabu-
lation shows that the juice of these contains 5.16 per cent acidity,
expressed as citric acid, while the juice of the United States lemons,
analy'zUd, contained 6.28 per cent acidity. But the quantity of juice
in the Meyer, averaging 92 cubic centimeters per fruit, is so far in excess

of that shown by the lemons imported from the United States, which
averaged only 49 cubic centimeters per fruit, that the actual citric
acid content of the Meyer is far in excess of that shown in the imported
stock. While the Italian lemons showed a still higher ratio of citric
acid in the juice, the amount of juice was correspondingly lower. A
rough calculation which has been made seems to indicate that if lemons
were bought on a basis of total citric acid content alone, the Meyer as
represented by those samples, would be worth about 50 per cent more
money than the imported lemons that were taken as samples from the
Commissary stock.
For comparison of the States lemons used in these anlayses, reference
may be made to Bul. No. 93 of the University of California Agricultural
Experiment Station, which shows an average juice content in Eureka
lemon amounting to 38 cubic centimeters, while those imported from the
United States and shown in the above tabulation averaged 49 cc.
The citric acid content in the California analyses averaged 7.66 per cent,
that is to say, the fruit analyzed at the University of California showed
a higher percentage of citric acid, but a correspondingly lower juice
It is to be noted that the percentage of acidity, in the juice of lemons,
increases as moisture is lost in the process of curing. The Meyer fruits
sent from the Experiment Gardens were rather lightly cured while the
imported fruit was of course fully cured before being shipped and
doubtless had lost some moisture, after shipping, by exposure to the air.
It would therefore appear that the Meyer, for local consumption at
least, is equal in every respect to the imported lemons, if not superior
to them. If considered as a lemon for export purposes, other standards
than those shown in the analyses would have to be taken into considera-
tion. The requirements of a commercial lemon are rather exacting,
as is true of most commercial fruits to-day, and are somewhat fixed by
custom as well as by essential characters. The market is accustomed to
a decidedly elongated and rather tapering lemon while the Meyer is inclined
to be less elongated. Whether the unusually handsome appearance of
the new variety would be sufficient to overcome the accustomed ideas as
to shape in any export market would have to be taken into consideration.
Those that were offered for sale at the Commissaries sold readily and
were in great demand. One of the most important characters in a
commercial lemon is its shipping quality and ability to endure handling
and to resist decays. No opportunity was afforded for such tests in the
case of the new lemon from China, except that a few were held at the
Gardens for observation. Those that had been gathered as green fruits,
as is customary in harvesting lemons, when possible, kept well for many



The trees of the Meyer lemon at these Gardens are of low spreading
habit, vigorous and rather open growth. The tree is reputed to be
dwarf. Here they are located where they receive the shade of bananas,
and some Hevea rubber trees. Their behavior, under these conditions,
suggests again that shade for some citrus trees, under tropical conditions,
may be advantageous. This is a problem which is worthy of further


The term Pomelo, although recognized as the correct common name
for this fruit in horticultural literature is less used than the name
grapefruit by the growers, the trade, and the consumer.
Most of the trees in the citrus orchard were planted out as i-year-old
budded trees about May, 1925, and hence, at time of harvesting in
January and February, 1930, had been approximately four and one-half
years planted. A few of the varieties will be mentioned here because
of their performance at the Gardens and their promise as fruits for
further culture on the Isthmus. Several varieties of Pomelo or grape-
fruit have produced well and yielded fruit of excellent quality. Promi-
nent among these is the McCarty (Syn. Indian River) (Plate 1V, Fig. 2).
In Florida, which is renowned for the quality of its grapefruit, this is
regarded as one of the very best varieties. There is always a possibility
of error in labels, but the fruits produced on the trees labeled McCarty
at the Gardens, correspond rather closely to the description of this
variety given by HumeI which is as follows: "McCarty (Indian River.)
Form oblate; size large, 4- x 5 inches; stem small; base slightly creased;
color very light yellow; rind a inch thick; oil cells large, slightly depressed;
sections 13, large, rather irregular; flesh grayish green; bitterness
marked; acidity and sweetness normal; pulp melting; juice plentiful;
juice-sacs large; quality excellent; seeds 49-59, large long, creased;
core inch, open. Season January to March.
The (iriuLin of this \ity is unknown. The late C. T. McC.irty, of Eldred, Florida,
from whom specimens were first received, and after whom it was named, wrote as follows:
"'This pomelo is known here as the Standard, or Indian River; I don't know its origin. It
came here from Rorkklci- 16 years a'u,, (about 1886).' One of the very best varieties.
Its frui,1111- habit is worthy) of note because it bears its fruit sinly0 on the branches."
The fruit on the trees at the Gardens checks with the above de-
scription, except that the flesh was somewhat golden in color, rather than
grayish ureen, the core was closed in the several specimens examined,
and in one or two instances the fruits did not hang singly. There is
l Hii 1. 1 tarold: TIhe Cultivation of Citrus Fruits, 1926. N,.-\w York: The MacM\illan
Corlp., i i.. |


FIG. 1.-Marsh grapefruit.

FIG. 2.-Ni c( ,irt. ,,,fruit.

I'. 16- a.

some evidence that environment may alter the color of flesh of citrus,
and it is not impossible that other slight changes may have been brought
about under the different conditions existing here. For the present,
at least, this variety at Summit is being propagated under the name
McCarty. Whether the identity is beyond question or not, the variety
grown here is a most excellent fruit of high quality and productivity,
so far as the limited experience can indicate.
Marsh (Marsh Seedless) which is the standard variety of California,
presents evidence of being a good producer under Canal Zone conditions
(Plate IV, Fig. i). The form is oblate-roundish, size medium, color
light yellow, flesh of good quality but somewhat lacking in the slightly
bitter principle that is characteristic of most pomelos. The variety,
as grown here, seems to have rather more seeds than it has in the United
States, but less than are found in other varieties. Although commonly
called a "seedless" grapefruit, it is not absolutely free from seeds in
Florida where it originated. The nearly seedless condition is in its
favor from the standpoint of the consumer, although this seems less
important than formerly, as pomelos are now more carefully prepared
for serving and special simple devices are on the market for removing
the core and the seeds. From the standpoint of the grower, seedlessness
affords some advantage, as such fruit may be held longer on the trees.
The Foster is another of the pomelos of much interest in the collection
because of its precocity, its heavy production, and its highly attractive
pink color of flesh and even of the rind. The trees of this variety were
among the heaviest producers and carried the fruit well without any
breaking of the limbs. The pink color of flesh is found in several of the
pomelos or grapefruit, and is quite common in the closely related
pummelo. But among the true pomelos or grapefruit, this variety, as
grown in the Canal Zone, appears to combine best the beautiful color
with excellent quality. Here again the character of color within the
fruit seems to differ in some degree from that regarded as typical of the
variety in Florida, where it originated. Hume states that "the pink
color in this variety is confined to the section membranes, and often
shows through to the rind." The fruit, as grown at the Gardens at
Summit, although corresponding otherwise rather closely with the
descriptions of Foster, is decidedly pink through the flesh and the color
extends to the rind in many places.
The Duncan (Plate V, Fig. i) is another of Florida's best (riapefruit
which has been doing well here and, as is true of all the other varietiLs
mentioned, must be more thoroughly tested in different parts of Panan:i
and the Canal Zone.



The pummelo, in its best varieties, is but little known or cultivated
in the Western Hemisphere, but in some of the Oriental countries it has
reached a high degree of perfection and is much prized as a dessert fruit
and also for its ornamental value. Although it is closely related to the
pomelo or grapefruit, and by some botanists is regarded as the same
species, variously determined as Citrus decumana, C. grandis and C.
maxima, other specialists in this group place the grapefruit by itself,
as a distinct species, designated C. paradisi, Macf. Whether the grape-
fruit is to be regarded botanically as only a variety of the Oriental
pummelo or otherwise, it is, from a horticultural viewpoint, distinct.
Everybody in this country is thoroughly familiar with the grapefruit,
but perhaps some have not seen the pummelo. Without attempting
here to discuss the latter botanically, it may be said that it is usually
larger than the grapefruit, with greater tendency to be pyriform. Per-
haps its most distinguishing character is in its juice-vesicles which are
large, long and tapering, and only very loosely adhering, so that they
can easily be separated without breaking and served in salad or dessert,
while these vesicles, in the grapefruit, adhere so closely that they can
not be separated without breaking. Hence the fruits have somewhat
different uses in culinary art. In the pummelo, the segments usually
have a thick leathery covering which, however, is not complete, leaving
the inner pulp-vesicles exposed when the fruit is opened. As already
indicated, the pulp may be light in color or almost any shade of pink.
The rind may be a light yellow, as in the ordinary grapefruit, or as dark
as an orange. The so-called shaddocks, of Florida and the West Indies,
may be regarded as seedling pummelos, and some are probably worthy
of being propagated by budding. But the best pummelos of the Orient
have been propagated by air-layering, or Chinese layering, for centuries.
The Amoy pummelo is renowned in China, while Siam has several
varieties of great merit.
Some of the pummelos of the Orient have been introduced into the
Canal Zone, through the United States Department of Agriculture.
One of the Siamese pummelos, known as Kao Pan, S. P. I. No. 14,012
(Plate V, Fig. 2), fruited at Summit in February and March. The
following is a brief description: Form, pyriform with prominent neck
and with apex flattened; rind, light orange yellow, inch to inch thick
except at neck where it is i 0 inches thick; flesh, tender, of good flavor,
golden yellow in color and having fairly abundant juice.


FIG. 1.-The Duncan grapefruit.

FIG. 2.-The Kao Pan-A Siaimes pummelo.

p. 18-a.


Several varieties of oranges have yielded heavily, for trees so young,
and have produced a good quality of fruit. Plate VI indicates the
heavy bearing of an unidentified variety of orange which came to the
Gardens under the name "Valencia" (Fig. I.), and also similar productiv-
ity in the Temple variety (Fig. 2). The Pineapple, Plate VII, Fig. i,
which is "Florida's most important midseason sweet orange," is one of
the most promising varieties on the Isthmus in point of quality and
apparent productivity. It ripens in January and February.
The variety introduced under the name "Valencia," from Costa Rica,
has been another heavy producer of oranges of good quality. It
appears to be different from the true Valencia, and ripened much earlier,
in fact at the same season as Pineapple, while fruit of the true Valencia
in the same orchard from other sources was still immature.
The Temple is usually regarded as a hybrid between the sweet orange
and the mandarin or loose-skinned orange, although its origin is unknown.
The rind is easily separated from the pulp, but is not so loose as in the
mandarin. The flesh is of good quality and free from rag. The illus-
tration shows a decided inclination to free bearing habits.


Nearly all of the citrus fruits harvested at the Gardens were submitted
to several treatments in preparing them for sale. It may be said
parenthetically that all fruits not required for experimental purposes
are sold, usually through the Commissary Division. It seems desirable
that some description of these processes of treatment be given here as
some of them at least are much needed in the handling of the crop of
oranges and grapefruit on the Isthmus.
The first process is washing with soap and water and is now
common in good citrus practice. Regularly prepared citrus washing
powders are much used, and of course, in commercial practice the work
is done by machinery and the fruit is brushed with mechanically operated
soft brushes which remove the dust, the sooty-mold, and the few scale
insects which may be found, but the washing process must not be at-
tempted as a substitute for insect control in the orchard. When the
washing is completed, the fruit passes to a rinsing bath where the .(,apy
water is removed. The second treatment which is now rathere\tensivelv
used in California is the bicarbonate of soda bath for the control of
various decays. This consists in passing the fruit through a solution
compo sed of three pounds of bicarbonate of soda per hundred poiun ds

of water, in which the fruit remains from three to five minutes. This
process also, although seemingly very beneficial in preventing decays, is
never considered as a substitute for the extreme care inpicking, grading,
packing, and shipping which has become standardized in good citrus
practice. Here in the tropics where fungi multiply so rapidly, it would
seem that this treatment might be especially valuable. But it is doubt-
ful whether it would be of much use in the keeping of oranges that are
gathered by the usual crude methods, thrown in bulk into trucks and then
carried to market. Such oranges must be sold at once and be consumed
at the earliest possible moment or heavy losses by decay are inevitable.
On the other hand it might be possible to do successful business and
extend the season of available seedling oranges by buying these on the
trees, carefully picking and grading them, selling the small and inferior
grades at once, and after cleaning and otherwise treating those of first
grade, placing them in cold storage for the return of better prices than
those that prevail during the height of the orange season.
The third process, which was used on nearly all citrus fruits at the
Gardens during the year, was the ethylene gas treatment to produce
attractive coloring. It is well known that oranges and grapefruit,
especially in the tropics, frequently become ripe before they have ac-
quired the desired color. The lack of color detracts much from their ap-
pearance and market value. Gases, especially ethylene, have now come
into very general use, in cases where the color acquired on the tree is not
sufficient. For the purpose, it is only necessary to have a tight room,
and a drum of ethylene gas equipped with gauge with which to measure
the volume of gas that is allowed to escape in the ripening room. With
this equipment, it is all very simple and anyone can soon acquire
familiarity with the operation, but it is important to remember that the
gas is inflammable and in 5 per cent concentration with air is explosive,
but no such concentrations are ever required. There is some difference
of opinion and practice as to the amount of gas used, the concentration
varying from i cubic foot of gas per 1,000 cubic feet of air to I to 5,000.
In some cases, the greater concentration is used for the first few hours and
followed by less concentrated mixtures, until the fruits are properly
colored. The best results seem to be attained by exposures of a few
hours follo%%ed by a brief period of ventilation before the gas is again
applied. In the experiments followed at the Gardens, the following
are some of the results obtained: Meyer (Hsien Yuang) lemons, all
green when picked, exposed mostly in 6-hour periods, at concentration of
I part to 3,00o0 became well colored after 32 hours of exposure. Oranges
and grapefruit, half-colored when harvested, exposed for 2 hours at
I to 3,000, ,2 hours at i to 5,oo000, and two 4-hour periods at the same
concentration, making a total of 12 hours exposure, all became fully

- I



FIG. 1.-An unidentified orange-received as "Valencia."

FIG. 2.-Tlihe Templ. orang-.

p. 20 .i.



colored. Again, oranges and grapefruit, estimated to be one-third
colored, were exposed 2 hours at i to 3,oo000 and 14 hours in divided
periods at i to 5,000ooo. All were well colored after this total of I6 hours
exposure. All of this work, of which the above will serve as examples,
was under the immediate supervision of the foreman, Mr. W. C. Dewey.


The foregoing reference is to the use of ethylene gas in the ripening
of citrus fruits. Experiments in its use with some other fruits also have
been conducted. One of the fruits used was the Bungulan (erroneously
Lacatan) banana. Much difficulty has been reported with this variety
on the ground that it frequently fails to color well in ripening and also
that the fruit falls from the bunch when ripe. The bananas selected
were of two different degrees of maturity, one lot being "full," as the
fruit is described when the fingers have become quite rounded and have
lost their angular appearance. The other lot was such as is called
"three-quarters full." Those two lots were treated with ethylene in the
proportion of I cubic foot of gas to 3,000 cubic foot of air, the treatment
being continued for three 2-hour periods each day for 3 days
making a total of 18 hours exposure. The chamber was ventilated
between each treatment and was left open at night as it was not practi-
cable to continue treatment at night. At the close of the treatment the
bananas of both grades had taken on a beautiful clear yellow color
but practically all of them fell from the bunches as soon as they were
handled. The flavor of the fruit was excellent in both lots. These
results do not help to establish confidence in the Bungulan as a
commercial fruit since it is essential that such must hold tenaciously to
the main stem of the bunch.
Mango fruit has also been treated with ethylene as a means of rapid
ripening. As mentioned in earlier reports, most mango fruits ripen
during rainy season and with the exception of a few varieties they are
very susceptible to Mango Anthracnose or "blight," which causes the
spotting and rotting of the fruit. Sometimes the fruits split and decay
upon the tree, but often they will withstand the disease fairly well until
harvested, after which the fungus growth proceeds more rapidly than
the'ripening process and the fruits decay before they are rcajly to be
eaten. The treatment with ethylene hastens the riptrimlg, apparently
without speeding up the fungus growth proportionately, and by this
means it has been possible to save some fruit for immediate use. It is
possible that the washing of the fruit immediately after harvesting with
bicarbonate of soda, as described elsewhere for the tri-:itment of citrus
fruit, might further tend to preserve it.


Rice is one of the most important sources of food supply in Panama.
In 1927, rice was imported to the value of 380,228 Balboas,' and in
the first half of 1928 the importation was valued at 302,461.43 Balboas.

No statistics are at hand for the second half of the year, but it would
appear that importation is increasing. In almost all of the inhabited
parts of the Republic, there is an abundance of idle land which could
be used to produce upland rice, so that any one living in the country
districts could easily raise sufficient rice for family use and never be in
need of this food which is the staff of life to a very large proportion of
the human race and is freely used by all races. One acre of the higher
yielding of the upland varieties at the Gardens would produce sufficient
rice for the use of an average family for one year.
The varieties of rices mentioned in the Report for 1929 have been
continued in cultivation anid seed has been distributed without cost to
all who have requested it. It has been announced in the press in both
English and Spanish that trial lots of seed were being distributed without
charg-. Twenty varieties of these rices were planted in the trial plots
in drills, Plate VII, Fig. 2. In the case of some varietiesvery poorstands
were secured due to poor germination or the carrying away of the seeds by
birds. In other varieties the stand was very good. At harvest time,
an estimate was made of the percentage of stand. The actual yields
were calculated on an acre basis, and are shown in the accompanying
table. No calculations have been made on a basis of 100 per cent stand.



I\ I I I i. I
I'Ir:u l..l .. . . .

I ",[I ] ] t l1 ln l > ,r|IL' .
K nllihr i ', ,,r .i. . .
p .l 1 l, l ., ,l . . . .

Per cent P.iddyv per
of acre, pounds
stand. (ea',.').
1i5 1,481
S50 714
90 2,142
I85 9Y7
90 2,528
8 997
90 1,180

1I.1I .IV\:1) FROM U. S. DEP.\IHT.MI:\T OF .\ll ;I{I('UiLT l:.
I 1 2 1 .
D 117..................1...................
l l l u I I I+,... . . . . . . . . . . . . . . .. . . . .
444 1 I . .. .. .... . ... .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .
R. 1. 422.. .,
. '. ', . . . . . .... . . . . . . . . . .
S ; ...............
.. .. . ... P I . . . . . .. . . .. .. . ... .
..... .. P I P 3 15 .. .. .. ........ .. ... .. ..... .. .... .............. :
1 ', . 1 . ... . . . . . . . . . .. . . . . . . . . . . . .
7 1 ; 1 ; I) 1 ") . .v .. .. .. . .. .. .. . .. .. . .. .. . . .. .... .. .. ..
1. ). 2A'
.. ... .. I {. I). 2 ;1 ... .. .................... .... ................-...

1 TheI 1: ,I,., t is equivalent to the gold ,llli.r.

811 11859
- t . I .(IS 't
SO 1,35
!1( 1,27(0
75 I,31;i1
i95 1,655
90 1,440
40 q17
75) 1,452
75 '!117
75 997
.ol 459
50 4511
7. 1,045

Ace. No.




FIG. .-The Pin*eapple orange.
FbIG. 1.-Tlie Pineapple orange.

FIG. 2.-Rice trial plots at harvest time, sugar cane trial plots in background.

p. 22-a.

Some of the yields shown in the above table may be considered high
for upland rices and compare favorably with the yields in the valley of
the Nile where the average is about 2,300 pounds of rough rice per acre,
or with those of the rice-growing countries of South America. In
British Guiana which is one of the two South American countries which
produce more rice than they consume, the average yield is reputed to
be about 2,450 pounds of rough rice per acre.' Considering that the
lowland method of culture is used in those countries and that the yields
are normally very much higher under this system in which the plants
are partly submerged in water, the yields of upland rice, in the tests
referred to, are very creditable. The advantage of the upland rice lies
in the fact that it can be grown on almost any farm, while lowland rice
requires a special location with abundant water and land specially
prepared and dyked.
Larger quantities of seed will be available for distribution this year.
It is recommended that these upland rices be sown so as to mature at the
beginning of the dry season, when the danger of rains in harvest times
will be past and while there is sufficient moisture in the soil to carry the
plants through the ripening period. In this locality, if the seed is sown
during the last week in August, most of the varieties will mature in the
last of December or early in January, approximately four months from
seeding. A very good practice would seem to be to plant a crop of,
quick maturing legumes early in the rainy season, which may be cut for
cattle food just before the rice is to be planted, or they may be piled up
and allowed to rot as a source of excellent fertilizer. This crop will not
only enrich the soil, but, if dense, will crowd out much of the grass and
weeds and thus reduce the labor of weeding the rice.


The growing of introduced varieties of sugar cane for distribution
among the cane growers of Panama has been continued along the lines
indicated in the Report for 1929. One of the chief objectives in this
work is to find choice canes, well adapted to the conditions in Panama
and resistant to the Mosaic disease, which has been devastating in mo,,t
of the cane fields of the Isthmus. Most encouraging reports have come
in from the plantations concerning some of the varieties, notably P. 0. J.
2725 and P. 0. J. 2714. One side of the cane testing plots is shown in
the background of Plate VII, Fig. 2.
Cop1d Ind, Edwin Binmliazn. Rice, London: %.11:NIlll0 and Co., Ltd.


The Gardens do not attempt to carry on any technical entomological
investigations and all problems in the identification of insects are
referred to Mr. James Zetek, Associate Entomologist of the U. S.
Department of Agriculture, located in Balboa, with whom close
cooperative relations exist. Mr. Zetek has furnished very valuable
information, and many identifications, including those used here.
There are certain insect problems which are experienced at the
Gardens and which may be of deep interest and importance to some
readers of this Report who may not receive the technical publications
relating to the same. For this reason, brief mention is here made of a
few\ such problems as seen from a horticultural rather than from an
entomological viewpoint.
The Papaya Fruit Fly, Texotrypana Curvicauda Gerst (Diptera,
Trypetidae). This is a very serious pest in papaya culture. It is by
no means new to the Isthmus, but has not given any trouble at the
Experiment Gardens until'this year. The female of this insect deposits
its eggs within the papaya fruits at almost any stage of their develop-
ment. The flies may easily be seen at work, and the evidence of their
having stung the fruit is manifest in the milky juice which exudes from
the papaya and becomes dried on the surface. This however, may
result from any abrasion. Fruits in which eggs have been successfully
deposited and hatched, may fall to the ground prematurely, but if
the papaya is nearly full grown when stung it may remain upon the tree
until ripe. Fortunately it usually is possible to recognize infested fruit
by its external appearance. The fruit, when cut open, will be found to
be infested with matggots and unfit for human food. The remedy which
has been used at the Gardens consists in gathering all stung fruit,
cutting it open, and immersing it in oil. If this practice is diligently
pursued it is possible to hold the flies well in check. There appears to
be also a wide variation among varieties, in their susceptibility to the
attacks of the insects.
.4 :y:ood-cutting beetle.-Another troublesome insect pest is one of the
Longhorned Bettles (Cerambycidae), familiar to many laymen by their
longi antennae which are frequently lying backward over the body and
often exceeding the latter in length. The species referred to here is
identified by Mr. Zetek as Trachysomus Thomsoni Auriu. The adults
of this insect, both male and female, girdle or completely cut off from
trees whole branches, sometimes several inches in diameter. The
cutting is so stggestive of the work of a beaver that the common name
Beaver Beetle might wevll be given to this insect. The females deposit

their eggs in the severed branches which furnish the necessary deadwood
upon which the larvae feed. The obvious method for the control of
these insects is in the gathering of all such branches and other deadwood
of the varieties affected and burning them before the adults are ready to
emerge. The injury caused by these insects has been found at the
Gardens in guava (Psidium guajava), crepe myrtle (Lagerstroeniia
Indica), and in the native forest tree Triplaris americana. Mr. Zetek
also records the avocado among its host plants.


It was mentioned in the Report for 1929 that a Revolving Fund had
been set up for the operation of the nurseries. The purpose was to make
this branch of the work self supporting, so far as it pertains to all plants
other than those that are yet in a purely experimental stage, and thus
to save the regular operation funds for the permanent development of the
Gardens. The plan has been working out very satisfactorily. The de-
mand for trees and plants is constantly increasing and by means of the
plan just outlined it is possible to expand the nursery operations and
thus to meet the need which otherwise could not be done. There is a
large call for orange, grapefruit, mandarin, mango, avocado, and various
shade and ornamental trees, but palms, crotons, hibiscus, bougainvilleas,
coffee-rose, acalypha, and many other ornamentals are also taken in
large numbers. Many new and less known things are distributed in
smaller numbers as the stock becomes available.
In the propagation of avocados an attempt is being made to produce
more trees in the open nursery row and less in the concrete tubes, which
have been used partly because some buyers prefer to get them in this
form and partly because our propagators have found it difficult to bud
avocados successfully without shelter in the rainy season. But it has
been found that budding can be successfully performed in the open
nursery row in the dry season. Seeds that are planted in the latter part of
the rainy season are in good condition to be budded when the dry
weather comes. Seedlings from plantings in the early part of the rainy
weather are likely to be much larger than is necessary or desirable for
budding when the rains have ceased. Some experiments are now being
tried with planting the earliest seed in paper pots and cleft-grafting the
seedlings by the seedling graft method while they are still in tender
growth. By having them in the paper pots, it is easy to invert them andIL
dip them in melted paraffin without disturbing the root system. WXhen
these grafts are established the plants are set out in nursery row and
allowed to develop. The practicability of this method for the purpose
sought is yet undetermined, but the grafting is not difficult.


In mango propagation, the former practice of using cement or concrete
tubes has been discontinued entirely. No difficulty is experienced by
the propagators in cleft-grafting mango seedlings in the nursery row,
and by this practice much stronger plants are produced. The ordinary
cleft-graft is used and is covered with wax paper until union is effected
and the cion has made a growth that requires the opening of the paper
The chief difficulty that has been experienced during the year, in
mango propagation, has been in the serious infestation of the seedlings
by an undetermined species of Thrips (Physopoda). These very minute
insects which are not likely to be found without the use of a good lens,
infest the terminal bud causing it to cease growth. New buds on the side
begin to open, but these also are quickly overcome by the Thrips and the
young seedling is stunted or even killed. When in this stunted condition
they will not receive and unite with a cion. Fortunately most of the
varieties of the mango now being propagated do not appear to be
seriously affected by this insect, but the seedlings before being grafted
are very susceptible. A very effective remedy has been found in
nicotine dust, applied with any good dusting gun. The important thing
is to detect early the work of the insects and apply the remedy before
the seedlings have had a serious set-back.


MR 24703-Panama Canal-7-14-31-1,500

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