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PORTO RICO AGRICULTURAL EXPERIMENT STATION
MAYAGUEZ, P. R.
Under the supervision of the
UNITED STATES DEPARTMENT OF AGRICULTURE
BULLETIN No. 32
Washington, D. C. June, 1928
EFFECT OF TOPPING ON YIELD OF COFFEE IN
PORTO RICO 1
By T. B. MCCLELLAND. Horticulturist
Coffee branches--_---------------- 1 Effect of topping and removal of
Treatment -------------------- 3 suckers ------------------------ 4
Conclusions ------------------- 7
The question of the advisability of topping coffee trees has recently
received considerable attention from coffee growers in Porto Rico.
The practice varies in different countries. In Colombia and Guade-
loupe, for instance, heading back of coffee trees is universally prac-
ticed, whereas in Porto Rico the trees are allowed to attain full height.
Dimorphism of branches must be taken into account in any system
of pruning coffee. The subject has been treated at length by Cook.2
A knowledge of the habit. of growth of the coffee tree and of the
differences between the kinds of branches is essential to a proper
understanding of any pruning system practiced.
The coffee seedling first produces a single upright stem. When the
stem is approximately a foot high, further elongation is accompanied
by the development of lateral branches. A pair arises from extra-
axillary buds at the base of the topmost internode, and the three
stems-the upright and the two laterals-elongate simultaneously.
1 In this bulletin the term coffee refers to the common type of Coffea arabica only.
some other species of the genus Coffea requiring wholly different treatment from that
recommended for Arabian coffee.
COOK, O. F. DIMORPHIC BRANCHES IN TROPICAL CROP PLANTS: COTTON, COFFEE, CACAO,
THE CENTRAL AMERICAN RUBBER TREE. AND THE BANANA. U. S. Dept. Agr., Bur. Plant
Indus. Bul. 198, 64 p., illus. 1911.
2 BULLETIN 3?, PORTO RICO EXPERIMENT STATION -
(Fig. 1.) Thereafter a pair of laterals will develop in like manner
at the base of most new internodes of the upright stem as this con-
tinues growth, but occasionally one or more internodes may be skipped
or a single lateral may develop instead of a pair. If a primary
,w'.. N....,., .... .... ... ..
FIG. 1.-A, simultaneous development of the primary lateral branches and the
upright stem; B, position of new uprights, developed from buds immediately
below the primary laterals
lateral be removed the loss is permanent, as the upright stem can:
replace no lost lateral. However, in the axils of the leaves and just:i
below each lateral branch on the upright stem are buds from which
there may develop new upright branches similar in structure andi
habit of growth to the original stem. In this way only can addi-i.
EFFECT OF TOPPING ON YIELD OF COFFEE
tional primary laterals be produced. The normal function of lateral
branches is to produce fruit and only occasionally is any fruit pro-
duced on an upright stem. In addition to producing fruit, primary
laterals may also produce from axillary buds secondary lateral
branches, which are similar in function to the primaries.
When growth is allowed to take its normal course, the original
upright trunk bends under the weight of a heavy crop and various
new upright branches develop from the axillary buds. These are
similar in structure to the original stem, developing primary laterals,
which in turn produce fruit. The tendency to develop secondary
laterals varies somewhat. with the variety, but on ordinary Arabian
coffee, the growth of which has been unchecked by topping, the
amount of secondary lateral growth is not very great. In conse-
quence, by far the larger part of the crop is normally produced on
primary rather than on secondary laterals. If upward growth is
checked by topping and by the removal of new uprights as they
appear, the production of secondary laterals on the primaries is
greatly stimulated, and a large amount of such growth develops.
For all practical purposes only flowers, fruit, and secondary lateral
branches may be expected to develop from the primary laterals,
though observations at the station revealed two instances in which this
failed to hold true. A tree which was topped at. 4 feet in December,
1910, and the growth of which was forced into the laterals by the
removal of all subsequently developing uprights, was observed in
May, 1916, to have developed three upright branches from near
the tip of a primary lateral. Their structure was that of the up-
right, not the lateral, and their lateral branches were in pairs and
arose from extra-axillary buds. The position of these "upright"
branches was more nearly horizontal than perpendicular and one
showed a marked tendency to produce laterals in a somewhat hori-
zontal plane. In 1918 a second tree was noted with several similar
uprights arising from a lateral. These uprights were rather
spindling and lacked the vigor of the normal upright. Although in
the case of neither tree was the development that of the wholly nor-
mal or typical upright, it partook more of the nature of the upright
than of the lateral.
The field selected for testing the effect of topping contained 161
trees at the beginning of the experiment in December, 1910. These
had been set in the summer of 1908. The size of the seedlings at
transplanting time was such as to indicate that the seed had been
derived presumably from the 1906 crop. The variety was Blue
Mountain of Jamaica, typical of the ordinary Coffea arabica and
indistinguishable in appearance and habit of growth from the Porto
The trees were set in 24 short rows of unequal length. Rows 1 and
2 were left untopped, rows 3 and 4 were topped at 6 feet, and rows
5 and 6 at 4 feet. In the same alternating sequence the remaining
18 rows were similarly treated. The first of each of the four pairs of
untopped rows received no pruning whatever, all suckers and growth
nglie uOl g1rll i MA i ur LU~ 1111m 111 UUVBIeUoIpmenUts Irom its larer%
growth of many oA
uprights or suc
These were r m
from time to .
growth to the
topped ste n
..from the later
The first p 'ruL'
was given in x
ber, 1910. DWi
the next six yer rdri.
suckers were re
from the trees:
3 to 5 times an
and during thi.tq
lowing five .y.iLI*
.- from 2 to 3it
*."The trees W
young when i
were top ped
plied with pri
laterals. Fig ......
shows the co
of one of the b
developed trees sa
eral months b
the first pruni
This tree was. 8
high and carried .
middle ones "el
more than 3
long. Some ot0i
FIeG. 2.-Coffee tree which carried 42 branches and more trees had developed.
than 1,500 cherries. Photographed in September. 1910, less rapidly and t
prior to pruning the time of the. fit'.
the time of the:..
pruning lacked the necessary height for topping. These were i
quently topped as their growth permitted.
EFFECT OF TOPPING AND REMOVAL OF SUCKERS
The appearance of the topped trees at four years after topping i ...........
shown in Figures 3 and 4. The dense mass of foliage is attractive
to the eye. The picking of the crop is greatly facilitated through
the production of the fruit on low branches within easy reach of th
EFFECT OF TOPPING ON YIELD OF COFFEE
The yield of the trees was recorded over a 10-vear period. 1912-
1921, the first record being taken at a little less than two years after
the first pruning. The depressing effect on production exercised by
severe pruning or topping was less evident in the early years of the
test than later. In the three-year period, 1912-1914, both the trees
FIG. 3.-Topped at 6 feet December, 1910, and photographed August, 1914
which were held to a single trunk and those which were topped at
6 feet produced each year within 10 per cent of the production of
the unpruned trees. Table 1 shows the average annual production
of coffee cherries per tree as affected by pruning for the period
TA13LE 1.-Effet of pruning on yield of coffee cherries per tree 1
iiiAverage prodiiition in Total Average Average prd tion in- Total Avera period 1912-1921
Tretmet o tresprodhe- produc- produc- produ 2
Traten f restion tion tion tion 1
1912 1913 1914 121941111 1915 1916 1917 1918 1919 1920 1921 16191181 Total Average
Liters Liters Liters Liters Liters Liters Liters Liters Liters Liters Liters Liters Liters itlers Liters Liters
Unprunedi ----------------------ii-- 2. 0 2.3i 2. 6 6ii.i9 2.3 4.i6 2. 0 i4.i2 1. 3 4.8 1.2 2.i8 .i20. 9 3.0i 27. 8 2.i8
Untopped, single trunk..--------------- 2. 2 2. 5 2. 7 7. 4 2. 5 3.0O 1. 4 1 1 9 3.1I .54 1. 2 13. 2 1.9 20.60 2. 1
Topped at 6 feet ---------------------- 1. 9 2. 4 2. 4 6.7? 2.2 3 .0 1. 6 1 2. 8 9 3 .0 9 1. 6 13. 8 2.0 20.5 2 .1
Topped at 4 feet ---------------------- 1. 7 1. 9 2. 4 6.0 2 .0 2.0O 1.38 2. 1 5 2. 2 8 1. 2 10.1 1.4& 16.1 1.6 W
YIELD OF PRUNED TREES IN PERCENTAGE OF UNPRUNED TREES
Per cent Per cent Per cent Per centi Per cen Per cent Per cent IPer cent Per cent Per cent Per cent Per cent Per cent
Untopped, single trunk --------------- 110 101, 114 1 107 --------- 65 70 74 69 65 42 43 63 --------- 74 --------
iiiiiiiiiTopped at 6 feetiiiiiiii--------liiii--i 95 104 i2 97iii -- 80 67 il 6i 75 17 l -- 74 -
....... Topped at 4 feet----------------------- 85 83 92 87 ---------iiiiiii 43 65 50 a8 46 67 43i 48 ----- 58
SThe number of trees included for averaging the annual yields varied somewhatfrorm year to year. .The range for each group was as follows: Unpruned trees, 22 to 27; untopped,
single trunk, 25 to 30; topped at 6 feet, 45 to 51; and topped at 4 feet, 39 to 44. Trees which were accidentally broken had to be elimtinated either permanently or until such time as
their condition approximated that of the others in their group. Somne of the trees died and had to be replaced. but no replacertuents under 6 years of age or within 3 years after
iiiiiiiiiiiiii iiii3iiixii iiii: ii~iiii ii! i = ===ii
setting were included.
EFFECT OF TOPPING ON YIELD OF COFFEE
For the three-year period as a unit the production of the trees
which were held to a single trunk and those which were topped at 6
feet differed from that of the unpruned trees by 7 and 3 per cent.
The difference in yield between the trees which were topped at 4 feet,
however, and the unpruned trees was 13 per cent in favor of the
The record of production for the seven following years showed the
depressing effect of heavy pruning to be cumulative. For this period
the trees which were held to a single trunk and those topped at 6 feet
produced only two-thirds as much as the unpruned trees, whereas
those that were topped at 4 feet produced slightly less than half as
FI(. 4.-Foreground, trees topped at 4 feet December, 1910, and photographed
much as the check. For the 10-year period as a whole the trees which
were held to a single trunk and those topped at 6 feet produced only
74 per cent as much as the unpruned trees, and those which were
topped at 4 feet produced only 58 per cent as much. The production
is shown graphically in Figure 5.
Topping coffee trees considerably facilitates collection of the crop
and also contributes to the uniform and well-kept appearance of the
plantation, but these advantages are gained at the expense of yield.
Such minor benefits compensate in only a small degree for the heavy
loss of crop entailed.
The normal production of coffee is largely upon primary laterals.
The tree is constantly producing new upright branches bearing pri-
mary laterals. If th-'
tree is topped AM
2 -- these new uprights 1
suckers are removti n t
altogether, the growi
1 11 IIIof secondary laterals
9/12 /9 /3 /9/ / production is f r o
I them rather than frwi
144 -primary laterals, -wit'
a resultant curtailmtlie
of crop. The develop
ment of new upright.
is essential for a 06
S2 mum crop. Althoiugil
in the test recountiol :
:4' the wholly unpri d.-!I
S trees gave the high e6
production, the inf~ri
/5 */1/6 /9/7 /1/8 ence that no pii
/1\ is advisable shoul4i4i
IN 7AWwrr be made. Ordin.Ci
'roPP4?r er 6 Er suckers are produced
SroerPPo A"r 4 Vf/ZET in such numbers as to.:
make the removal at
some of them ad :-
S2 ,tageous to the bes
development of th
tree. The strongest
M and best-located suck-
II l I ers well distributed !
over the, tree should be!:'
/9/9 /920 /92/ /W4-/92/
left. The removal of
FIG. 5.-Average annual production of coffee cherries te wae s rs
per tree as affected by pruning the weaker suckers ai::i
those which crowd the:il
better ones aids the development of the latter. Each tree presents an ::|'
individual problem, and the number of suckers which should be left::,::
varies with the development and condition of the tree.
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