40 
BULLETIN 1422, U, 
DEPARTMENT OF AGRICULTURE 
growth and many of them show severe die-back. Xone of the area 
has been clean weeded, and practically all the trees hare been planted 
too close except those interplanted with other trees, where inter- 
ference is just as great. The soil here appears not to. be good, so 
there is a combination of unfavorable circumstances. 
At Utinga. outside Para, there is a small plantation which is now 
clean weeded, whatever its past treatment has been. The soil is 
rather sandy, and the appearance of the trees suggests that of trees 
in sandy areas (permatangs) in Sumatra. The age of the trees 
could not be ascertained. Bark measurements were made at three 
different heights from the ground. The average for 36 trees was 
6.4 millimeters at 1 foot from the ground, 6.1 millimeters at 2 feet, 
and 5.9 millimeters at 3 feet. 
Planted trees, most of which were in poor condition, were observed 
at various points along the Braganca Railway. Nearly all of them 
are undersized for their age, and most of them have the bottle-shaped 
trunks characteristic of trees grown in poor soil. On all of them the 
bark is very hard and contains little latex. The best trees seen at 
the experiment station were from Igarape Assu. These were 10 
years old and of nearly normal size. The bark was soft and very 
full of latex. These trees were grown from seeds brought from the 
Acre Territory, and their superiority may be varietal rather than due 
to site and treatment. 
In Table 8 girth measurements are given for trees from a number 
of different plantings at Cocal Grande, near Obidos. This planta- 
tion is the property of Paul Lecointe, who has done experimental 
work on rubber for many years. Most of the trees were planted 
between rows of cacao. The older trees are growing in an alluvial 
loam which is well drained. Most of these are now fine trees, 
though not so large as they should be for their age. The six trees 
grown from seed from the Purus are very superior in their develop- 
ment. 
Table S. — Girth measurements of rubber trees in the lower Amazon region 
Location 
Age 
(years) 
Num- Girth at 
berof Treatment \™% 
x - ee - meters) 
Remarks 
Cocal Grande, near 
fl9 to 20 
21 to 22 
23 to 24 
s 2o to 26 
(?) 
24 
I 11 
( 15 
1 13 to 14 
ll3 to 14 
s 
4 
Planted between rows of cacao 
102 
132 
139 
do 
139 
129 
170.5 
58 
125 
70.2 
93 
166.3 
Obidos. 
3 
6 
14 
3 
30 
18 
3 
. do 
do 
Jungle cleared and planted 
4 bv 4 meters. 
do 
Very poorly developed. 
Cacoal Imperial, 
near Obidos 
Cainama (old trees, 
Planted in cacao, 4 by 4 
meters. 
Planted in cacao, 5 by 8 
meters. 
Do. 
Do. 
Do. 
age doubtful ) . 
The other trees are growing in heavy clay, which is submerged 
from one to two months each year. All of the trees have been 
planted rather close, and in the main they have not had proper care. 
The ones not interplanted with cacao have grown up in grass. Many 
of them are badly affected with leaf disease. They are generally 
