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LONCHOCARPUS, DERRIS, AND PYRETHRUM CULTIVATION 23 
Pichilingue, Ecuador, have attempted methods of harvesting derris— 
root mechanically, with encouraging results. In these initial studies 
a universal-type tractor mower, equipped with bush guards, canning- 
pea-type vine lifters, and heavy dividers on both inside and outside 
shoes, proved to be a practical device for cutting prostrate derris 
vines prior to removal from the field. For windrowing vines, an un- 
modified side-delivery rake was not entirely satisfactory, since it 
clogged when it could not rip aside those vine runners left uncut by 
the mower. 
A high-speed vertical screw plow drawn by a heavy-duty tractor 
(fiz. 14) was found capable of cutting 12- to 13-inch-deep furrows and 
at the same time was able to throw the embedded derris roots free and 
cut-clean from soil where they could easily be picked up by hand. 
SELECTION OF SUPERIOR VARIETIES 
When derris first became a product of commercial importance, a 
relationship between species and the rotenone content of their roots 
was recognized. Further investigations revealed that certain selec- 
tions within species were superior to others; thus, a considerable num- 
ber of promising clones were segregated. Others are still being estab- 
lished in the hope that roots of even better quality can be grown so as 
to make cultivation of the crop more profitable. 
In 1936, experiments reported by research workers in the Federated 
Malay States (4) indicated that the insecticidal value of derris roots 
depends more upon the genetic qualities of parent plants than upon 
minor differences in soils and growing conditions. Most pioneer work 
in selecting superior derris stocks was undertaken in the Federated 
Malay States and in the Netherlands East Indies. Perhaps the root 
of highest rotenone content now obtained is from certain clones of the 
Changi No. 3 variety of D. elliptica. 
From time to time, strains of derris were introduced by agricultural 
stations in the Tropics of the Western Hemisphere, but it was not 
until Walter Bangham of the Goodyear Rubber Plantations Co. 
brought 13 outstanding selections of Changi No. 3 to Panama, in 1935, 
that research workers in the American Tropics were provided with 
the high-quality foundation stocks which may make derris cultivation 
profitable in that part of the world. These clones, originally obtained 
from Malayan stocks, were grown first in Sumatra and later on the 
Goodyear Pathfinder Estate at Kabasalan, Zamboanga, Philippine 
Islands. From there, propagating material was taken by Bangham 
to the All-Weather Estate near Ciricito, Panama. 
At that time it was planned to use derris as a cover crop on tubber 
plantations that the Goodyear Rubber Plantations Co. was establish- 
ing at All-Weather. In 1939 Atherton Lee, then director of the 
Puerto Rico Experiment Station, visited Panama and learned about 
Bangham’s derris. Arrangements were made to ship propagating 
material to Puerto Rico in 1940. Living material of 9 of the 13 
clones reached Puerto Rico, where subsequent experiments indicated 
that some of the numbers would produce roots containing as much 
as 10 percent rotenone (/3). 
In 1943 the Office of Foreign Agricultural Relations sent the writer 
to the All-Weather Estate, which had subsequently been purchased 
