- 4S - 
gave •" . ults when used ?.lone a J -. 3-1 f to 10! :i s 
water in this el?:berr.r.ent, but e canine re ial cherry grower failed I . 
entirely satisf story control ~f aphids r-hen he - ne treai 
merit during a cool spell, with temperatures ground 60° to 65° F. Thin 
indicated thai dor:-::- .- s t.c centre] cherry :-: -Kit's should be used 
during y/arn weather 1 ■ c ults, a: 5 bhe case ". uch 
insecticides ar for i ontrcl of j e aphids. 
ffyzus persicae (Suls. ), the --re." ; - ■ aphid, spinach aphid, or 
tobacco aphid 
ext : 
pli 
powdo] 
1924 r-clndrc and Sievers ( 188 ) reported that derris used as a fund 
(bumec) was effective. 
DeOhg and JVhite (7G) in 1924 reported that a eommertial derris ex- 
tract diluted 1:500 gave a 50-percent control of the green pea.- . Ld, 
Diluted 1:300 a maximum control of 68 percent was obtained. 
Van der Meer Mohr (196) in 1S27 reported that K, per sicae is a 
serious pest of tobacco in Deli, -Sur.iatra. The seedbeds are infested 
from the adjacent forests, and the Tiling plants in tho field are eitl r 
infested in the same way or by the introduction of infested secdlii 
from tho bods, li the bods stre v ry badly infested the should 
bo destroyed or dipped in derris solution^, experiments having shown that 
this does not harp then. In the plantations a da atch should be 
kept for the first traces of infestation. Spraying with a solution of 
derris is advised. The application must be repeate< r 4 to 5 days. 
Deli Froefs'taticn of Medan, Sumatra (69) ir 1929 published 
information or. the use of tuba (derris") root extrac lir.st M, persicae 
on tobacCo, Fulmek in 1922 ■ introduce tuba root on a 
large sc, r combating +-};is insert, Even in excessive 
quantities it did no e tobac i - root extract is 
made as follov r s: The ieces 1 to 2 inches 
lone and mixed with sin times it; :- • sher 
or less tratcr is I I. root is cr I in 20 to 30 minutes 
by vertically running millstones, >roughlj sieved, and i 
residue prcssec by a hydraulic . : - - iquid passes 
throu Tiro s is rnixe< - first extract. The liquid 
is 1 ' : ith 0.5 percent of formalin and, when put 
t?ghtly : casks, : y p for seme months. This Ls- 
fectory for the Deli conditions because tho cxtraot is only during 
the planting season and y ithin a short time. This is ; xr the 
cheapest insecticide for the Deli planters. The manufacture is under 
continuous control of tie entomologists c r ' the experiment stati- . 
An aver ' 00 liters of the stock solution is sent ye to 
the tobacco planters. Derris is far superior to nicotine sulfate in 
killing E. pers icae. ' soap does not effect t Lai 
qualities. 
