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last days of April, v:hen most of the leaves vera about l/2 inch out. 
Subsequent observations disclosed that approximately 90 to 95 percent 
of the hatched aphJ.ds (Siphocoryno a venae) were deed on this block 
within 48 hours after spray app] i cation. — Ginsburg and Granett (124_) 
in 1935. 
[According to P. W. Mason, the aphids referred to in the two 
preceding paragraphs probably are R. prunif olia c. 1 
Rhopalosiphum pseu dobras s?. c ae (Davis), the turnip aphid; false cabbage 
aphid, Indian mustard aphid, or 
turnip louse 
Hclndoo, Sievers and Abbott (18&.) in 1919 killed 100 percent of 
this species in laboratory tests with derris dust. 
Darley (62) in 1931 found that in tests in the field, rotenone at 
a concentration of 1:100,000 as a contact poison in spray form compared 
favorably in toxicity with nicotine at 1:10,000 and pyrethrins at 1:74,800. 
Penetrol at the same concentration ( 1:200 ) was used in each spray. 
Rotenone at 1:100,000 killed 98.5 percent of these aphids in 43 hours. 
Little (183) in 1931 reported that field experiments on this species 
with the powdered root of [Cracca] Tep hrosia virgi n! ana showed that the 
plant has considerable promise as a contact spray. At 1:400 in water a 
spray of the powdered root of T. virginiana killed 93 percent of the tur- 
nip aphids. 
Turner ( 271 ) in 1932 reported that rotenone dissolved in oil- 
soluble sulfonate and applied at the rate of 1 part in 40,000 gave 
excellent control of' (Aphis) Rhopalosiphu m pse udobrassi cae on radishes 
in greenhouses. At the rates of 1:50,000 and 1:60,000 the results were 
not so satisfactory. 
In November 1933 Alien (5) reported that at Eaton Rouge, La., 
rotenone, in addition to killing the turnip aphid, protected the turnip 
plants for several days from attack by chewing insects, Derris dust 
diluted with tobacco dust of "-grade to 0.5 percent rotenone content, and 
derris dust diluted with sulfur dust to 0.5 percent rotenone content, 
protected plants from leaf-eating species from G to 8 day- 
a. 
Foliafume (a pyre thrum-dor ris spray with spreads r) at 1:400 killed 
88 percent.— Penick and Company ( 225 ) rn 1936.. 
Allen (6) in October 1S34 reported that a dust containing 1 percent 
of rotenone rave promising results for the control of the turnip aohid on 
turnips and mustard. Equa] parts of finely ground tola. ceo dust and 300- 
mesh dusting sulfur were used as a diluent. Ts.c author stated that the 
^.erris-root-dus t mixture should be thoroughly applied in such a manner 
that a light coating of it reaches the undersides of the leaves. It may 
be applied to wet or dry plants preferably in late afternoon. Good 
results have been obtained by making applications immediately after rains. 
