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dusted at weekly intervals "beginning 3 ^eeks after transplanting, tl 
derris dust and a 50-percent lead arsenate dust each gave effective 
control up to the time Haen hearting began, the untreated plants in 
the control plots being heavily infested. The 2 treatments ^ere coJ| 
tinued during the late stages of growth, ^hile the hearts --"ere form-T 
ing, and in each of 5 tests derris proved more effective than lead 
arsenate on plants approaching maturity. Of a total of 50 cabbages] 
treated, derris gave 47 marketable hearts, lead arsenate 38, and the 
untreated plants 9. 
In field experiments ^here 4 dustings at 7- to 10-day intervals 
were applied to cabbages during their early stages of growth, 1 part 
of finely pondered derris root mixed ^ith 9 parts of talc "-as not 
appreciably less effective than a dust consisting of equal parts of] 
lead arsenate and kaolin. 
Headlee ( 186 ) in 1935 reported effective control on cabbage and c 
flower with, a derris dust containing 0.8 percent of rotenone and 2.8 per- j 
cent of total extractives. This dust consists of 16 parts • of ground derris 
(5 percent rotenone and 18 percent total extractives), 25 parts of sulfur, 
and the balance clay or talc. Fifteen to 18 pounds per acre ^ere required 
when applied without hoods and from 8 to 10 pounds ^hen applied with hoods. 
The South Carolina Agricultural Experiment Station ( 381 ) in 1935 re* 
ported that experiments of the 1934-35 season indicated that a derris pow- 
der and clay dust mixture containing 0.5 percent of rotenone is approxi- 
mately as toxic as, and in some cases superior to, undiluted calcium ar- j 
senate, to paris green and lime (1:9), and to synthetic cryolite and clay 
(1:3). 
TV L, Thomas ( 410 ) in 1935 recommended 1 part of derris containing 
percent of rotenone mixed with 9 parts of finely ground conditioned sulfur 
for the control of this species in Texas. In 1936 Mr. Thomas (411) re- 
ported that in Texas derris-sulfur dust (0. 5 percent rotenone) gave good 
results in control '"hen applied at the rate of 20 to 25 pounds per acre, 
Veitch ( 457 ) in 1935 reported that in Queensland derris ducts in pr- 
liminary trials gave good results, but have not "been so extensively tested 
as derris spray, which is now recommended in place of lead arsenate be- 
cause it gives even better control and leaves no injurious residue. 
Walker and Anderson ( 465 ) in 1935 summarised result s obtained with | 
derris and pyrethrum dusts at the Virginia Truck Experiment Station. In 
1933 a derris dust containing 0.5 percent of rotenone and a pyrethrum dust- 
containing 0.3 percent of pyrethrins gave satisfactory control of the lar- 
vae, while dusts containing 0.25 percent of rotenone and 0.1 percent of 
pyrethrins did not. In 1934, under conditions of very heavy larval infes- 
tation on heading broccoli, it required from 40 to 50 pounds per acre of 
a derris dust containing 0.75 percent of rotenone, applied with a traction 
duster, to control this pest. There did not appear to be very much dif- 
ference between the effectiveness of gypsum, talc, and inert clay, or a 
finely ground tobacco dust when used as carriers for derris for the con- 
trol of cabbage worms. A bentonite carrier did not appear to give as 
