-73- 
Mc Campbell ( 259 ) in 1934 recommended derris dusts for the control 03 
the cabbage looper on cabbage in Colorado. 
The United States Department of Agriculture, Bureau of Entomology ai 
Plant Quarantine, ( 435 ) in 1934 stated that the preferred dust for the cc 
trol of the cabbage loopor on cabbage is derris or other rotenone dusts z 
the preferred spray is pyrethrum-derris extract. [For further discus si 01 
of dusts and sprays, see (435_) under Pi oris rapae (L. ), p, 106 ,] 
TTalker and Anderson ( 464 ) in 1934 reported the folio-wing results of 
tests made in a broccoli field: 
: Rotenone 
: Amount : 
Dust 
: content 
: applied : 
Control 
Percent 
Percent 
Percent 
Derris-talc 
0.5 
55 
70 
Derris-clay 
.25 
32 
68 
Derris-clay 
.5 
42 
79 
Derris-clay 
1.0 
40 
71 
Kubatox 
.4 
37 
65 
Cubor dust 
31 
45 
Sprayrite 
.43 
48 
44 
Pyrethrum-talc dusts containing 0.3 or 0,5 percent of pyrethrins gav 
better control (96 and 95 percent, respectively) than did the derris dust 
Eight different diluents for derris dust were tested, each being mixed wi 
derris powder (4 percent rotenone) in the weight ratio of 1 part of derri 
to 7 parts of the carrier. Talc gave the best control, closely followed 
by gypsum and Inert C (a clay). The large amount of gypsum used was due 
to its greater weight per volume. The newly made lime dust, flour, and 
coarse tobacco dusts ranked intermediate, whereas the old lime and the zii 
sul fate-lime gave the poorest control. Finely ground tobacco dust gave 
almost as good results as did the talc and gypsum. In 1935 the same auth- 
ors ( 465 , 466 ) summarized results obtained with derris and pyre thrum dusts 
at the Virginia Truck Experiment Station, In 19 33 a derris dust contain- 1 
ing 0.5 percent of rotenone and a pyrethrum dust containing 0.3 percent oi 
pyrethrins gave satisfactory control of the cabbage looper and of diamond 
back moth larvae, whereas dust containing 0,25 percent of rotenone and 0.1 
percent of pyrethrins did not give satisfactory control. There was little 
difference between the effectiveness of gypsum, talc, and inert clay, or a 
finely ground tobacco dust when usod as carriers for derris, A bentonite 
carrier was no t/l^tis factory as tho othors. The addition of 5 percont 
by weight of finely ground dusting sulfur soemed to improve the effective- 
ness of a dorris-talc dust. Based on rotenone content, a cube dust did nO 
seem to give so satisfactory control of cannage worms as did a derris dusi 
Walker and Anderson ( 467 ) in 1936 reporting experiments made in 1932-36, 
said that repeated applications of dorris and cube dusts containing ; from 
0.5 to 0.75 percent of rotenone and from 2 to 3 percent of total c xtracti-i 
