-106- 
The United States Department of Agriculture, Bureau of Entomology 
( 435 ) in 1934 issued recommendations for the control of some important 
truck-crop insects. The preferred dust for the control of the common 
cabbage worm on cabbage was derris or other rotenone dusts and the pre- 
ferred spray was pyrethrum-derris extract combined , 
Derris dusts containing 0,5 percent to 1.5 percent rotenone 
have given very promising results in 4 sections of the Eastern and 
Southern States, Satisfactory diluents for the derris root powder 
are finely ground tobacco dust, finely pulverized clay, or talc. 
Clay and talc have the advantage of being more economical in cost 
and nore readily available in s oae sections than tobacco dust. 
Both have the disadvantage of leaving an objectionable whitish de- 
posit on the cabbage when applied near the harvesting period. 
The use of tobacco dust eliminates the apoearance of undesirable 
deposits on the plant and, under favorable climatic conditions, 
may aid in the control of aphids. Derris retains its insecti- 
cidal value longer than does pyrethrum. In 0hio excellent re- 
sults were obtained with commercial dusts containing approximate- 
ly 0,55 percent of rotenone against the cabbage looper and the 
common cabbage worm. Sulfur has been used successfully as a 
diluent on cabbage and squash. Commercial pyrethrum-derris ex- 
tracts in combination have given good results in Ohio, when 
used at twice the strength recommended by the manufacturers* 
A,t the 1934 meeting of the American Association of Economic 
Entomologists, reported by the United States Department of Agri- 
culture, Bureau of Entomology and Plant Quarantine (437) , Ccry 
led a discussion of field results with arsenical substitutes for the 
control of vegetable insects, Roney and Thomas of Texas reported 
that derris-sulfur dust (0,5 percent rotenone) successfully con- 
trolled the imported cabbage worm, W, H, White reported that as a con- 
trol for the imported cabbage worm derris was more effective than pyr - 
thrum, paris green, cryolite, or calcium arsenate, whereas pyrcthrum 
was superior to the last three materials. In general, dusts gave bet- 
ter results than sprays. 
The United States Department of Agriculture, Bureau of Entomoh 
and Plant Quarantine (441) in 1935 reported that i: -plot tests on 
cabbage showed definitely that derris dusts containing from 0.5 to 1*0 
percent of rotenone are effective against the impor go worm* 
Pyrothru. : dusts are less effective* The Bureau ( 442 ) in 1936 r id 
results of various tests with rotenone, dorris, and jube. On cat 1 , 
derris-dust mixtures wore more effective against th 
worm than pyr-:thrum, cryolite, or calcium nr • ' . 
California demonstrated thrt dust mixtures of • , , >r 
ga\-o satisfactory results in the control of tl • common 
species of c- r^.r- on cauliflower. In tory tests 4 round 
root of devil' s-shoostrings was as effect;-'.' 1 gainst the common spec: 
of cabbage worms as derris or cube containing equal percentages of 
activo ingredients. 
