.. -:.r* 
-109- 
il ■ ' ■ • , 
Howard, in a typewritten report to .the . Division "of '.Truck. Crop and 
Garden Insect Investigations in 1935, stated that derris.. root mixed with 
talc, infusorial earth, or tobacco dust so as to contain from.O.S to 0.75 
percent of rotenone, and used at intervals of 7 to 10 days at r dosages of 
25 to 30 pounds per acre per application,, .was very effective, Derris 
dusts were more effective than derris powder in water, but the latter 
was more effective than the derris extract : in water .used as a spray.... 
Cube root, used either as a dust or a spray, gave similar results to derris, 
provided the rotenone content was the same. ...,'• . 
Howard and Davidson (195) in 1935 advised .that derris sprays or dusts 
were the best insecticides for the control of cabbage worms in 0hio o 
Derris or cube dust containing 0.05 to 0,1 percent of rotenone applied at 
the rates of from 20 to 25 pounds per acre, gave good control of the im- 
ported cabbage worm. Three or four applications were necessary in some 
instances. Good results were also obtained by the application of derris- 
or cube-roo't sprays containing 0.01 percent of rotenone. 
Howard, Mason, and Davidson (197) in 1935 reported the same results. 
Ground pyrethrum powder from which the pyrethrins had been extracted 
proved to be a suitable diluent. 
List and Sweetinan ( 255 ) in 1935 reported the results of tests with 
derris, cube, pyrethrum, paris green, cryolite, calcium arsenate, and. 
lead arsenate, applied 'as dusts with- the Root .hand duster, against cab- 
bage worms in Colorado. Dosage varied but did not exceed '10 pounds 'per 
acre. The diluent was Celite FC, a diatOrnaceous earth, 5 percent of which 
is coarser than 150-mesh and 10 percent coarser than 325-moshi All dusts; 
were prepared by mixing in a ball-mill type mixer 15 minutes'. Pyrethrum 
powder containing 0.18 percent of pyrethrins, derri's powder, containing 
0,5 persent of rotenone, and cube powder containing 0.5 percent of rotenone 
vrere equally efficient. In another series, p'yr'thrum powder containing 
0.18 percent of pyrethrins, derris powder containing 0,5 percent of rote- 
none, cube powder containing 0,5 percent of rotenone, and a mixture con- 
taining 12,5 percent of paris green were all of equal value. A-' dust 
6ontaining 0,1 perdent of rotenone was as effective as one containing 
0,4 percent of rotenone. Tests showed no 'significant difference between ' 
dusts, containing 0,5 percent and 0,4 percent of rotenone. No significant 
difference was found between dusts containing 0,3 percent of rotenone and 
0.6 percent of rotenone. Morning and evening applications of a cube dust 
containing 0,5 percent of rotenone were not significantly different. 
The South Carolina Agricultural Experiment Station ( 38l ) in 1935 re- 
ported that a dorris powder-clay-dust mixturo containing 0,5 percent of 
rotenone was a pproximntcly as, toxic, and in somo cases superior to, un- 
diluted calcium arsenate, paris green and limo (li9) and synthetic cryo- 
lite and clay (l:3). 
