-108- 
Y, r . J. Reid ( 344 ) in 1934 reported that at Charleston, S. C, 
derris-root powder continued to prove toxic to the species of cabbage 
worms present, including common cabbage worms, ^he degree of control 
obtained with derris powder was- proportionate to the strength of materi- 
al used* Best results followed the use of a mixture containing 1.5 per- 
cent of rotenone. An increase in this concentration to 3*4 percent in 
1933 did not apparently increase the kill. A mixture containing only 
0.1 percent of rojfc-ononc showed some toxicity* 
Swingle ( 397 ) in 1934 compared the action of derris and pyrethrum* 
Films of gelatine were impregnated with derris or pyrethrum by adding 
0.7 percent of the powder to a 10-percent solution of gelatin and were 
dried at room temperature on a piece of tinned sheet metal. Cabbage- 
leaf sandwiches were made with 7/8-inch circular discs of this impreg- 
nated gelatin and tests were made with full-grov/n cabbage worms. Derris 
under these conditions acts as a powerful stomach poison but has. no con- 
tact action on larvae allowed to crawl over the derris-^elatin film. 
Pyrethrum, on the other hand, has no effect as a stomach poison but is 
a potent contact poison. (Also reported by the United States Department 
of Agriculture, Bureau of Entomology ai d Plant ku^rantinc ( 44l ) in 1935.) 
R. E. Campbell (63) in 1935 reported that in laboratory tests cube 
dusts have been slightly nore toxic than h^ve derris dusts with an equiva- 
lent rotenone content. Talc was used as a diluent in each case, and 
applications were made with a precision duster at r dosage of 1 gm. per 
plant. Mr. Campbell, in a typewritten report to the Division of Truck 
Crop and Garden Insect Investigations, of the Bureau of Entomology & 
Plant Quarantine, stated that he made field tests at San Fernando, 
Calif., in March 1934 with derris and cube dusts containing 0.5 percent 
of rotenone on cabbage. Applications were made by means of hand dust- 
ers at the rate of 22 pounds per acre for derris 1 and 50 pounds per acre 
for cube* Derris destroyed 54 percent, as compared with 47*7 percent 
for cube* 
Headlee (l86_) in 1935 reported effective control on cabbage and 
cauliflower v/ith a derris dust containing o 8 percent of rotenone 
and 2*8 percent 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. From 15 to 18 pounds 
per a6re were required when applied without hoods and from 8 to 10 
pounds v/ith hoods * 
Hervey, Huckett, and Glasgow ( 189 ) in 1935 recommended a dust con- 
taining 0,5 percent of rotenone, made by diluting derris or ( Lth 
talc or clay, used rt the rate of 20 to 35 pounds per acre. A spray 
of 4 pounds of derris powder (4 percent rotenone) plus 4 pounds of sk ■ - 
milk powder per 100 gallons of water may also bi used* M.uckett and 
Hervey (204) reported in 1935 that dusts containinr 0«5 percent of re - 
none were effective* 
