-72- 
on June 27-28, July 6, and July 18, under favorable conditions, at rates 
equivalent to 60 gallons per acre, increasing tc 80 gallons for sprays; 
for dusts, 25 to 23 pounds, 30 pounds, and 36 pounds per acre per each suc- 
cessive application in series 1 and 22 pounds and 33 pounds per acre per 
successive application in series 2. Derris dusts gave satisfactory results 
in the field for the control of cabbage trams. A derris-clay dust (0.5 
percent rotenone) applied four times at about 15-day intervals during a 
10-week period of infestation gave as satisfactory results as five or seven 
applications at shorter intervals. A derris-clay dust of 0.5-percent-rote- 
ncne strength gave as satisfactory results as dusts of 1-pcrcent-rotenone 
strength. A dust of 0.33-percent-rotenone strength was not so effective. 
Talc, clay and tobacco dust gave a promise of being satisfactory diluents 
for derris dusts. Hydrated lime apparently affected adversely the toxicity 
of derris dusts. Rotenone sprays did not give so high degree of control as 
dusts, possibly owing to the apparently greater infestation in the sprayed 
section. A rotenone spray of 1:10,000 dilution was as effective as sprays 
of 1:5,000. There was very little difference in the comparative merits of 
the various spreaders used "with rotenone when applied as freshly mixed 
sprays. Proprietary derris products included Hellspra He. 1, Cubor spray, 
Cubor dust, and Derox. 
Huckett (202) in 1S36 reported insectary tests with pyrethrum, derris 
(4,5 percent rotenone and 16 to 18 percent total extractives), and nico- 
tine against the cabbage looper. The results with derris against third 
instars were as follows: .. 
Mortality after 
Spray formula 96 h ours 
P erce nt 
Derris powder 2.5 gm. , skim-milk powder 72,5 
2,5 gm, , water 500 cc. 70,5 
Derris powder 2 gm., skim-milk powder- 61.7 
2,5 gm., water 500 cc. 62,7 
Derris powder 1.25 gm., skim-mil 1 .: powder 56,7 
2,5 gin., water 500 cc, 57,1 
Chocks 0,0 
5.0 
Powdered derris root (4.5 percent rotenono, 15 to 18 percent total 
extractives), at strengths comparable to 4, 3, and 2 poun" : of powder P r ;r 
100 gallons of water, gave higher mortality of imported cabbage worms than 
of cabbage looper larvae. The effectiveness obtained against the cabbage 
looper at the greatest strength of derris was scarcely satisfactory. 
Huckett ( 203 ) in 1938 stated that young larvae of the cabbage looper are 
susceptible to derris powder but that the elder larvae are resistant. 
Huckett and Hervey (204) in 1935 reported that in general the cabb 
looper is more difficult to control than the other on cabbage, 
such as the imported cabbage worm and th nondbac!: mot] -- uso 
of a difference in immunity to the poison, /ences in feeding habits, 
or other factors is not known. Hervey, sgow (] 1955 
recommended a dust containing 0,5 percent of roten 
derris or cube with talc or clay, used at of 20 to 35 pound:- r 
acre. A spray consisting of 4 pounds of derrj s povdor (4 percent rotenone) 
plus 4 pounds of skim-mi] r 100 gallons of water also be used. 
