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The derris or cube root powder and the diluent are first poured 
together into the mixer. Approximately 10 to 12 quarts of rounded stones, 
1 to 1-1/2 inches in diameter, are then placed in the mixer to aid in 
the mixing process. The cover of the hopper is clamped on, the mixer is 
placed in operation, and the material is mixed for 5 minutes. After 
this preliminary mixing, the mixture of the conditioner and water is 
atomized into the mixture of derris or cube root powder and talc inside 
the mixer (while the latter continues to roll) through the hole cut for 
this purpose in the center of the cover. The nozzle of the atomizer is 
inserted in this hole and held steadily while the mixer, with its contents, 
continues to revolve. It requires usually about 3 minutes to atomize 
the proper quantity of the conditioner into a 60-pound batch of the dust 
mixture. As soon as this process is completed the hole in the center of 
the cover of the mixer is plugged, and the mixing is continued for a 
period of 25 minutes. At the expiration of this period the mixer is 
thrown over to the emptying position and the dust mixture is dumped onto 
a large-mesh screen which separates the finished material from the stones. 
Although talc has been mentioned specifically as a suitable diluent 
for use in preparing a dust mixture for combating the pea aphid, it should 
be emphasized that there are other available non-alkaline materials, such 
as finely ground clay, diatomaceous earth, infusorial earth, tobacco dust, 
or sulphur, which may be used for this purpose. Hydrated lime, however, 
should not be used as a diluent for derris or cube or other rotenone- 
containing insecticides. 
Brannon (45) in December, 1937, reported that recent experiments 
at the Norfolk, Va. , laboratory, designed to determine the relative 
effectiveness of derris, derris- sulphur, cube, cube-sulphur, pyrethrum- 
sulphur, and sulphur alone, applied as dusts or as sprrys for the control 
of the Mexican bean beetle in association with the green clover worm, 
Plathypena scabra Fab. , infesting snap beans, showed that in general 
the dusts were more effective than sprays for the control of the latter 
insect on beans. The derris and cube dust mixtures contained 0.5 percent 
rotenone, the derris and cube sprays contained 0.015 percent rotenone, 
and the pyre thrum- sulphur dust mixture contained 0.1 percent total 
pyrethrins. Wettable sulphur was used as a spray at the rate of 2 pounds 
to 50 gallons of water. It was also noted that sulphur dust alone gave 
foliage protection against Plathypena scabr a comparable with that obtained 
when sulphur was used in combination with derris, cube, or pyre thrum, and 
that a derris -sulphur dust mixture gave better protection than a derris- 
talc dust mixture. These results indicate that sulphur acts as a repellent 
against P. scabra and that in instances where this pest occurs in 
association with a Mexican bean beetle infestation, sulphur should be used 
as a diluent for derris or cube for the combined control of the two insects. 
Weigel and Nelson (459) in December, 1937, reported that experiments 
performed against Tetranychus telarius L. and Thrips t abaci Lind. on 
greenhouse-grown tomato and cucumber plants, in which four sprays were 
applied at 4-day intervals, gave the following results: A derris spray 
having a rotenone content of 0.0056 percent was as effective as one with 
0.0112 percent rotenone content; the derris sprays used were superior to 
