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.Hutson ( 206) in .1934 reported that pyrethrum and. derris dusts (1 percent 
rotenone) were very efficient ir. the control of -cabbage Worms in Michigan. 
Hutson ( 208 ) in 1936 stated that cabbage worms and many other insects on 
plants from which, residues are difficult to reiove .are readily -controlled 
by derris or pyrethr<um ..sprays or dusts. Derris and pyrethrum work "best 
vjhen finely ground if used as dusts; and when the proper spreader is pres- 
ent, £f used as sprays. Tobacco dust, talc, bentonite, clay, chalk, sul- 
fur, and flour are good nixing materials; soap, emulsified oils, and sul- 
fated alcohols are good spreaders for sprays. A good insecticidal dust 
contains 0.5 to 0,75 percent of rotenone. Applied at the rate of 15 to 25 
pounds per acre the dust will control cabbage worms and most caterpillars. 
Five pounds of ground derris with 1 pound of powdered skim milk or 2 gal- 
lons of ski:?, mill:, or 3 pounds of thoroughly dissolved soap or 3 to 6 ounces 
of one of the sulfated alcohols makes 100 gallons of effective spray. 
Hutson ( 209 ) in 1937 recommended derris dust (0.5 to 0.75 percent rotenone) 
for the control of most caterpillars. 
The New York State Agricultural Experiment Station ( 300 ) in 1935 
reported that derris dusts controlled worms on cabbage and cauliflower on 
Long Island. Dust mixtures containing not less than 0.5 percent rotenone, 
applied at about 14-day intervals, gave satisfactory protection from worms. 
Talc, Georgia clay, and tobacco dust made the most satisfactory diluents. 
Spray mixtures of rotenone were not so effective as derris dusts. 
Stahl (390) in 1934 reported that in all of his derris tests with the 
celery leaf tier the repellent effect of the dust was much less than with 
several species of cabbage worms. The amount of feeding of the cabbage 
worms decreased as the concentration of rotenone in the dust increased 
from 0.1 to 3,0 percent, but there was some feeding in all cages. 
The Wisconsin Agricultural Experiment Station ( 486 ) in 1934 reported 
the results of tests -of rotenone dust against cabbage worms in Wisconsin. 
A 2-percent-rotenone dust proved more effective than any of 13 sprays and 
dusts, arsenical and other, used in comparative trials. Each of the spray 
materials was applied to 20 heads of cabbage in 1 row. Three rows, 50 
heads of cahhagc per row, were used to test each dust. A similar number 
of heads of cabbage were used as checks. Counts were taken 48 hours af-t 
the materials had been applied. The check lot showed 4.4 worms per head. 
All the materials except lead arsenate-hydrated lime dust (1:1) and 2 per- 
cent of rotenone showed an average of 1 worm more per head. The lead 
arsenate-hydrated lime dust showed 0.9, while the 2 percent rotenone dust 
showed 0.6 percent, ^either of these latter sprays discolored the foliage 
or resulted in ether injury, as did several of the other materials triod. 
Further tests wero made to compare the toxicity to insects of the rotenone 
dust with that of the lead arsenate-hydrated lime dust (1:1), and 
cium arsonate-hydrated lime dust (ill). usts were applied to 1-1/2 
acres of cabbage at about 20 pounds per aer . ults clearly showed that 
the rotenono dust was at least as efficient nioal 
dusts. Since tho surfaco of the oabbage loaf 1ms a waxy coating, it . 
necessary to employ stickers such as blood albumon, fish-oil sOc.p, or hj 
drated lime-ferric, oxide, when arsenicals aro used. Such carriers arc not 
needed with prepared rotenone dust. 
