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the regular dust in reducing the infestation on entire plants, "but "both 
dusts were equally effective in reducing the infestation in "blossom clus- 
ters. This special derris-talc dust was made "by atomizing into the derris- 
talc, while it was "being mixed, a solution composed of 1 percent of a 
sodium oleyl alcohol sulfate and 2 percent of water. Considering "both 
spraying and dusting tests together, the special derris-talc dust appeared 
slightly "better than the sprays in reducing the infestation on entire 
plants. Dusts and. sprays reduced the infestation in "blossom clusters 
eoually well. These results were referred to "by Roark (2^0 in his re- 
view of the comparative value of derris and cube. 
Bronson and Dudley (28) in 193& reported on conditioning agents 
for increasing the effectiveness of rotenone-bearing dust?- against the 
pea. aphid. They concluded that, in botrh the greenhouse and the field, 
derris- or cube-dust mixtures conditioned with a spreading and wetting 
agent have been shown to be superior, as insecticides against the pea 
aphid, to plain derris- or cube-dust mixtures. Under field conditions 
this superiority of the conditioned dust mixtures has amounted to approx- 
imately 12 percent, which may be the difference between satisfactory and 
unsatisfactory aphid control. In general, conditioned derris- or cube- 
dust mixtures reinforced by the addition of nicotine or an aliphatic thio- 
cyanate have been superior to conditioned dust mixtures. Field data indi- 
cated that derris and cube -were equally effective against the pea aphid. 
Dudley and Bronson (8_5) reported results of experiments against 
the pea aphid in southern Wisconsin in 1938, wherein dust mixtures and 
sprays containing rotenone, as well as nicotine vapor, applied to large- 
scale experimental plots, indicated that all these insecticides resulted 
in an increase in yield, as compared with the untreated check plots, and 
that, owing to the conditions of pea aphid infestation existing that year, 
there were no outstanding differences between these treatments. From the 
19^8 work against the -oea anhid they concluded that, even with excellent 
growing conditions and a light aphid infestation, an adequate financial 
return was obtained by treating the peas with the above-named insecticides. 
Dudley and Bronson also reported ( 222 ) that in a large replicated- 
plot experiment satisfactory aphid control was obtained by treatment with 
derris spray, derris-dust mixture, and nicotine vapor, but not with nico- 
tine dust. The largest increase in the yield of shelled peas resulted 
from the derris-dust treatments, with the nicotine-vapor treatment second, 
and the derris-spray treatment third. The plots treated with nicotine 
dust yielded less than the checks. Derris spray was used at a rotenone 
concentration of 0.01 percent plus sodium oleyl sulfate and in some cases 
also 1 percent aliphatic thiocyanate. 
In February 1939 Dudley and Bronson (So) reported that an analysis 
of the wind velocities at the experimental plots at Waunakee, Wis., during 
the 2 , -'-hour period of each day during June for the 3 years 193^-3^ showed 
that on an average during this period, when dusting operations against 
the pea aphid are usually performed in Wisconsin, there was a total of 
6? hours of daylight when the wind velocities ranged from to U miles 
per hour, as compared with a total of 223 nocturnal hours when the wind 
was in the same velocity range. It is within this velocity range that 
dusting operations against the pea aphid can be most effectively performed 
irifunmm— tsamm 
