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applied 6 or 8 days before blooming, a later application is likely tr "bo 
necessary. One year of experiments with rotenone (cube) dusting- showed 
it to be inferior to rotenone sprays. In general, dusting was less ef- 
fective than spraying. 
Howard and Mason (155) i n 1937 summarized information on the use 
of derris and cube sprays and dusts-. It nay be necessary to use a dust 
containing 1 percent of rotenone in the control of the pea aphid. A 
spray containing 3 pounds of derris or cube powder (U percent rotenone) 
is effective. A wetting agent is necessary. 
Knowlton and Soronson ■ U~ l ) in April 1937 recommended derris or 
cute (U percent rotenone) at 3 pounds per 100 gallons of water applied 
at a pressure of at least J>00 pound? for the control of the pea aphid in 
Utah. To be most effective such a spray should be applied or. a ouiet, 
warm day and before the pea aphid cause?, noticeable injury tc the plants. 
• The Maine Agricultural Experiment Station (1^0) in 1^37 discussed 
the use of rotenone against pea aphids in that State. Reference was 
made to the use of highly concentrated' rotenone or of nicotine in a. 
liouid base f the base often being a light, highly refined oil, and to 
their distribution from airplanes. Preliminary experiments with hand 
apparatus strongly indicated that an effective wetter and spreader is 
necessary for satisfactory cortrol. The percentage of rotenone, the 
fineness of materials, the presence of an effective adhesive wetter. or .' 
spreader, thoroughness of apnlica.tioa, proper timing of application of 
the insecticide in relation to the presence of aphids on the peas, and 
weather conditions all may influence the effectiveness of the dust or 
spray. Observations in Main* during the last 3 years have led to the 
conclusion that the stage of growth of the pea. T ~ines is an important con- 
sideration in timing the sprays. If aphids are present when the pe-^s are 
in bloom they are a potential threat to the -crop. Rotenone applied then 
will remain effective for about a week, and under Maine conditions a sec- 
ond application is rar ly necessary. 
-:. Agricultural Experiment Station ( 217 ) in 1° 7 7 reported 
that preli Lnary observations indicate the rot- : _ one- b paring sprays to be 
of value ir com! ti - the pea aphid. Tr. ■ nicotine sulfate, soap is also 
of value but its effects do not appear tc last as long as these of the 
roter.one-b; aring sprays. Various new spreading' and wetting agents were 
also used. 
" l.^er (2°:) in 1-17 reported that 1/2 pound of Ultravet added to 
3 pound? of cube (4 percent rotenone a'nd 1- percent total Extractives) 
in 100 gallons of water increased the control of the nee aphid from 93 • 5 
to 9S.7 percent, and 1 pound of Ultrawet plus 7 pounds of cut'" gave a 
control 0"^ 98.8 percent. 
Cra.ufurd-?enscn (3 7 ) in l c 7? reported that o ?. aphids were reared 
in a greenhouse under standard conditions and used for the laboratory 
testing of liquid contact insecticides, especially derris preparations:. 
The result?- of trials or. en" cne lay were comparable and indicated the 
comparative toxicities of the insecticides tested, but when the same 
insecticide was tested on different "".ays the results were incoordinate. 
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