• -29-. , 
-duets and sprays and the. results showed that these materials, applied 
either as spray or dust, appeared to "be the most satisfactory ones devel- 
oped thus far for the control of this aphid. Adequate spraying or dust- 
ing equipment is essential to aphid control, as is proper material and 
time of treatment. In 1939 the Bureau (2J35) reported that insecticides 
containing rotenone had proved effective 
In 1938 the Bureau (282) published suggestions for the control of 
the pea aphid, prepared "by a committee of entomologists at the annual 
meeting of the American Association of Economic Entomologists at Indian- 
apolis, Ind. , on December 27, 1937. The following recommendations were 
based on observations and data accumulated from experimental work done 
east of the Rocky Mountains: 
Satisfactory control of the pea aphid has been accom- 
plished by several methods. These include, without sugges- 
tion of preference (l) dusting, (2) use of nicotine vaporizer, 
and (3) spraying. Success in the use of any of these methods 
will depend entirely upon adeauate and efficient equipment 
and properly timed, thorough application. (l) Busting with 
derris or cube : Field experiments with derris or cube dust 
mixtures containing talc or other suitable carriers, condi- 
tioned with a liquid spreading and wetting agent, have re- 
sulted in satisfactory control. Such dust should contain 
approximately 1 percent of rotenone. In applying these dusts 
the boom should be completely enclosed and a trailer 25 feet 
or more in length should be used. Dusts should be applied 
at the rate of 35 to ^0 pounds per acre. The speed of the 
machine should not exceed 3 miles per hour or 300 feet per 
minute. Dusting is much less effective when the wind velocity 
exceeds 8 to 10 miles per hour. Spraying is an effective 
method of control, but its economic usefulness is conditioned 
by the nearness of an adequate water supply. On the basis 
of ground derris or cube root containing U percent of rote- 
none, 3 pounds should be used per 100 gallons of water, with 
corresponding dilutions where the content is greater or less 
than U percent of rotenone. A spreading and wetting agent, 
in either liquid or dry form, is necessary. The application 
per acre should be from 125 to 200 gallons. Pressure should 
be from 225 to 300 pounds, and depends on size of disc aper- 
tures, type of nozzle, and pump capacity. An infestation of 
35 aphids per sweep of a standard collecting net, for an aver- 
age of 5 sweeps in different parts of the field, usually 
indicates that treatment should be begun. 
The Bureau in February 1938 distributed a summary of the remarks 
made at the Pea Aphid Conference ( 222 ) at Indianapolis, Ind., in December 
1937. Shropshire of Illinois reported on the efficiency of the numerous 
wetting agents offered for use with derris and cube. Over 50 of these 
combinations and dilutions were tested in replicated plots, and it was 
found that some of the best wetting agents were the poorest for use with 
derris or cube for aphid control on peas. Results of experimental work 
in 1937 tended to verify results obtained in 1936 with both nicotine and 
derris or cube for pea aphid control. They further show that cube is as 
