- 39 - 
sodium sulfonate and sodium olcyl sulfate vrere used as wetting agents. 
For the control of^ the pea aphid, canners now have 'a choice of two 
effective insecticides — nicotine in a gas form and rotenone in either 
wet sprays or dusts. Nicotine as nor/ used gives, excellent commercial 
control under proper conditions/, and rotenone materials also are r;ood 
if carefully applied. Any insecticide containing at least 1 percent 
of rotenone will probably be effective, applied either as a spray or a 
dust, and all the 1 percent rotenone materials tested, as well as the 
nicotine-gas method, reduced pea aphid population by 90 to 95 percent • 
within a day or two in trials conducted by Wilson at Columbus in 1937. 
Field treatments in this and other areas in many instances gave equally 
good control where the insecticides were properly applied. 
The conditions under which rotenone dusts are used may have some 
bearing on the amount needed. About 30 pounds per acre of a dust con- 
taining 1 percent of rotenone is a safe amount under most circumstances. 
As little as 20 pounds was used with good results in trials in 1933, 
but it may be risky to try economizing to this extent, particularly if 
weather conditions are not such as to make the rotenone immediately 
effective. — Wisconsin Agricultural Experiment Station ( 3J?Q ) in May 1939. 
The Wisconsin Agricultural Experiment Station (322) in 1940 reported 
that 2-year trials have indicated that if a properly mixed dust containing 
0.75 to 1 percent of rotenone is stored in a dry warehouse, it will 
usually be about as effective the second year as it is the first. In 
fact, one good commercial dust held over from the 1937 season gave 
excellent results in 1938 and also satisfactory results in 19 39. Three 
others mixed in 1938 proved satisfactory in 1959. Experiments in pea 
aphid control carried out on 57 l/4-acro plots on a farm near Waunakee, 
Dane county, in 1939 brought out especially favorable results with 
derris-dust mixtures. Although aphid infestations were very light at 
this location, derris-dust mixtures appeared to increase yields in 
several cf these tests. Average yield increases in three experiments 
were 612, 555, and 555 pounds per acre, respectively. 
Rotenone ousts cause relatively slight injury to ladybeetles, im- 
portant aphid predators. Only adult beetles were rafther consistently 
injured by rotenone dust, and even the adults often were able to lay 
large numbers of eggs after being dusted. Larvae were seldom. injured 
unless they had just molted at the time the dust ras applied. The eggs 
of lady beetles were uninjured, even when heavily coated with dust. 
Macro si phuia solanifolii (Ashm.), the potato aphid 
Kclndoo and Sievers ( 188) in 1924 reported that cube as a dust and 
as an infusion ras effective, but us^d r.s a cold-r.ater extract with 
soap it had practically no effect. The cold alcoholic extracts of cube 
and derris plus soap were effective, 
Kelsall et al, (169) in 1926 reported the results cf tests with 
derric against the potato aphid in the irisectary. The presence of 
moisture had a marked effect in increasim: the toxicit ,r of derris. 
