-49- 
rotenone dust, and a 0.25 peroent rotenone-1 peroent IDT dust on dupli- 
cate half-acre plots. Applications were made with a motorized duster, 
with a 25-foot dusting curtain, at the rate of 45-50 pounds per acre* 
In sprayed plots initial control was about equal between the rotenone 
and DDT sprays but after a week the population on the DDT plot began 
to build up rapidly while the population on the rotenone plots remain- 
ed low. The 3-percent DDT dust was the poorest treatment and the 
rotenone-DDT dust next to the poorest. The other dusts gave excellent 
control. The DDT-sprayed plots gave 90 percent and the DDT-dusted 
plots 70 percent of normal yield based on the rotenone plots.— N. J. 
Agr. Expt. Sta. (275) . 
In laboratory tests in 1943 DDT shov«r a toxicity to the pea aphid 
comparable to that obtained with rotenone dust mixtures. Results of 
field experiments at Madison, Wis., did not substantiate these consist- 
ent laboratory results. For example, in one experiment the application 
of 5-percent DDT dust with a power duster at the rate of 35 pounds per 
aore, followed by heavy rains, resulted in 99 percent control after 7 
days as compared with 88 peroent for a 0»5-percent rotenone dust contain- 
ing 2 peroent of a light mineral oil. In this experiment the average 
yields of shelled peas per aore in five quart er-aore plots were 1,517, 
859, and 495 pounds, for the DDT, the rotenone, and the check treatments* 
In a second experiment, also followed by rains, a 5-peroent DDT dust 
gave less outstanding results than those obtained with several dosages 
and strengths of rotenone dust mixtures. In a third experiment, under 
wet conditions but accompanied by very little precipitation, both the 
5- and 10-peroent strengths of DDT were less effective than a dust con- 
taining 0*75 percent of rotenone and 2 percent of a light mineral oil. 
—White (373). 
Field experiments in 1944 indicated that DDT was highly toxic to 
the pea aphid, but for best results the amount would need to be increas- 
ed from 3 percent to 4 or 5 percent.— Wilson (376 ) • 
Careful examination of the ground under hairy vetch at Oregon City, 
Oreg., disclosed that 5-peroent DDT dust had killed insects of several 
species. Pea aphids were present in large numbers on some of the plots, 
but only a few appeared to have been killed by DDT.— Rockwood and Reeher 
(303 ) . ' 
Macro slphum solanlfolii (Ashm.), the potato aphid 
In field experiments tomato plants (7 replications) were sprayed 
five times with tribasic copper sulfate, flour, DDT (4-2-1-100) or 
calolum arsenate, lime (4-8-100) • The applications were made with a 
knapsack sprayer at 10-day intervals starting July 13. Both treatments 
were about equal against the potato aphid. The general appearance and 
vigor of the DDT-treated plots was definitely inferior to that of the 
