Strength of Rotenone Dust Mixtures and Rate of Application in Pea Aphid Control

Abstract

During the progress of research in the control of the pea aphid, Macrosiphum pisi, at Madison, Wis., an investigation was made to determine the proper % of rotenone to be used in a dust mixture and the most desirable quantity of dust to apply per acre, and also whether an increase in one would compensate in effectiveness for a comparable decrease in the other. All materials were applied by means of a power duster to i-acre plots, and each treatment was replicated 5 or 6 times. By varying the rotenone content of dust mixtures from 0.125% to 1.5% and the quantity of dust applied per acre from 20 to 60 lbs., it was possible to arrange the quantity of rotenone applied per acre into 3 categories, viz., 0.075 lb., 0.15 lb. and 0.3 lb. Conclusions:[long dash]When an oil-conditioned rotenone-bearing dust mixture is employed, the quantity of rotenone applied governs, within limits, the resulting mortality of the pea aphid; when as much as 0.3 lb. of rotenone per acre is applied, it makes little difference whether a dust mixture of high rotenone content at a low rate is used or a dust mixture of low rotenone content at a higher rate; a marked decrease in aphid mortality occurs in an oil-conditioned dust mixture when the rotenone content is decreased from 0.375% to 0.25% or lower.