The effect of the adjuvant, Break-Thru S240, on whorl penetration and efficacy of foliar insecticide applications against Chilo partellus

Abstract

Insecticide sprays registered for the control of maize stem borers are all intended for whorl application. Chemical control of these pests is complicated by their cryptic feeding habit inside plant whorls. The aim of this study was to investigate whether addition of the organosilicone adjuvant, Break-Thru S240, to insecticide sprays would result in improved stem borer control. In one experiment the position of stem borer feeding damage inside plant whorls was quantified to have a standard for comparison and evaluation of the effective distances of downwards movement of spray applications into whorls. The distance of movement of spray applications at five adjuvant rates (50, 100, 200, 400 & 600 ml ha−1) into whorl leaves was determined. A colorant was added to spray applications to facilitate measuring the distances of downwards movement of water into each whorl leaf. A 14% increase in downwards movement of sprays into the target zone was observed with addition of the adjuvant. Efficacy of insecticide sprays for control of C. partellus with and without the adjuvant was evaluated under field conditions. Increased levels of efficacy were observed with addition of the adjuvant but not with all the insecticides.