The Effects of Spray Adjuvants on the Insecticidal Activity of Success® (spinosad) on Lettuce and Melons

Abstract

Studies were conducted in the field and laboratory to investigate how the addition of spray adjuvants to Success affected its insecticidal activity against leafminers, thrips and lepidopterous larvae. Studies were also designed to evaluate the knockdown and residual mortality of Success against worms when applied with a buffer to produce an acidic spray solution. Results indicated that Success applied without an adjuvant appeared to provide the most consistent adult mortality of Liriomyza leafminers. In contrast, the addition of a penetrating surfactant (crop oil concentrate) resulted in significantly greater larval mortality consistent with the leafminer feeding behavior. Efficacy of Success against lepidopterous larvae and western flower thrips was not improved using a spray surfactant. However, addition of buffering agents to Success spray solutions significantly affected efficacy against beet armyworm and cabbage looper. Lab bioassays and field studies showed that knockdown mortality was not affected, but residual efficacy was significantly reduced when Success was applied in an acidic (pH 4.2) spray environment.