Systemic toxicity and field efficacy of imidacloprid, pymetrozine, and triazamate against Myzus persicae (Homoptera: Aphididae) on spinach

Spinach, Spinacia oleracea, L., plants infested with green peach aphids, Myzus persicae (Sulzer), were used in laboratory and field studies to determine the systemic activity and field efficacy of three recently developed aphicides. Outer leaves of laboratory test plants were treated with various rates of the compounds. Aphid mortality was recorded for treated outer leaves and nontreated inner leaves to determine translaminar and systemic efficacies, respectively. Concentrations equivalent to suggested rates of triazamate, through systemic movement in the plant, were sufficient to control greater than or equal to 90% of aphids on nontreated leaves. Imidacloprid also produced a level of aphid control through systemic activity; however, the suggested rate was not as effective against aphids on nontreated leaves as that of triazamate. Mortality from pymetrozine was erratic on both treated and nontreated plant parts. In the field study, imidacloprid and a high rate of triazamate were more effective than other treatments. A low rate of triazamate typically was not different from pymetrozine. All aphicide treatments included in the field study resulted in fewer aphids than in nontreated control plots.