Impact of Insecticide Seed Treatments and Foliar Insecticides on Aphid Infestations in Wheat, Incidence of Barley Yellow Dwarf, and Yield in West Tennessee.

Several species of aphids (Hemiptera: Aphididae) infesting wheat may reduce yield by the transmission of barley yellow dwarf (BYD). Neonicotinoid seed treatments and foliar application of insecticides are two common methods to control aphid infestations and reduce BYD. An analysis was carried out across 33 insecticide efficacy tests performed in west Tennessee during the last 11 yr to determine how insecticide seed treatments and/or a late-winter foliar insecticide application affected aphid populations, incidence of BYD, and yield. A significant decrease in springtime aphid populations and incidence of BYD was observed when using a seed treatment, a foliar insecticide application, or both. Average wheat yields were increased by 280-381 kg/ha (5.3-7.2%) if an insecticide seed treatment was used or when a foliar insecticide application was made. Compared with insecticide seed treatments, average springtime aphid populations and the incidence of BYD were lower when a foliar insecticide was applied. A foliar insecticide application made in addition to insecticide seed treatments increased yield by an average of 196 kg/ha (3.4%). The yield increases over the nontreated control suggest that wheat growers in west Tennessee can use insecticides to manage aphids and prevent transmission of BYD. Consideration of environmental conditions, whether or not insecticide seed treatments were used, and scouting can be used to help make decisions on when or if to apply foliar insecticides.