A field trial was conducted to assess the efficacy of selectedinsecticides for managing cotton aphid, Aphis gossypii Glover, innonirrigated cotton crop at the Revels Farms near Everetts, NC.The field was planted with ‘Stoneville 5020GLT’ cotton on 5 May2019 at a seeding rate of 50,000 seeds/acre. Individual plots were4 rows by 30 ft long with a 36-inch spacing between row centers.The plots were arranged in an RCB design with 17 treatments includingan untreated check (Table 1), and treatments were replicatedfour times. The plots received insecticide treatments on 18 Jul 2019.Insecticide treatments were carried out using a pressurized backpackand a spray boom, fitted with TeeJet TX-10 cone spray tips spaced36 inches apart delivering 10 GPA carrier volume at 40 psi pressureabove the canopy. Post treatment aphid counts were taken on 22 Jul,25 Jul, and 1 Aug; 4, 7, and 14 DAT, respectively. To estimate thecotton aphid density, the fifth leaf from the plant top were sampledfrom 10 random plants per plot and total aphid counts were noted.To normalize the data distribution, A. gossypii counts from 4 DATwere square-root (x + 1) transformed, and 7 and 14 DAT werelog10(x + 1) transformed before analysis. Data were analyzed usingANOVA (PROC MIXED, SAS v. 9.4), and mean separations werecarried out using Fisher’s LSD (P ≤ 0.05). Untransformed means arepresented (Table 1).
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