Evaluating the Application Timing and Efficacy of Bifenthrin for Managing Brown Stink Bug in Corn, 2018

The objective of this study was to assess the insecticidal efficacy of bifenthrin applications on managing brown stink bug, Euschistus servus (Say), at various stink bug susceptible corn growth stages. This experiment was conducted at a grower’s corn field near Four Oaks, NC (35.3745, −78.3598). ‘DeKalb DKC67-44’ (Monsanto Company, St. Louis, MO) corn was planted on 20 Apr 2018 at a seeding rate of 28,000 seeds/acre. Experimental plots were arranged in an RCB design with five treatments including an untreated check and treatments were replicated 4 times. Individual plots were 8 rows by 200 ft long, with a 30-inch spacing between rows. Insecticide treatments were applied to the treated plots by using a New Holland TC-35 tractor with a 3-point hitch offset plot sprayer mounted with a 10-ft spray boom and fitted with TeeJet TX-26 spray tips spaced 20 inches apart delivering 20 gpa carrier volume at 30 psi pressure. Sniper 2 EC (bifenthrin, 6.4 fl oz/acre) was the only insecticide applied during the trial. Treatment included: 1) Bifenthrin application at the V6 corn growth stage; 2) Bifenthrin application at the V17 corn growth stage; 3) Bifenthrin application at the R1 corn growth stage; 4) Bifenthrin applications at the V6, V17, and R1 corn growth stages; and 5) Untreated check. Insecticide application dates and the corresponding dates of observations are listed in Table 1. Post-treatment E. servus adults count was taken from four random subsamples within each plot and each subsample consisted of brown stink bug adult counts from 20 consecutive plants. The observations were taken from the middle six rows of a plot. All the above ground vegetation of corn plant was inspected for E. servus. Before analysis, E. servus counts from the subsamples with in a plot (n = 4) were averaged and expressed as a number of E. servus adults/20 plants. Data were analyzed using ANOVA (PROC MIXED, SAS v. 9.4), and mean separation was carried out using Tukey–Kramer (P ≤ 0.05).

The population pressure of E. servus adults in the untreated check was below the economic threshold throughout the trial period. The application of bifenthrin on the 24 May, to early vegetative stage (V6) corn, did not significantly lower the E. servus adult numbers in the treated plots (treatments 1 and 4) at 2 DAT, compared with untreated check (Table 2). However, the bifenthrin application during pretasseling corn growth stage (V17; treatments 2 and 4) on 12 Jun significantly lowered E. servus numbers at 3 DAT, compared with the untreated check. Similarly, the bifenthrin application during the silking (R1) corn growth stage (treatments 3 and 4) on 25 Jun significantly reduced the stink bug numbers compared with the untreated check. Moreover, during the last set of observations on 29 Jun, plots that received bifenthrin treatment—even at V17 corn growth stage—continued to have a significantly fewer E. servus than the untreated check (17 DAT).

This research is supported in part by industry gifts of products and funding. We thank Dan Mott, Ricky and Danny Joyner for their cooperation, and Nutrien Ag Solutions for industry support