Insecticide Evaluations for Control of Brown Wheat Mite in Winter Wheat, 2022

Two trials were conducted in 2022 to evaluate efficacy of selected insecticides on brown wheat mite infesting winter wheat. Trial 1 was conducted at the Levi Johnson farm in Alfalfa County near Goltry, OK. ‘Uncharted’ wheat was sown on 20 Oct 2021 in 7-inch rows. Individual plots measured five rows by 20 ft. Treatments were arranged in a RCB with three replications. Insecticides were applied 15 Mar 2022 when wheat growth stage was at Feekes 3.0 using a CO₂-charged handheld sprayer through 8002 flat fan nozzles at 40 psi for a total 22 gpa. Posttreatment counts (7 DAT) were taken on 21 Mar 2022. Samples were collected from a 1.3-ft² area/plot using a Vortis’ vacuum sampler (Burkard Manufacturing Co., Hertfordshire, United Kingdom), holding them in a freezer set at −0°F for 3 d, screening the sample through a series of USA Standard Testing Sieves (No. 16, 20, 40, 60, and 200), and examining the contents.

Trial 2 was conducted at the Jimmy Wayne Kinder farm in Comanche County near Geronimo, OK. ‘Duster’ was sown on 27 Sep 2021 in 7-inch rows and individual plots measured five rows by 20 ft. Treatments were arranged in a RCB with four replications. Insecticides were applied 29 Mar 2022 when wheat growth stage was at Feekes 4.0 using a CO₂-charged handheld sprayer through 8002 flat fan nozzles at 40 psi for a total 22 gpa. Posttreatment counts (9 DAT) were taken on 6 Apr 2022 using two sampling methods. The first sample involved collecting mites from a 0.65-ft² area/plot using a ‘Vortis’ vacuum sampler, holding them in a freezer set at −0°F for 3 d, screening the sample through a series of USA Standard Testing Sieves (No. 16, 20, 40, 60, and 200), and examining the contents. The second sample was obtained from a 1.3-ft² area from each plot by tapping wheat leaves to dislodge living mites onto a 20 × 20 cm gridded sticky card (Trècè Inc., Adair, OK). All sticky trap cards were then covered with clear plastic wrap. Data were analyzed with ANOVA and treatment means separated by with a Fisher’s protected LSD (P ≤ 0.05). No yield was obtained in either trial.

In Trial 1 (Table 1) mite pressure was moderate. Plots received 0.14 inches of precipitation on 17 Mar, and 0.24 inches on 18 Mar. All treatments but Baythroid significantly reduced mite numbers; however, percent control ranged from 46 to 64%. In Trial 2 (Table 2), mite pressure was very high. Plots received 0.32 inches of precipitation on 1 Apr, and 0.43 inches on 4 Apr. Mustang MAXX was not evaluated, in Trial 2, but all other treatments, including Baythroid, reduced mite numbers with percent control ranging from 81 to 88% (Vortis sample) and 85 to 98% (sticky card sample).¹

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