Rescue Insecticide Applications for Management of Pale Western Cutworms in Winter Wheat, 1995

Abstract

An established winter wheat field near Bruce, SD, was chosen to evaluate the performance of foliar-applied insecticide treatments in plots artificially infested with PWCW larvae. The field had been planted on 15 Sep at a rate of 1.2 million seeds/acre using 17.8-cm row spacing. Each treatment plot consisted of a 1 m2 section (5 1-m long rows) of winter wheat enclosed within a metal barrier. Barriers were constructed of 30.5-cm wide strips of galvanized steel flashing material that were folded to form a square, then driven 20.3 cm below the soil to prevent emigration of larvae from treatment plots. Infestation took place on 6 and 17 May with a total of 18 laboratory-reared PWCW larvae being placed into each plot. The study involved a performance comparison of 16 insecticide treatments combinations and an untreated check. Treatments were arranged in a CRD and replicated 4 times. Insecticide applications were carried out (24 May) using a CO2-propelled backpack canister sprayer system equipped with TeeJet 8003 flat fan nozzles delivering 20 gpa. Live cutworm counts (to determine insecticide efficacy) began at 21 DAT (14 Jun) and continued through 11 Jul. Sampling of an individual plot consisted of extracting all soil within the metal barrier to a depth of ca. 20 cm and sifting it through 0.6-cm mesh hardware cloth to retrieve all live larvae. Data were analyzed via SAS’s General Linear Models (GLM) procedure and means were compared using DMRT.