No 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.

Winter wheat was planted (8 Sep) at a rate of 75 lb per acre in a Lismore silty clay loam soil in 17.5-cm rows using a 10-row International drill near the Northern Grain Insects Research Laboratory, Brookings, SD. The experiment was arranged in CRBD with 4 replications. Treatments were randomly assigned to 1-m2 plots of winter wheat. Individual treatment plots were artificially infested (2 Oct) with laboratory-reared RWA. Pretreatment counts (6 Oct) indicated 25.8 RWA/tiller were present. Foliar rescue applications were carried out (9 Oct) using a hand-held spray boom equipped with 6 TeeJet 8002 nozzles spaced 12 inches apart that delivered 20 gpa at 25 psi while travelling at 3 mph. Miles, Inc. provided the material for seed treatments (Gaucho 480 FS), which was applied 2 wk prior to planting time for comparison with foliar-applied rescue treatments. The 5 DAT (14 Oct) RWA census was performed by randomly selecting 4 tillers from each quadrant and one from the center of each 1-m2 plot. Additionally, a 23 DAT count (1 Nov) was conducted in the same manner to determine residual RWA control. Aphid count data were subjected to SAS’s General Linear Models (GLM) procedure and means were compared using Duncan’s Multiple Range Test

Evaluation of several insecticide against potato leafhopper infesting alfalfa were made at 2 locations in SD, Beresford and Brookings. Plots were 30 ft × 30 ft. All treatments and the untreated check were replicated 4 times in a RCBD. Insecticides were applied in a final spray volume of 20 gal per acre at 35 psi using a hand-held sprayboom consisting of 4, 8002S nozzles on 19 inch centers. Applications were made on 22 Jul at Beresford and 31 Aug at Brookings. Early harvest was made on the day of insecticide application at both locations. Potato leafhopper populations were monitored by taking 10 sweeps per plot with a standard 15 inch diam net prior to application and at 4, 7, 10, and 14 DAT at Beresford. At Brookings, samples were obtained 1 d before and 1, 4, 7, 10 and 14 DAT. Yield was obtained from a 45 ft2 area in the center of each plot 14 DAT for each experiment.

Efficacy trials were conducted at 5 locations (Aurora, Bruce, Cavour, Delmont, and Garretson) in SD. Individual treatment plots consisted of single rows, 12.2 m to 15.2 m in length, and spaced 96.5 cm apart. Experimental design for all studies was a RCB with 4 replications. Granular insecticide formulations were applied with modified Noble metering units mounted on a specially-adapted Kinze 4-row corn planter. Metering units were ground-driven, and all units were calibrated on the planter. Liquid insecticides were applied using CO2-powered delivery systems individually mounted on each row of the planter. Each system was calibrated to deliver 20 gpa. Banded insecticide treatments (granular or liquid) were applied in an 18-cm swath over the open seed furrow (T-band) in front of the furrow-closing wheels, and were incorporated by the wheels and drag chains. Infurrow treatments were placed directly between double-disk furrow openers and into the open seed furrow. Pioneer IR-3751 (100-day) corn seed was planted at a rate of 23,000 kernels per acre at all study locations. Five roots per replication were dug, washed, and rated using the Iowa 1 to 6 scale to measure rootworm larval damage. Root injury ratings were recorded and analyzed using SAS’s General Linear Models procedure, and DMRT was used to compare treatment means.