Biorational Insecticides for Control of Annual White Grubs on a Golf Course Fairway, 1996

Abstract

Abstract This study was conducted in Lincoln, NE on a golf course fairway. The turf (20% Kentucky bluegrass and 80% perennial rye) was maintained at a mowing height of ⅝ inches. Thatch accumulation (finger compressed) in the plot area was 0.375 to 0.50 inch. Field conditions at the study site were: soil type, silty clay loam; soil organic matter, 4%; soil pH, 6.2; water pH, 7.0. Environmental conditions at the time of application were as follows: soil moisture 21% by wt; air temperature 84°F; soil temperature 80°F; relative humidity 52%; wind direction and velocity 196° at 4 mph. Plots were 40 inches X 15 ft and the experimental design was a RCB with 4 replications. Liquid applications were applied on 13 Aug 1996 using either a Cushman prototype subsurface applicator designed to place liquid insecticide treatments at the soilthatch interface (avg depth 0.5 inch), or a CO2 sprayer with a TeeJet 8002 nozzle at 30 psi and delivering 3 gal/1000 ft2. Granular insecticides were applied using a pre-calibrated Gandy 24H12 drop spreader. Following applications, plots were irrigated with 0.35 inch of water. Post-treatment precipitation totaled 0.07 inch. Treatments were evaluated 27 DAT on 5 SEP by removing from each plot three, 8-inch diam turf-soil cores (1.05 ft2 total area) to a depth of 3 inches and counting the number of surviving grubs. Pretreatment counts indicated 10-20 SMC/ft2 with 32% first instar, and 68% second instars in the test area.