Insecticidal Control of Annual White Grubs Using Artificial Infestations, 1991

Abstract

Abstract Five insecticides were evaluated for SMC grub control using artificial infestations at the University of Nebraska Agricultural Research and Development Center near Mead, NE. Kentucky bluegrass was maintained at a mowing height of 2 inches. Thatch accumulation was 0.75 to 1.0 inch. Turf-soil cores (8 inches in diam by 4 inches deep) were removed on 16 Apr from plots and potted into corresponding 8 inch deep PVC containers. These had been filled to within 4 inches of the top with soil. Container bottoms were covered with aluminum window screen. Containers were placed into the soil with top rims at ground level. The plot area was then irrigated to reestablish plant growth. First and second instar SMC grubs were collected from a nearby untreated turf area on 1 Aug, and ten grubs were introduced into each of two containers in each plot. Grubs which had not burrowed into the turf-soil core after 10 min were replaced. Insecticide treatments were applied on 8 Aug. Field conditions at the time of application were as follows: air temperature, 70°F; soil temperature (4-inch depth), 73°F; soil type, silty clay loam; soil organic matter, 3-5%; soil pH, 6.2-6.6; water pH, 6.7; soil moisture 22%. Granular formulations were applied over containers with a precalibrated Gandy 30H12 spreader. Liquid formulations were applied with a C02 sprayer using an LF-4 nozzle at 24 psi and 5 gal/1000 ft2 spray volume. Experimental design was a randomized complete block with 4 replications. The test area was irrigated with approximately 0.5 inch of water immediately following insecticide applications. An additional 4.5 inches of irrigated water was applied and 0.44 inch of rain fell during the posttreatment period. Product efficacy was evaluated 29 Aug by removing and breaking apart the contents of each container to obtain a grub survival count. Grub counts from the two containers were combined prior to analysis.