Subsurface and Conventionally Placed Granular and Liquid Insecticides for Control of Annual White Grubs, 1991

Abstract

Abstract This study was conducted on a golf course fairway in Lincoln, NE. The predominant grass species was perennial ryegrass maintained at a mowing height of ys inches. Thatch accumulation (finger compressed) in the plot area was 0.25 to 0.5 inches. Field conditions at the study site were; soil type, silty clay loam; soil organic matter, 3-5%; soil pH, 6.7; water pH, 7.0. Soil moisture was maintained near field capacity throughout the study. Insecticides were applied on 6-7 Aug to 5 x 5ft plots. The experimental design was a randomized complete block design with 4 replications. Subsurface treatments were applied using either a Cushman prototype Subsurface Applicator or a modified Ryan Mataway Overseeder. Both liquid and granular subsurface insecticide applications were placed at the soil-thatch interface (average depth of 0.24 inch). Conventional granular and liquid insecticide applications were applied with a Grandy 30H12 drop spreader or a C02 sprayer using an LF-4 nozzle at 24 psi and delivering 5 gal spray/1000 ft2, respectively. Immediately following applications plots were irrigated with approximately 0.5 inch of water. An additional 1.0 inch of rain fell and the test area was periodically syringed during the post-treatment period. Treatments were evaluated 20 DAT on 26 Aug by removing from each plot six, 8-inch diam turf-soil cores (2.1 ft2 total area) to a depth of 3 inches and counting the no. of surviving grubs.