Fall Control of Annual White Grubs Using Artificial Infestations, 1987

Plugs of bluegrass turf were cut with a standard 6-inch cup cutter and potted into 6-inch-diam × 6-inch-deep plastic pots on 17 Sep. Larvae of the southern masked chafer, Cyclocephala immaculata, were placed into these pots at the rate of 4/pot. Pots were dampened to ensure survival of turf. Treatments were applied 21 Sep to pots arranged in a randomized complete block design with 3 replications. Pots were placed in a 5- × 5-ft plot with treatments applied to this area. Liquid treatments were applied with an R&D Systems CO2 pistol belt sprayer with Delavan LF-3 nozzles calibrated to deliver 30 gal of dilute spray/acre at 30 psi. Granular treatments were applied with a shaker bottle to apply the product evently over the treatment area. Clay granules were added to granular treatments to a uniform weight of 30 g to ensure even distribution of the products. Approximately 0.5 inches of water was applied with sprinklers to the plots within 2 h of application. Additionally, 0.5 inches was applied 25 Sep; 1 inch of rainfall occurred on 28 Sep. The split-rate trial of DZN AG500 had one-half labeled rate (1.98 lb (AI)/acre) applied on 21 Sep, and again on 28 Sep. As the soil was already wet from the inch of rain fall during the previous 24-h period, only 0.25 inches was applied to the DZN split-rate treatments. Data were taken on 24 Sep (72 h), 28 Sep (1 wk), and 5 Oct (2 wk). Sample cores were carefully torn apart, and all grubs recovered from each replicate. The number of living and dead grubs were recorded. The summary % dead figure represents all replicates over all 3 time periods; a total of 36 grubs is used in calculating the summary % dead.