Preventive and Curative Insecticide Applications for Control of White Grubs, 1991

Preventive treatment applications were made on 29 May. Plots were 8 × 8 ft arranged in a completely random design on a golf course fairway; the plot area was later converted to rough. Treatments were replicated 4 times. Granules were applied with a hand shaker. Triumph 4 E was applied in 2 liters of water/plot with a sprinkler can. All treatments were watered in with 2 liters of water (by sprinkler can) about 10 min after application. Environmental conditions at application were: air temperature, 32.5°C; soil temperature, 29°C (2 inches and moist); RH 60%; sky clear. Pretreatment counts of grubs avg 12.2/ft2 (90.6% Japanese beetle and 9.4% black turfgrass ataenius). Curative treatment applications were made on 9 Aug in an area adjacent to the preventive treatment plots. Plot size, experimental design, and application methods were the same as for the preventive trial. Environmental conditions at application were: air temperature, 24°C; soil temperature, 25°C; (1 inch and moist to wet); RH, 86%, overcast. Pretreatment counts of grubs avg 60.9/ft2 (98.4% Japanese beetle and 1.6% black turfgrass ataenius). For both trial areas, thatch was about 1/2 inch thick. As part of the original fairway, the plots were irrigated periodically with the fairway irrigation system. Soil type across the trial areas was loam, consisting of 37.0% sand, 46.9% silt, and 16.1% clay; pH was 5.7 and organic matter 7.7%. Evaluations were made by using a cup changer (4.25 inches diam) to remove 4 plugs (2-3 inches depth) from each plot for larval counts.