Timing of Insecticide Applications to Control White Grubs, 1996

Two insecticides were applied on three dates coinciding with different stages of Japanese beetle development at the Orchard of Golf Driving Range in West Lafayette, IN. Treatment plots were 10 x 10 ft, arranged in a RCB design, replicated 4 times, with 3 untreated plots in each replicate. Treatments were applied on 27 Jun (pre-egg laying), 2 Aug (egg laying to first instar), and 23 Aug (first to second instar). Merit 0.5G was applied with a homemade salt shaker. RH-0345I01 was applied at 34.5 gpa and 40 psi using a CO2-powered backpack sprayer with 8002 nozzle tips. Irrigation (0.5 in) was applied to plot areas within 30 h after applying treatments. Evaluation was done on 28 Sep by extracting cores from five random locations within each plot using a golf-hole cup cutter (0.90 sq ft.). Soil to a depth of 4 inch, thatch and turfgrass from each core was examined for the presence of live grubs. The average number of live grubs in five subsamples within each plot was used as the dependent variable in the statistical analysis of the data.