Influence of Application Date on the Efficacy of Insecticides Applied for Control of Japanese Beetle Larvae on a Golf Course Fairway, 1996

The study was conducted on a fairway at Twin Lakes Golf Course in Ontario, Ohio. Insecticides were applied 6 Jun, 16 Jul, and 13 Aug to plots 10 X10 ft arranged in a RCB design with four replications. Granular materials were applied with a shaker jar. Liquid treatments were applied using a CO2 sprayer and Teejet™ XR8006VS nozzles at 29 psi pressure that delivered a volume of 1 gal/1000 ft2. On each application date, the area received approximately 1/4 inch post-treatment irrigation. Site conditions were as follows: irrigated fairway, five year history of grub infestations, level, 60% Kentucky bluegrass and 40% annual bluegrass, no thatch. Environmental conditions at the 6 Jun treatment were as follows: JB — none present; turf—dry, 1 1/4 inch ht; soil — 31.8% moisture, 60°Fat 1 inch and 62°Fat 3 inch; weather—sun and clouds, 62°F, variable 0-15 mph wind. Environmental conditions at the 16 Jul treatment were as follows: JB—adults present; Turf—dry, ¼ inch ht; soil — 25.7% moisture, 68°F at 1 inch and 62°F at 3 inch; weather: cloudy, 72°F, 0-10 mph wind. Environmental conditions at the 13 Aug treatment were as follows: JB —first instars present; turf—dry, ¼ inch ht; soil—22.2% moisture, 70°F at 1 inch and 3 inch; weather—mostly sunny, 75DF, no wind. Evaluation on 1 Oct (116, 76, & 43 DAT) involved counting the number of live larvae in each of six 7 X 7 inch sampling areas per plot. Analysis of variance was done on plot totals and means separated by LSD test at P = 0.05.