Fall Control of White Grubs with Labelled Insecticides and Entomogenous Nematodes on a Golf Course, Syracuse, Ny, 1986

Six insecticides and 1 species of entomogenous nematode were applied to a fairway at Drumlins Country Club, Syracuse, NY on 21-22 Aug for control of a mixed population of Japanese beetle, and European chafer grubs. The fairway consisted of Kentucky bluegrass (40%), annual bluegrass (45%), bentgrass (10%), and broadleaf weeds (5%). Thatch was minimal (<.25 in.) with plot. The experimental design was RCB with 4 replications. Individual plots were 10 ft by 10 ft. Granular materials were applied with a precalibrated Gandy 2.5 spreader. Liquid materials were premeasured in the laboratory and applied in 2 directions within each plot with 11.4 liters (3 gal) of water through a watering can. At treatment time (21 Aug) the following environmental conditions existed: air temp, 80°F; soil temp (1 inch); 78°F; (3 inch), 75°F; soil pH, 5.64; water pH, 6.78; soil moisture, 23%. The nematodes, HeterorhabdUis heliothidis (Khan, Brooks, and Hirschmann), were applied a day later at a rate of 2000 per inch2 in 11.4 liters of water to the center 4 ft2 of each plot. Following treatment, the plots were irrigated by sprinkler for 10 min. Posttreatment counts were taken 47-48 DAT (8 Oct) by cutting 1 ft by 10 ft strip (2.25 inches deep) lengthwise through each plot with a mechanical sod cutter and examining the sod and underlying soil for grubs. Three 1-ft2 samples of sod were examined in each plot and the no. of surviving grubs were counted. In the nematode-treated plots, separate sets of samples (four 1-ft2 samples) were taken from the center 4 ft2, where nematodes had been applied, and the surrounding 6 ft2. Grub species identifications were made in the field. At this time Japanese beetle grubs were predominantly third instars with some second instars; all European chafer grubs were third instars.