Control of White Grubs with Insect Growth Regulators (Igr’S) on a Home Lawn, 1990

Three IGR’s and 2 standard insecticides were evaluated for control of white grubs. At treatment time (2 Jul), the grub population consisted of 75% Japanese beetle (all 1st instars) and 25% Phyllophaga sp. (75% 1st instars and 25% 2nd instars). The avg no. grubs in pretreat samples was 32.5/ft2. Experimental plots were arranged in a completely random design and replicated 3 times. Plot size was 10 × 10 ft. Treatments were applied in 2 liters of water with a hand-held sprinkling can and irrigated immediately with 4 liters of water applied with a hose proportioner. Environmental and soil conditions at treatment were as follows: air temperature, 29°C; RH, 51%; soil, moist; soil temperature, 29°C (2 inches); soil pH, 6.0; organic matter, 5.2%; thatch layer 0 to 1/8 inch. Precipitation over the 9 wk posttreatment period was 5.1 inches. Four locations on each plot were sampled using a cup changer (4.25 inches diam).