Selected Rates of Conventional and Biorational Insecticides for Early Season Sod Webworm Control, 1997

Abstract

Abstract Insecticides were evaluated for control of sod webworm larvae on a Kentucky bluegrass lawn at the Gering Cemetery, in Scotts Bluff County, Nebraska. The turf (80% Kentucky bluegrass, 20% perennial rye and tall fescue) was maintained at a mowing height of 2.5 inches. Thatch accumulation (finger compressed) in the plot area was 0.5 inches. Field conditions at the study site were: soil type, silt loam; soil organic matter, 2.3%; soil pH, 8.4. Weather conditions at the time of application were as follows: soil moisture 22% by wt; air temperature 71°F; soil temperature 70°F; relative humidity : 27%; wind direction and velocity 108° at 7 mph. Plots were 6 X 10 ft and the experimental design was a RCB with 4 replications. Treatments were applied on 5 May. Liquid insecticides were applied using a CO2 sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 87 gpa finished spray. Following applications, plots were irrigated with 0.25 inches of water. No rain fell during the post-treatment period. Treatments were evaluated 3, 7, and 14 DAT (8, 12, and 19 May) by mixing 0.5 oz Lemon Dawn® per gal of water and applying 2 gal of the dilution to each of two 6 ft sampling areas per plot (12.0 ft2 total area). Larvae that moved to the grass surface after 30 minutes were collected and counted.