Effect of Date of Application on Efficacy of Entomopathogenic Nematodes Against Annual Bluegrass Weevils, Golf Course Fairway, 1994

Abstract

Abstract Entomopafhogenic nematodes (Steinernema carpocapsae formulated as Exhibit) were applied at a rate of 1 billion nematodes per acre on one of three dates (18 Apr, 2, or 16 May) to plots which were 20 ft wide and 80 ft long. Plots were replicated 4 times in a CRB design. The plots were established on a golf course fairway in Scarborough, NY consisting primarily of annual bluegrass (40%) and creeping bentgrass (60%) maintained at 0.5 inch mowing height. All materials were applied using a Toro boom sprayer set to deliver 50 gal/acre. The entire test area received 0.25 inch irrigation ca. 1 h after application on each date. Conditions at the time of application: 18 Apr—soil temp, 45°F, air temp, 72°F, water temp, 44°F, sunny, light breeze; 2 May—soil temp, 55°F, air temp, 60°F, water temp, 52°F, gusty NW wind (5-20 mph); 16 May— soil temp, 63°F, air temp, 72°F, water temp, 60°F, steady west wind (5-10 mph). Product efficacy was evaluated on 13 Jun by removing 12 cores (1.85 inch diam, 1.5 inch deep) from the left side of each plot and 12 cores from near the center of each plot and inspecting the cores under magnification in the Amherst laboratory. Insect counts were made by combining totals from 3 plugs per recorded observation (4 observations per plot, 20 observations per treatment). At the time of sampling, the population was 20% early instars (lst-3rd), 25% 4th instar, 45% 5th instar, and 10% pupae.