Integrated pest management effects on weed populations managed without herbicides in the Pacific Northwest

Abstract

AbstractPesticide usage on public school grounds is a concern in the U.S. Pacific Northwest. Our objective was to determine how variations in primary cultural management practices (mowing, fertilization, and irrigation), in the absence of herbicide applications, can affect turfgrass quality, and weed populations. Three experiments were conducted over three years at the OSU Lewis‐Brown Horticulture Farm in Corvallis, OR on a mixed stand of cool‐season turfgrass. Findings from the mowing study show that the 10.0 cm weekly mowing height resulted in significantly fewer weeds than plots maintained at 5.0 cm. Results from the fertility study indicate that fertilization, at 4.9 and 9.8 g N m–2 yr–1, reduced weed populations as compared to non‐fertilized plots. No differences in weed incidence was observed between treatments in the irrigation trial, but plots receiving irrigation weekly (0.6 cm applied four times per week and 80% ETref replacement applied four times per week) maintained acceptable turf quality throughout the trial.