Response to Vertical Mowing and Ethofumesate Treatments for Annual Bluegrass Control in Bermudagrass Turf1

Abstract

AbstractAnnual bluegrass (Poa annua L.) is a major weed in bermudagrass (Cynodon spp.) golf greens overseeded with cool‐season grasses. Herbicides are often ineffective or may injure the overseeded grass. This study was initiated to determine the effects of sequential vertical mowing and ethofumesate [( ± )‐2‐ethoxy‐2,3‐dihydro‐3,3‐dimethyl‐ 5‐benzofuranyl methanesulfonate)] treatments on a bermudagrass green. Treatments were arranged as a split plot design with whole plots as vertical mowed treatments in a randomized complete block and subplots as ethofumesate treatments stripped across all whole plots with four replications. One‐half of each whole plot was overseeded with perennial ryegrass (Lolium perenne L.) in each of 2 yr. The bermudagrass was an established 'Tifway' Cynodon transvaalensisBurtt‐Davies ✕ C. dactylon (L.) Pers.] growing on a sandy loam (clayey, kaolinitic thermic Typic Hapludult). Vertical mowed treatments included: none, low (25% leaf removal), and high (60% leaf removal) intensity prior to overseeding and applying ethofumesate. Ethofumesate treatments were made at time of overseeding in October or delayed until bermudagrass was dormant in November. Herbicide treatments were also applied at the same time to nonoverseeded common bermudagrass [Cynodon dactylon (L.) Pers.] infested with annual bluegrass. October vertical mowing reduced bermudagrass quality the following spring. Quality was reduced with increased intensity. Vertical mowing and ethofumesate applied in October reduced quality in April and May more than either treatment alone. Transition from cool‐season to bermudagrass was generally slowest in the high‐intensity vertical mowed turf.