Speedzone has Potential for Postemergence Goosegrass Control in Perennial Ryegrass and Creeping Bentgrass

Goosegrass (Eleusine indica [L.] Gaertn.) is a C4 summer annual distributed throughout the transition zone and can be problematic in sports fields and lawns, but more often is problematic in golf course greens and tees where preemergence (PRE) herbicides are rarely used because of frequent reseeding in-season. The postemergence (POST) herbicides monosodium methanearsonate (MSMA), fenoxaprop-ethyl, or sulfentrazone are commonly used to control goosegrass on golf courses. However, MSMA has recently lost most of its labeled uses (EPA, 2013), while fenoxaprop-ethyl is restricted from use at mowing heights less than 0.25 inch (Anonymous, 2005) and sulfentrazone is restricted from use on golf course greens or tees (Anonymous, 2012). In July 2011, control of goosegrass was reported when Speedzone was applied to golf course tees to control summer annual broadleaves in Omaha, NE (J. Calentine, personal communication, 2011). This was further reported anecdotally at multiple sites in Nebraska later that summer. Therefore, we began our studies in 2012 with the objectives of confirming if Speedzone has potential for goosegrass control and if so, what application rates and intervals are most effective while still safe on cool-season turfgrasses. The experiment was conducted in 2012 and 2013 at the John Seaton Anderson Turf Research Facility near Mead, NE. In October of 2011, sand-based thinly cut sod of Kentucky bluegrass (Poa pratensis) and perennial ryegrass (Lolium perenne) from a tee on a local goosegrass-infested golf course was moved to the experimental site, distributed evenly and tilled into the top inch of soil. Soil type on the experimental area was Tomek silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) with pH 6.9 and 2.7% organic matter. A perennial ryegrass blend was seeded at 3 lbs/1000 sq ft in April 2012 to establish a thin turf cover. Following establishment, the area was irrigated to prevent water stress, mowed at 0.625 inch, and not fertilized to minimize turf competition with goosegrass. Before goosegrass germination and initiating treatments, glyphosate was applied Published in Applied Turfgrass Science DOI 10.2134/ATS-2014-0025-BR © 2014 American Society of Agronomy and Crop Science Society of America 5585 Guilford Rd., Madison, WI 53711