Long-Term Efficacy of Annual Bluegrass Control Strategies on Golf Course Putting Greens

Abstract

Aerification of golf course putting greens in the summer rather than in the early fall does not decrease annual bluegrass cover.• Monthly applications of iron sulfate were ineffective at reducing annual bluegrass.• Methiozolin, paclobutrazol, or bispyribac-sodium provided the greatest reduction of annual bluegrass when used over multiple years. AbstractAnnual bluegrass (Poa annua L.; ABG) is among the most common weeds of highly maintained turf in the United States. Though many labeled active ingredients exist for control in golf course fairways, few labeled options exist for putting greens. Further, ABG has demonstrated resistance to several herbicide modes of action commonly used on fairway turf. The use of a systems approach coupling cultural and chemical controls with diverse modes of action could limit the potential for further ABG resistance development. Our objective was to evaluate a systems approach to ABG control on putting greens by examining seven season-long programs of plant growth regulators, herbicides, and/or iron sulfate fertilizer with July or September hollow tine aerification over 2 or 4 years in three Midwestern US states. Aerification timing did not influence annual bluegrass cover at any of the three locations. The effectiveness of season-long treatments varied by location, but methiozolin, paclobutrazol, or bispyribac-sodium consistently reduced ABG. Monthly applications of iron sulfate alone did not effectively control ABG. Several treatments reduced ABG, but none completely removed annual bluegrass. Currently, methiozolin and bispyribac-sodium are not registered for use on putting greens in the US but show potential to control ABG. As such, paclobutrazol was the most effective product of those tested that is currently available for use on US putting greens. Future availability of herbicides such as methiozolin and bispyribac-sodium would provide needed options to allow for the rotation or addition of multiple-control strategies in an ABG control system to limit resistance development.

Annual bluegrass weevil, paclobutrazol, and overseeding for annual bluegrass control in cool‐season turfgrass

“…Previous field studies have shown that 1 yr of similar paclobutrazol regimen eliminated 85% of annual bluegrass on creeping bentgrass fairways (Woosley et al, 2003). The efficacy of sequential paclobutrazol applications for annual bluegrass control is also demonstrated on putting greens through the work of Patton et al (2019) and Reicher and Sousek (2017). In our research, effects of paclobutrazol were less dramatic at Forest Hill than at Hort Farm 2.…”

Adding a late fall application of Proxy (ethephon) before two traditional spring applications improves seedhead control of annual bluegrass

“…This is somewhat expected because vernalization and photoperiod requirements to initiate ABG flowering are variable across populations and thus are expected to differ across locations (Johnson & White, 1997a, 1997b). The differing level of response to Proxy applications is also not unexpected given the differential responses to herbicides and the growth regulator Trimmit (paclobutrazol) at different locations (Patton et al., 2019; Reicher et al., 2015).…”

Suppression of Annual Bluegrass in Creeping Bentgrass Putting Greens Using Plant Growth Regulators

“…The efficacy of these active ingredients in regard to annual bluegrass suppression has been previously reported Murphy, 1995, 1996;McCullough et al, 2013;Woosley et al, 2003). However, it has been reported that their efficacy is highly dependent on the environment/location, application rates, and timing (Patton et al, 2019;Reicher et al, 2015). Moreover, the need for the use of long-term sequential application programs was emphasized because reinvasion might occur when treatments cease.…”

“…Annual bluegrass control in putting greens is currently managed through a combination of proper cultural practices and chemical applications (Flessner et al, 2013;Xiong et al, 2015). Cultural management practices reported to reduce annual bluegrass intrusion in creeping bentgrass putting greens include planting creeping bentgrass cultivars with increased density, clipping removal during annual bluegrass seedhead production, interseeding creeping bentgrass, shade reduction, nitrogen (N) and phosphorus (P) fertilization reduction, top-dressing, drainage improvement, soil moisture reduction, aeration, and thatch control (Baldwin, 1993;Baldwin and Brede, 2011;Gaussoin and Branham, 1989;Patton et al, 2019;Raley et al, 2013;Rossi, 2001). Despite best management practices, annual bluegrass often reinvades or persists due to an exhaustive seed bank in the soil (Adams, 1989;Baldwin, 1993;Rossi, 2001).…”