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

Abstract

Annual bluegrass (ABG) (Poa annua L.) is a prolific seed producer in the spring on golf courses that in turn decreases aesthetic quality and trueness of ball roll on coolseason putting greens. Proxy (ethephon) applied twice in the spring after green-up is the current industry standard after the loss of Embark (mefluidide) from the turf and ornamental market. However, plant growth regulators including Proxy have been used for years to help suppress ABG seedheads with inconsistent success. The primary objective of this study was to determine if ABG seedhead suppression is improved by adding a late fall application of Proxy to the two traditional spring applications of plant growth regulators at nine locations with diverse environments. A second objective was to determine the importance of including Primo Maxx (trinexapac-ethyl) in fall and spring applications. Adding a late fall application of Proxy prior to the two spring applications (F+S+S) improved control of ABG seedheads over the traditional two spring applications (S+S), but the magnitude of improvement varied among locations. Abbreviations: ABG, annual bluegrass; AUSCPC, area under seedhead cover progress curve; CBG, creeping bentgrass; DAISA, days after initial spring application; F+S+S, Proxy + Primo Maxx applied once in fall plus twice in spring; GDD, growing degree day; S+S, Proxy + Primo Maxx applied twice in spring. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Plant growth regulator and low‐dose herbicide programs for annual bluegrass seedhead suppression in fairway and athletic‐height turf

“…Ethephon applied alone was more effective at suppressing annual bluegrass seedheads when applied in the winter as well as the spring, compared to spring applications only. This is consistent with previous seedhead suppression research (Askew, 2017; Reicher et al., 2020). Compared to mefluidide, ethephon alone was not as effective at reducing seedhead production.…”

“…An increase in ethephon seedhead suppression efficacy when mixed with trinexapac‐ethyl in our study is consistent with results from Reicher et al. (2020) on creeping bentgrass greens. Our data also suggest that similar improvement may be obtained by mixing prohexadione calcium instead of trinexapac‐ethyl.…”

“…When applied three times, as in these studies, mixing ethephon with trinexapac‐ethyl or prohexadione calcium will increase chemical cost by $135 and $369 ha −1 , respectively. The use of trinexapac‐ethyl with ethephon is supported by previous research conducted on creeping bentgrass greens (Reicher et al., 2020) but combinations of ethephon with prohexadione calcium or ethofumesate are novel.…”

“…Askew (2017), Raudenbush, Elmore, Nangle, and Tuck (2020), and Reicher et al. (2020) found that applications of ethephon during the winter months increase consistency and magnitude of annual bluegrass seedhead suppression.…”

Germinability of annual bluegrass seed during spring in the Eastern United States

“…The increasing number of herbicide resistance cases in ABG makes the use of integrated pest management strategies essential as reliance on herbicides alone may no longer be efficacious. Certain plant growth regulators can function to reduce the development of ABG seedheads (Reicher et al, 2020), but their influence on seedbank or the germinability of ABG seed is as yet unstudied. A nonchemical control strategy is to reduce the weed seedbank in soil by preventing weed seed production (Norsworthy et al, 2012).…”