Golf Course Management

NOV 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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70 GOLF COURSE MANAGEMENT 11.18 Adam Van Dyke, M.S., CPAg Improving seedhead suppression of annual bluegrass, Part 2 Mixing ethephon with some common snow mold fungicides in winter improved annual bluegrass seedhead suppression over traditional spring programs and was safe to cool-season greens. Ethephon is the only seedhead-suppressing plant growth regulator (PGR) currently avail - able to golf turf managers. Recent research in Utah has shown that annual bluegrass (Poa annua L.) seedhead suppression in spring can be improved by making non-traditional ap - plications of ethephon in winter in addition to traditional spring PGR programs — either before snow cover and/or after snow melts (2). As this novel approach was implemented on golf courses in the western United States, ques - tions were raised concerning the best way to incorporate these winter ethephon applications at a time of year when snow mold fungicides are being applied. e pre-snow timing (late November) and post-snow timing (February/ March) evaluated in the previous research (2) can coincide with traditional fungicide appli - cations in northern regions with snow cover. In those trials, winter ethephon applications be - fore snow cover were made separately and a few days to several weeks before fungicides were applied. After snow melted, fungicides were excluded to remove any possible confounding effects on spring seedhead suppression. So, can ethephon be mixed with snow mold fungicides in winter? e Bayer Green Solutions Team promotes the addition of eth - ephon (as Proxy, a Bayer product) with its snow mold fungicide program (1). However, independent results from replicated studies are not widely available to turf managers, so the objective of this research was to evaluate the mixing compatibility, turf safety and efficacy of including Proxy with some common snow mold fungicides used in winter. (Although this research was carried out using Proxy, post- patent products containing ethephon, the ac - tive ingredient in Proxy, are available.) Research Two experiments were conducted simul- taneously from November 2016 through May 2017. One was on a 90% annual blue - grass:10% creeping bentgrass (Agrostis palus- tris Huds.) putting green at Forest Dale Golf Course in Salt Lake City, grown on native push-up soil with sand topdressing applied. e other was on an 80% annual blue - grass/20% creeping bentgrass putting green at Murphy Creek Golf Course in Aurora, Colo., grown on a sand root zone. Turf on both greens was mowed at 0.125 inch (3.18 mm), with small amounts of nitrogen and sand topdressing applied consistently across all treatments in spring. No aerification was done in spring, and no other commercial products were applied during these studies. Treatments Proxy was mixed with some common fun - gicides used to protect turf from snow molds in winter. e fungicides chosen are com - monly used in the region and included either Interface Stressgard (iprodione and trifloxy - strobin, Bayer) + Mirage Stressgard (tebu - conazole, Bayer) or Instrata (chlorothalonil, propiconazole and fludioxonil; Syngenta) at the pre-snow timing, and Mirage or Banner Maxx II (propiconazole, Syngenta) at the post- snow timing. Treatment details including product rates and application timings are listed in Table 1. Pre-snow treatments were applied in late-No - vember 2016, and post-snow treatments were applied in mid-February 2017 — as noted in previous reports of winter ethephon applica - tions in northern U.S. regions (2). Treatments were applied with a backpack sprayer at 40 psi through TeeJet AI11002VS nozzles in 2 gal - lons/1,000 square feet (87 gallons/acre or 81.4 ml/square meter) to 4-foot × 6-foot (1.2-meter × 1.8-meter) plots arranged in a randomized complete block and replicated four times. e winter fungicide + Proxy treatments also received the standard spring seedhead programs used at each golf course and were compared to fungicide-only treatments in Editor's note: This is the second of a two-part series evaluating winter applications of ethephon for improving seedhead suppression of annual bluegrass in spring. In the November 2017 issue of GCM, the author compared results from pre-snow cover and/or post-snow melt applications of ethephon applied before traditional spring programs with results from spring program applications alone.

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