Research Report
Effects of Fertility on Putting Green Recovery Following Methiozolin (PoaCure) Applications Virginia Tech Researchers: Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist, and Katelyn A. Venner, Graduate Research Assistant Research Sponsors: Moghu Research Center, Daejeon, South Korea
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aintaining superior putting green quality is an integral part of a golf course superintendent’s job. Unfortunately, many factors, including weed pressure, make it difficult to maintain greens at the level of quality expected by many golfers. Annual bluegrass (Poa annua) is a problematic grassy weed on golf course putting greens due to its light green color, excessive production of seed and need for intensive management during the summer months. Few effective herbicidal controls exist for annual bluegrass on creeping bentgrass putting greens, and even more are used on greens without proper labeling. Fortunately for superintendents, a new herbicide, methiozolin (PoaCure), has demonstrated its ability to completely control annual bluegrass with the utmost safety to creeping bentgrass when applied at appropriate rates. Sometimes, however, methiozolin removes
annual bluegrass more quickly than desired, resulting in a voided turfgrass canopy. Previous research performed in 2012 at Virginia Tech determined that methiozolin rate does not affect turfgrass recovery. Another experiment performed at the Blacksburg Country Club resulted in rapid annual bluegrass loss following an aeration event. These earlier trials helped steer a series of small trials in 2013 to investigate the effects of fertility from foliar fertilizer alone or in conjunction with a Primo growth regulator program or from a biostimulant program on the lateral recovery of creeping bentgrass turf following canopy voids. Canopy loss in these studies was caused by rapid loss of annual bluegrass cover due to high-rate PoaCure treatments on mixed annual bluegrass and creeping bentgrass greens and from an intensive aeration event on predominately creeping bentgrass greens.
Trial 2. April 20, 2013
16 | Virginia Turfgrass Journal May/June 2014 www.vaturf.org
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Two trials were initiated on March 22, 2012. Trial 1 was conducted at the Virginia Tech Golf Course and replicated on two separate, push-up-style practice greens maintained at 0.13". The entire trial was treated with methiozolin at 3.6 oz./1,000 ft2, followed by 0.6 oz./1,000 ft2 twice at 2-week intervals in order to facilitate rapid removal of annual bluegrass. Trial 2 was conducted at the Turfgrass Research Center (TRC) on a USGA specification ‘L-93’ green that is maintained at 0.125". This trial was aerated to remove 30% of the turfgrass canopy on May 5, 2013. In trial 2, plots contained either no methiozolin or methiozolin applied at 0.6 oz./1,000 ft2 6 times at 2-week intervals. All cultural treatments were the same between trials and were as follows: • No cultural treatment • Increased fertility using Bulldog 20-20-20, a commercially available N-P-K product • Increased fertility plus trinexapacethyl (Primo) at 0.125 oz./1,000 ft2 • Increased fertility via Floratine biostimulant products All fertility treatments were applied every two weeks beginning on April 14, 2013, and plots subject to increased fertility received an extra 0.125 lb. N on top of the normal fertility regime. The biostimulant program provided an equal amount of macronutrients to the other increased fertility programs. Light box images, normalized differential vegetative index (NDVI) and visual ratings were taken weekly for the duration of the study.