Nitrogen and Trinexapac-ethyl Applications for Managing 'Diamond' Zoysiagrass Putting Greens in the Transition Zone, U.S.

As a result of the increasing popularity of fine-leafed zoysiagrasses on golf courses, a 2-year field study was conducted to assess 'Diamond' zoysiagrass [Zoysia matrella (L.) Merr.] putting green performance at The Cliff's Communities Turfgrass Research Facility in Marietta, SC. Factors included four nitrogen (N) fertility rates and two trinexapac-ethyl (TE) regimes. Foliar applications of 0, 4.9, 9.8, and 14.7 kg.ha(-1) N were made once weekly for 7 and 15 weeks in 2009 and 2010, respectively. Trinexapac-ethyl was tank-mixed and applied weekly for 7 weeks during July to August at 0 or 0.017 kg a.i./ha totaling 0.120 kg a.i./ha for both growing seasons. Putting green performance was measured by assessing turf quality (TQ), ball roll distance (BRD), surface firmness (SF), leaf tissue nutrient concentrations, and thatch accumulation. Turfgrasses receiving 4.9 kg N/ha weekly exhibited acceptable TQ and greater SF and BED than plots receiving 14.7 kg N/ha weekly on all rating dates in 2010 before seasonal dormancy. Trinexapac-ethyl reduced clipping yield by 15% to 43% and influenced BED, SF, and tissue nutrient concentration across the 2-year study. Surface firmness decreased as total N input increased during the 2010 growing season and is presumably the result of an increase in leaf tissue causing a cushioned putting surface. Linear regression of thatch accumulation and SF were analyzed and found to be significant at four rating dates in 2010 indicating that as thatch organic matter increased, SF decreased. Nitrogen input for 'Diamond' zoysiagrass putting greens grown in the transition zone should begin at 73.5 kg.ha(-1)/year with supplemental N applications applied as needed.