Varying Levels of Nitrogen and Trinexapac-Ethyl on Putting Green Performance of 'diamond' Zoysiagrass.

‘Diamond’ zoysiagrass (Zoysia matrella (L.) Merr.)  is a fine textured warm season turfgrass that is gaining popularity on golf courses in the transition zone and further south.  Its shade and salt tolerance, excellent wear tolerance, and texture make it a turfgrass cultivar that is being evaluated for further use.  To assess ‘Diamond’ in a putting green application a two year field study was conducted at the Cliffs Environmental Research Complex in Marietta, SC.  The project focused on putting green turfgrass performance of ‘Diamond’ zoysiagrass under varying levels of ammonium nitrate and trinexapac-ethyl (TE).   Treatments of 0 kg ha^-1, 4.9 kg ha^-1, 9.8 kg ha^-1, and 14.7 kg ha^-1 ammonium nitrate were applied weekly with a CO₂ pressurized backpack sprayer delivering 561 L ha^-1.  TE was applied at 0 L a.i ha^-1 and 0.017 L a.i ha^-1 weekly.  Treatments in 2009 commenced July 28^th and finished September 10^th. 2010 treatments began May 20^th and terminated on August 25th.  Parameters measured included: turf quality, ball speed, firmness, thatch accumulation and depth, and tissue nutrient contents.  Nitrogen rate significantly affected thatch depth, surface firmness, ball speed, turf quality, and tissue nutrient contents.  Surface firmness and ball speed decreased as nitrogen rates increased.  All nitrogen levels resulted in acceptable turf qualities and were significantly higher than control treatments.  Applications of TE increased ball speed and leaf tissue K contents.  Management of fertility and TE significantly influence the putting green performance of ‘Diamond’. Applications of 9.8 kg ha^-1 ammonium nitrate with TE weekly provided acceptable turf quality, and significantly increased ball speed and firmness.