Influence of Fall Fertilization Programs On the Traffic Tolerance and Recovery of Sprigged Bermudagrass Varieties.

Cold tolerant bermudagrasses (Cynodon spp.) are popular choices for athletic fields in the transition zone due to their rapid growth rate and high density.  However, the ability of a bermudagrass turf to withstand traffic from a typical American football schedule in the fall of its establishment season can be a challenge due to the intensive use and the onset of winter dormancy.  This research evaluated first season traffic tolerance and spring recovery of three vegetatively-established bermudagrasses (Patriot, Riviera, and Wayland, an experimental ecotype) to varying levels of fall N fertilization and simulated traffic.  Four 9.3 m² plots of each grass were established at the Virginia Tech Turfgrass Research Center on 16 June 2010 using sprigs generated from 0.9 m² of shredded sod per plot for each cultivar.  All plots received N as urea at a level of 49 kg ha^-1 per month in June and July, irrigated to promote active growth, and were mowed three times weekly at 2.5 cm.  A traffic simulator was applied weekly to one half of the bermudagrass plots to simulate the traffic of three football games per week from 30 Aug through 7 Nov 2010.  Nitrogen fertilization treatments (applied in strips perpendicular to traffic treatments) were Aug alone (A, 49 kg N ha^-1 on 1 Aug.), Aug+Sept. (AS, 49 kg N ha^-1 on 1 Aug and 1 Sept), and Aug+Sept+Oct (ASO, 49 kg N ha^-1 on 1 Aug and 1 Sept, plus 24 kg N ha^-1 on 1 Oct.).  Patriot established the quickest, followed by Riviera, then Wayland.  As anticipated, AS and ASO fertilization provided higher visual quality ratings in both trafficked and non-trafficked plots and higher % ground cover in trafficked plots until a killing frost on 15 Oct. However, the differences in treatment response between AS and ASO were usually insignificant.  Patriot and Riviera demonstrated better fall traffic tolerance and overall turf health than Wayland based on % ground cover ratings and Normalized Difference Vegetation Index (NDVI) measurements. As measured by visual ratings and NDVI, overall turf health was enhanced by AS and ASO fertilization treatments as compared to A alone.  The Wayland ecotype tended to have faster greening and higher % ground cover ratings than Riviera or Patriot in both trafficked and non-trafficked plots through late May 2011.