Effects of Trinexapac-Ethyl On the Traffic Tolerance of Four Bermudagrass Cultivars.

Bermudagrass [Cynodon dactylon (L.) Pers.] is the most commonly used warm season turfgrass on athletic fields in the southern United States.   Trinexapac-ethyl (TE) data describing the effects of TE on bermudagrass athletic fields is limited.  A two year study was initiated at the University of Tennessee (Knoxville, TN) in 2008 evaluating the effects of TE applications on the traffic tolerance of four bermudagrass cultivars.  The experiment was a 4 x 3 x 2 factorial with 3 replications including bermudagrass cultivars ‘Tifway’, ‘Riviera’, ‘Patriot’, and ‘Celebration’,  TE treatments (no TE, TE at 6.49 g a.i. ha^-1 applied until 14 days prior to trafficking, and TE at 6.49 g a.i. ha^-1 applied until overseeding), and overseeding (no overseeding and overseeding at 67 g m^-2).  TE treatments were applied sequentially, on 14 day intervals, beginning on 18 July.  30 games of simulated traffic were applied with a CADY traffic simulator beginning 10 September.   Digital image analysis was performed to quantify turfgrass color and percent cover.  ‘Tifway’ and ‘Celebration’ maintained greater percent cover over both ‘Riviera’ and ‘Patriot’ under simulated traffic.  For instance, after 18 games of simulated traffic ‘Tifway’ and ‘Celebration’ yielded 62% and 58.5% cover, respectively while ‘Patriot’ and ‘Riviera’ measured 24.18% and 49.5%, respectively.  TE applications applied until two weeks prior to trafficking yielded increased percent cover on all rating dates from initial traffic until 5 November  (17 games and initial bermudagrass dormancy) compared to applications of TE applied until overseeding.  No differences were detected between plots not receiving TE and those treated with TE until two weeks prior to trafficking on the same rating dates for 9 out of the 13 dates. These data suggest that applications of TE on bermudagrass athletic fields should be ceased at least two weeks prior to the onset of traffic stress.