‘TifEagle’ Bermudagrass Response to Plant Growth Regulators and Mowing Height

Ultradwarf bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] cultivars require considerable field research to determine best management practices for successful long-term culture. A field study was conducted in 2004 and 2005 on an experimental 'TifEagle' bermudagrass putting green in Clemson, SC, to examine effects of plant growth regulators (PGRs) applied bimonthly and three mowing heights on turf performance. The PGRs included ethephon [(2-chloroethyl)phosphonic acid] at 1.91 kg a.i. ha ―1 , flurprimidol [α-(1-methylethyl)-α-[4-(trifluoro-methoxy)phenyl]-5-pyrimidine-methonol] at 0.07 kg a.i. ha ―1 , trinexapac-ethyl [4-(cyclopropyl-α-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] at 0.0175 kg a.i. ha ―1 , all pairwise PGR combinations at half the individual rates, and a nontreated control. Turf was mowed five times weekly at 2.50, 3.25, or 4.00 mm. Lateral regrowth with ethephon and trinexapac-ethyl was comparable to nontreated turf, while flurprimidol impeded lateral regrowth ∼25%. All three PGRs reduced dry clipping weights, with flurprimidol most effective (>50% each harvest) and ethephon least effective (maximum 17%). Turf quality for trinexapac-ethyl, ethephon, and flurprimidol was excellent (8.0-8.4), acceptable (6.8-7.1) and unacceptable (3.6-5.2), respectively. Compared to the control, root length density increased 33% with trinexapac-ethyl, unaffected by ethephon, and reduced 25% with flurprimidol. Flurprimidol increased ball roll distances in morning (AM) and (PM) by 21 and 26 cm, respectively, trinexapac-ethyl provided increases of 5 and 10 cm, respectively, while ethephon had no effect, compared to the control. No evidence of synergistic effects was observed for PGR combinations. Raising mowing heights increased lateral regrowth, turf quality, and root length density but decreased ball roll distances. Best overall performance of TifEagle bermudagrass was achieved with trinexapac-ethyl, as it increased root length density, provided excellent turf quality, reduced vertical growth, did not impede lateral regrowth, and increased ball roll distances, compared to the control.