Ethephon and Gibberellic Acid Inhibitors Influence Creeping Bentgrass Putting Green Quality and Ball Roll Distances.

Plant growth regulators (PGRs) are often applied in combinations to reduce turf clippings, enhance turf quality, and suppress Poa annua L.; however, effects of PGR combinations on putting green ball roll distances have not been reported. Two field experiments were conducted on an 'L-93' creeping bentgrass (Agrostis stolonifera var. palustris Huds.) putting green in Clemson, S.C., to investigate effects of four PGRs with and without a subsequent application of ethephon at 3.8 kg⋅ha-1 a.i. 6 days after initial treatments. The PGRs initially applied included ethephon at 3.8 kg⋅ha- a.i., flurprimidol at 0.28 kg⋅ha-1 a.i., paclobutrazol at 0.28 kg⋅ha-1 a.i., and trinexapac-ethyl at 0.05 kg⋅ha-1 a.i.. Ball roll distances were enhanced 3% to 6% (4 to 8 cm) by exclusive flurprimidol, paclobutrazol, and trinexapac-ethyl treatments. The additional ethephon application reduced ball distances 2% to 9% (2 to 11 cm). Paclobutrazol and trinexapac-ethyl treated turf receiving the additional ethephon application had longer or similar ball roll distances to non-PGR treated turf. The additional ethephon treatment reduced turf quality to unacceptable levels 1 and 2 weeks after applications. However, bentgrass treated previously with trinexapac-ethyl and paclobutrazol had 8 to 16% higher visual quality following the additional ethephon treatment relative to non-PGR treated turf receiving the subsequent ethephon application. Overall, ethephon may have deleterious effects on monostand creeping bentgrass putting green quality and ball roll distances; however, applying ethephon with GA inhibitors could mitigate these adverse effects. Chemical names used: [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] (trinexapac-ethyl); {α-(1-methylethyl)-α-[4-(trifluoro-methoxy)phenyl] 5-pyrimidine-methanol} (flurprimidol); (+/-)--(R*,R*)-β-[(4-chlorophenyl) methyl]-α-( 1, 1-dimethyl)-1H-1,2,4,-triazole-1-ethanol (paclobutrazol); [(2-chloroethyl)phosphonic acid] (ethephon). [ABSTRACT FROM AUTHOR]