Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2002
Publication Date: 3/30/2002
Citation: Fagerness, M.J., Yelverton, F.H., Livingston, D.P., Rufty, T.W. 2002. Temperature and trinexapac-ethyl effects on bermudagrass growth, dormancy and freezing tolerance.. Crop Science. Interpretive Summary: Growth regulators are used by golf course managers to prevent the rapid growth of bermudagrass in the summer and fall. The effect of the regulator trinexapac-ethyl (TE) on dormancy, growth response and freezing tolerance is not known. The results indicated that applications of TE in the fall, when temperatures were cooler at the time of application, led to decreased turfgrass density and quality, probably due to phytotoxicity and a limited ability to recover. There were some indications that applications of TE caused changes in root growth and freezing tolerance, but the changes were inconclusive.
Technical Abstract: In the transition zone in the southeastern U.S., growth regulators are being applied to bermudagrass in summer months and, recently, also in the fall. The purpose of this study was to investigate the role of temperature and trinexapac-ethyl (TE) interactions in bermudagrass growth responses, dormancy, and freezing tolerance. A series of experiments was conducted in growth chambers and over two years in the field. TE was applied at normal field rates, 0.11 kg a.i. ha 1. The results indicated that TE reduced vertical growth, and increased stolon production and turf density and quality when applied at high temperatures. TE was most effective at reducing vertical growth at low temperatures, but there was no effect on stolon development. Applications of TE in the fall, when temperatures were cooler at the time of application, led to decreased turfgrass density and quality, probably due to phytotoxicity and a limited ability to recover. There were some indications that applications of TE caused some changes in root growth and freezing tolerance, but the changes were transient and largely inconclusive. The negative effects of fall TE applications on density and quality would appear to reduce bermudagrass competitiveness, and they explain the effectiveness of TE in aiding transitions to over-seeded species.