Turf quality and freezing tolerance of 'tifway' bermudagrass as affected by late-season nitrogen and trinexapac-ethyl

Bermudagrass [Cynodon dactylon (L.) Pers.] is the most widely used species for intensively managed turf sites in the southern United States and in the transition zone. I However, the lack of cold tolerance in many cultivars can result in significant winter injury. There is a limited body of information in the literature regarding management of bermudagrass to enhance cold tolerance, especially as it relates to N nutrition and the use of plant growth regulators (PGRs). As such, a 2-yr field study (1998-1999 and 1999-2000) was conducted to examine the effects of late season N fertilization and trinexapac-ethyl (TE) applications on morphology, quality, and freezing tolerance of 'Tifway' bermudagrass. During both years, monthly N applications were terminated on either 15 July, 15 August, or 15 September, while applications of TE were made on 15 August; 15 August and 15 September; or 15 August, 15 September, and 15 October. Late season applications of N and TE enhanced the fall green color retention of bermudagrass and promoted early spring green-up (SGU). Neither N nor TE had a consistent effect on growth and development of bermudagrass rhizomes or stolons, and neither treatment had a consistent effect on the freeze tolerance of rhizomes. However, a positive attribute of these treatments is a significant increase in the overall green period of bermudagrass (20-25 d), which can prolong the playability of high maintenance sports facilities. From these studies we have concluded that, contrary to what is commonly believed, late season applications of N did not affect the freeze tolerance of bermudagrass rhizomes.