Are Heat Tolerant Kentucky Bluegrasses Better Suited for the Transition Zone?.
Travis C. Teuton1, John C. Sorochan1, J. Scott McElroy1, Christopher L. Main2, and Thomas C. Mueller1. (1) University of Tennessee, 2431 Joe Johnson Drive, 252 Ellington Bld., Knoxville, TN 37996, (2) Clemson University, 2200 Pocket Drive, Florence, SC 29506
Dura Blue and Thermal Blue Kentucky bluegrasses have been bred for heat and drought tolerance, and offer an alternative to traditional Kentucky bluegrasses and tall fescue in the transition zone. Experiments were conducted in two locations during 2003 and 2004 at the University of Tennessee in Knoxville, TN. Nitrogen was applied at 49, 146, and 294 kg N ha-1 yr-1 to ‘Apollo®', ‘Dura Blue', and ‘Thermal Blue' Kentucky bluegrasses as well as ‘Dynasty' and ‘Kentucky 31' tall fescue. Acceptable turfgrass color observations for Apollo, Dura Blue, Dynasty, and Thermal Blue (6.7 to 7.4) occured from March thru November. Kentucky 31 had a paler green, less desirable color. All Kentucky bluegrass varieties were below the minimum 6.5 quality evaluation when treated with 49 kg N. However, applying 146 and 294 kg N from March thru November improved Kentucky bluegrass quality to > 6.7. Quality observations for Dynasty and Kentucky 31 were acceptable (6.6-7.1) throughout the growing season. Dry tissue weights were highest for Kentucky 31 and Thermal Blue within each nitrogen fertility level. No differences in brown patch incidence were observed on Dynasty and Kentucky 31 and ranged from 21 to 31%. Dollar spot incidence was observed on all Kentucky bluegrass varieties from 7 to 24% with Thermal Blue having the greatest foliar disease incidence. All turfgrass species tested were acceptable for use in the transition zone with Apollo and Dura Blue Kentucky bluegrass being the most desirable.