Establishment and maintenance during establishment of hybrid bluegrass (P. arachnifera Torr. × P. pratensis L.) in the transition zone.

The transition zone is one of the hardest places to maintain high-quality turfgrasses, and the overall research objective was to determine best management practices to establish new turf cultivars in this zone. Hybrid bluegrasses (P. arachnifera Torr. x P. pratensis L.) have been bred for heat and drought tolerance and may offer a new alternative to other turfgrasses. The specific cultivars examined in this research were 'Thermal Blue ® ' and 'Dura Blue ® '. Experiments were conducted during 2003, 2004, and 2005 in Knoxville, TN. 'Thermal Blue' was seeded at 50,100,150, 200, and 250 kg·ha ―1 of seed. 'Thermal Blue's' ideal seeding rate was between 100 and 150 kg·ha ―1 of seed in 2003 and 50 kg·ha ―1 in 2004. 'Thermal Blue' was also seeded in January, April, July, and September of each year with 100 kg·ha ―1 of seed. All seeding dates took ≈11 months to become well established. However, July seeding produced poor turf quality (less than 6) and was the only seeding date deemed unacceptable. 'Thermal Blue' and 'Dura Blue' were fertilized with ammonium nitrate at 100, 200, and 300 kg N/ha/year and urea formaldehyde at 200 and 300 kg N/ha/year starting in March of each year. These treatments were maintained at 2-, 3.5-, and 5-cm mowing heights. 'Thermal Blue' had higher quality evaluations and produced more clippings than 'Dura Blue' throughout the year. Higher fertility regimens increased quality evaluations in April but decreased quality evaluations in October. Increasing the mowing height improved turf quality and decreased biomass production for both grasses. A proposed optimum method for establishment included seeding 'Thermal Blue' in April at 150 kg·ha ―1 and fertilizing with 300 kg·ha ―1 of nitrogen and them mowing at 5-cm height. 'Thermal Blue' and 'Dura Blue' are adapted for the transition zone, but summer heat stress may cause turf quality decrease in the fall.