Cultural management and nitrogen source effects on ultradwarf bermudagrass cultivars

Increasingly, vegetative selections from 'Tifdwarf, 'Tifgreen', or other hybrid bermudagrass [Cynodon dacrylon (L). Pers. X C. transvaalensis Burtt Davy] are slowly replacing Tifdwarf as the bermudagrass of choice for putting greens. The cultivars Champion, MS Supreme, TifEagle, and Floradwarf are examples of released ultra-dwarf bermudagrasses. The objective of this research was to evaluate these four cultivars, Tifdwarf, and an experimental ecotype (Mobile 9) for turf and overseed quality, color, shoot density, and thatch as affected by cultural management and N source. Management programs were: (i) standard, with two vertical mowings at 2.5 cm deep per year plus topdressing, one core aerification, and monthly summer spiking, or (ii) high, with monthly summer vertical mowing at 1.3 cm deep plus topdressing, monthly summer core aerification, and an additional light topdressing each month. Nitrogen sources were urea or methylene urea, each applied at 4 g N m(-2) per month. The high management program was too intensive to maintain turf of acceptable quality, because turf could not recover between frequent vertical mowings. Turf color and quality were often improved by application of soluble N, while thatch depth was unaffected by N source. Thatch depth and shoot density were affected by cultivar, with Tifdwarf and MS Supreme having lower thatch depths throughout much of the study. Quality and density of Poa trivialis L. overseeding were largely unaffected by cultivar or management, indicating that a quality overseed could be established through dense bermudagrass turf without intensive cultivation and that overseeding was not affected by the higher shoot densities of the ultradwarf bermudagrasses.