Effect of Cultivar, Seeding Rate, and Nitrogen Fertilization on Kentucky Bluegrass‐Perennial Ryegrass Turf Mixtures1

Abstract Perennial ryegrass (Lolium perenne L.) (RG)‐Kentucky bluegrass (Poa pratensis L.) (BG) mixtures, seldom recommended in the past, are becoming more popular since the development of several turf‐type RG cultivars. Older RG cultivars produce poor quality turf because of coarseness and poor mowing quality. The objective of this study was to determine whether a relatively new turf‐type RG cultivar can be grown in a mixture with BG without sacrificing turf quality. A series of mixtures containing one of three RG cultivars (‘Manhattan,’ ‘Pelo,’ and ‘Linn’) and one of three BG cultivars (‘Pennstar,’ ‘Windsor,’ and ‘Kenblue’) was planted on a Typic Fragiudalf soil (Wooster silt loam) in the field in 1972. Three RG seeding rates (0.25, 0.5, and 1.0 kg/100 m2) and two N fertilizer rates (1.7 and 3.4 kg/100 m2) were used. BG was seeded at 1 kg/100 m2 on all plots. Botanical composition of the turf was obtained by counting BG and RG tillers in four samples from each subplot. Quality was determined by rating each subplot on a 1 to 9 scale. The results indicated that Manhattan, a turf‐type RG, produced a high quality turf when mixed with any of three BG cultivars. Mixtures containing Linn, an older RG cultivar, were generally poor in quality but quality differed according to which BG cultivar was in the mixtures. Mixtures containing Manhattan RG or Pelo, an intermediate quality RG, were dominated by the RG, especially in the 2nd year, while those containing Linn RG were dominated by the BG. Mixtures containing Windsor or Pennstar BG averaged higher in quality than those containing Kenblue BG. However, this difference was not apparent in mixtures containing Manhattan RG. Seeding rate had an effect on composition, primarily the 1st year. N rates were not associated with differences in quality or composition. It is concluded that turf‐type RG can be used successfully in mixtures with BG.