Assessing the Species Composition of Tall Fescue and Kentucky Bluegrass Mixtures.

Tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) cultivars are often seeded as mixtures throughout the cool temperate and transition climatic zones of the United States. The objective of this study was to assess the effect of wear stress on the species composition of tall fescue and Kentucky bluegrass mixtures. Individual plots of Kentucky bluegrass and tall fescue were seeded at 45 and 436 kg ha^-1, respectively, in September 2010 on a loam in North Brunswick, NJ. Species mixtures were seeded at 218 and 23 kg ha^-1 of tall fescue and Kentucky bluegrass, respectively. Wear was applied using the Rutgers Wear Simulator during autumn 2011, 2012, and 2013. Turfgrass species composition was assessed by visually identifying twenty-four randomly selected tillers from each plot in July 2012 and August 2013 and 2014. Data were analyzed using a 5 x 4 x 2 factorial of Kentucky bluegrass cultivars (no-Kentucky bluegrass, ‘Midnight II’, ‘Blue Note’, A05-361, and A05-361), tall fescue cultivars (‘Falcon V’, ‘Mustang 4’, ‘Justice’, and ‘Greenkeeper’) and wear (no-wear and wear) arranged in a strip plot design with three replications. The Kentucky bluegrass factor explained 86, 82, and 82% of the total variation in species composition during 2012, 2013, and 2014, respectively; whereas, the tall fescue factor explained only 1, 2, and 2% during 2012, 2013, and 2014, respectively. The Kentucky bluegrass component of mixtures was much greater for Midnight II and Blue Note than A05-361 and A05-344 across all tall fescue in all three years. Regardless of Kentucky bluegrass entry, Kentucky bluegrass populations were greatest in Greenkeeper tall fescue in 2013 and 2014. Wear had no effect on species composition in any year. Data from this research suggests Kentucky bluegrass cultivar selection is a highly important factor governing the composition of tall fescue and Kentucky bluegrass seed mixtures.