Traffic Tolerance of Kentucky Bluegrass Varieties In Blends and Monostands.

Traditional recommendations for athletic field construction have included the blending of turfgrass varieties to provide advantages over single-variety stands in highly stressed environments. Whether these environments include high trafficked areas, disease pressure, or weed interactions, it has been assumed that turfgrass blends out perform monostands. For instance, prior to the use of Kentucky bluegrass blends, entire monostands were devastated by strip smut, a cultivar specific disease. Therefore, recommendations have historically suggested three or more cultivars to prevent complete decimation. However, due to recent advancements in breeding technology, single cultivars bred for generalized disease resistance, aggressive tillering, and herbicide resistance may be used in place of a blend, which was previously necessary to provide all of these characteristics. Research, using a randomized complete block design, was initiated on a Colwood loam (fine-loamy, mixed, active, mesic Typic Endoaquoll) in East Lansing, MI on 25 September 2009. Three blends comprised of 7 new and old varieties were established along with the 7 varieties in monostands to be assessed for traffic tolerance. The blends and monostands were then subjected to twelve traffic events (10 passes per week) with the Brinkman traffic simulator beginning 3 August 2010 and evaluated for various response variables. Data collected in the first year of research showed that the blends did not out perform all of its constituent varieties in quality, cover, and surface strength characteristics during traffic applications on native soil. In addition to these findings, identical results were shown on a separate but similar experiment receiving 2.4 cm of high sand-based topdressing prior to traffic applications. In some instances, varietal monostands actually outperformed the associated blend in the aforementioned response variables. Two varietal treatments had higher turfgrass cover and quality ratings on 2 of the 12 rating dates.  Early results suggest that using a turfgrass monostand may not be detrimental to turfgrass health and performance.