Evaluation of Cool-Season Turfgrasses Under Two Irrigation Regimes in the Willamette Valley of Oregon.

Evaluation of cool-season turfgrasses under two irrigation regimes in the Willamette Valley of Oregon.

Crystal Rose-Fricker, Colin Scott, Melodee Fraser, Pure-Seed Testing, Inc.

The use of cool-season turfgrasses for soil erosion, turf landscapes, home lawns, parks, sports fields, and golf courses has become more dependent on species and cultivars that can maintain green cover with less water.  The use of evapotranspiration (ET) rates to monitor water usage in turf has been reliable and repetitive.  Two turf trials with identical entries were seeded during the fall of 2009 near Canby, OR.  The trials were planted adjacent to each other, but were irrigated independently.  Entries were seeded into 1.6 m x 1.6 m plots with three replications and mowed at 5 cm. One trial was maintained with no supplemental irrigation for six weeks during the summer and the other at 30% of the previous week's reference ET (ET₀).  The objective of the study was to evaluate the response of different cool-season turfgrasses to the different irrigation regimes.  Throughout the summer of 2011 the percentage of green cover for each plot was evaluated by digital image analysis.  The top-performing entries in each irrigation zone were different. With no irrigation, tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] blends maintained 42% green cover, significantly higher than other entries.  At 30% ET₀ ‘Berkshire' hard fescue (Festuca brevilipa R. Tracey), ‘Treazure II' Chewings fescue [F. rubra L. subsp. fallax (Thuill.) Nyman], ‘Soil Guard' hard fescue, and ‘Tar Heel II' tall fescue were also in the top statistical group. Kentucky bluegrasses (Poa pratensis L.) maintained about 30% green cover, while perennial ryegrasses (Lolium perenne L.) had less than 20% green cover at 30% ET₀.  With no irrigation, the second statistical group included Tar Heel II, ‘Shademaster III' strong creeping red fescue (F. rubra L. subsp. rubra), ‘Coronado TDH' tall fescue, and Coronado TDH blended with ‘Faith' tall fescue. Without irrigation, Treazure II fell to 0.6% green cover.  The study will be repeated during the summer of 2012.