Evaluation of Agrostis Species and Cultivars and a Wetting Agent for Use on Golf Course Fairways under Reduced Irrigation

Optimization of management practices and selection of turfgrasses with traits that help to prolong turf quality and function under drought stress are important factors for turfgrass success under reduced irrigation conditions. The primary objectives of our research were to evaluate the performance of standard and improved cultivars of three bentgrass (Agrostis L. spp.) species in response to a wetting agent and reduced irrigation under fairway conditions. Turfgrasses included ‘Penncross’, ‘L‐93’, ‘13M’, and ‘T‐1’ creeping bentgrass (Agrostis stolonifera L.), ‘Tiger II’ and ‘Revere’ colonial bentgrass (Agrostis capillaris L.), and ‘Greenwich’ and ‘Legendary’ velvet bentgrass (Agrostis canina L.). Irrigation treatments were conducted from June through August in 2011 and 2012 and included: (i) a well‐watered (WW) irrigated control and no wetting agent application; (ii) a drought (DRT) treatment that received no irrigation and no wetting agent; and (iii) a drought treatment with no irrigation but received two pre‐applications of a wetting agent (DRT+WA). Withholding irrigation in the DRT and DRT+WA treatments resulted in a decline in volumetric soil moisture content, visual turf quality (TQ), and normalized difference vegetation index (NDVI) compared with WW plots; however, there were no significant differences in any of these parameters between DRT and DRT+WA in either year. Among the species, colonial bentgrass generally exhibited the highest TQ and velvet bentgrass the lowest TQ, which was associated with significantly higher thatch content (∼30%) for velvet bentgrass compared with other cultivars. Among the creeping bentgrass cultivars, T‐1 and 13M generally exhibited the highest TQ and NDVI, but were not significantly different from colonial bentgrass cultivars irrespective of irrigation regime.