Surfactant Effects on Creeping Bentgrass and Annual Bluegrass Exposed to Different Irrigation and Traffic Stress Treatments

Creeping bentgrass (Agrostis stolonifera L.) and annual bluegrass (Poa annua L.) are turfgrass species that experience water and excessive foot traffic stresses on putting greens. The objective of this study was to investigate whether a soil surfactant would play a role in promoting tolerance to excessive water, water deficit, and traffic stress on annual bluegrass and creeping bentgrass sand-based rootzone putting greens. A soil surfactant was applied as a foliar spray (18.5 L ha(-1)) to creeping bentgrass cultivar Penn A-4 and annual bluegrass field plots and watered-in under three target soil volumetric water contents (SWC) (8, 12, and 16% SWC). Foot traffic was applied in summer 2013 and 2014 with a traffic simulator to represent low traffic (5688 rounds of golf), moderate traffic (11,376 rounds of golf), and no traffic (control). The effect of a soil surfactant on turfgrass quality, normalized difference vegetation index (NDVI), and SWC at two depths was measured. Statistical interactions existed between soil surfactant application and target SWC. Soil surfactant-treated turfgrass affected SWC differently across irrigation regimens, with suboptimal (8% SWC) and excessive (16% SWC) resulting in increased and decreased moisture retention, respectively. Turf treated with a soil surfactant had greater turf quality than the untreated control in late summer in each year. A soil surfactant can increase annual bluegrass and creeping bentgrass turf quality during water deficit, excessive water, and/or foot traffic conditions.