Adam C. Moeller*, Cale A. Bigelow, Jared R. Nemitz, and Glenn Hardebeck

Wetting agents are routinely applied to golf course putting greens to improve rootzone moisture content and distribution.  There are anecdotal field reports that certain products may negatively affect functional characteristics, like surface firmness, especially for high shoot density bentgrass cultivars.  The objective of this study was to evaluate the functional characteristics of two contrasting creeping bentgrass cultivars: ‘Penncross’ and ‘A-4’, grown on a sand-based research putting green as affected by three commercially available wetting agents with varying hydraulic properties.  Wetting agents were initially applied late fall (Nov.) and resumed in March prior to the 2006 growing season at label recommended application rates and intervals.  Spatial differences at 25 locations within individual plots for surface firmness, using the Clegg Impact Soil Tester (0.5 kg model), water infiltration using a double ring infiltrometer and volumetric moisture content across the 0-5.7 cm depth were determined twice during the middle of the growing season approximately 5-10 days after product application.  Among products in each individual cultivar block there were no treatment differences on either measurement date.  Among cultivars, however, ‘A-4’ was significantly softer (120 g_max) than ‘Penncross’ (132 g_max) when averaged across all treatments including the untreated control.  Although previous studies have demonstrated wetting agent benefits they are most beneficial when turfgrasses are under severe drought stress, a condition not observed in this study.  Future research needs to continue to examine product responses for functional characteristics like surface firmness under varying environmental conditions.