Color enhancement of creeping bentgrass (Agrostis stolonifera L.) turf with foliar-applied urea-nitrogen

Golf course superintendents typically apply low rates of nitrogen as a foliar spray to creeping bentgrass putting greens during the summer months. Color responses from these applications are difficult to predict. The objectives of this research were to determine the sources of the varied color responses of creeping bentgrass (Agrostis stolonifera L.) turf maintained as a golf putting green from foliar applications of urea nitrogen. Experiments were conducted in the field and greenhouse in the vicinity of Lexington, KY in 2003 and 2004. Data collected using a handheld chlorophyll meter correlated well with tissue N and chlorophyll. Responses to foliar-applied N were not consistent at N rates less than 12.2 kg N ha-1, indicating that rates of at least 24.4 kg N ha-1 may be necessary for a measurable color change to occur. The addition of Fe had no quantifiable effect on turfgrass color. There were generally no differences in the color or growth response between creeping bentgrass cultivars to foliar-applied urea. Tissue N levels have a greater effect on the degree of color change than environmental conditions at the time of spraying, or the formulation of urea N used.