Influence of Phosphorus and Nitrogen on Annual Bluegrass Encroachment in a Creeping Bentgrass Putting Green
Open Access
- Author:
- Raley, Robert Brandon
- Graduate Program:
- Agronomy
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 26, 2012
- Committee Members:
- Peter Landschoot, Thesis Advisor/Co-Advisor
- Keywords:
- nitrogen
phosphorus
creeping bentgrass
annual bluegrass
putting green - Abstract:
- Annual bluegrass (Poa annua L.) encroachment into newly established creeping bentgrass (Agrostis stolonifera L.) putting greens is a concern for golf course turfgrass managers attempting to maintain uniform and consistent putting surfaces. An integrated approach to controlling annual bluegrass would benefit turf managers by reducing pesticide use and potential for herbicide injury. The primary objective of this study was to determine the influence of phosphorus (P) and nitrogen (N) containing fertilizers on annual bluegrass encroachment into a newly established creeping bentgrass putting green. The second objective was to determine if tissue P and N concentrations and soil Mehlich 3-P concentrations are associated with annual bluegrass encroachment. This 1-yr field study was conducted at the Joseph Valentine Turfgrass Research Center in University Park, PA on a 2-yr-old sand-based putting green originally seeded to ‘Penn A-4’ creeping bentgrass. Treatments included four N rates (195, 293, 391, and 488 kg N ha-1 yr-1) and four P rates (0, 43, 86, and 129 kg P ha-1 yr-1). Criteria for evaluating treatments included population of annual bluegrass, tissue N and P concentrations, soil Mehlich 3-P concentrations, clipping yields, and turfgrass color. Results show annual bluegrass populations increased in plots treated with P versus plots in which no P was applied. The annual bluegrass population in the 0 kg P ha-1 yr-1 plots decreased by 2% over the two-year experiment; whereas, the population increased from 2.9 to 6.8 percent in plots receiving 43 to 129 kg P ha-1 yr-1. Treatments ≥ 43 kg P ha-1 yr-1 resulted in a greater increase in annual bluegrass from the pre-treatment population when compared to treatments with no P; however, no differences in percent change in the annual bluegrass population were detected among the 43, 86, and 129 kg P ha-1 yr-1 treatments on any assessment date during the study. Nitrogen treatments had no influence on annual bluegrass encroachment, and no N-by-P treatment interaction occurred during the study. Treatments producing turf with tissue P concentrations ranging from 4.0 to 5.5 g P kg-1 tended to show a lower percent change in annual bluegrass populations than treatments producing turf with tissue concentrations > 5.5 g P kg-1. Annual bluegrass populations did not continue to increase as tissue P concentrations increased from 6.0 to 9.1 g P kg-1. A linear relationship was found between P treatments and Mehlich 3-P in both years of the experiment. Mehlich 3-P concentrations were positively correlated with percent change in annual bluegrass in 2005, but not in 2004. Results from this study confirm previous findings by researchers that additions of P fertilizer in creeping bentgrass putting greens enhance annual bluegrass encroachment, but contradict some reports of N additions promoting annual bluegrass encroachment. Although critical levels of tissue P in putting green turf that promote annual bluegrass encroachment were not identified, levels < 5.5 g P kg-1 were less likely to show increases in annual bluegrass.