Nitrogen Fertilization of Newer Bentgrass Cultivars.

Creeping bentgrass (Agrostis palustris  Huds.) is the most common turfgrass used for putting greens in much of the northern United States. However, its high quality surface means that use will always be pushed southward, into areas for which it is marginally adapted. Newer cultivars of bentgrass are often underrepresented in research, and thus the objective of this work was to examine the performance of newer creeping bentgrass cultivars at two southern locations, when managed under varying nitrogen (N) fertilization rates. Beginning in Jan 2016, experiments were conducted at the Atlanta County Club (ACC) (Marietta, GA) and the experiment station at Griffin, GA, on established (seeded Sept 2015) USGA-type putting greens consisting of 3 replicated blocks of ‘Pure Distinction’, ‘AU Victory’, ‘007’, ‘V8’, ‘T1’ and a ‘Penn A1/A4’ mix. Nitrogen treatments were foliar urea at 0, 0.24, 0.5, 1.0, 1.5 and 2.0 g N m^-2, sprayed every other week. Collected data included relative color and quality, green firmness, and root and shoot densities. In the early spring (Feb-May) of 2016 bentgrass quality, color and shoot density generally increased as N rate increased, regardless of cultivar. However, with the onset of summer heat bentgrasses fertilized with the two highest rates of N were severely affected, with significant tissue damage and death. At the ACC June (2016) shoot density was highest in Pure Distinction, followed by AU Victory, and then shoot density in 007, Penn A1/A4, T1 and V8 were equal. June root length density was greatest in T1, followed by V8, with root length density in all other cultivars equal. In 2017 highest N rate treatments were reduced to prevent summer damage to the bentgrass.