Seedling Emergence and Establishment of Annual Bluegrass (Poa annua) in Turfgrasses of Traditional and Creeping Perennial Ryegrass Cultivars

Annual bluegrass is a cosmopolitan, cool-season grass that adapts to different environmental conditions. It is one of the main weeds of turfgrass, and its control is mainly achieved through chemical and cultural practices, although little importance is given to the competitive ability of turfgrass species or cultivars. A field study was performed in northeastern Italy from October 2012 to June 2014 to evaluate the competitive ability of selected perennial ryegrass cultivars to suppress emergence and establishment of annual bluegrass seedlings. Two creeping perennial ryegrasses (‘CSI' and ‘PPG-PR171’) and two traditional cultivars (‘Azimuth' and ‘Presidio') were compared. In late autumn in both years, annual bluegrass was sown in a marked area (30 cm by 30 cm) in the turfgrass. Emerged seedlings were counted weekly, and emergence dynamics were modeled. In the second year, final density of annual bluegrass allowed to grow in turfgrass was also evaluated in summer. Results showed that both seedling emergence...