Renovating to Perennial Ryegrass Using Glyphosate Tolerant Cultivars, ‘JS501' and ‘Replay'.

A typical fairway renovation to a new species is usually a long process and often involves extended periods of course closure.  Another challenge when renovating is to control weed invasion while the newly seeded area is maturing.  With the release of glyphosate tolerant perennial ryegrass (Lolium perenne L.) cultivars, JS501 and Replay, there is potential to renovate with minimal downtime and weed invasion since both cultivars can tolerate glyphosate at the seedling stage.  Preliminary trials were conducted in 2010 at the Coeur d' Alene (CDA) Golf Resort in Idaho and Bulls Eye Country Club in Wisconsin to develop a program for renovation.  At both sites, the primary existing species was annual bluegrass (Poa annua L.), creeping bentgrass (Agrostis stolonifera L.), and crabgrass (Digitaria spp.).

Based on these two trials, preliminary recommendations for a renovation program are 1) apply glyphosate 1 week prior to seeding, 2) scalp and verticut on the day of seeding, 3) re-apply glyphosate 2 to 3 weeks after the initial application, 4) re-seed at this time, 5) if needed, apply a final glyphosate application once the stand is mature (at least 8 weeks after final seeding).  Best treatments from these two trails resulted in greater than 80% perennial ryegrass.

To further strengthen these recommendations, a replicated field trial was initiated in 2011 to refine the glyphosate application schedule and ryegrass seeding timing when converting from a creeping bentgrass fairway.  Glyphosate application (0.29 kg ae ha^-1) treatments include an application 2 weeks before seeding (WBS), 1WBS, day of seeding, 1 week after seeding (WAS), 2WAS, and an untreated control.  Seeding rate treatments include 586 kg ha^-1 day of seeding (DOS), 293 kg DOS + 293 kg 2WAS, 195 kg DOS + 390 kg 2WAS, and 147 kg DOS + 147 kg 1WAS + 147 kg 2WAS + 147 kg 3WAS.  Treatment factors are arranged in a randomized complete block design with four replications.