Kentucky bluegrass and perennial ryegrass mixtures for establishing midwest lawns

Abstract

Mixtures of turfgrass seed are commonly used to establish lawns, with kentucky bluegrass (KBG) and perennial ryegrass (PRG) comprising two of the more commonly used species. In the humid regions of the Midwest United States, KBG is a desirable species, but slow germination makes it difficult to establish compared with PRG. The objective of our study was to evaluate establishment rate and species composition over 3 years of a turf stand seeded with different ratios of KBG and PRG (wt:wt) maintained as a lawn. Repeat experiments were initiated in 2007 and 2008 and conducted for 3 years in West Lafayette, IN, with seed mixtures of KBG:PRG of 100:0, 90:10, 80:20, 70:30, 50:50, and 0:100 wt:wt of pure live seed. Plots were seeded late August each year and percent turfgrass cover was rated up to 6 weeks after seeding (WAS). To evaluate stand composition after establishment, percent KBG cover was rated annually in August for 3 years using transect counts after selective removal of PRG with the herbicide chlorsulfuron. Likely as a result of greater crabgrass (Digiaria sp.) competition during establishment in 2007, 100% PRG, 50:50, 70:30, or 80:20 KBG:PRG ratio had the highest percentage turf cover at 6 WAS, whereas there was no difference between treatments at 6 WAS in 2008 when crabgrass competition was lower. Regardless of turf cover during establishment, all treatments except 100% PRG shifted to greater than 95% KBG cover by 3 years after establishment. For the region in which our study was conducted, it may be desirable to seed with a higher proportion (greater than 50%) of PRG to speed initial establishment for customer satisfaction, erosion control, and/or to offset years with high weed pressure. Under lawn conditions similar to our study, seeding ratios with high KBG (80:20 or 90:10 KBG:PRG) will likely shift to a stand composition of greater than 95% KBG within 2 years, whereas all other ratios lower in KBG will likely shift similarly within 3 years. Chemical names used: 2-chloro-N-{[(4-methoxy-6-methyl-1,3,5-triazin-2 yl)amino]carbonyl}benzenesulfonamide (chlorsulfuron).