Influence of Plant Growth Regulators on Transition of Bermudagrass Putting Green Overseeded with Perennial Ryegrass

Abstract

Abstract Field studies were conducted for 3 years on putting green turf to determine the influence of the plant growth regulators (PGR) pronamide (PRON), ethephon (ETHR), mefluidide (MEFL), and maleic hydrazide (MH) on the transition from overseeded perennial ryegrass (Lolium perenne L. ‘Yorktown II’) turf to hybrid bermudagrass [Cynodon dactylon (L.) pers. × C. transvaalensis Burtt-Davy ‘Tifgreen’] in the spring. All PGR treatments were effective in increasing bermudagrass coverage over untreated grass; however, all reduced turf quality to some degree, with the exception of ETHR. The high PGR rates generally had lower turfgrass quality than the low rates. The March and early April application had the greatest bermudagrass coverage in 1982 and 1985, whereas the early March treatment generally had lower turfgrass quality than later applications. PRON at 0.28 kg·ha−1 applied as a single application in 1985 had higher initial bermudagrass coverage than when applied as split application, but split application maintained higher turfgrass quality than the single application. The split application of MEFL at 0.56 kg·ha−1 provided greater bermudagrass coverage than the single application when applied 6 Mar. or 3 Apr.; however, the split application resulted in lower quality than obtained from a single application applied on 6 Mar. in 1985. PRON at 0.28 kg·ha−1 and higher rates reduced growth and corresponding mowing requirements. Chemical names used: 1,2-dihydro-3,6-pyridazinedione (maleic hydrazide); N-(2,4-dimethyl-5-[([trifluoromethyl]-suIfonyl)amino]phenyl) acetamide (mefluidide); 2-chloroethyIphosphonic acid (ethephon); and 3,5-dichloro-(N-1,1-dimethyl-2-propynyI) benzamide (pronamide).