Effects of mowing height, N-rate and P-rate/ mycorrhiza on quality and competition against annual meadowgrass on putting greens with red fescue as predominant species.

Red fescue (Festuca rubra) appears to be the most environmentally friendly turfgrass species used on golf greens due to its low requirements for nitrogen (N) and water and its high resistance to snow mould. Disadvantages of pure red fescue include its low density and potential susceptibility to invasion by annual bluegrass (Poa annua). The utilisation of arbuscular-mycorrhizal (AM) fungi as a method to control annual bluegrass was suggested by Gange (1998), who reported a negative relationship between the performance of annual bluegrass and the abundance of AM. The objective of this study was to determine effects of mowing height (4.0 or 5.5 mm), N-rate (0.5, 1.0 or 1.5 kg 100 m-2 yr-1), P-rate or inoculation with a commercial source of AM fungi (0 kg or 0.18 kg P 100 m-2 yr-1 without inoculation or 0 kg P100 m-2 yr-1 with SYMBIVIT® ) on quality, thatch and mycorrhiza colonisation and competition against annual bluegrass on a green with red fescue as the dominant species. The study was conducted from 2010 to 2013 at Bioforsk Landvik on a USGA green with a peat-amended rootzone (10% v/v). The green was seeded in June 2010 with pure red fescue (40% F. r. trichophylla and 60 % F. r. commutata), 90% red fescue plus 10% colonial bentgrass (Agrostis capillaris) or 90% red fescue plus 10% velvet bentgrass (Agrostis canina).