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

Summary

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®[1]) 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).

Results show that the competitive ability against annual bluegrass increased with increased density of mixed greens (especially with velvet bentgrass) vs. pure red fescue greens, and at 5.5 mm vs. 4 mm mowing height. The competition of annual bluegrass against fescue and fescue/bent increased while the abundance of AM fungi in the soil decreased with higher N rates, but we have no evidence that these responses were causally related. Application of P or inoculation with SYMBIVIT® had no effect on turf density or on mycorrhiza which, by the end of the trial, was abundant even without inoculation (63-68%). However, SYMBIVIT® led to a slight increase in phosphorus (P) removal from the soil, as shown by P-AL values. Increasing rates of P also resulted in increased competition from annual bluegrass. It seems that the inoculation with AM fungi through top dressing in the first months after seeding was inefficient, and that established greens benefit little from such inoculation.

The overall impression was influenced by the same factors as the density. A significant interaction species x N-rate revealed that in this study golf greens with red fescue as the dominant species required at least 1.0 kg N per 100 m^-2 yr^-1 to produce acceptable turf quality and density.

[1] SYMBIVIT^® - mycorrhiza inoculum, Norsk Mykorrhiza, Oslo, Norway/Symbiom Ltd., Sazava 170, Czech Republic. SYMBIVIT® contains 15 000 - 25 000 propagules L^-1 of six Glomus spp. (G. etunicatum, G. microagregatum, G. intraradices, G. claroideum, G. mosseae and G. geosporum)

Fundings (kSEK)

Project participants

Tatsiana Espevig

Researcher

Norwegian Institute for Bioeconomy (NIBIO), Department for Urban Greening and Environmental Technology, Turfgrass Research Group, Landvik, Reddalsveien 215, 4886 Grimstad, Norway.

+47 406 23 778

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