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Turf ryegrass: NZ vs US. 32

Jul 10, 2023 | GILBA BLOG

US turf type perennial ryegrass at Sydney University
Contents hide
1 NZ vs US turf ryegrass
2 Mediterranean cultivars establish quicker in colder conditions.
3 Mediterranean cultivars grow more over winter.
4 Poa management
4.1 Jerry Spencer

NZ vs US turf ryegrass

When it comes to the choice between NZ and US turf type perennial ryegrass cultivars there is some confusion. Both of these perennial ryegrass varieties make contrasting claims about their respective performances. Newer US varieties like Intense perennial ryegrass claim exceptional wear tolerance, increased disease resistance and a dark green colour.

The problem is having looked at the research we think we have got confused and completely misunderstood it. The trial we refer to throughout this is available as a free download at the end of this report.

Buy Intense PRG Ryegrass.

 
We are firm believers in independent trial data and sports turf seed selection is no exception. These recent blogs help support this claim:
 
 
A good example of this is in the use of Mediterranean germplasm (winter active ryegrass) in preference to continental (summer active) varieties.
 
 
The schooling is that the Mediterranean varieties will outperform Continental varieties in our part of the world due to their ‘winter activity’.
 
It’s claimed that the three big advantages of Mediterranean cultivars compared to Continental cultivars are:
 
  • Mediterranean turf ryegrass cultivars will germinate and establish more rapidly later in the autumn, in colder conditions;
  • Mediterranean cultivars grow more over winter and
  • They are better for managing winter grass.
  • One thing that isn’t different is that they all are susceptible to sulfonylurea herbicides.
 

Mediterranean cultivars establish quicker in colder conditions.

Few Turf Managers have the luxury of being able to oversow with perennial ryegrass later in the autumn. However, when you look at Independent NZ Trial data where both Continental and Mediterranean germplasm were included (2005-2007) the results don’t exactly support this claim.
In fact, in the case of early seedling vigour and density (Table 1) Continental germplasm did much better than the Mediterranean varieties. These trials include Mediterranean varieties still sold in the Australian marketplace.

Mediterranean cultivars grow more over winter.

With this one we thought no issue. New Zealand is generally regarded as being colder than Australia so these Auckland based trials should be a good test of ‘winter activity’. If the above statement is true then the NZ Mediterranean cultivars should outperform the Continental germplasm.

This is easy enough to check. In these NZ Trials, density was recorded after 61 days with sowing being carried out in April 2005. The April mean temperature for Auckland is 16.2C. Weather conditions over the trial period fitted the norm.
Table 2 in the report is density 61 days after seeding so by then we are well into the winter and temperatures have fallen.
Obviously at this time the Mediterranean cultivars will be streets ahead. Mmm actually nope.
All of the Continental cultivars of turf type ryegrass were in the top LSD for density in contrast to the Mediterranean germplasm.

Poa management

The third advantage, is that Poa annua blends into the mid-green foliage of the Mediterranean cultivars. This is in contrast to the Continental turf type perennial ryegrass cultivars where it sticks out like the proverbial.

 

This third one is interesting in that surely using a variety that outcompetes winter grass is preferable to just “putting up with it?”.
 
 
In the US NTEP trials it includes an assessment of Poa competition. The end result is that the majority of the US varieties used in these trials and now available in Australia show less winter grass invasion.
NZ sports turf institute trial report into turf type perennial ryegrass cultivars
Jerry Spencer senior turf agronomist and soil scientist
Principal Agronomist at  • 0499975819 • [email protected] • Website •  + posts

Principal agronomist, Gilba Solutions Pty Ltd

BSc Hons Soil Science (Newcastle). Former STRI agronomist. Author of Nutrition of Sports Turf in Australia (CSIRO/Landlinks Press). 35+ years advising on sports turf, golf and stadia across Australia, NZ, UK and Europe.