The Lockdown – Lowdown Week 5

What’s new this week?

We’ve dropped the cutting height on the whole trial down one mm in cutting height in one go – a suggestion that was met with a few deep breaths by the team at STRI who are the custodians of good practice.

However in this situation, in order to keep the trial relevant, we have cut at the existing 5mm height for the sake of the data, and then followed those assessments with an immediate drop from 5mm to 4mm – with no immediate visable impact.

The 100 GDD applications have also finally been made – it felt like that day would never arrive at Bingley. To put that into perspective around the rest of the country, I’ve listed some locations below and the date we would have reached 100 GDD, if you assume the start day was 17th April. (Easy to work out, check out our GDD calculator….)

  • Poole 4th May
  • Newquay 4th May
  • Swansea 4th May
  • Cambridge 7th May
  • Sandwich 7th May
  • St Andrews 15th May
  • Nairn 17th May
  • Bingley 17th May

Anyway we finally got there – well pretty close anyway – we applied the Primo on the 15th May knowing we’d reach 100 GDD on the 17th May – GDD application windows always seem to fall on a weekend!

We have also reached our monthly Qualibra and SeaMax application which also went down on Friday – and when appropriate, Primo was tank mixed with this.

Applications to date

The 7 day applications have now seen 5 applications at 0.4l/Ha with no additional N in the tank and no noticeable downturn in turf colour or quality, yet. Surely we can’t apply that quantity of growth regulator during a cold, dry spring without seeing some downturn? – well apparently we can.

Here’s a short video of the Week 5 results as ‘things begin to start to change’

Changing – Lockdown Turf Trials

The Data

Clipping yield

The clipping yield data is showing that, this week, the additional applications are layering up so now we are achieving 54% clipping reduction in the 7 day plots, compared to 27% in the 100 GDD plots. As the temperature begins to rise, we expect see this level of suppression reduce as the Primo’s longevity should reduce as the temperature increases.

The 100 GDD application plot received its second application on the day of assessment. The objective of using GDD is to guide application timing to ensure you apply before you come out of suppression.

You can see from the above chart that we were still achieving 27% suppression. In hindsight I wish we’d put a 150 GDD application interval in too, as 100 GDD hasn’t really pushed it enough.

Sward height

The same trend continues with sward height. The one cut per week regime is still producing more regrowth. I still think this is a direct correlation with plant health but I’m starting to wonder if there is anything else going on here. Last week’s spike (3 day weekend, rainfall and fertiliser) has returned to normal levels but the trend remains the same.

Still a simple correlation between more Primo and more suppression going on here.

Evenness of cut

I’ve broken the below graphs down a little differently this week, they are plotted so you can see the impact of the various amounts of Primo Maxx and its impact on evenness of cut. You can see that the more Primo, the more consistent the evenness of cut is. I assume that by reducing the clipping yield by up to 54% we give the mower a better chance of getting a high quality cut, whatever the cutting regime.

Evenness of cut
Evenness of cut
Evenness of cut
Evenness of cut


My thoughts:

  • Less maintenance = healthier turf – still
  • Does perceived ‘healthy’ turf make for a good playing surface? – if evenness of cut is a measurement of playing surface, then no but its looking increasingly like we can bridge that gap with Primo.
  • More regular Primo apps = more suppression
  • Benefit of additional mowing is very short lived and lost after 2 days of no mowing

Now we’re into the program fully, I’m looking forward to watching the clipping yields to see what achieves the greatest level of consistency.

I’m becoming increasingly interested seeing if we can utilise the suppression properties of PrimoMaxx II to reduce labour inputs and retain standards.

By the end of this week we’ll have applied 6 x Primo Maxx II applications at 0.4L/Ha in low temperatures with no additional N, which is pretty extreme – I was expecting to see some downside to this, which we haven’t yet? Join me next week to see how we’re getting on.

Leave a Reply