Primo Maxx II How long / how much?

Lots of phone calls and messages about Primo rates at the moment. Understandably people are concerned now about lower staffing levels or potentially having to shut down the golf course for a period.

Primo is a turf care great tool to help reduce growth and could be a real help in the upcoming months helping you reduce labour required.

Primo on left untreated on the right

If I apply at higher rates will I get a longer period of growth suppression?

How long the suppression period is, is highly dependent on temperature – which is why the Growth Degree Day model works so well with Primo. The higher the rate the more suppression you’ll get but the higher the risk of yellowing. Increasing rates can prolong the period of growth suppression slightly but by doubling the rate you WILL NOT double the period of suppression – you will, however, have less growth during that period of control.

If longevity is more important then multiple applications will give a better result than higher rates.

What rate should I go with?

Fairway trial

The rate you use will directly impact the clipping yields – simply put the higher the rate the fewer clippings but the more risk you have of some yellowing turf. The above graph shows how as we increased the application rate we increased the levels of control.

Yes, but how high a rate can I go?

This will be influenced by a number of things

  • Species of turfgrass
  • Height of cut
  • Amount of stress the plant is under when applied
  • Climatic conditions

You’ll have experience of what works for you on your site and in-depth knowledge of what areas grow at what speed. To ensure the best value I’d be looking at variable rates for different surfaces and areas.

The label is something that’s really worth looking at here. We’ve all evolved our Primo programs over time to our favourite rate and timings but the advice on the label is robustly trialled and authorised at registration.

There will be a temptation to push rates higher on greens in order to keep them under control through these difficult periods. The 0.4L/Ha is the top rate on the label for greens but this can be applied every 7 days. If more suppression is required then I’d apply another 0.4l/Ha on day 7 or leave it depending on what’s needed. Even at those rates and intervals I’d expect to see significant yellowing. However that may be the lesser of two evils at the moment. Fairways and Roughs are a different story and will tolerate far more regulation – and yellowing is far more acceptable. The above table gives a clear indication of the limits of the label.

When choosing a rate it’s worth thinking through the risks.

What are the legalities regarding Primo Maxx? I’ve written a blog about that too. Just click here.

I’ve also written a blog about Primo risks, when to start applying Primo and what to add. Read that blog here.

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