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Winter Primo and IPM

Phosphite, Iron Sulfate, and Primo application,
Jan 03, 2014
Primo Maxx (Trinexapac-ethyl) is a plant growth regulator that is primarily used during the warm summer months. It has a lot of uses such as reducing top growth, decreasing nitrogen requirements( kind of), improved shade performance, improved turf density and quality, and many other claims.
About the extent of the fusarium currently on the putting greens.
Last pesticide app was Daconil Oct 22 2013, 2 phosphite, iron and Primo apps since then.
Over the past few years I have applied Primo mostly in the summer months based on a 150 growing degree day (GDD) application interval which is optimal for Poa annua. I have also applied it sporadically during the winter months with not too much thought put into it other than reducing the number of times I have to mow greens in the winter when my staff are laid off and it's just me.

Recently I thought of how winter Primo applications could fit into my IPM program. Last winter I had good success using phosphites, iron, and lightweight rolling. I also monitor growth rates to determine when the optimal time to mow is to reduce any stresses associated with mowing too often or scalping from not mowing enough. I also used Civitas last winter but the surface sealing in the cold weather was unacceptable in my opinion. Again, I used Primo, but it was sporadic and almost whimsical. Could Primo enhance my efforts to fight Fusarium?

To be honest I have never really looked too seriously into it. Not many people use Primo through the winter and I have never read anything pertaining to using plant growth regulator during the winter months.I have come across some articles about using Primo in the fall but nothing about using it all winter long. Why would we? The grass is already growing super slow. Most people use Primo for putting green consistency and green speed related reasons. These typically aren't issues in the winter. Well I have a few hypothesis that I think should be looked at more seriously in the future.
That's as high as the sun gets this time of
year.
  1. Primo reduces top growth by up to 50%. During the winter it can be hard to get out to mow, conditions are usually very wet or frosty and turf damage from mowing is almost inevitable. Anything that can be done to reduce this mechanical stress should be beneficial to plant health.
  2. Primo enhances turf quality in low light (shady) conditions. Now the growth potential this time of year is almost 0 so light really isn't that important. Having said that there is a noticeable improvement in turf quality in areas that receive more light. There is also a noticeable reduction in turf disease in areas that are less shady. Maybe the shade quality effects could help the turf in the winter.
  3. Reduced winter fertilizer applications. The greening effect of repeated Primo applications could help keep the greens looking good even when the fertilizer supply is cut off when the growth potential hits 0.
  4. Enhanced winter density. Keeping a dense sward is often a challenge this time of year due to many reasons namely the fact that it's winter and damn cold! Maybe Primo can help keep density up during the winter.
  5. Primo has a much lower EIQ than most pesticides. With the light application rates and extended application interval in the winter (often up to a month or more) Primo has a very light environmental footprint when compared to almost all other pesticide applications. If Primo can be used to reduce pesticide requirements even a little it should help drive down the environmental impact of our operations.
  6. Primo applications are relatively cheap. At about $20 per acre every 150 GDD. This adds up to less than $20 a month during the winter! How much does every pesticide application cost? What does it cost to mow the greens? The savings could be significant.
  7. Green speed. Yeah, who cares? It's January for crying out loud!
Now all of this is unproven and purely my hypothesis as far as I know. I think it is something that should be looked into in the future and is something that I plan to play around with this coming winter. Unfortunately it is extremely hard for me to set up a proper test to really get to the bottom of winter Primo applications. Who knows? Primo in the winter could turn out to be a terrible idea, I don't know.

If anyone is using Primo in northern latitudes during winter please let me know how it is going? What are you noticing? Has it affected your pesticide applications? Have you noticed any negative effects? Post in the comments below and let me know what you think!
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