Keith Fellenstein said: Larry Allan said: Melvin Waldron, CGCS said: Keith Fellenstein said: Couple things to consider: During these hot days, growth regulators don't last as long. Tighten up your application window or increase rates. High organic and nitrates pushing excessive growth...watch fertility in the spring and summer. Venting can create a fertilizer response as oxygen introduced into the profile stimulates microbial activity releasing nutrients.
Studies I have heard about with growth regulators if I remember correctly, it doesn't matter the rate, it all has to do with the 200 growing degree days model.
Mel
I agree with Mel on the 200 degree day model. I read up on it, I think from the Noer Turfgrass research centre, and it really does work perfectly. Just remember that it is base 0C and add up the days highs in Celsius until you hit 200, then reapply.
Remember to do it in Celsius or some of you guys will be applying every 1.5 to 2 days. It's likely time you guys join the rest of the world anyway
All growth regulators or just trinexapac-ethyl?
Keith, the study I heard about it was Trinexapac-ethyl, and it was only on cool season greens height. I'm not sure about warm season greens, definitely cool season greens height.
Red,
I was e-mailed a handy dandy PGR GDD tracker excel spread sheet from our speaker who did the presentation. I just plug in the numbers (F) and it does all the math for me. Keith while I was looking up the tracking sheet, I did notice there is a tab for Trimmit, but it wasn't mentioned in the instructions. The tracking spread sheet came from the University of Wisconsin.
And it does work at 200 GDD when the Primo wears out it wears out and the grass just takes off.
Mel