[jha4aamu]

This clip was taken from some of Bill Kreuser's work that is few years old now(the GDD numbers have been revised and upped a bit since this research), but it was noted that the best visual turfgrass quality on KBG was at the .20 fl oz/M rate. The trial had consisted of rates of .10, .20, and .40 fl oz/M each applied at 100, 200, and 400 GDD base 0c. I personally have had good success staying in the .20-.30 oz/M range depending on the time of year and reapplying based on his current KBG GDD reapplication intervals of 274-287 GDD base 0c for those spray rates. Too high of a rate or reapplying too soon will give you that over regulated/shredded leaf tips look.

my t-nex app rates were always between the .75oz/k - 1oz/k range and i have noticed that shredded leaf tip in several areas. i plan on using ~280 gdd interval for my t nex apps now and dropping it to .3oz/k going forward, and hopefully that address that leaf tip issue.

on the topic of reapplication/over regulation, how would one know when to reapply the pgr after an initial app of 1oz/k? i assume the recommended 300 gdd interval is based on a proper app rate of between .2oz - .3oz. but is there info/data on reapplication interval if you feel you have over applied the previous app?

 

[ISU]

Fellas- put down my first app of PGR ever (anuew) and literally 5mins after Mother Nature decided to put down some heavy rain for 10mins straight....my question is the following, I'm a safe to assume that I just waisted product and safe to reapp or should I still wait next 3 weeks to reapp? mainly wondering if I'm okay to reapp as soon as I can again. I had checked the forecast prior to putting down PGR app and wasn't supposed to rain until midnight which would have given me at least 7 hrs of timeframe for product to sit on the leaf but apparently Mother Nature had different plans (or wheather man got it wrong once again).

Below is image to give an idea of how much rain we had.

 

[Greasmatta]

Hello all.

I have ordered some PGR and have some questions.
Here in Sweden it's quite hard to get hold of chemicals for the lawn if you are not an professional.
But I manage to order some PGR from Poland.
It is Syngenta made with 25% of trinexapac-ethyl. Noticed that Primo Maxx has 12.5%.

What do you think of application rate.
The Syngenta label mentions
0.3-0.6 litre/acre (metric) depending on Cultivation
Using Google translate from polish.

For "Spring barley, Winter barley, Oats, spring wheat, Winter wheat, Winter triticale, Winter rye"

Nothing about lawns.

What du you think using half of Primo Maxx max application rate as max rate for Syngenta 25%.
Because it has double the amount of trinexapac-ethyl.

Does that sound logical?

Is it ok to start using PGR in any time of growing season?

Cheers!

 

[g-man]

That sound very logical.

 

[Greasmatta]

Ok thank you.
Do you think it is ok to start anytime in growing season or is it 2nd mowe in spring that is the starting point.
Sorry for complete noob questions

 

[bernstem]

@Greasmatta You can start at any time, though you will see the most benefit in regards to stress resistance, density, and tillering if you start earlier. General recommendation is to start low and increase dose as needed. For low cut grass, with Primo, 0.3-0.4 seems to be the most common dose. For typical lawn height, 0.4-0.6 is more likely where you want to be.

 

[Greasmatta]

Great. Cheers!

 

[ScottW]

My first year using PGR (T-NEX). Lawn is mostly TTTF with some KBG and some patches of what is probably K31 (front lawn has never been fully reno'ed, but probably will this fall). Mowed at 2.5" HOC in spring and will be looking to raise it to 3" and then 3.5" (highest my mower will go) very soon.

I'm fairly certain I have reached the point of over-regulation.
First app was at the 0.3 oz/M rate on May 14. Followed greenkeeper GDD target for the 0.3 oz rate of 287.
GDD target reached and next app at 0.5 oz rate on May 30. On this day, before spraying, the lawn looked pretty good (pic below). GDD target for the 0.5 oz rate is 317.
A week later on June 6 I noticed some white mycelium and dollar spot lesions in just a few places, but overall the lawn looked good. Sprayed propiconazole on June 7. You can probably tell where this is going.
I made another app of T-NEX at the 0.5 oz rate on June 16, which was 2 days past the GDD target.
Yesterday I noticed the lawn has gotten funky. It's a more muted green with gray/yellow tinge when viewed at certain angles.

I had read of the potential for over-regulation with PGR + DMI fungicides, but I think I have now experienced it first hand. :lol:
But I honestly don't know how much of the over-regulation is from the addition of the propiconazole, or if I'm simply using too much PGR too often.

I question whether I should be sticking firmly to the GDD targets on greenkeeper. Those are based on clipping yield suppression rather than any of the qualitative improvements (density, color, stress management etc). The GDD target is when maximum clipping suppression has been reached, 45-50% or so. The modeling shows that when going past the GDD target, the level of suppression gradually decreases for a good while before going into proper rebound (faster than unregulated) growth.
For example, in this weather applying on/near the GDD target means an app every 2 weeks. But a week later than the target date (150% of the original targeted GDD interval) the model still shows 20% suppression. So it won't be maximally suppressed but will still be growing slower than unregulated grass.

Trying to figure out exactly how to approach this but I need to either extend my intervals, or back off the rate, or both.
FWIW, I have been mixing in either FAS or Main Event with my PGR and have also made occasional spoon feedings of N at 0.25 lbs/M, but am still at just 1.14 lbs N total for the year so far. Could probably use some more N but I don't want to go nuts heading into hotter weather.

Thoughts/comments from the PGR cognoscenti?

May 30:

June 19 (different angle but you get the idea):

 

[Pete1313]

Oh I've been down this road with t-nex and propiconazole. Couple quick questions? What rate of propiconazole? Did you leave it on the leaves or water it in? Did you tank mix anything with it?

I personally stick to the GDD model for reapplying t-nex. More consistent suppression.

 

[ScottW]

I used 2 fl oz/gal/M of propiconazole 14.3, which is the higher rate because I actually had DS lesions in the lawn. (The lower preventative rate for this product would be 1 oz/gal/M)
That was tank mixed with 1 oz/gal/M of dissolved granular urea for a tiny bit of N.
It was sprayed in the evening and left on the leaves overnight and the entire next day (36 hours or so; high temp on that day was 82F) before I ran sprinklers on the second morning afterwards.

 

[Pete1313]

@ScottW, looking back thru my spreadsheets from 2018.

5/4/18 - T-nex @ .4oz/M
5/26/18 - Propiconazole 14.3 @ 2 oz/M
Left propiconazole on the leaves for foliar. 90°+ temps around the time applying propiconazole. No good, overregulation. Grass alittle unsightly, did not have to mow for a while.

7/1/18 - T-nex @ .3 oz/M tank mixed with propiconazole @ 1 oz/M.
Not sure why I tank mixed them, left on leaves, upper 80's temp. Similar issue as before, just not as bad.

9/8/18 - T-nex @ .13 oz/M also tank mixed with propiconazole @ 1 oz/M.
Left on leaves, mid 70's temp. Minimal issues, but still slight overregulation.

This year
5/30/20 - T-nex @ .3 oz/M
6/12/20 - T-nex @ .2 oz/M
6/18/20 - Propiconazole @ 2 oz/M
I dropped the last T-nex rate down in anticipation of the Propiconazole. This time with the propiconazole i immediately watered it into the soil with .2" of irrigation. Temps are mid 80's. Growth is good right now, but we will see what the propiconazole does to slow it down.

I think your rates were too high on the T-nex when combined with later using propiconazole. I'm also not sure if putting propiconazole on as a foliar amplifies the effects when the lawn is under T-nex regulation. I played it safer this year by dropping the T-nex rate beforehand and watering in the propiconazole. We will see how my experiences go this year. The good news is your lawn will recover.

 

[ScottW]

@Pete1313 Thanks, had not really considered watering in the PPZ before, but I can see how that might help. I'm coming up on the end of that 2-week coverage window so I'll reassess whether I need another app. I also have some Cleary's (thiophanate-methyl; Group 1) that I could run instead if necessary.

I will definitely be backing off the T-NEX rate regardless. Looking back, I was pretty happy with the subjective quality of the lawn at the 0.3 oz rate and that's more important to me than clipping yield suppression. Even before applying PPZ, growth had slowed way down with the 0.5 oz rate, so I probably should have known better. Live and learn, at least it should recover.

 

[g-man]

Propi does have a regulation effect to it. There is a new feature on the greendkeeperapp that displays the combined effect of both pgr and dmi fungicides. But it is part of the premium $$$ package. I think the premium is too expensive for us.

 

[Pete1313]

I took a screenshot of this from some greenkeeperapp email/post, but is the best we can gather without a premium membership.

 

[DiabeticKripple]

new to the PGR game, just got my anuew today.

i have seedlings that are about a month old, and i just seeded some areas that didnt take.

i would like to spray tenacity again, PGR and PPZ to clear up some powdery mildew and leaf spot.

think the seedlings can take it? or should i just wait until they are more mature?

for reference you can check my journal, i just have spots of seedlings and the rest of the lawn is going crazy with all the water.

 

[ScottW]

@DiabeticKripple Keep in mind that propiconazole is a PGR (see above).
This is my first year using T-NEX and I have no experience with Aneuw. I have over-regulated my turf from using both T-NEX + PPZ (even though they were applied a week apart) because I didn't realize how severely the two would tag-team the lawn. This was on my mature turf only, because I've avoided spraying my spring seeded areas when applying the PGR.

PPZ can actually help establishment and is fine on new seedlings. It will slow their top growth a bit, but encourage rooting & tillering, and new seedlings need to be protected from fungus. Therefore, the PPZ can be sprayed everywhere.

Tenacity, if you're applying to extend the pre-m activity in your overseeded areas, it's fine. Not sure I'd blanket spray it over the mature turf as well, just because the silvering is unsightly and you're also pondering hitting it with PGR.

If most of the lawn is growing like crazy, you could apply PGR as well, but caution is the word of the day here. Either use a very low rate, or just hold off while PPZ is active. Maybe see how much suppression you get from the PPZ and go from there. You can always add things to your lawn but it's difficult to remove them after you spray.

 

[bernstem]

Propiconazole has phytotoxic effects as long as it is in the plant. If you apply in 70 degree weather, but a week later it hits 95 you can see phytotoxicity from the heat since the Propiconazole is still in the grass. I have switched to the FRAC 7 fungicide Velista in the heat because of this. Another option are the "cooling" DMIs, but they are expensive and might just be marketing.

 

[DiabeticKripple]

a HOT day here is 80f. Doesnt ever really get above that and humidity stays low around 40% so i dont really get the heat stress you mericans get.

Ill spray the PPZ first and wait a bit before applying the Aneuw. Clear the issues up before starting the regulation.

 

[Jp6940]

I have a 5lb jug of Apogee. Is this what you are referring to as a PGR? I purchased it for a good price for the early summer as I had a lot of poa a and seed heads. Never used it
Can I use this? Is this what you are referring to as a PGR? I just didn't see any names mentioned.

 

[JSS]

How soon would you consider applying a pgr to new seedlings? I have just renovated 12k ft with Bluebank, Bewitched, and Mazama 2.5 weeks ago. The seedlings have just exited the pout stage and are growing nicely. I mowed at 7/8 today and removed about 3/8.
I got excellent coverage with very few spots that need to fill in. Should I wait until spring for pgr or apply after a few more mowings?