# Pre M for Winter weeds after reno



## Matthew_73 (Jul 9, 2019)

I have Tenacity and Prodiamine... I used GCI Cool Blue... I had a few spots of Poa in spring... Curious if I can or would be in my best interest to spray in a few weeks... Or is it too late as new week will be in the low 70.s and upper 60's I am on 45 DAG


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## RVAGuy (Jul 27, 2020)

The cool season lawn guide says to apply it 60 DAG, as does the Prodiamine label I use. If you seeded at the earliest recommended end of August, you wouldn't apply Prodiamine until the end of October or the beginning of November.


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## BrainBailey (Nov 20, 2019)

I'm in the same boat. Curious how effective prodiamine will be in late October, early November. I'm in lower Michigan, so air temps should be averaging around 45 degrees. Anyone have an opinion? Would I be wasting money?


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## Big Boy Stan (Aug 27, 2020)

Just another me too looking for this advice.

60 DAG for me will be Nov 10. I am in south New Jersey. Is that too late for a pre-m to do any good?

Also, I can get Anderson's .48% Barricade for $29 (5000sq ft) or Scotts Weedex Halt for $19. Is the Barricade better then the Halts?


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## Jersey_diy (Sep 5, 2020)

If your soil temp is above 55 and your grass is 60 DAG then you will get some use out of the prodiamine. If soil temps are below 55 then germination of POA or any other weed isn't likely.


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## MarshalOfFire (Apr 22, 2020)

FWIW you can cheat and apply dithiopyr earlier than 60 DAG. Not sure i would recommend 3 days after emergence, but I would be comfortable putting it down 30 days after.

https://www.jstor.org/stable/3988908?seq=1


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## shadowlawnjutsu (Jun 9, 2020)

Big Boy Stan said:


> Just another me too looking for this advice.
> 
> 60 DAG for me will be Nov 10. I am in south New Jersey. Is that too late for a pre-m to do any good?
> 
> Also, I can get Anderson's .48% Barricade for $29 (5000sq ft) or Scotts Weedex Halt for $19. Is the Barricade better then the Halts?


Does this apply if I reseeded at 21 DAG?


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## GregKeller (Sep 7, 2020)

I am in a similar boat. I am only at 18 DAG, and ordered some dithiopyr. I'm going to put it down as soon as it gets here. Read the study linked above and my takeaway was that beyond 14 DAG, there is very little impact on bluegrass.


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## Justmatson (Apr 4, 2020)

I'm pretty sure most of you are to late with a pre emergent app to control poa a. 
It has most to do with the soil temps. If your soil temps have fallen below 70-65f and if there was any poa a seeds, there's a good chance they have germinated already. 
They will continue to grow throughout fall, winter and spring.

You need to wait 60 DAG or 2 mowing before applying Prodiamine. I wouldnt recommend applying dithiopyr earlier then 60 days either. That is an old study.

Here's recommendations from Purdue with pre-emergents:

https://www.agry.purdue.edu/turfnew/tips/2008/04_10delays.html


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## shadowlawnjutsu (Jun 9, 2020)

That's one reason why I try to get tenacity down on time because 60DAG would be too late for poa germ. But I'll still put down prodiamine before my 2nd app of tenacity wore out.


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## Matthew_73 (Jul 9, 2019)

How late is tooo late... I am approaching 50 days and temps will be under 70 for the remaining 6 days... I have Tenacity.,.. Or just apply Prodiamine now....


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## GregKeller (Sep 7, 2020)

Justmatson said:


> I'm pretty sure most of you are to late with a pre emergent app to control poa a.
> It has most to do with the soil temps. If your soil temps have fallen below 70-65f and if there was any poa a seeds, there's a good chance they have germinated already.
> They will continue to grow throughout fall, winter and spring.
> 
> ...


Just because it's old, doesn't mean the info isn't valid. Here's another study (even older, that seems to confirm a similar hypothesis) https://www.jstor.org/stable/3988464?seq=1


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## Justmatson (Apr 4, 2020)

GregKeller said:


> Justmatson said:
> 
> 
> > I'm pretty sure most of you are to late with a pre emergent app to control poa a.
> ...


Follow the product label

From the product label:
*Turfgrass 
Use Dimension 2EW on seeded, sodded, or sprigged lawns, ornamental 
turfgrass and unimproved turfgrass that are well established. Newly 
established turf must have developed a good root system and a uniform 
stand, and have received at least two mowings following seeding or 
sprigging before making the first application of this product. Note 
precautions below for sodding. Use of this product on turf that is not 
well-established, or has been weakened by weather, pest, disease, 
chemical, mechanical or other related stress, may result in turf injury.*


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## RVAGuy (Jul 27, 2020)

@Justmatson +1


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## GregKeller (Sep 7, 2020)

Ok, so maybe I'll hold off on putting it down. I'll have two mows in by this weekend though. I wonder how to measure "a good root system and uniform stand". Obviously don't want to screw up my hard work to get things going, but I had a reno last year go south because of weed pressure. This years stuff seems to be going much better and I'd like to stay ahead of the 8 ball, so that was my thinking of putting down the preemergent soon to get some benefit. My soil temps are hovering around 70, and will be north of 55 degrees until the end of october (according to greencast)


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## GregKeller (Sep 7, 2020)

So I just got a bag of granular dithiopyr delivered from domyown and the label specifically mentions newly seeded cool season grass (***, tttf, perennial rye) and says it is safe to use 2 weeks after first sign of germination. Maybe a difference between granular and spray? Not sure but thought I'd put this out there. Planning on getting it down tomorrow. Soil temps at 68, so still a good shot at keeping some of the weeds away in the less filled in spots.


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## SumBeach35 (Jul 11, 2019)

My thoughts are you're better off blanket spraying for any Poa A in spring(Ethofumesate) if your grass type tolerates and applying prodiamine with it as long as you dont have any other seeding to do.


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