# What's wrong with my Prodiamine applications?



## DetroitRocker (Jun 14, 2017)

Hi all -

This is the second year in a row that my fall application of Prodiamine has been an absolute bust. Weeds of every shape and size pop up in early January, and my lawn now looks like it's been abandoned for a few months :lol:

The application is always done on around September 1, and I know the amounts I am spraying are correct (I take the max amount and divide it by two). Note that my Spring application (around March 1 - 15) tends to do the job just fine - it's rare I have any weeds during the summer.

Is there something obvious I am missing? Should I try another type of pre-emergent? I never had this issue with granules.


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## Huff (Oct 22, 2018)

Since it looks like you have coverage of almost your entire lawn with weeds, I'm gonna disregard simply missing areas with your application. An entire failure could be due to too much rain too soon after application, not enough rain to water in the application or mis-measuring what amount you're putting down. The first time I mixed my Prodiamine WDG, I was super careful to get the right amount of product and still ending up applying half of what I thought I was applying. Luckily I realized after spraying that I only used a half rate of a half rate and planned accordingly. I reapplied a 1/4 rate 2-3 months later. Pre-emergents aren't a 100% slam dunk that you won't get any weeds, but you've got a lot more than just a few. None of my neighbors use any kind of pre-emergent, so their weed infested lawns put a lot of pressure on my lawn to keep the weeds out. I'm resigned to hoping for 75-80% protection and post treating the rest. Hope this helps.


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## DetroitRocker (Jun 14, 2017)

Thanks, Huff!

What is interesting is that the front was an entire failure, but the side of the house (about 800 sq ft of coverage) looks to be 80% protection. I'm at a loss, since this is the second fall application it's happened.

I used .415 oz per 1,000 sq ft (half of the .83 oz max).


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## cfinden (Aug 7, 2018)

@DetroitRocker it's hard to tell but a lot of those weeds look like broadleaf, prodiamine isn't good at controlling broadleaf weeds, mostly grassy weeds like crabgrass, Poa annua, etc.

Some people use a Pre emergent called Gallery that does work on broadleaf weeds.


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## cldrunner (May 14, 2019)

DetroitRocker said:


> Hi all -
> 
> This is the second year in a row that my fall application of Prodiamine has been an absolute bust. Weeds of every shape and size pop up in early January, and my lawn now looks like it's been abandoned for a few months :lol:
> 
> ...


I live in North Texas as well. You seem to have some poa in there. I use prodiamine in the spring and fall. I would suggest you also use Simazine in the late fall after grass goes dormant and again in Jan-Feb. Simazine is ultra cheap and great on poa and other winter weeds. I only see a few broadleef weeds in your picture but I see alot of poa. I use 1 pint of simazine in the fall and spring for about 25,000 ft. I share it with my neighbors as well. I also go a little heavier on the prodiamine and have not seen any negative results.

You might also want to go late September with prodiamine and a few weeks earlier with spring app. Especially how warm it's been.

https://www.solutionsstores.com/simazine-4l


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## DetroitRocker (Jun 14, 2017)

Thanks for the info @cldrunner. I was hoping not to have multiple apps throughout the dormant season, but may be what I'm faced with going forward.


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## Stellar P (Apr 13, 2018)

DetroitRocker said:


> Thanks for the info @cldrunner. I was hoping not to have multiple apps throughout the dormant season, but may be what I'm faced with going forward.


Maybe consider Atrazine also. Works as a pre and post-emergent. If you have spots where the concentration of Prodiomine wasn't enough, you may have some early/mid spring pre-emergent coverage if you spot spray all the weeds with that.


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## Redtwin (Feb 9, 2019)

I'd be careful using Atrazine on Bermuda.

https://www.domyown.com/can-use-southern-ag-atrazine-on-bermuda-grass-with-out-any-harmfull-effects-on-my-lawn-qa-6030.html


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## Stellar P (Apr 13, 2018)

Redtwin said:


> I'd be careful using Atrazine on Bermuda.
> 
> https://www.domyown.com/can-use-southern-ag-atrazine-on-bermuda-grass-with-out-any-harmfull-effects-on-my-lawn-qa-6030.html


Good catch. I didn't know it wasn't compatible with Bermuda. Disregard what I said then. My bad.


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## McDiddles (Feb 24, 2020)

Its hard to tell but I believe the weeds pictured are mostly Poa annua. And some broadleaf's. Poa is known to be resistant to prodiamine, along with quite a few other herbicide groups. This includes tirazine products like Atrazine and Simazine. A quick google search will give you more answers on that. Basically you can expect to get little to no control for poa with anything except Specticle from Bayer. and it aint cheap!

Secondly: if you putting out the prodiamine on Sept. 1, you're about 5 months out from that application and it's on it's way to wearing off, or already worn off anyhow. Which probably explains some of the broadleaf weeds. If your splitting the rate I'd recommend doing two applications. Sept 1 is probably fine, then another 6 weeks later so that your applying the max labeled rate for single year use. Also, make sure it gets watered in per the label instructions.


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## Grass Clippins (Apr 30, 2018)

@DetroitRocker You may want to read through this topic. I didn't see it mentioned in your thread but if you aren't weighing it with a gram scale then you are likely laying down a very weak dose.

1 tsp of prodiamine weighs 0.11 oz.
0.185 ounces/# is the minimum application rate
a little over 1.5 tsp/# would get you the minimum
a little over 3.5 tsp/# would have gotten you the 0.415 oz/# fall application


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## DetroitRocker (Jun 14, 2017)

Thanks @Grass Clippins. Confirmed that I am using a gram scale and using the max .83 oz/K application rate. Actually the same on @Ware recommended in that thread!

It sounds like perhaps I need to do 4 apps per year @ .2075/K on March 15, June 15, September 15 and December 15 (appx). Or perhaps switch to something like Specticle or Snapshot. Both are expensive, but perhaps would be more effective, as my lawn isn't responding to the Prodiamine application as well as it should.


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## DetroitRocker (Jun 14, 2017)

I called Do My Own Pest today looking for input as well. The first thing they mentioned was that they no longer recommend Prodiamine because of resistance issues for Poa. Makes sense as my spring apps work well, and the last two fall apps have been a complete fail. Here is a research paper on it from 2015.

https://pdfs.semanticscholar.org/2864/74c5418600d1a55c205b34198ef4432d2202.pdf

They recommended Pendulum instead.


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## cldrunner (May 14, 2019)

For those of us in Texas here is a great resource.

https://aggieturf.tamu.edu/wp-content/uploads/ESC036.pdf

Add a different MOA. That is why I recommended Simazine(very cheap). Specticle is a different MOA but very expensive for a 2750 Sq. ft. lawn unless you can split. Rotating Pre's is favorable but for small lawns it is very costly. I thought about Specticle but I have had outstanding results the last two years with Simazine + Prodiamine/Dithiopyr combo.

Matt Martin @grassfactor also has a great video on this as well.

https://www.youtube.com/watch?v=NVS8jTiWFo8


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## McDiddles (Feb 24, 2020)

DetroitRocker said:


> I called Do My Own Pest today looking for input as well. The first thing they mentioned was that they no longer recommend Prodiamine because of resistance issues for Poa. Makes sense as my spring apps work well, and the last two fall apps have been a complete fail. Here is a research paper on it from 2015.
> 
> https://pdfs.semanticscholar.org/2864/74c5418600d1a55c205b34198ef4432d2202.pdf
> 
> They recommended Pendulum instead.


Pendulum is Pendimethalin, a Dinitroaniline. Same MOA as Prodiamine. Meaning you'll likely get the same results. The cheapest option is as @cldrunner recommend, Simazine.


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