# Simazine app rates



## bradleymichael (Jun 3, 2020)

Hey all, sorry if this has been previously posted but I couldn't find any definitive answer. I'm looking to spray Simazine and Prodiamine within the next few days but I'm nervous on how much to apply of the Simazine as I have read it can harm the Bermuda if too much is used.

Can someone help me to determine how much Simazine per 1k?


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## p1muserfan (Jul 7, 2019)

From page 9 of the label on DoMyOwn, "Where annual bluegrass is the major weed, use 1 qt./A (22 ml or 0.75 fl. oz. per 1,000 sq. ft.). Use 2 qts./A (22-44 ml or 0.75-1.5 fl. oz. per 1,000 sq. ft.) for control of other weeds."


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## cldrunner (May 14, 2019)

@bradleymichael @p1muserfan I would stay at the lower rate of 1qt per acre or .75 oz per 1000 if you have a hybrid bermuda.

Where annual bluegrass is the major weed, use 1 qt of Princep Liquid per acre (22 ml or 0.75 fl oz/1,000 sq ft). Use 1-2 qt/A Princep Liquid (22-44 ml or 0.75-1.5 fl oz/1,000 sq ft) for control of other weeds. *However, do not exceed 1 qt/A of Princep Liquid per treatment on newly sprigged turfgrass or on hybrid bermudagrass.*

I always stay at the lower rate on my tiff 419.


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## bradleymichael (Jun 3, 2020)

Yes I do have a hybrid Bermuda, although I'm not sure which one. Thank you for the information!


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## WDE46 (Mar 11, 2019)

Prodiamine is the active ingredient. What products do you have? The concentration changes how much you measure to put out.


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## tincan (Sep 4, 2020)

WDE46 said:


> Prodiamine is the active ingredient. What products do you have? The concentration changes how much you measure to put out.


Sounds like OP is putting out two separate products -- Prodiamine and Simazine, which coincidentally, I am putting them out today.

Prodiamine @ 0.4oz / 1k
Simazine @ 0.5oz / 1k


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## Wfrobinette (Feb 3, 2019)

tincan said:


> WDE46 said:
> 
> 
> > Prodiamine is the active ingredient. What products do you have? The concentration changes how much you measure to put out.
> ...


Can you explain why you use both?


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## cldrunner (May 14, 2019)

@Wfrobinette I did a Fall application of Prodiamine, Simazine, and Isoxaben.

I wanted more than one mode of action and better overall weed coverage by using more than just prodiamine. Prodiamine attacks through cell division.  Simazine is great for POA and attacks through the root growth.

I added Isoxaben to the mix this year as it is a broadleaf only pre-emergent. I added it to better control Henbit during the spring and Spurge during the fall.

Prodiamine and Simazine are very cost effective to put down. Isoxaben is pretty expensive but worth it to better control the broadleaf weeds and actually have three modes of action which may be overkill but I think is a great strategy.


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## tincan (Sep 4, 2020)

Wfrobinette said:


> tincan said:
> 
> 
> > WDE46 said:
> ...


It's for the reason that cldrunner mentioned. I have a Poa problem this year. Hopefully, Simazine would help.


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## bradleymichael (Jun 3, 2020)

WDE46 said:


> Prodiamine is the active ingredient. What products do you have? The concentration changes how much you measure to put out.


Yes prodiamine is the active ingredient, it is also what the product I have is called... Prodiamine 65WDG....


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## Wfrobinette (Feb 3, 2019)

tincan said:


> Wfrobinette said:
> 
> 
> > tincan said:
> ...


Got it. FWIW, I used dimension over the winter(over seed of TT Annual Rye) and had very little weed pressure.

I did have some nutsedge. Spurge came around July or so just around the edges.

Last year I had a ton Poa but did see any come spring. It's entirely possible is was mixed in the rye and I just didn't see it. And got smoked when I sprayed the rye down.


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## WDE46 (Mar 11, 2019)

tincan said:


> WDE46 said:
> 
> 
> > Prodiamine is the active ingredient. What products do you have? The concentration changes how much you measure to put out.
> ...


Right but Prodiamine is the AI and there are generics Prodiamine 65WDG (65%), Prodiamine 4L (41%), various granulars with "Barricade", Barricade 4FL (41%), Barricade 65WG, etc. So really just two different spray formulations but 65WDG has 50% more AI than 4L and so he could over apply.



bradleymichael said:


> Yes prodiamine is the active ingredient, it is also what the product I have is called... Prodiamine 65WDG....


Yes but there are a couple concentrations of "Prodiamines" available.


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## bwright (Sep 6, 2018)

How long does the Simazine last? I note the label says to put down in October at least, I was wondering how long one application stays active?


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## cldrunner (May 14, 2019)

@bwright Soil persistence is affected by temperature, soil type, rainfall, and PH of soil. In one study I read the half-life of Simazine was reached in 60 days. Another study showed 90-120 days depending on soil and PH. I make my application in North Texas around Sept 1 and again around Nov 1.. That also meets the two application label limit per year for me.

The date of POA emergence varies between locations and years, but generally begins when night temperatures are in the 60's and daytime temperatures are below 85°F. For North Texas we are in these ranges now. Those two applications give me about 5-6 months of coverage in my mind.

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=8633&

http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/simazine-ext.html
Soil half-lives of 36 to 234 days on sandy loam, 16.3 to 25.5 weeks on loamy sand and silt loam, and 75 days on an unspecified soil type have been reported. Residual activity remains for 2-7 months (2-4 kg/ha) after application.


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## bwright (Sep 6, 2018)

So, if I put it out October 1, per the label, will I be late? We Are in that temprature band now.

I applied Prodiamine September 12, 2020 at half rate, too. But wanted a dual mode of action pre-emergent this year. The Poa just drives me nuts in the spring.


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## cldrunner (May 14, 2019)

bwright said:


> So, if I put it out October 1, per the label, will I be late? We Are in that temprature band now.
> 
> I applied Prodiamine September 12, 2020 at half rate, too. But wanted a dual mode of action pre-emergent this year. The Poa just drives me nuts in the spring.


@bwright No you are not to late. The prodiamine will try to keep the seed from germinating at cell division. If a seed does germinate then Simazine will attack the root and inhibit photosynthesis. The benefit of having two different modes of action.


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## TNTurf (Mar 20, 2019)

Where are you guys getting your Princep? Locally, it comes in a 2.5 gallon jug that is not that expensive but for my half acre lawn thats like 14 years of supply.


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## cldrunner (May 14, 2019)

@TNTurf I got mine from https://www.seedranch.com/Princep-Herbicide-p/princep-2-5gal.htm

I saw another thread lately where someone posted they bought https://www.keystonepestsolutions.com/simazine-90df-herbicide-10-pounds-same-as-princep-cal-90-471?zenid=5429e35ad5daaed417d7db8a26b102e1

Granular DF is a little less expensive and may have a longer shelf life. I have not tried the granular.


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## tincan (Sep 4, 2020)

cldrunner said:


> I saw another thread lately where someone posted they bought https://www.keystonepestsolutions.com/simazine-90df-herbicide-10-pounds-same-as-princep-cal-90-471?zenid=5429e35ad5daaed417d7db8a26b102e1
> 
> Granular DF is a little less expensive and may have a longer shelf life. I have not tried the granular.


That's probably me. I prefer the granules, thinking they may have a longer shelf life. It is also probably easier to portion out in small amounts (e.g. very hard to pour a small amount of liquid from a huge 2.5 gl bottle).


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## tincan (Sep 4, 2020)

cldrunner said:


> @bwright No you are not to late. The prodiamine will try to keep the seed from germinating at cell division. If a seed does germinate then Simazine will attack the root and inhibit photosynthesis. The benefit of having two different modes of action.


Very nice explanation! I sure hope it gets rid of my Poa problem come spring.


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## DeepC (Aug 12, 2020)

cldrunner said:


> Very nice explanation! I sure hope it gets rid of my Poa problem come spring.


Any updates? How did the simazine work out on the poa?


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