# Prodiamine & Dithiopyr in same application?



## 440mag (Jan 29, 2018)

Hello TLF'ers and Happy "_we're getting closer_" Spring! 

I have read both my labels and done some searching here but, thus far, I am not seeing where my intentions are going get me (or my soil) into any "trouble."

But, when in any remaining doubt, I always ask here!

*Q - Can anyone point me to any advisory - or your own knowledge / experience - against spraying Prodiamine and Dithiopyr in the same application?*

Due to a series of unforeseen calamities - and opportunities - strung out between March and May, I need to get BOTH my Prodiamine 65WDG *and* my Dithiopyr ("Dimension 2 EW") down in same spray tomorrow. (I am in luck as no wind tomorrow and expectations for some rain the following 4 days in a row! :thumbup: )

As has been pointed out to me in long past threads, both need to be full strength as I continue to battle Barnyard Grass and Goose Grass which shows up as soon as late March / 1st of April! (it was pointed out to me it keeps coming back every year because I wasn't using full strength app.s). Also, the last several summers have shown I can get by without a split app in Spring here ...

Like so many in this transition zone I'm in, whole swaths of turf seeded last Fall were literally WASHED AWAY by the 2nd wettest February on record for us (it really did approach biblical in steady intensity and overall inches - there was one instance of 4" in six hours!!!!!!!  :shock: )

But, as happens to me every Spring, I can only choose one from the two following:

"No seeding = no grass / open, bare dirt til Fall" or...

"No noxious, nasty weeds (broadleaf but, especially the worst of the annual grasses!)

Thanks in advance for any advice!

Label, Dithiopyr ("Dimension 2 EW"): https://www.pestrong.com/attachment.php?id_attachment=426
Label, Prodiamine 65WDG: https://www.domyown.com/msds/Prodiamine_65_WDG_Label.pdf


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## SNOWBOB11 (Aug 31, 2017)

Did someone recommend spraying both to control those weeds? Reason I ask is I don't see any reason to use both. Prodiamine lists both the weeds your targeting as weeds it controls so why not just use it?


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## 440mag (Jan 29, 2018)

Hi, SnowBob!

Oh, I gotta go back and read the Prodiamine label; I don't remember seeing Barnyard Grass or Goose Grass on the Prodiamine label (I mighta missed it). Using both has come out of repeated years of trying one or the other and having some stuff slip through - I'll see if I can find it but one reference I've bookmarked shows Prodiamine as being optimum for broad leaved weeds and Dithiopyr being more effective at annual grasses ...

But no, no one has actually recommended I use both, just that I start using maximum recommended amounts

I used to put the Prodiamine down in Feb and 5 weeks later the Dithiopyr but this year, both my calendar and my "plans" have been torpedoed so, tomorrow is it.


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## 440mag (Jan 29, 2018)

You're right SnowBob, here is a reference on Prodiamine:

Chemical name - Prodiamine
Trade name - Barricade, Stonewall
Delays - Wait 60 days after seeding or until after the second mowing, whichever is longer.
*Notes*
This product is a selective pre-emergence herbicide that provides residual control of many grass and broadleaf weeds in established turf grasses (excluding golf course putting greens) and lawns; landscape ornamentals; and established perennials & wildflower plantings. This product controls susceptible weeds by inhibiting weed seed germination and root development. Most effective weed control will be obtained when this product is activated by at least 0.5 inch of rainfall or irrigation prior to weed seed germination and within 14 days following application.
*Do not apply this product to putting greens or areas where dichondra, colonial bentgrass, velvet bentgrass or annual bluegrass (Poa annua) are desirable species.
This product will not harm most established ornamental trees, shrubs, and flowers.
This product may be applied as a single application or in sequential applications to control weeds germinating throughout the year. All applications must be made prior to germination of the target weeds. This product will not control established weeds. Maximum use rate selection should be based on turf species. The length of time of residual weed control provided by this product is related to the rate applied.
Maximum Application Rate per Calendar Year
.20% Prodiamine granular
NORTHERN GRASSES - Kentucky bluegras, Perennial ryegrass, Fine fescue and Tall fescue
Tall Fescue (including turf-type) 750 lb/acre (17.22 lb/1,000 sq ft) 1.5 Lbs AI per Acre
Kentucky Bluegrass and Perennial Ryegrass
500 lb/acre (11.48 lb/1,000 sq ft) 1.0 Lb AI per Acre
Creeping Red Fescue
375 lb/acre (8.60 lb/1,000 sq ft) 0.75 Lb AI per Acre
WEEDS CONTROLLED
When used in accordance with this label, this product will provide control of the following weeds:
• *Barnyardgrass
• Goosegrass*
• Lovegrass
• Speedwell
• Bluegrass
• Annual (Poa annua)
• Henbit
• Panicum
• (Texas, Fall, Brown Top)
• Sprangletop
• Carpetweed
• Itchgrass
• Pigweed
• Spurge, Prostrate
• Chickweed
• Common, Mouseear
• Johnsongrass (from seed)
• Purslane, Common
• Witchgrass
• Crabgrass (large, smooth)
• Junglerice
• Pusley, Florida
• Woodsorrel, Yellow (from seed)
• Crowfoot grass
• Knotweed
• Rescuegrass
• Cupgrass, Woolly
• Kochia
• Shepherd's Purse
• Foxtails, Annual
• Lambsquarter, Common

1. In many areas a single application of 330 to 750 lb/acre of this product will control the above listed weeds and goosegrass. However, under heavy goosegrass pressure and/or an extended growing season, most effective weed control can be obtained by making an initial application of 330 to 500 lb/acre followed after 60 to 90 days by a second application at doses that would not exceed those given in the Maximum Annual Rate Table. Do not exceed the maximum rate for turf grass species listed in the Maximum Annual Rate Table above.
2. Suppression only. Sequential applications may be made so long as the total amount of product applied does not exceed the maximum annual application rates recommended for each turf species. All applications must be made prior to germination of weed seeds.
3. Applications for this weed should be made in late summer, fall or winter prior to germination.


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## 440mag (Jan 29, 2018)

And here is the one on Dithiopyr:

Chemical name - Dithiopyr
Trade name - Dimension, Preen Crabgrass Control
Delays - Applications to well-established turf with good root system and uniform stand and has received at least two mowings.
Notes*
Use of this product on certain varieties of Fine Fescue may result in undesirable turf injury. The following Fine Fescue varieties have been found to be sensitive to this product: 'Atlanta', 'Banner', 'Beauty', 'Biljart', 'CF-2', 'Enjoy', 'HF-93', 'Highlight', 'Ivalo', 'Jamestown', 'Koket', 'Majenta', 'Mary', 'Pennlawn', 'Tamara', 'Tatjana', 'Waldorf', and 'Waldina'. Not all varieties of Fine Fescue have been tested.
*Reseeding or overseeding of residual of treated areas with this product should be delayed until 12 weeks from the time of application.
DO NOT apply to flowers, vegetables, shrubs, or trees.
Dithiopyr is both pre-emergent and post emergence herbicide. The early post-emergence crabgrass control is only effective on crabgrass if applied before crabgrass has displayed its fifth leaf or first tiller.
NORTHERN GRASSES - Kentucky bluegrass, Perennial ryegrass, Fine fescue and Tall Fescue
This product may be applied as a single application, as a split application, or as a sequential application for crabgrass control in the spring, summer, or fall.
DO NOT apply more than 11.47 lb of this product per 1,000 sq ft per application, and no more than 34.41 lb of this product per 1,000 sq ft per year.
Spring Applications
For single applications made in the spring or early summer, this product should be applied at the appropriate rate corresponding to one of the three control programs listed in Table 1 below, depending on the user's location, the turfgrass mowing height, and whether the use is considered to be pre-emergence or early post-emergence at the time of the application. The duration of residual weed control provided by this product is directly related to the total rate applied, but will vary somewhat depending on weather, weed pressure, turfgrass competitiveness, and the user's location within a region.
Use Program #1 for pre-emergence control at sites where the turfgrass is cut high (e.g., homeowner lawns). This program provides 3-5 months of pre-emergence crabgrass control. This program should not be used for early post-emergence crabgrass control.
Use Program #2 for pre-emergence control at sites where (a) turfgrass is cut low (e.g., golf fairways), and (b) turfgrass maintenance or weed control has not been conducted during the previous year. This program provides 4-6 months of pre-emergence crabgrass control. This program may also be used for early post-emergence control at sites where turfgrass is cut high (e.g., homeowner lawns).
Use Program #3 for pre-emergence control at sites where (a) turfgrass is cut low (e.g., golf fairways) and (b) turf maintenance or weed control has not been conducted during the previous year. This program provides 4-6 months of pre-emergence crabgrass control. This program may also be used for early post-emergence control at sites where turfgrass is cut low (e.g., golf fairways).
Subsequent, sequential pre- and/or post-emergence applications should be made where longer periods of control are desired.
Where split fertilizer applications are recommended, the rates in Table 1 may be split across applications made 6-10 weeks apart and prior to crabgrass emergence.
Used as directed for crabgrass control in the spring, this product will also control (at the"Program 3" rates) the following weeds when applied prior to their emergence:
• *barnyardgrass
• goosegrass*
• ryegrass (annual & perennial)
• bluegrass (annual)
• smutgrass
• crowfootgrass
• lespedeza (common)
• foxtail (yellow & green) *Also controlled at the "Program 2" rates.
• oxalis (buttercup, creeping & yellow woodsorrel)
• purslane (common)
• kikuyugrass
• speedwell (corn)
• spurge (prostrate & spotted)


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## 440mag (Jan 29, 2018)

Thinking as I am only confronted by goosegrass and barnyard grass in roughly less than 1/3 of the entire spread (and Prodiamine at the max rate worked in the remaining 2/3 last year) perhaps I will either:

1) use a combo of Prodiamine and Dithiopyr at the full max rate in just those challenging areas; or,

2) use just Dithiopyr at the full max rate in only those challenging areas.


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## SNOWBOB11 (Aug 31, 2017)

I can't really speak with confidence on which one is better for your target weeds as I've never had to deal with those specific weeds. If it were me I'd be a little concerned about using both at full strength. I'd probably go this route that you listed for the prodiamine if it's possible for you to do split apps.

In many areas a single application of 330 to 750 lb/acre of this product will control the above listed weeds and goosegrass. However, under heavy goosegrass pressure and/or an extended growing season, most effective weed control can be obtained by making an initial application of 330 to 500 lb/acre followed after 60 to 90 days by a second application at doses that would not exceed those given in the Maximum Annual Rate Table.

Sorry I can't be of more help. Hopefully someone with more experience with those weeds will chime in.


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## 440mag (Jan 29, 2018)

Thanks partner! Sigh. I swear, if I could I would just do a reno but,that just is not a spice in the pie, right now! Times like these I gotta keep things in perspective and remember there are much, much worse challenges I could be dealing with First world problems, sheesh! :lol:


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## troksd (Jul 27, 2018)

Dithiopyr provides better broad leaf control. At the high rate it will last around 100 days. Prodiamine lasts up to 9 months, but provides very little broadleaf control. I would not apply both at the same time ([cough] [cough] root pruning). U could put down 5 month of Prodiamine and then at the end of the 5 months put down Dithiopyr. U are better off Putting down prodiamine + triclopyr + tenacity (and carfentrazone if U have it) now. Follow that up in mid March - April with Fusilade II + Fenoxaprop +Tenacity (This would catch a ton of grassy weeds, including some control of Dallisgrass)


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## mowww (Jan 16, 2018)

I think both prodiamine and dithiopyr are the same MOA, I'd be worried about root clubbing. Try a root and shoot inhibitor like freehand.

If worried about goose try Ron star for pre and Pylex for post. Both are unbeatable.


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## Green (Dec 24, 2017)

mowww said:


> I think both prodiamine and dithiopyr are the same MOA, I'd be worried about root clubbing. Try a root and shoot inhibitor like freehand.
> 
> If worried about goose try Ron star for pre and Pylex for post. Both are unbeatable.


I think you're essentially right, but even so, we should clarify now that Dimension is not a Dinitroanaline like Prodiamine, et. al. The exact mode of action may differ because of that. I don't know how much alternating between DNA herbicides and Dithiopyr would help prevent resistance due to that similarity, though.


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## 440mag (Jan 29, 2018)

Morning, all!

Thanks troksd: I HAD IT BACKWARDS (for some reason I thought Prodiamine was more effective on Broadleafs and Dithiopyr on grassy weeds - appreciate your getting me straight!) I have prodiamine + triclopyr + tenacity but, to my knowledge, not currently carfentrazone or Fusilade II or Fenoxaprop for that matter. Couple of years ago I'd order all 3 first things Monday morning but, my passion for jet skis and wintering in FL is putting big dents in my annual lawn scaling budget, ha-ha!

Thanks mowww, green: Geez, I think this may be the first I've heard about freehand, Ron star OR Pylex - gonna start looking for best prices on RonStar, now!

Most of all, THANK YOU to everyone that has taken the time to help me out here - gonna just go with max rate of Prodiamine and assess things when we return in late April / early May (til then, fingers crossed!)


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## cldrunner (May 14, 2019)

Table 1 of this doc has most of the Pre's and there MOA.

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


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## 440mag (Jan 29, 2018)

cldrunner, THANK YOU!

Now, THAT is an awesome reference - :thumbup:

Thanks!


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## 440mag (Jan 29, 2018)

I found this paragraph interesting:

"_Using herbicides with different MOAs separately or in tank-mixtures over the course of the same season is another good strategy. *One way to deploy different MOAs in the same year is to apply pre-emergence herbicides such as prodiamine, pendimethalin, or dithiopyr, in combination with post-emergence herbicides. This strategy for preventing resistance is common in row crop systems, because pre- and post-emergence herbicides typically have a different MOA*._"


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## cldrunner (May 14, 2019)

@440mag 
I have found deploying two MOA has stepped up my game and weeds are no longer a issue. Sure, I go through the lawn every few months and spot spray but that is all. I go cheap with Prodiamine and Simazine for the bulk of protection in liquid form. I am also using dithiopyr as well. Overall, I can treat 20,000 sq ft for less than $25 a year. Simazine has really helped me with POA issues.

I may supplement some granular Sunniland pre- emergent(Dithiopyr) that is pretty cheap at some Lowes locations.

https://www.lowes.com/pd/Sunniland-50-lb-20000-sq-ft-Crabgrass-Preventer-0-0-7/1000008818

Rotating is good. The trick for large lawn homeowners is finding a cost effective balance between liquid and granular. I would rather spend my money on weed preventer than some of the "fancy extra stuff" we have seen people pushing lately.


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## 440mag (Jan 29, 2018)

Wow, THANK YOU! I was not aware of Simazine til you mention it (I let escaping to FL, jet skiing and sporting clays distract me from checking these forums for 1/2 a year ... WHAT was I thinking?!!!!


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## 440mag (Jan 29, 2018)

Just finished reading that reference a 3rd time (bookmarked it!) and found the summary of benefit, as well ... I have always known about the necessity for avoiding resistance in using fungicides; now I see I must add pre-emergents to that category (and my annual turf budget) as well!

"*Summary*
_Using a single herbicide MOA over many years makes it likely that herbicide-resistant weeds will develop. Tank mixing or making sequential appli- cations of herbicides with different MOAs in the same season or rotating herbicide MOAs from one year to the next dramatically reduces the likeli- hood that herbicide-resistant annual bluegrass will develop.
When weeds are resistant to a certain MOA and the plan is to use only one herbicide for control,
Figure 4. The examples above indicate how a WSSA group number is displayed on the label. This makes
it easier to select herbicides with different modes of action. Group 29 indicates a product that inhibits the acetolactate synthase (ALS) enzyme. Group 2 indicates a product that inhibits cellulose biosynthesis. (These are not actual herbicide trade names and are provided for the purposes of demonstration)
future applications should rely on a different MOA. If multiple herbicides will be applied in a given sea- son, you should use at least two different MOAs.
Addressing current and potential herbicide resistance requires careful planning. If you suspect resistant plant populations, it is important to docu- ment when they emerge, where they occur, and what products have been used. Current herbicides are highly effective at very low application rates. How- ever, given these product improvements, it is increas- ingly important to carefully select the MOA or com- binations of MOAs that will best eliminate resistant biotypes and prevent new ones from developing._"


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