# Prodiamine



## Sidney (Jun 12, 2017)

Well, I guess the Prodiamine that I measured out and sprayed on my 5500 sq ft lawn didn't work. I have a ton of weeds in both the front and back lawn. I sprayed on October 8th when the ground temp was still in the mid 70's. This is the first time I sprayed Prodiamine. I think I read somewhere on this board that it usually doesn't work the first time and that I have to spray it every year. Is that true? Or should it have worked this time? I feel like I wasted several hours mixing, pumping and spraying on October 8th. So disappointed!


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## Ware (Jan 28, 2017)

It should have worked, but the longer you're on a good pre-emergent regimen the less weed seeds you'll have for potential breakthrough.

How much product did you spray? (i.e. describe your mixture)

How much rainfall or irrigation within the 2 weeks following application?


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## Sidney (Jun 12, 2017)

1.5 - 2.0 tsp per gallon of water per 1000 square feet. Watered in right away. I don't have any other notes about watering that week and I can't remember if I turned on the sprinkler system or if it rained that week.


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## Ware (Jan 28, 2017)

Sidney said:


> 1.5 - 2.0 tsp per gallon of water per 1000 square feet. Watered in right away. I don't have any other notes about watering that week and I can't remember if I turned on the sprinkler system or if it rained that week.


And just to confirm we're speaking the same language - you're using a Prodiamine 65 WDG product, right?

If so, where did you get that "1.5 - 2.0 tsp per gallon of water per 1000 square feet" rate? At first glance, that is a little alarming in itself because 2.0 tsp is 33% more product than 1.5 tsp. I would definitely strive to be much more accurate with your measurements - more on this below.

You didn't by chance pull that 1.5 tsp from the "Compatibility Test" section of the label, did you? Because I don't see teaspoon mentioned anywhere else on the label. If so, note that is a fractional rate for testing tank mixture compatibility with other products in a 1-quart jar at a 25 gal per acre (0.57 gal per thousand) spray rate:

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Without knowing more, my best advice would be to leave the measuring spoons in the kitchen and buy a gram scale. They are inexpensive. Then use Table 1 on the label to calculate your dose:

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For example - if you're not doing a split app in the fall/winter (which is fine - I don't), I would apply half the annual max for bermudagrass - which is 0.415 oz of product per thousand, or approximately 2.28 oz over your 5500 ft2. Note that is ounces weight, not ounces volume because Prodiamine 65 WDG is a dry product.

All that said, if you insist on using a volumetric conversion for the application rates listed in Table 1, I would defer to the Equivalent Measurements chart on page 4 of the label:

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It says the annual max rate for bermudagrass (0.83 oz per thousand) is approximately 2.25 tablespoons per thousand - so half the annual max would be 1.125 tablespoons.

Google says that would be 3.375 teaspoons - so my best guess is that at 1.5-2.0 teaspoons per thousand you only applied only 44-59% of what you should have - which would definitely explain breakthrough weeds here at the 3-month mark.

Hope this helps. :thumbsup:


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## mtroo (Jul 31, 2018)

@Ware I am just curious why you suggest a gram scale when Table 1 is in imperial units.


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## Ware (Jan 28, 2017)

mtroo said:


> Ware I am just curious why you suggest a gram scale when Table 1 is in imperial units.


Sorry, a "gram scale" is just a term to describe a scale that will accurately measure weights in the range we're working with. The scale I linked above will measure up to 100g, and it has 4 different weight modes (g, oz, ozt, dwt) - so you don't have to worry about conversions. For our purposes it basically has a range of 0-3.5 oz.

Here is another one that will weigh up to 7oz, and has additional modes for weighing in carats (ct) and grains (gn). It also includes a test weight to check calibration.


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## lvlikeyv (Jan 26, 2019)

This was my first year with prodiamine as well. I'm getting quite a bit of weeds (poa and henbit) too but looking back I don't think my application was very thorough and I had a moderate rain shortly after that likely reduced the efficacy. 
I have long linear streaks of weeds that look like I may have missed some areas during the application. I'm going to used a cross hatch pattern next time to ensure full coverage and watch the weather a bit closer. It's all a learning process.
I also had a fiber cable installed that undoubtedly broke the pre e barrier as I have weeds following the path of the cable. Even with the amount of weeds I have now, it's a small fraction of what I was getting before using a preemergent.


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## Sidney (Jun 12, 2017)

I guess I did use the Compatibility Test section. I didn't see the other page that you posted (Table 1: Maximum Application Rate...") on my bottle.

Oh well, it's only Winter weeds, right? I do have a gram scale, so hopefully I can get it right in April.

Thanks for you help @Ware


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## cldrunner (May 14, 2019)

lvlikeyv said:


> This was my first year with prodiamine as well. I'm getting quite a bit of weeds (poa and henbit) too but looking back I don't think my application was very thorough and I had a moderate rain shortly after that likely reduced the efficacy.
> I have long linear streaks of weeds that look like I may have missed some areas during the application. I'm going to used a cross hatch pattern next time to ensure full coverage and watch the weather a bit closer. It's all a learning process.
> I also had a fiber cable installed that undoubtedly broke the pre e barrier as I have weeds following the path of the cable. Even with the amount of weeds I have now, it's a small fraction of what I was getting before using a preemergent.


Getting rainfall right after spraying prodiamine is a "good thing". Prodiamine should be watered in for best results within 10 days according to the label. I try to water .5 to 1 inch within a day. Either sprinkler or trying to spray right before forecasted rain.


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## Ware (Jan 28, 2017)

cldrunner said:


> Getting rainfall right after spraying prodiamine is a "good thing". Prodiamine should be watered in for best results within 10 days according to the label. I try to water .5 to 1 inch within a day. Either sprinkler or trying to spray right before forecasted rain.


Yes, the label calls for at least 0.5" of rainfall or irrigation within 14 days following application. That said, a total washout would probably not be ideal.


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## SwBermuda (Jun 9, 2019)

lvlikeyv said:


> This was my first year with prodiamine as well. I'm getting quite a bit of weeds (poa and henbit) too but looking back I don't think my application was very thorough and I had a moderate rain shortly after that likely reduced the efficacy.
> I have long linear streaks of weeds that look like I may have missed some areas during the application. I'm going to used a cross hatch pattern next time to ensure full coverage and watch the weather a bit closer. It's all a learning process.
> I also had a fiber cable installed that undoubtedly broke the pre e barrier as I have weeds following the path of the cable. Even with the amount of weeds I have now, it's a small fraction of what I was getting before using a preemergent.


Just use a dye to mark where you have sprayed! I literally just did this yesterday for my prodiamine app. More or less my back yard looked like zebra stripes. The dye will really help you in terms of areas you may have missed and will show you ( in my case) how crappy you can be at liquid applications


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## lvlikeyv (Jan 26, 2019)

SwBermuda said:


> Just use a dye to mark where you have sprayed!


Agreed. I've used the marker dye before, but my sprayer was a cheap $5 pump sprayer from WM. I've upgraded a bit and need to give it a try again. I'd like to get on Ware's level with that insane sprayer cart with the wide boom! Is that home made? or did you buy it? If that's home made you should do a video on how you made it.

In terms of rain; It wasn't extremely heavy, but it was a moderate amount for over an hour. I considered it a loss when it occurred.


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## rhanna (Jun 7, 2017)

when is a good time to kill the winter weeds, like henbit? I've noticed it coming up but i dont want to spray to early


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## Ware (Jan 28, 2017)

rhanna said:


> when is a good time to kill the winter weeds, like henbit? I've noticed it coming up but i dont want to spray to early


Prodiamine will not kill anything that is actively growing. For the Henbit I would probably use something like Speed Zone. As far as killing weeds with a post-emergent herbicide - if you can see it, it's not too early to spray.


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