Typically 1lb/1000 per 1 month of coverage.

 

Doesn't the answer depend on how much prodiamine is actually on a # of product? I've never fully grasped this either, but do remember seeing something on here about how to calculate this. I think it was a post by gman if I'm not mistaken (?).

 

Following

 

It will depend on the level of prodiamine in the bag you buy. The granular bag on DoMyOwn is 0.37% ai, the bag at Yard Mastery is 0.38%, and the LESCO bags that were (still are?) on sale at Lowes, which is what I used, are 0.68%. The LESCO bag shows a table for "when is it safe to overseed in the fall after spring pre-m appication" and that's what I used for timing reference. There is also a maximum amount of product for the year, which may or may not affect your calculations. I used the five-month level, applied in early April, and will apply the remainder of the annual max sometime in late august, early september. For reference, my application rate for the five-month ended up just about 2.25# product/M.

 

If the label only gives you acres divide the lbs/acre number provided by 43.560 which will convert to lbs per thousand (there are 43,560 sq ft in an acre). As mentioned always go by the label as some products have different concentrations.

 

Can someone check my math?

According to the label Prodiamine 65WDG use .4 oz per 1000²ft which is 1.5 Level teaspoons.

I have a 2 gallon sprayer which I tested and it sprays at a rate of ~1.2 gallons per 1000²ft

So that means to get a consistent .4 oz/1000²ft spray rate --> 0.4oz * 2g /1.2g = 0.67 oz per 2 gallons

I don't have a scale, so in teaspoons that's 0.67oz * 1.5 Teaspoons / .4 oz = ~2.5 teaspoons per 2 gallons.

Sounds very low.

But if I am right just substitute your sprayer size and rate.

 

Can someone check my math?

According to the label Prodiamine 65WDG use .4 oz per 1000²ft which is 1.5 Level teaspoons.

I have a 2 gallon sprayer which I tested and it sprays at a rate of ~1.2 gallons per 1000²ft

So that means to get a consistent .4 oz/1000²ft spray rate --> 0.4oz * 2g /1.2g = 0.67 oz per 2 gallons

I don't have a scale, so in teaspoons that's 0.67oz * 1.5 Teaspoons / .4 oz = ~2.5 teaspoons per 2 gallons.

Sounds very low.

But if I am right just substitute your sprayer size and rate.

You're going about it a bit differently than most but yes, it seems 0.67oz is the amount to use in your 2-gal sprayer (if you're calibrated at 1.2gal/1000).
You can also try to speed your walk just a bit and get to 1gal/1000, which makes it a super easy calculation.

Btw, I'm getting ready to spray some myself and weighed out a tablespoon (which is 3 tspn?) and it weighs 0.32oz or 9g.

 

Great I was confident I had it, but your weighing throws a monkey wrench

Your weight: 1 Tablespoons is about 5mls, so if you get 9 grams that means its density is about 1.8g/ml, which is about the same as sand.

Label: 1.5 teaspoons is about 2.5mls and 0.4oz would be about 11 grams, so that would mean its density is 4.4g/ml which is about the same as Titanium.

The label says 65% Prodiamine, 35% other, who knows what the "other" is but it's probably more silica compounds vs heavy metals, so your weighing makes sense, while the label doesn't.

 

Great I was confident I had it, but your weighing throws a monkey wrench

Your weight: 1 Tablespoons is about 5mls, so if you get 9 grams that means its density is about 1.8g/ml, which is about the same as sand.

Label: 1.5 teaspoons is about 2.5mls and 0.4oz would be about 11 grams, so that would mean its density is 4.4g/ml which is about the same as Titanium.

The label says 65% Prodiamine, 35% other, who knows what the "other" is but it's probably more silica compounds vs heavy metals, so your weighing makes sense, while the label doesn't.

You totally belong at TLF with that level of analysis! 😝
..and we're totally hijacked this thread as well. 🙊

 

It is dry oz not liquid oz. The math is easier in grams. I use 5g/ksqft for ~3month coverage.

It is a very tiny amount.

 

Build it into a spreadsheet. # prodiamine per acre = H2*0.0068*43560/6500 where H2 = pounds applied., 0.0068 is % lesco prodiamine, acre sq ft/sq ft of my lawn. Gives me my target of 0.80# per acre. 6 months control. I applied 17.6#.

 

It's easier for me to measure volume than weight. I did the math a few years ago, and came up with 2 tsp/ksqft. That's what I've been using, and I am happy with the results.

 

Typically 1lb/1000 per 1 month of coverage.

I'm a newbie here, but that seems wayyyyyyyyy off compared to everyone else's recommendation. Can this be explained better or edited so guys like me are led in the correct direction? I'm not picking on @PodScot fwiw, just trying to understand the numbers here cause I just used 8 Oz (weight) for 21,000 sq/ft...
For all I know, I'M WAYYYYYYYYY off. 😂

Thanks

 

Typically 1lb/1000 per 1 month of coverage.

I'm a newbie here, but that seems wayyyyyyyyy off compared to everyone else's recommendation. Can this be explained better or edited so guys like me are led in the correct direction? I'm not picking on @PodScot fwiw, just trying to understand the numbers here cause I just used 8 Oz (weight) for 21,000 sq/ft...
For all I know, I'M WAYYYYYYYYY off. 😂

Thanks

I think the OP is referring to the 50# bags. Granules does make you think the jug though.

 

Typically 1lb/1000 per 1 month of coverage.

I'm a newbie here, but that seems wayyyyyyyyy off compared to everyone else's recommendation. Can this be explained better or edited so guys like me are led in the correct direction? I'm not picking on @PodScot fwiw, just trying to understand the numbers here cause I just used 8 Oz (weight) for 21,000 sq/ft...
For all I know, I'M WAYYYYYYYYY off. 😂

Thanks

He was responding to the OP who was asking about granular (ie Spreadable) Prodiamine, the kind you buy at the big box stores. At least that was my original impression. WDG (wet table dispersible granule) is the one you put in water & dilute, weighed to the gram. I think we've conflated the two. 🤷🏻‍♂️

Edit: I see pennstater has the same impression as I, and is quicker on the trigger.

 

Ok. Thanks for the clarification.