# calculating rates for spray chemicals



## ga_dawg (Mar 1, 2018)

I've been reading threads on thelawnforum for some time now and finally decided to join. I've read through the threads on the Bermuda Triangle, the spray wand, the teejet and some others. My questions are about making sure I get all the variables (including chemical concentration) correctly setup so I don't do damage to my lawn.

I'm getting ready to spray Celsius on my lawn to take out the broadleaf weeds that are coming in earlier this year than I expected. Based on the threads I've read I plan on using a teejet XR 11004VK tip and a 21 psi constant flow valve walking at 2mph. I believe I should apply Celsius at a rate of 1 gallon per 1000 sq ft so that's how I selected the tip and psi for the CFV. The label for Celsius has low, medium, and high application charts, what do most folks mix at? Did I interpret all of the things I've read correctly?

How about for Prodiamine or PGR? Do you always aim for a rate of 1 gallon per 1000 sq ft? The Prodiamine label seemed to be for 25gallon tanks (much bigger than my 4 gallon back pack sprayer). How do I calculate those properly? BTW I have a teejet AI11003 for Prodiamine since that's what I read in the threads. Will the same CFV work or do I need another one?

Sorry, a lot of questions in one post, but I want to make sure I get the applications correct so I don't kill the lawn. Thanks in advance for the help!


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## g-man (Jun 15, 2017)

Welcome to TLF.

Great questions. It shows that you have done your homework. The estimates for the nozzles are just estimates. The next step for you is to calibrate yourself. Aim for the 1gal/1000sqft rate.

Self calibration (one of many ways)

Measure an area of your concrete drive way (ie 1000sqft).
Fill your tank with one gallon of water and setup the wand/nozzle.
Spray your concrete at a constant walking speed with a constant nozzle height. 
At the end of the 1000area you will either still have water, ran out of water without finishing or it was perfect.
If perfect, then you are good. If too much water then repeat at a slower walking speed. Not enough water, then pick up the speed.
Repeat until you get it consistent. The concrete dries up fast so you could keep trying. Ignore the stares from the neighbors.

I personally do a practice run like this at the start of the season. The rest is just mixing the ai per 1000sqft per the product label.


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## Colonel K0rn (Jul 4, 2017)

Welcome to TLF @ga_dawg. Be sure that you calibrate your wand with your pressures and walking speed to determine how much water you spray over 1K ft. I used landscaping flags to mark off a 50 x 20 area in my back yard, and sprayed water over that area. I started off with 3 gallons of water, and walked the area, trying to maintain a comfortable walking pace, and wand height. When I was done, I had 2 gallons of water left. This tells me that at the speed I was walking, I usually use 1 gallon of water when I'm using my hand can.

Now when I'm using my battery-powered Chapin 24V sprayer, it usually puts out 1.5 gallons over 1K ft, so I have to keep that in mind when I use it for broadcast sprays, but most of the time, it's for stuff that isn't super-critical, since I haven't modified it yet to use TeeJet nozzles, but soon(TM). I calculated that I needed to mix my Prodiamine for my front yard of 5,500 sqft to be 8.25 gallons and 43g of prodiamine (converted oz to grams). This gave me enough mixed solution for the front yard, and will put me for a reapplication date of 6 months.

I guess to make the math simple, try to shoot for 1 gallon per 1K sqft. Most labels will have the oz/grams per 1K sqft, so it makes the math easier. One thing I will tell you is that Celsius is effective, it's just a slow kill in cooler weather like we've been having. I did a broadcast spray 10 days ago of Celsius + Certainty on all of the weeds that I had in my yard, and our temps have been in the high 70's, with 2-3 days in the mid 80's. We're supposed to get to 87 tomorrow. Celsius kills quicker when the weather is warmer. So don't expect a super fast kill.

I will say that the Celsius + Certainty has been effective on the poa.

Regarding PGR, start out with a lower rate, and get a feel for how your grass will respond. You don't have to soak the grass, just a fine mist will work, and you'll fall in love with the stuff. I'm telling you, after using it last year, I'm sold.


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## Ware (Jan 28, 2017)

For the Celsius, if you know what weeds you are targeting you can use the charts on the label to find the appropriate rate. Otherwise, I would use the high rate of 0.113oz per gallon to cover 1k square feet. The one gallon per thousand is not critical - the product rate (0.113oz) is. This is where your sprayer calibration becomes important. Sounds like you are on the right track with that with the tip and CF valve you have selected. You'll just want to practice spraying (with water only) a 1k square feet area until you are comfortable with how much you are spraying per thousand. Per the label, I would add a nonionic surfactant to your mix. If you don't have any, you should be able to pick some up at any farm store.

For the Prodiamine, the max annual rate for bermuda is 0.83oz per thousand. You will divide that into the number of apps you plan to make each year to achieve close to year round control. Some use 2 apps at half the annual max - some use 3-4 apps. There is a chart on the label that gives you an estimated length of control at each rate. As you're starting out, I would recommend more apps at a lower rate.

Was the AI11003 nozzle a typo? To me it would make more sense to keep the last number the same (AI11004) so that your calibration doesn't change. It's not the end of the world, but it would keep the amount of carrier (water) you need consistent from product to product, tip to tip.

Welcome to TLF, and let us know if we missed something. Looks like I type slower than these guys. :lol:


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## high leverage (Jun 11, 2017)

ga_dawg said:


> I've been reading threads on thelawnforum for some time now and finally decided to join. I've read through the threads on the Bermuda Triangle, the spray wand, the teejet and some others. My questions are about making sure I get all the variables (including chemical concentration) correctly setup so I don't do damage to my lawn.
> 
> I'm getting ready to spray Celsius on my lawn to take out the broadleaf weeds that are coming in earlier this year than I expected. Based on the threads I've read I plan on using a teejet XR 11004VK tip and a 21 psi constant flow valve walking at 2mph. I believe I should apply Celsius at a rate of 1 gallon per 1000 sq ft so that's how I selected the tip and psi for the CFV. The label for Celsius has low, medium, and high application charts, what do most folks mix at? Did I interpret all of the things I've read correctly?
> 
> ...


If you are a visual learner check out CGI Turf Services on Youtube


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## ga_dawg (Mar 1, 2018)

> For the Prodiamine, the max annual rate for bermuda is 0.83oz per thousand. You will divide that into the number of apps you plan to make each year to achieve close to year round control. Some use 2 apps at half the annual max - some use 3-4 apps. There is a chart on the label that gives you an estimated length of control at each rate. As you're starting out, I would recommend more apps at a lower rate.


Sounds like for 4 treatments a year I would mix at 0.275oz per gallon (using 1 gallon per thousand sq ft). I assume that any blue marker or surfactant I use counts are part of my carrier so I don't dilute more than desired.



> Was the AI11003 nozzle a typo? To me it would make more sense to keep the last number the same (AI11004) so that your calibration doesn't change. It's not the end of the world, but it would keep the amount of carrier (water) you need consistent from product to product, tip to tip.


No, I did get an AI11003. I'll pick up an AI11004 to keep the rate the same before I get Prodiamine out.

As others have suggested, I'll be sure to calibrate my walking speed to match the sprayer setup first.


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## Ware (Jan 28, 2017)

ga_dawg said:


> Sounds like for 4 treatments a year I would mix at 0.275oz per gallon (using 1 gallon per thousand sq ft). I assume that any blue marker or surfactant I use counts are part of my carrier so I don't dilute more than desired.


My math says 0.83 ÷ 4 = 0.2075 oz

0.275 x 4 = 1.10 oz, which would exceed the maximum annual rate by almost 33%. Looks like you just left out a zero in your post though. :thumbup:

The amount of tracking dye you add will be negligible, so I wouldn't worry about accounting for it.


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## Ware (Jan 28, 2017)

If you don't have a gram scale, I would get one. They are cheap and make accurately measuring these small quantities much easier.


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## g-man (Jun 15, 2017)

Also, there are a couple of online calculators to get grams per lawn areas. This is the one I use.

https://thelawnforum.com/viewtopic.php?t=921


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## Redtenchu (Jan 28, 2017)

ga_dawg said:


> I assume that any blue marker or surfactant I use counts are part of my carrier so I don't dilute more than desired.


The amount of Surfactant, Dye and product will be so small when mixing 3-4 gallons I wouldn't worry about subracting those from the total.


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## ga_dawg (Mar 1, 2018)

Ware said:


> My math says 0.83 ÷ 4 = 0.2075 oz
> 
> 0.275 x 4 = 1.10 oz, which would exceed the maximum annual rate by almost 33%. Looks like you just left out a zero in your post though. :thumbup:


Yep, Thanks for catching that. Typed too fast and didn't catch my typo!

Thanks for everyone's advice!


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