oz. per acre vs. oz. per gallon confusion

[Ruark]

Almost all of my herbicide spraying is done with a hand sprayer. For example, I'll have a 20 gallon tank in the back of the truck, clipped to a 12V battery, and a 50 foot hose. I'll park the truck in an appropriate spot and spray weeds and brush within reach of the hose. A lot of it is simply spraying individual plants, one at a time. Much of my property just isn't accessible to a boom sprayer.

In some places, e.g. a small clearing, I even use a little 3-gallon pump sprayer.

My issue is that with a lot of chemicals, the instructions are written in terms of "ounces per acre" for different plants. For this plant, it's 8.4 oz/acre. For that plant, over 12" tall, it's 13.5 oz/acre. And so on.

I have a heck of a time calculating these amounts to fit my hand sprayers. What I really need is an "ounces per gallon" measurement. Is there a quick-and-dirty way to convert "17.3 ounces per acre" to "ounces per gallon"? Remember, I'm not really area-spraying, I'm spraying individual plants or clusters of plants. I'd appreciate some help.

Thanks

 

[JSCATTLE]

Find out how many gallons of water per acre usually its 20 gal per acre . then do the math .

 

[Angus Cowman]

Find out how many gallons of water per acre usually its 20 gal per acre . then do the math .

:nod: :nod:
so if it calls for 17.3 oz pr acre then you divide 17.3 by 20 and you get .865 oz pr gallon so in a 3 gal sprayer you would use 2.5oz

 

[novatech]

Couldn't you spray a 218 square feet, which is 1/200 th of an acre.
Measure the amount of water sprayed, say .5 gallons.
.5 gallons X 200 = 100 gallons per acre.
At 13.5 oz.per 100 gallons
Your 20 gallon sprayer is 20% of 100 so 20% of 13.5 is2.7 oz per 20 gallon tank.
I think I did the math correctly but some may want to correct me.

 

[JSCATTLE]

Couldn't you spray a 218 square feet, which is 1/200 th of an acre.
Measure the amount of water sprayed, say .5 gallons.
.5 gallons X 200 = 100 gallons per acre.
At 13.5 oz.per 100 gallons
Your 20 gallon sprayer is 20% of 100 so 20% of 13.5 is2.7 oz per 20 gallon tank.
I think I did the math correctly but some may want to correct me.

Angus did the math correctly. If you use the dilution rate . Grazon for instance is 20 gallons of water per acre . If you dilute the chemical to 100 gal of water per acre rate it will not be affective .

 

[novatech]

Couldn't you spray a 218 square feet, which is 1/200 th of an acre.
Measure the amount of water sprayed, say .5 gallons.
.5 gallons X 200 = 100 gallons per acre.
At 13.5 oz.per 100 gallons
Your 20 gallon sprayer is 20% of 100 so 20% of 13.5 is2.7 oz per 20 gallon tank.
I think I did the math correctly but some may want to correct me.

Angus did the math right . You have to use the dilution rate . Grazon for instance is 20 gallons of water per acre . Not how much water your sprayer will spray per acre . You have to calibrate your big sprayer to spray 20 gal per acre .

Sorry I have never been able to make the tractor go the proper ground speed matching the the number of heads and the pressure needed. Every formula I have ever used measures ground speed and amount sprayed per head and width of sprayer. The oz. per acre are based on what the sprayer puts out at the ground speed being used at the time. The gallons suggested by manufacturers are suggested. You still calibrate by measuring reality. The numbers i used were to show the math not intended to be taken as actual.
http://msuextension.org/publications/Ag ... 0915AG.pdf
Please advise me as to how to calibrate a hand sprayer to put out 20 gallons an acre. You going to run or walk. It is a heck of a lot easier to find out how much you are putting out than try and adjust your walking speed to equal the precise gallons recomended.
Maybe that is what you will put out but how do you know until you do it?

 

[JSCATTLE]

When I calibrated my 200 gallon sprayer I marked off 1 acre square . Put 20 gallons of water in the tank and started spraying . Took me 4 times to get it to where 20 gallons was gone at the same time the acre was covered . I wrote down ground speed pressure and tractor rpms. As far as the 20 gallon sprayer goes .he ask how to figure the amount of chemical not how to spray at the correct rate.

 

[novatech]

When I calibrated my 200 gallon sprayer I marked off 1 acre square . Put 20 gallons of water in the tank and started spraying . Took me 4 times to get it to where 20 gallons was gone at the same time the acre was covered . I wrote down ground speed pressure and tractor rpms. As far as the 20 gallon sprayer goes .he ask how to figure the amount of chemical not how to spray at the correct rate.

I understand that works on your pasture. My pastures ground conditions change from pasture to pasture. This means the ground speed will change.

so if it calls for 17.3 oz pr acre then you divide 17.3 by 20 and you get .865 oz pr gallon so in a 3 gal sprayer you would use 2.5oz

Where does the acres covered come into play? How much is the hand spray putting out. You have no idea what tip is on it. No idea how fast or slow he is going. It took you 4 times with a tractor to get it right with controllable equipment. If he marks off a given area and sprays water then he knows or at least gets some idea. Please Google calibrating a sprayer and show me where it advises doing it the way you do. I have never herd of it. I'm not saying it won't work just a heck of a lot of trouble.
By the way the amount of water to be used is from 10 to 40 gallons per acre. as per specimen label for Grazon P & D which I use ever year and have been for many years.

 

[wbvs58]

If a concentration for spot spraying is not given, it is a bit of a guess. Most spot spraying is done to point of runoff. The concentration of spray should be to kill the target plant but not surrounding non target plants. If no rate is given by manufacturer, it is a bit of a problem. I don't think any of the calculations given so far answer the question, only a starting point to try.
I think contacting the manufacturer and asking for a rate would be the only way and even they may be stumped, saying their product is only made for broadacre, boomspray use.
Ken

 

[JSCATTLE]

You still don't understand the original post . He said how do you figure oz. For a small sprayer when everything is in oz. Per acre . In order to find oz. Per gallon you first have to have the dilution rate of the chemical . Ie x amount of chemical per acre / diluted in say 20 gallons of water. It's impossible to calibrate a hand sprayer. And if you figure your chemical wrong you could kill non Target species . Or worse loose your herbicide licence because you are putting out more than you are supposed to . U can use the calibration charts on the net if you want to do it that way . I never tried to tell him how to calibrate his sprayer . I just told him how to find the oz. Per gallon rate . Your the one that brought up calibration .

 

[Ruark]

If a concentration for spot spraying is not given, it is a bit of a guess.

EXACTLY. Again, I'm talking about strolling around with a little pump sprayer or 15 gallon sprayer and spraying spots or individual plants, not "X square feet." Like, I see 3 or 4 horseweeds sticking up over there..... squirt, squirt.

 

[Angus Cowman]

If a concentration for spot spraying is not given, it is a bit of a guess.

EXACTLY. Again, I'm talking about strolling around with a little pump sprayer or 15 gallon sprayer and spraying spots or individual plants, not "X square feet." Like, I see 3 or 4 horseweeds sticking up over there..... squirt, squirt.

Yes it is a guesstimate but what you asked for was how to figure oz pr gallon instead of oz pr acre and what JS and I told you was a way to figure oz pr gallon
if you are so concerned about putting too much on then I don't know what to tell you
JS and I answer your question
Also JS and I are in the U.S.A and our restrictions and applications vary greatly from what WBVS58 has to deal with in Australia or our friends north of the Border in Canada

 

[novatech]

If a concentration for spot spraying is not given, it is a bit of a guess.

EXACTLY. Again, I'm talking about strolling around with a little pump sprayer or 15 gallon sprayer and spraying spots or individual plants, not "X square feet." Like, I see 3 or 4 horseweeds sticking up over there..... squirt, squirt.

Like you I have done the squirt, squirt. You still need to calibrate properly. Not enough you don't kill the weed. To much the leaves fall of but the herbicide does not have time to get to the roots. It has nothing to do wit what country you live in. Read the specimen label, it gives different rates for different weeds at different stages of growth.
http://www.exnet.iastate.edu/Publications/PM1271.pdf
http://commodities.caes.uga.edu/turfgra ... KCALIB.htm
http://lancaster.unl.edu/ag/factsheets/handspray.pdf
http://salinespringsconservation.files. ... ation3.pdf
It makes no difference wither your are spot spraying or continuous spraying. The calibration is done the same way.
The reason they make people get licenses is so they will not guess.
Don't believe me google it yourself. Cut and paste "calibrating pump up sprayers for spot spraying"
I don't believe you will find anyone advising you to guess.

 

[inbredredneck]

What is the name of the weed spray that you is tryin to spray?

 

[piedmontese]

well if the rates are different for different weeds what do u do when u got a bunch of different weeds in your pasture? walk around all day with a calculator and recalculate for every type of weed? sometimes people make things way too difficult.

 

[Ruark]

With spot spraying, you are really saturating the target plants much more than you do when you spray a field. In this case, you are likely applying more than the "per acre" amount. Since you are spraying such a TINY area (e.g. a single plant) and there are so many factors, it isn't really practical to calculate things on a per acre basis.

 

[novatech]

well if the rates are different for different weeds what do u do when u got a bunch of different weeds in your pasture? walk around all day with a calculator and recalculate for every type of weed? sometimes people make things way too difficult.

Most weeds can be handled with the same rate especially at the early growth stage. I spray for what I have most of. Anything that does not die gets taken care of later with the herbicide and rate designed to kill it. There are other weeds that cannot be killed unless done seperatly and at the proper time or growth stage. Calibrating a sprayer is not rocket science. It is easy and takes very little time. Proper calibration makes more efficient use of your time and herbicide. With a pump up sprayer, or any other hand held sprayer, you only have to find out the amount being sprayed one time unless you change nozzles. Once you know how much water it sprays per acre then you calculate the amount of concentrate to mix in with it for any type you want to use. For each type write it down and you never have to do it again with that sprayer.
It totally amazes me that people don,t do the research. The answers all all there on the Internet. If you have an argument as to what I am saying, back up your argument. Show me I will stand corrected. It would not be the first time.

 

[novatech]

With spot spraying, you are really saturating the target plants much more than you do when you spray a field. In this case, you are likely applying more than the "per acre" amount. Since you are spraying such a TINY area (e.g. a single plant) and there are so many factors, it isn't really practical to calculate things on a per acre basis.

Spray the market off area the same way you would spray when actually applying the herbicide.
If you are agreeing with guessing at the amount to add then why did you ask the question?
Please inform me how mixing up 20 gallons diluted spray is anywhere close to the proper dilution rate. When spot spraying how are you going to know when you have covered 1 acre.
The amount of time I have spent on here trying to inform you how to do it right is far greater than the time it would take you to mark off an area, spray, do the math, and mix at the proper rate.
Did you bother to goggle up any of the sites I posted?
I have done nothing but take my time and inform you how to do this more accurately. But your opinion is the guess will work better, despite the math. :bang:

 

[Ruark]

Yes, I googled those sites, and see how that calculation can work. The only problem I might have is your comment, "Spray the market off area the same way you would spray when actually applying the herbicide." That's a highly variable activity, when the way you would "actually apply" the herbicide is to spray an individual plant or cluster of plants until it is drenched. But I'll look at it. I apologize for annoying you.

 

[novatech]

Yes, I googled those sites, and see how that calculation can work. The only problem I might have is your comment, "Spray the market off area the same way you would spray when actually applying the herbicide." That's a highly variable activity, when the way you would "actually apply" the herbicide is to spray an individual plant or cluster of plants until it is drenched. But I'll look at it. I apologize for annoying you.

If I seem annoyed I apologize. Frustrated maybe. But I attribute that to my lack of skill in communication.The way they recommend is to spray as if it were a boom sprayer. When you spray make sure you are getting good leaf coverage. Any more is a waste. I had the same habit until I looked at my herbicide bill. That is all that is necessary on most weeds. Brush can be a different story ( huisache is sprayed at 1% grazon pd.). I boom spray my hay fields but in pastures I use hand held wand sprayers, sometimes electric tank and sometimes backpack, for thicker areas of weeds. I do not enjoy walking around in 100 degree heat so I try and do it right the first time. Sometimes doing it right means less chemical. Proper calibration and timing result in a better, more economical, and time saving kill.
A single outlet pump up or hand held electric is nothing more than a boom sprayer with only one nozzel. The chemical should be applied the same way. How you apply is as important as how much. You spray one individual plant the same way you would spray a row or group.