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Spray Calibration
Backpack / Knapsack/ Handheld Sprayer - 1/128 method
Step 1: Establish a plot that is 18.5’ × 18.5’
Step 2: Spray plot uniformly with water at a constant rate and pressure and have
someone time how long it takes, record the time it took to spray the plot.
Time required = _______seconds.
Step 3: Spray into a bucket for the above seconds.
Step 4: Measure the number of ounces of water in the bucket.
Volume sprayed = _______ounces.
Step 5: The number of ounces collected from the bucket is equal to the gallons per acre sprayer will deliver.
Gallons Per Acre = ______GPA.
Adding the correct amount of pesticide to the sprayer.
Step 6: GPA from Step 5 = ________GPA.
Step 7: Determine volume of spray tank.
Tank volume = _______gallons.
Step 8: From the label determine the amount of pesticide to apply per acre.
_________oz. Pesticide per acre rate.
Step 9: Calculate the amount of pesticide to add to the spray tank.
________oz. per acre rate × (_______gal. in tank ÷ ______GPA)
= ______________Total amount of pesticide to add to the tank.
Boom Sprayer Calibration
Step 1: Speed Determination. Ideal speed is around 4 mph.
Mph = 0.682 × (distance in ft. ÷ time in sec.)
Step 2: Boom sprayer width determination. Once desired speed is determined, spray
water at the determined speed and at spray pressure. Then measure off spray
width.
Step 3: Area spray determination.
(Spray width × 100ft) ÷ 43560 = ________of an acre.
Step 4: Time how long it takes to drive 100 ft at spray speed.
Time required = _______seconds.
Step 5: Spray into a bucket for the above seconds.
Step 6: Measure the number of ounces of water in the bucket.
Volume sprayed = _______ounces.
Step 7: Gallon Per Acre spray volume determination. Convert oz. (step 6) sprayed in
to gallons sprayed. Then determine spray volume per acre.
Gal. ÷ answer to step 3 = _______gal / acre spray volume.
Adding the correct amount of pesticide to the sprayer.
Step 6: GPA from Step 5 = ________GPA.
Step 7: Determine volume of spray tank.
Tank volume = _______gallons.
Step 8: From the label determine the amount of pesticide to apply per acre.
_________oz. Pesticide per acre rate.
Step 9: Calculate the amount of pesticide to add to the spray tank.
________oz. per acre rate × (_______gal. in tank ÷ ______GPA)
= ______________Total amount of pesticide to add to the tank.
