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Calibration

How much pesticide do I add to the tank?

• Gallons per acre or GPA

• How many acres can we spray with a certain volume

• What is the labeled rate

• Dose calculation (how much do I add to the tank)

• Calibration Strip Method

• Single Nozzle Method

• 128th acre method

But first….Determining GPA

with a backpack or hand sprayer 18 ½ feet

18 ½feet

Backpack - GPA

• 18 ½ x 18 ½ foot square

• Spray & time yourself

• Spray into bucket

• Collect in Ounces

• Ounces = GPA

• Why does this work?

Backpack GPAExample

• Sprayed calibration square and it took 45 seconds

• Sprayed into bucket for 45 seconds and collected 64 ounces

• GPA = 64

Calibration Strip Method

• Take a small area and relate it to an acre

• Need to know area of small area (calibration strip)

• Amount of liquid sprayed over strip

• Number of strips in an acre

• One acre = 43,560 ft2

Calibration Strip Method

• 66 feet (swath) x 66 feet (calibration strip)• = 4,356 ft2

• 43,560 ft2 = 10 strips

4,356 ft2

• 3 gallons per strip• 10 strips x 3 gal/strip• GPA = 30

Boom Sprayers• No matter what method of

calibration is used, you need to….– check nozzle spacing

– check output across the boom.

Checking Nozzle Spacing & Height

Nozzle Orientation

Nozzle output

Checking Nozzle Output

20”

Remember!Check Nozzle Spacing

Then……

51 oz 50 oz 42 oz

Check Nozzle Output!

Output should be within 10% of the average of all the nozzles

• Nozzle 1 = 51 oz• Nozzle 2 = 50 oz• Nozzle 3 = 42 oz 143 oz

143 oz 3 = 48 oz 4.8 or 5

43………48……..53 maybe 45½…48….50 ½ Check Nozzle # 3 Check Nozzle 1& 3 Recheck Recheck

10% 10%

10%

Nozzles Output in Ounces 21 Seconds

1. 14.0

2. 13.0 ***** 3. 16.0 4. 15.0 5. 15.0 6. 15.0 7. 14.0 8. 15.0 9. 16.0 10. 16.0 149.0

Average = 14.9 or 15 ounces

+10% = 16.5 ounces -10% = 13.5 ounces

Boom Sprayer Calibration Strip Method

• Need swath width (W)

• Course length (L)

• Number of strips in one acre

43,560 ft2

L x

W

Amount of liquid applied per strip

Using test strip

Collect from each nozzle using test strip time.

Figure your GPA• Example:

– Swath width is 35 ft– Course length is 200 ft– Calibration strip = 7,000 ft2 (35 x 200)– There are 6.22 strips in one acre (43560 ÷ 7000)– You collect from all the nozzle into one bucket

• 4 gallons

– 6.22 x 4 = 24.88 or 25 GPA

Broadjet

34

100 43560 = 12.8 3400

0.5 gin 13 sec.

12.8 x 0.5 g = 6.4 GPA

Boom-GPA

15 ounces = 15 GPA

Check the label

May be too low.

How many acres can you spray.

Volume used

GPA

How many acres can you spray - Example

• Have a 1000 gallon tank. Only want to apply 500 gallons.

• GPA = 25• 500 gallons = 20 acres 25 GPA• Backpack 5 gallons = 0.078 acres 64 GPA

Acres - Example 2

• Suppose you only want to spray 10 acres.

• GPA = 25 (25 GPA)

• 25 GPA x 10 acres = 250 gallons

Dosage Determination

• Listed rate per acre …Read the label

• Lbs. of a.i. per acre– Liquid – % W.P.

Listed Rate Per Acre

• Acres x labeled rate = dose

• 10 acres x 1 pint/acre = 10 pints in a given volume– 300 gallon mix = 10 acres

30 GPA– 10 pints of product to make a 300 gallon mix.

Pounds per Acre - LiquidExample – 1 lb of a.i. is recommended per acre

1 gal. Formulation x 1 lb a.i = 0.5 x 1 = 0.5 gal formulation/acre

2 lb a.i. Acre

Rate = 1 = 0.5 gallons formulation/acre

Lbs. a.i./gallon 2

Dry Formulations• 2 lbs per acre of an 80% WP is prescribed

1 lb formulation x 2 lb a.i. = 2.5 lbs formulation/acre

0.80 lb a.i. Acre

Rate per acre = 2 lb a.i. = 2.5 lbs

% a.i. 0.80

How much product to add to tank.

• Rate/acres x acres treated

• Example:

1 pt/acre x 10 acres = 10 pints.

• Backpack 0.078 acres x 16 oz. = 1.2 oz.

Boom Sprayer GPA128th Acre Method

• Measure distance between nozzles.• Use chart for test course distance. • Nozzle output must be close to uniform• Ounces collected from one nozzle = GPA

Nozzle spacing (in.) Test Strip (ft) 20 204 * *340 ÷ spacing (ft)

30 136 36 113 38 107 40 102

Broadjet -= 128th Acre Method

• Measure swath width• Set calibration course Swath width Course length 35 156 * *5460 ÷ W (ft)

40 136 45 121

• Time yourself• Collect for same time• Pints collected = GPA