Midwest Vegetable Guide - 2022 - 42

Pesticide Application and Safety
5. Adjust each setting, and recalibrate until the desired
delivery rate is obtained.
Sprayers
Sprayers use a pump mechanism that runs independently
from the tractor wheels, or your legs. They are often powered
hydraulically, electrically, or through a hand pump or the
tractor PTO. If the pressure remains constant, then halving
ground speed will double output, and doubling ground
speed will halve output. If ground speed remains constant,
then quadrupling pressure will double output, and
quartering pressure will halve output.
Boom sprayers apply a sheet-like mist along the length of the
boom, band sprayers apply a narrow band over a row with
one or more nozzles grouped together, wand sprayers have
one nozzle used for small or irregular shaped targets, and
airblast sprayers generate a high-speed directional fog.
Here are suggested steps to calibrating selected sprayers.
Once output is found in gallons per acre, calculate acres per
tankful of spray solution by dividing gallons per tank by
gallons per acre of output, and determine the required amount
of product to dilute in the tank by multiplying acres per
tankful by the rate per acre of product.
Boom Sprayer Calibration
For effective applications, make sure to calibrate boom
sprayers carefully. To calibrate a boom sprayer:
1. Fill tank with water.
2. Adjust spray pressure and speed of tractor for nozzle size
and output using manufacturer's directions.
3. Spray 1/4 acre (10,890 sq. ft.). Distance of travel will
vary with boom width.
For example, a 22-foot boom must travel 495 feet to
cover 1/4 acre:
1/4 acre (10,890 sq. ft.)
boom width (22 ft.)
=
distance of travel
(495 ft.)
4. Measure amount of water needed to refill the tank. This
amount was applied to the 1/4 acre; thus, four times this
amount is the gallonage per acre.
Band Sprayer Calibration
1. Fill tank with water.
2. Adjust spray pressure and speed of tractor for nozzle size
and output using manufacturer's directions.
3. Spray 1/4 acre (10,890 sq. ft.). Distance traveled will
vary with number of nozzles on the sprayer and width of
the band sprayed by each nozzle.
For example, spraying a 20-inch band over 4 rows using
1 nozzle per row requires 1,630 ft. to cover 1/4 acre:
42
Midwest Veg Guide 2022
1/4 acre (10,890 sq. ft.)
band width (1.67 ft.)
÷
number of
nozzles (4)
=
distance of travel
(1,630 ft.)
4. Measure amount of water needed to refill the tank. This
amount was applied to the 1/4 acre; thus, four times this
amount is the gallonage per acre.
Wand Sprayer Calibration
1. Fill tank with water.
2. Spray 1/128 acre (340 sq ft.) with the pace and nozzle
distance you would be using for application.
3. Measure amount of water needed to refill the tank. This
amount was applied to the 1/128 acre; thus, the number
of fl. oz. required to refill the sprayer is equal to
gallonage per acre.
4. Calculate acres per tankful of spray solution by dividing
gallons per tank by gallons per acre of output, and
determine the required amount of product to the tank by
multiplying acres per tankful by the rate per acre of
product recommended.
Airblast Sprayer Calibration
1. Fill tank with water.
2. Adjust spray pressure and speed of tractor for nozzle size
and output using manufacturer's directions.
3. Spray 164 ft., measure the time to complete the course,
and measure the effective spray swath. For a
unidirectional unit, measure the swath from the sprayer
to the end of the deposition cloud. For a bidirectional
unit, measure the swath from one end to the other end of
the deposition cloud. Do this three times to calculate the
average time to travel 164 ft, and spray swath. Record
speed and PTO speed or pressure settings for future
reference.
4. Measure amount of water needed to refill the tank. This
amount was applied to the fraction of an acre; thus, four
times this amount is the gallonage per acre.
For example, spraying a 10 ft. swath over a164 ft course
used 2 gallons. The gallons per acre is calculated this
way:
1 acre
volume measured
(2 gal.)
x
43,560 sq. ft.
area of swath
(10 ft. x 164 ft.
=
output
(53 gal/ac.)
Midwest Vegetable Guide - 2022

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