Advanced Sprayer Workshop 2012 by Jason Deveau

Contents
Learning Goals
Page 2
Why, When and Where to Calibrate
Page 3
Pre-Calibration Inspection
Page 4
Adjust the Air-Stream Direction
Page 6
Tower Power
Page 7
Confirm Sprayer Pressure
Page 8
Calibrate Travel Speed
Page 9
Nozzle Positions – On or Off?
Page 10
Crop-Adapted Spraying
Page 11
Determine Ideal Sprayer Output
Tree-Row Volume
Page 12
Coverage Constant and Tree Shape
Page 13
Canopy Density
Page 14
Ideal Output
Page 15
Calculate Sprayer Output for Each Side
Page 16
Determine Spray Distribution over Boom
Page 17
Match Spray Output to the Crop Stage
Page 18
Select Nozzles
Page 19
Confirm Nozzle and Sprayer Output
Page 20
Venturi Nozzles
Page 22
Confirm Coverage with Water- and Oil-Sensitive Paper
Page 23
About Advanced Sprayer Techniques 2012
Page 24
Advanced Sprayer Techniques
Page 1
Learning Goals
Upon completing this workshop, spray operators will be better able to:
1. Calibrate their airblast sprayers.
2. Optimize their airblast sprayer settings to the size, shape and density of their trees
for the best performance.
3. Confirm sprayer performance using water- and oil-sensitive paper.
4. Be able to perform the “Gear Up, Throttle Down™” method for reducing fuel
consumption and reducing fan speed for early season applications.
Spraying has changed a lot since 1910. There’s always more to learn.
Advanced Sprayer Techniques
Page 2
Why, When and Where to Calibrate
Why to calibrate
Calibration is essential because it:
•
confirms the sprayer is operating
correctly;
•
confirms each nozzle is delivering the
desired output and spray quality;
•
ensures the correct product rate (e.g. litres
per hectare) is applied;
•
reduces product wastage and
environmental impact.
A nasty HSS whirl plate (credit: H. Zhu)
When to calibrate
Product rates and sprayer output requirements change depending on the crop type, the
plant spacing and the crop and pest staging. Therefore, calibrate for each significantly
different situation. An airblast sprayer should be calibrated:
•
at the beginning of each season;
•
mid-way through the each season as crops grow and fill in; and
•
after changes to application equipment or settings (e.g. nozzles, operating
pressure, pump, tractor or tractor wheels).
Where to calibrate
Sprayers should be calibrated in the planting that you intend to spray, so do it in the
vineyard, nursery or orchard. Calibrating a sprayer on a hard surface (such as pavement)
can induce errors as high as 15% compared to calibrating in the planting because sprayers
move more slowly on soft ground. Calibrate away from buildings and wells.
Advanced Sprayer Techniques
Page 3
Pre-Calibration Inspection
Always wear suitable personal protective equipment. Fill the decontaminated sprayer
half full of clean water and park it on level ground. Perform the following:
•
Ensure all hoses and fittings are sound while under pressure.
•
Ensure all filters, screens, strainers and nozzles are clean.
•
Ensure tire pressure (tractor and sprayer) is correct.
•
Ensure universal joints, sprayer-tractor hitch and all connections are clean,
lubricated and secure.
For PTO-driven sprayers, start the pump and set tractor engine speed to the desired
rpm’s. Open the manifold valve to fill the lines to begin spraying. Adjust the pressure
regulator, or set the main by-pass, to obtain the desired operating pressure. Perform the
following steps:
•
Check that each nozzle shut-off valve or nozzle body flip position is working.
•
Check that the agitation system is functioning properly.
•
Search for and correct any leaks while under pressure.
A nasty ceramic disc-core – core is completely plugged (credit: H. Zhu)
Advanced Sprayer Techniques
Page 4
Pre-Calibration Checklist and Helpful Conversions
Inspection Checklist
(Feel free to create your own to fit your sprayer)
Pump and Lines
Valves, Diaphragms and/or Plungers
Checked/Replaced
All Hoses and Fittings Sound (while
under pressure)
Pump Flushed and Spray Discharge
Clear
Pump Lubricated
Strainers and Nozzles
All Strainers from Tank Opening to
All Nozzles Clean and Unbroken
Each Nozzle Shut-off Working
Nozzle Strainers Clean and Unbroken
Check valve diaphragms clean and functional
Regulators and Gauges
All Gauges True
Regulator(s) and/or Bypass Valve(s)
Move Easily
Belts and Power Take Off
All Belts have Proper Tension and No
Wear
PTO Greased, Connection Zones
Checked and Guard in Place
Propeller and Agitation
Propeller has no Nicks or Cracks or
Residue and does not have any
Lateral Play
Jets Oriented to Scrub Bottom of Tank
OR Propellers Secure, Shaft Greased
and Packing Tight (No Leaks)
Airflow and Direction
Volutes or Deflectors Adjusted to
Steer Air into Canopy
Air Reduced in Early Season Through
Lower RPMs and Low Gear
Spray Pressure Adjustment
Sprayer Pressure Set to Desired
Pressure
Ribbons Used to Determine Which
Nozzles Should be Active
Each Boom Operating at Desired
Pressure
Metric / Imperial Conversions
1.0 L
1.0 L
1.0 m
1.0 ha
= 0.264 U.S. gal (most common in catalogues)
= 0.22 Imperial gal
1.0 km/h = 0.62 mph
= 39.4 in
1.0 L/ha = 0.106 US gal./ac
= 2.47 ac
1.0 L/ha = 0.09 Imperial gal/ac
Advanced Sprayer Techniques
Page 5
Adjust the Air Stream Direction
Adjust the Air Stream Direction
The air stream created by the sprayer
fan carries the spray mixture into the
target (e.g. tree, bush, shrub, vine,
etc.) and distributes it throughout the
foliage. To reach all leaf surfaces
and achieve adequate pesticide
coverage, all of the air in and around
the foliage must be replaced by the
spray-laden air-stream.
The air stream direction, or angle of attack to the foliage, is equally important. Research
has shown that radial fans skew the air coming out of the sprayer – it goes up on one
side and down on the other. This can have a negative impact when spraying berries or
grapes and it should be corrected. Here’s how you can see what’s happening:
•
Park the sprayer in the alley between the crops.
•
Tie short lengths of ribbon (i.e. 45 cm or 18 in) to the nozzle bodies and onto the
ends of deflectors (if present) and turn on the air. Beware the fan intake – long
ribbons might get sucked in.
•
Adjust outlets and/or deflectors to aim air into the canopy, just over and just
beneath it.
•
This should be performed for EACH significantly different crop sprayed with the
sprayer. Multiple set-ups might be needed for really diverse plantings.
Strong ribbons
will show where
air and spray is
going. Use your
deflectors to
adjust.
Advanced Sprayer Techniques
Page 6
Tower Power
Spray towers are a means to get air and nozzles closer to the target. When you reduce the
distance-to-target, you reduce the chance of wind, evaporation and drag from stealing the
product before it gets to the plant; that means less pesticide drift and more deposit in the
canopy. Many growers report that towers are so efficient that they have reduced
their sprayer output because their old volumes were drenching the targets!
Towers are not for all
situations. They must be:
•
taller than the highest
target (e.g. tree), and
•
used on level ground, or
the tower will tip and
yaw, potentially
missing or overshooting targets.
The ribbon-indicator trick can
be used with towers, too. Drill
a 1/8 inch hole in the end of
each deflector and tie on the
ribbons. If any ribbons are
wavering from lack of air,
compensate by re-positioning
neighbouring deflectors. This
may result in surprising
positioning, but it will create a
more consistent overall air
output.
The perils of tower sprayers on uneven ground.
Another reason for considering
towers is that nozzles are often
better positioned to penetrate
the tree canopy. This depends
on how the branches grow and
are pruned, of course.
Spray from towers often aligns with branches, improving spray
penetration. Concept from K. Blagborne, Slimline Manufacturing Ltd.
Advanced Sprayer Techniques
Page 7
Confirm Sprayer Pressure
To confirm that the main pressure gauge is accurate, install a second oil-filled gauge
in-line beside the main pressure gauge. This may not be possible with all sprayers.
Two gauges keep each other honest – this home-made assembly costs ~$25.
Pressure in the booms is often less than the desired operating pressure:
•
Install an oil-filled pressure gauge in
the last nozzle position of one of the
two booms. The nozzle cap or entire
nozzle body may need to be removed
for this step. Fittings are easily
obtained to match metric or imperial
threads.
•
Turn on the spray and compare boom
pressure to desired pressure. All
nozzles should be open during the
test, so only spray clean water from a
decontaminated sprayer.
•
Adjust the main pressure regulator
until the desired boom operating
pressure is reached.
Advanced Sprayer Techniques
There are many ways to install a gauge onto a
nozzle body. Here are three.
Page 8
Calibrate Travel Speed
Travel speed must be slow enough to allow the air-stream to completely replace the
air in the canopy. Too slow a travel speed prolongs the operation and blows spray
through the canopy, missing the target and increasing wastage.
In most operations, this will generally be about 5 km/h (~3.1 mph).
For those without global positioning equipment, you have to calibrate travel speed to
account for speedometer errors due to wheel size, wheel wear or slippage. It is
important to perform this step in the field in typical weather conditions so it accounts
for soil type, slope of terrain and the average weight of sprayer:
•
•
•
•
•
•
•
Measure out a distance of 50.0 m and mark the start and finish positions with
stakes or wire marker flags. The course should be level.
Fill the sprayer tank half full of clean water.
Select the gear and engine speed in which you intend to spray. Be sure that the
blower is going without discharging spray.
Bring the sprayer up to speed and begin timing as the front wheel passes the first
flag (Easier when there are two people).
Stop the timer as the front wheel passes the second flag.
Stay out of any ruts and run the course two more times.
Determine the average time for the three runs (see example).
Calculate travel speed using one of the following formulae, depending on preferred
units:
Travel Speed
(km/h)
=
50 metres x 3.6
Average drive time in seconds
Travel Speed
(mph)
=
50 metres x 2.2
Average drive time in seconds
Advanced Sprayer Techniques
Page 9
Nozzle Positions – On or Off?
Once the air has been adjusted and
deflectors set, it is time to decide which
nozzles should be on or off. This will
depend on the height of the crop, the angle
of the spray (e.g. hollow cones generally
produce an 80º cone), and the nature of the
nozzle body: some nozzle bodies can be
swiveled up or down a few degrees to
adjust the spray angle. Be careful not to
swivel nozzle bodies too far or the valve
will close and the nozzle won’t operate.
Spray distribution across the boom, and
overall output, should be adjusted twice a
year to ensure the sprayer will uniformly
cover the target with the optimal volume.
This accounts for both canopy growth and
fruit set.
For example, apples will cause boughs to
hang low and will require a different spray
distribution.
Grape
growers
will
eventually adjust the spray to focus on the
fruit, not the foliage. Be aware that
Turn off nozzles and adjust deflectors to just
multiple crops will require multiple
overshoot the top and bottom of the canopy. Don’t spray
settings – one size does not fit all!
the ground – that’s not what you’re trying to protect!
(Top picture: bad. Bottom picture: good!)
Homemade deflectors
on this FMC® sprayer
greatly improved
performance.
Advanced Sprayer Techniques
Page 10
Crop-Adapted Spraying
Crop-Adapted Spray Calculator – 3 years of testing and counting…
The following steps can easily be done on paper with a calculator. But, try this new
tool which can tell you so much more, including:
• how many tanks,
• how much pesticide per tank (including the last, partial tank),
• how long the job will take,
• how fast to drive,
• which nozzle rates to put where, and
All this, and it gives you a hardcopy and digital spray record afterwards.
Advanced Sprayer Techniques
Page 11
Determine Ideal Sprayer Output
Step 1 – Calculate Tree-Row Volume (TRV)
Multiply the canopy width (drip-line to drip-line) by the tree height, by the area of a
hectare (a constant) and divide by the total row spacing.
“Calculating Tree-Row Volume”
A
Canopy
Width
(m)
6.0
x
B
Tree
Height
(m)
4.5
x
C
Hectare
Area
(m2)
10,000
÷
D
Row
Spacing
(m)
9.0
=
A x B x (C ÷ D)
Tree Row
Volume
(m3/ha)
30,000.0
In the case of inter-cropped varieties or mixed-size plantings, err on the side of caution
and use the largest trees to calculate Tree-Row Volume.
Worked Example
Suppose the canopy width is 6.0 m, tree height is 4.5 m and the row spacing is 9.0 m. The
area of a hectare is 10,000.0 m2 (a constant). Therefore:
6.0 m x 4.5 m x 10,000.0 m2 ÷ 9.0 m = 30,000.0 m3/ha.
Advanced Sprayer Techniques
Page 12
Determine Ideal Sprayer Output
Step 2 – Apply the Coverage Constant
Multiply the TRV by 0.06 litres which is the calculated volume of dilute spray that will
suitably cover 1.0 m3 of post-blossom (i.e. full foliage) canopy to the point of run-off.
This figure is an average derived from a literature review of 25 instances where volumes
were established through experiment, or based on historical evidence, from six countries
spanning 1964 to the present. The mean volume was 0.074 + 0.03 l/m3 canopy for
multiple varieties and planting parameters throughout the growing season.
It’s been tested in a number of Ontario orchards and appears to provide suitable coverage.
Worked Example
0.06 L/m3 x 30,000.0 m3/ha = 1,800.0 L/ha.
Step 3 – Tree Shape: Match Trees in the Block to the Illustrations
Standard TRV assumes a full, rectilinear canopy, which is not generally true of apple
orchards. Compare the average tree in the block to be sprayed with the following
illustrations and multiply the carrier volume from Step 2 by the appropriate discount
factor. Discount factors are based on simple geometry. If you are unsure which shape best
matches your orchard, go with a larger volume.
Cube
1.0 x
Column
0.75 x
Dome
0.75 x
Cup
0.75 x
Cone
0.6 x
Sphere
0.5 x
Worked Example
In this case, suppose the block is predominantly spindle-shaped trees, so the 0.75x Dome
discount is most appropriate. Therefore:
0.75 x 1,800.0 L/ha = 1,350.0 L/ha.
Advanced Sprayer Techniques
Page 13
Determine Ideal Sprayer Output
Step 4 – Canopy Density: Match Trees in Block to the Illustrations
Carrier volume should be further adjusted to reflect foliar development and branching
density (i.e. orchard age, stage of growth, pruning practices and root stock). First
determine if you’re a re pre- or post-1.0” fruit. That’s the first discount. Then compare
the density of the block to be sprayed with the following illustrations. There’s the second
discount. Multiply the carrier volume from Step 3 by the appropriate discount factors.
This new dilute volume should bring the application to the point of run-off.
Advanced Sprayer Techniques
Page 14
Determine Ideal Sprayer Output
Step 4 continued – Canopy Density: Match Trees in Block to the Illustrations
Worked Example
Suppose that we’re talking about large trees, but with very few scaffolds, very well
pruned with no suckers, early in the season. That’s pre-1.0” fruit and we’ll say the canopy
is somewhere between Moderately Open and Extremely open.
0.8 x 0.55 x 1,350.0 L/ha = 594.0 L/ha.
While there is no definitive minimum carrier volume for broadcast hydraulic applications
in apple orchards, there is a threshold where there are not enough droplets to suitably
cover the target. Based on practices in Ontario, using a carrier volume lower than 400
L/ha may not suitably cover an established orchard, particularly after the 1.0 inch fruit
stage of development. It is not advisable to spray less than this volume.
It’s important to consider the sprayer output pre-season and about half-way through. The
canopy will grow, fill and change and it will require a new sprayer output and spray
distribution. Check out the water-sensitive paper in the picture below:
Advanced Sprayer Techniques
Page 15
Calculate Sprayer Output for Each Side
So now you know your travel speed. You also know what your ideal sprayer output
should be (Let’s say 550 L/ha), but you don’t know what nozzles you need to achieve it.
Air-blast disc-core, disc-whirl and moulded nozzles are categorized based on their output
per minute. A set of nozzles on one boom, when added together, produce the output per
side. Use one of the following formulae, depending on the units you prefer:
Output per
side (US
gal./min./side)
Output per
side
(L/min./side)
Output per
side
(L/min./side)
=
Target Sprayer
Output (US gal. /
ac)
x
Travel Speed
(mph)
x
Row
Spacing (ft)
x
Row
Spacing (m)
x
Row
Spacing (m)
1,000 (a constant)
=
Target Sprayer
Output (L/ac.)
Travel Speed
(km/h)
500 (a constant)
=
Target Sprayer
Output (L/ha)
Travel Speed
(km/h)
1,220 (a constant)
Advanced Sprayer Techniques
x
x
Page 16
Determine Spray Distribution over Boom
Once you know your travel speed and your ideal output per side, you have to select a set
of nozzles to produce that output at your operating pressure. Remember, choose nozzles
that give the correct total output AND the desired spray pattern.
Based on the ribbon test, you know how many nozzles you need. Often, operators will
divide the output over the spray boom to direct most of the volume at the thickest foliage.
There are exceptions, such as shifting higher volumes to the top of the boom to counter
high winds when trying to reach the tops of high trees, or when trying to protect the grape
zone. See the sample spray distributions below:
(A) Suggested spray distribution for airblast sprayers on classic spindle apple
trees. (B) If the canopy is of uniform depth, such as a vine, spray distribution
should also be uniform, where each nozzle sprays the same rate. These
distributions may change when there is fruit to protect.
Advanced Sprayer Techniques
Page 17
Match Spray Output to the Crop Stage
When sprayer output and distribution
are adjusted twice a year to ensure the
sprayer will uniformly cover the target
with the optimal volume, considerable
pesticide savings could be realized.
By maintaining the label-directed
pesticide concentration and eliminating
excessive volumes, operators can
better match the growing and filling
leaf canopy.
The top graph shows how the leaf area
within a growing and filling canopy
increases over the season.
The middle graph shows how spraying
the same volume throughout the season
means a lot of overspray (waste) early in
the season.
The bottom graph shows how using one
set of nozzles to spray less volume early
in the season, then changing nozzles to
spray more later in the season has the
potential to save a lot of pesticide without
compromising spray coverage.
Advanced Sprayer Techniques
Page 18
Select Nozzles
Once you know what your target sprayer output is for one boom (i.e. one side) of the
sprayer, and you have an idea how you want to distribute the spray over the manifold,
you have to select your nozzles. Most catalogue tables appear like the example below.
Don’t have a catalogue? GET ONE! Ask your sprayer parts supplier – they’re free!
from Spraying Systems®
Advanced Sprayer Techniques
Page 19
Confirm Nozzle and Sprayer Output
In theory, the sprayer is now set up to deliver a specific output per side. In fact, the output
may be different than expected. One way to check is to fill the sprayer with enough water
to spray one hectare and then go spray the hectare – if the tank is empty, the sprayer is
operating correctly. Most operators, however, do not have a test hectare marked off.
Alternately, the operator can measure the actual output-per-minute of each nozzle. This
does not capture travel speed issues, but does double-check nozzle accuracy. Here are the
steps for the timed-output test:
•
Clean the sprayer, fill it half-full with clean water and park it on a level surface.
•
With the fan off, bring the sprayer up to operating pressure. Start spraying with all
nozzles open. You’re going to get wet so dress appropriately.
•
Place a collection vessel under the nozzle to be tested. Use a short length of
braided hose to direct the spray into the vessel, if required. Better still, use dairy
inflations.
•
Collect spray for one minute, or if the output is very high, for thirty seconds. One
minute is preferable because it improves the accuracy. Be sure to double the
output if only measuring for thirty seconds.
•
Determine the nozzle output either by looking at the graduations on the side of the
collection vessel, or preferably, weighing the output on a kitchen scale. If using a
scale, one gram of clean water equals one millilitre. Remember to “tare”, which
means subtract the weight of the collection vessel.
•
Convert the findings to either
U.S. Gallons per minute or
Litres per minute; whichever
corresponds to the ratings in
the nozzle manufacturer’s
catalogue.
•
Replace any nozzles that are
10% more or less than the
rated output (see formulae on
page 21); 5% is preferable, if
possible. If two or more are
out by 10%, replace all
nozzles.
Advanced Sprayer Techniques
Worn brass whirl plate after 100 hours of use in a
typical apple orchard (A) vs. a new one (B).
Page 20
Helpful Conversion for Determining Nozzle Output
Anyone that has tried to determine nozzle output knows that it sounds easy until you try
it. The problem is all the possible conversions from one unit to another. Therefore, here is
a crib-sheet for determining nozzle output with ALL the constants for any situation.
If collecting in ounces, converting to U.S. Gallons per minute:
U.S. Gallons per minute
Output in ounces per minute
128 (a constant)
=
If collecting in millilitres or grams converting to U.S. Gallons per minute:
U.S. Gallons per minute
Output in grams or millilitres per minute
3,785.4 (a constant)
=
If collecting in ounces, converting to Litres per minute:
Litres per minute
=
Output in ounces per minute
33.8 (a constant)
If collecting in millilitres or grams converting to Litres per minute:
Litres per minute
=
Output in grams or millilitres per minute
1,000 (a constant)
If collecting in ounces, converting to Imperial Gallons per minute:
Imperial Gallons per minute
=
Output in ounces per minute
153.7 (a constant)
If collecting in millilitres or grams converting to Imperial Gallons per minute:
Imperial Gallons per minute
=
Advanced Sprayer Techniques
Output in grams or millilitres per minute
4,546.1 (a constant)
Page 21
Venturi Nozzles
Consider drift-reducing Venturi nozzles, which use air induction and a large exit orifice
to create coarse (or very coarse) droplets rather than driftable fines. Growers report less
“mist” hanging in the crop while spraying with AI tips and the sprayer does not appear to
create a big plume, which is good when there are onlookers.
Teejet® AITX Conejets:
Ceramic tips, air-induced
and colour-coded output.
Similar in cost to ceramic
disc-cores.
International research and trials here in Ontario indicate that applications from venturi
nozzles are as efficacious as disc-core or disc-whirl. However, in cases where trees are
very large or dense (e.g. standard apple) or where pest pressure is very high, coarse
droplets may not be appropriate. This is because coarse droplets lose momentum and fall
out of the air more quickly than fine droplets, and that can affect distribution in large
canopies. Further, with coarser droplets there are fewer to impinge per unit area on the
target. Despite the caveats, don’t dismiss Venturi nozzles - these issues are rare.
Spray pattern from venturi
tips deep in an apple
canopy at 750 L/ha. Image
is actual size.
Low-pressure Venturi nozzles on a Turbomist®.
Advanced Sprayer Techniques
Page 22
Confirm Coverage with Water- and Oil-Sensitive Paper
In an attempt to confirm
suitable
coverage,
some
growers look for wet foliage,
some perform shoulder checks,
and others look for residue. A
better strategy is the use of
water- and oil-sensitive paper.
Place sheets in the hardest-toreach portions of the canopy
(e.g. for apple trees, near the
trunk about 2/3 up the tree)
using clothespins or paper
clips. Then go ahead and spray.
Generally, a count of 85
discrete
fine/medium-sized
droplets per square centimetre,
and a total coverage of about
20% should be sufficient for
most products. Note: The 85count is too high for the
coarser droplets produced by
air induction nozzles.
It’s debatable, but 85 fine/medium-sized
drops per square centimetre, and about
20% total surface covered is adequate
airblast coverage for most pesticides.
The penny is here to give scale.
It’s easy to lose the cards in the
canopy, even with no leaves, so
write on the back to indicate
their location and tie colourful
flagging tape nearby.
Water-sensitive paper – cheap,
simple, and available in Ontario.
Ask your spray equipment supplier.
Advanced Sprayer Techniques
Page 23
About Advanced Sprayer Techniques 2012
This workshop was developed by the Ontario Ministry of Agriculture, Food and Rural
Affairs and delivered through the Ontario Apple Growers. Funding was provided by the
Farm Innovation Program (FIP). This project was funded in part through Growing
Forward, a federal-provincial-territorial initiative. The Agricultural Adaptation Council
assists in the delivery of Growing Forward programs in Ontario.
Special Thanks to Slimline Manufacturing LTD for contributing to this year’s workshop
and demonstrating the “Gear Up, Throttle Down™” Method.
For more information about this workshop, the materials,
or to obtain additional copies, contact [email protected]
Advanced Sprayer Techniques
Page 24