PAYER OR
CH ISTMA
TREE
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The UniversityofGeorgia
College of Agriculture
Cooperative Extension Service
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Sprayers for Christmas Trees
by
Paul E. Sumner
Extension Engineer
The equipment used for applying insecticides, fungicides, herbicides and
foliar colorants can be classified as sprayers. Christmas trees sprayers can
be three point hitch or trailer type units. These sprayers can be either
hydraulic boom or air blast, with hydraulic boom sprayers being the most
preferred type of application equipment. Boom sprayers get their name from the
arrangement of the conduit that carries the spray liquid to the nozzles. Booms
or long arms on the sprayer extend across one, two, or between rows as the
sprayer passes over the field. Air blast sprayers are being used more for
applying insecticides or fungicides. Air blast sprayers have a boom like the
hydraulic sprayer except the blast of air is the carrier for the chemical.
Growers are getting better penetration into the tree structure with air blast
sprayers. Figure 1 shows equipment necessary for a properly working hydraulic
boom sprayer.
Each component is important for efficient and effective
application. An air blast sprayer has similar components.
TANKS
Sprayer tanks are available in many sizes, shapes and materials. The tank
material should be chemically stable and non-corrosive to materials being applied
(Table 1). The filler hatch should be large enough for easy filling and
cleaning. The tank bottom should be designed to minimize left over spray and
have a drain at the lowest point. All tanks should have a calibrated sight gauge
visible from the operator's position.
Table 1.
Tank Construction
Relative
Cost*
Type
Advantages
Galvanized Steel
Inexpensive
Size and Shape
Corrosion
5
Polyethylene
Inexpensive
Non-corrosive
Tough, durable
Difficult to repair
Sunlight deteriorates
polyethylene
4
A1unri num
Moderately expensive
Resists corrosion
Lightweight
Cannot be used
with liquid N
3
Fiberglass
Strong, durable
Moderately expensive
Will break or crack
(can be repaired)
2
Stainless Steel
Strong
Corrosion Resistant
Expensive
1
Disadvantages
* 1 - Most expensive; 5 - Least expensive
1
By-Pass Line
Agltallon Line
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+ Control\ Valve
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+
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DraIn
Boom
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Figure 1.
Basic equipment necessary for a properly working boom sprayer.
~1I
Figure 2.
Typical nozzles used for hydraulic agitation
- 2 ­
STRAINERS
Strainers are essential to filter the spray liquid to prevent nozzle
blockage, thus causing uneven application of chemicals.
Strainers are used in three places on most sprayers. Tank screens are
coarse (10-20 mesh) that remove large objects where the tank is being filled.
The line strainer located between the pump and tank. These have a large surface
area and 30-80 mesh screen. The line strainer removes sand, scale, rust and
other small foreign objects preventing pump damage. Nozzle strainers are located
in the nozzle body and usually 50-200 mesh depending upon nozzle opening size.
AGITATORS
Keeping the chemical in the tank in total suspension is essential for
uniform application. Agitation requirements of various chemicals depend largely
upon the formulation of the chemical being applied. Soluble liquids and powders
do not require special agitation once they are in solution, but emulsions,
wettable powders, and liquid and dry flowables will usually separate if not
agitated by some means. Agitation can be accompl ished by mechanical or hydraulic
systems.
Mechanical agitators can be paddles, propellers, or similar devices mounted
on a shaft near the bottom of the tank. Rotation should be kept to a minimum
«200 rpm) to avoid foaming. These are driven mechanically from the power source
for the pump or by a 12-volt electric motor.
Hydraulic agitation (Figure 2 ) is the most common type.
Fluid is
circulated under pressure to a nozzle or tube with holes inside the tank. The
amount of flow should be controlled so that as the tank empties, flow decreases
to reduce foaming.
Agitation with jet nozzles requires additional pump capacity of five to
seven gallons per minute per 100 gallon tank. Use of a siphon nozzle which
creates a vacuum that increases the discharge from the nozzl e and thereby
increases the mixing action 2 l/ Z - 3 times.
This method is particularly
effective when pump flow is marginal. A sparge tube may also be utilized for
agitation. It consists of a pipe or tube with several discharge holes in the
bottom of the tank.
PUMPS
Three factors to consider in selecting the proper pump for a sprayer are:
1.
Capacity - The pump should be of proper capacity or size to supply
the boom output and to provide for agitation. The boom output,
depending upon the number and size of nozzles, and 20-30% for pump
wear is recommended. Capacities of pumps are given in gallons per
minute or per hour.
- 3 ­
Sizing the Pump
The size of pump needed depends on (1) rate of application, (2) travel
speed, (3) tank size and (4) sprayer width.
Pumps are rated in gallons per minute (GPM) which can be calculated with
this formula:
(ft) x GPA
GPM = MPH x Width
500
It is a good idea to allow additional capacity to compensate for tank
agitation and pump wear. You can by changing above formula to this:
GPM
MPH x width (ft) x GPA
500
+
.02
x tank size (gal) x 1.2
For example: To spray 20 GPA at 3 mph with a 16-ft (two rows 8 feet apart) boom
you should have a pump rated at about 10 GPM.
3 x 16 x 20
GPM =
9.5
+ (.02 X 300) X 1.2
500
The formula adds 2.0 GPM per 100 gallon of tank capacity for agitation (with
heavy wettable powders increase this to 0.05 or 5 GPM/I00 gal.) The 1.2 factor
adds 20% for pump wear.
2.
Pressure - The pump must produce the desired operating pressure for
the spraying job to be done. Pressures are indicated as pounds per
square inch (psi).
3.
Resistance to corrosion and wear - The pump must be able to handle
the chemical spray materials without excessive corrosion or wear.
Care should be used in selecting a pump if wettable powders are to
be used. Table 2 lists the various pumps and their advantages and
disadvantages.
PRESSURE REGULATORS
Flow of spray liquid from the pump to nozzles is controlled by a pressure
regulated valve (PRV) (Figure 3). This consists of spring-loaded diaphragm or
ball valve which can be set at a particular pressure. When this pressure is
exceeded, the valve opens and the excess liquid allowed into a by-pass line
returning to the spray tank. Liquid returned to the spray tank in this way
provide partial hydraulic agitation of the spray liquid. A separate flow line
to the agitator in addition to the by-pass line from the pressure regulating
valve is necessary on all sprayers. When the pressure gauge is mounted next to
the valve, readings have to be checked against pressures measured at the
nozzles, so that account is taken of any drop in pressure between the valve and
the nozzles.
- 4 ­
TIlBLE 2. SUHHARY OF HIE VARIOUS TYPES OF PUHPS USED FOR SPRAYING
Cnl1RACTERISTIC
PISTON
Adaptability: Handle
corrosive or abrasive
lIaterials
Wide range of
application. Will
handle corrosive and
abrasive laterials
Oil elulsion, non­
abrasive laterials.
Cannot be used with
wettable powders.
Works best with oil
elulsions and non­
abrasive laterial.
Recoillend not using
copper cOlpounds.
Rubber rollers for
slurries &wettable
powders.
Will handle all
chelicals which
will not attack
diaphragl.
Will not handle
abrasives.
Will handle coarse &
abrasive laterials.
Durability
Basic parts have long
life.
Lilited life under
adverse conditions.
Pressure drops with
wear.
Haintains pressure
with wear.
Cannot operate dry.
Pressure drops
rapidly with wear.
Pressure drops with
wear.
Serviceabi li ty
Readily serviced.
Parts not usually
replaced. PUlP
readily replaced.
Special technique in
servicing. Worn
parts can be
replaced.
Readily disasselbled
for service.
Parts readily
changed.
Certain lodels can
be serviced.
Construction
(er i tical par ts)
Cylinders-ceralic,
stainless steel,
bronze.
Bronze gears,
stainless steel
shaft.
Rollers-nylon or
rubber. Case­
nickel, cast iron.
Rubber or synthetic
diaphragl.
Hickel cast iron and
stainless steel
shaft.
Case: Cast iron or
plastic. Ilpellers:
Cast iron, bronze
and plastic.
Pressure Range
0--1000 psi
0--100 psi
0--150 psi
0--150 psi
0--120 psi
0--50 psi
RPH (Operating Range)
~OO
500 to 1800
300 to 1000
500 to 800
500 to 600
1200 to 3500
Gallons per .inute
3--10
0--65
5--50
}--10
0--100
0--100
Rgguired horsepower
2 to 6 HP
1/6 to
1/2 to 5 JIP
3 to 5 HP
1/6 to 4HP
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Displace.r.nt
Posi ti ve
Seli-posi ti ve
Seli-posi ti ve
Posi ti ve
Seli-posi ti ve
Han-positive
Direction of rotation
Clockwise
Either
Clockwise
Either
Clockwise
Clockwise
Type
Bronze or ball
Bronze
Bronze or ball
Ball
Bronze
Ball sealed
Lubrication
Grease
Grease
Sealed or grease
Grease
Grease
or grease
PTO, belt, or chain
PTO
PTO, belt, or chain
PTO, belt, or chain
GEAR
ROLLER IHPELLfR
U1
to 1000
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liP
DIAPIIRAGH
I1HtRHAL GEAR
CEHTRIFlJGIlL
to 3 HP
BEARINGS:
T~
drive
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beltLJlLcl!ain_ _ PTO, belt, or chain
Re turn to Tank
From Pump
Figure 3.
To Nozzles
Pressure Regulator
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EVEN FAN
FLAT FAN
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SOLID CONE
Side View
FLOOD TYPE
Figure 4.
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Examples of spray nozzles used on christmas trees.
- 6 ­
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HOLLOW CONE
CONTROL VALVE
Between the pressure regulating valve and the nozzles, an ON/OFF valve is
positioned so that it can be easily operated by the tractor driver. Often there
is a simple mechanical lever for the driver to operate, but for the totally
enclosed safety cabs, electrically operated solenoid valves are required for
remote control and to avoid pipes containing pesticides being in the cab. When
the spray boom is divided into three sections, left, right, and central, the
main valve is often a seven-way valve, so that individual sections, pairs or the
whole boom can be operated. This is particularly useful when the edges of
fields are being treated and part of the boom is not required.
CONDUITS
Pipes and/or hoses are used to carry spray material from the tank to the
nozzles. These conduits must be capable of withstanding pressures created by
the system pump. Hoses should have a burst pressure well above the normal
working pressure of the hose.
Hoses are available with one ply, two ply and
wire reinforced construction. The wire reinforced hoses should be used where
very high operating pressures are anticipated (over 200 psi). As hose size
(diameter) increases, the working pressure decreases.
Suction hoses should be at least as large as the inlet port on the pump.
The suction hose should be wire reinforced to prevent collapse of the hose.
Collapsed hoses restrict flow to the pump and accelerate pump wear.
Hose size on the pressure side of the pump depends on the flow rate, hose
1ength, and operat i ng pressure.
Sma11 hoses may restri ct flow and create
unnecessarily high pressures.
This results in accelerated pump wear and
increased possibility of ruptured hoses.
Table 3.
Pump (GPM) out put
up to 12
12
25
26 - 50
51 - 100
Suggested Hose Sizes for Boom Sprayers
Suction Hose
3/4"
1 "
1 - 1/4"
1 - 1/2"
Pressure Hose
5/8"
3/4"
1 "
1 - 1/4"
Hoses should be constructed of material that is resistant to the chemical
action of spray material used. Two common materials used for sprayer hoses are
EVA (ethylene vinyl acetate) and EPDM (ethylene propylene diane monomer).
Remember that restrictions in the hose will affect pressure and output.
Quick connect couplings and fittings with inside diameters smaller than the
inside diameter of the hose will restrict flow.
- 7 ­
NOZZLES AND SPRAY PATTERNS
Nozzles consist of a body, cap, filter and tip. Various types of nozzle
body are available with either male or female threads or special clamps,
sometimes with hose shanks, for connecting to booms.
A 50-mesh filter is
usually adequate, except for very small orifice tips when an 80, 100, or 200­
mesh filter may be needed.
Nozzle tips are the most neglected and abused part of the sprayer. Since
clogging can occur when spraying, it is necessary that the nozzle tips and
strainers be cleaned and tested after each application before being used again.
When applying chemicals be sure to control all of the factors in the spraying
operation (ground speed, operating pressure, spray height, etc.), this will
ensure proper placement and amount of pesticides to the plant canopy. Figure
4 is examples of nozzles used for spraying christmas trees.
Particle Size
Sprayer particle or droplet size is one of the most important factor in
applying chemicals. Droplet size is determined by pressure and nozzle outlet
size (orifice). The lower the pressure and larger the nozzle the larger the
droplet. Conversely the smaller the nozzle and higher the pressure the smaller
the droplet size. A large droplet being propelled by high pressure will go
further than a small droplet.
When applying fungicides and insecticides the following should be noted.
The chri stmas tree canopy exh i bits a outer ski n that is hard to penetrate
through. It is advised that spray nozzles be operated at high pressures with
small outlets to achieve maximum penetration and coverage. It may necessitate
adding additional nozzles to achieve desire application rate.
Particle size for applying herbicide should be large. Drift is a problem
when using herbicides so larger the droplet less likely to drift away from the
target area. Pressure should be maintained as low as possible but not to effect
the spray pattern.
Determining the Nozzle Size
Once you have selected gallons per acre, operating speed and pressure,
and know the nozzl e spac i ng, you can cal cul ated the nozzl e fl ow rate (GPM)
needed to apply desired amount of pesticide. Use this formula:
GPA x MPH x W
GPM
5940
The formula computes gallons per minute or the nozzle flow rate using
these inputs: GPA equals gallons per acre or the amount you decided to apply;
MPH is your ground speed as selected; Wis row width or spacing between nozzles
The divided (5940) is a precalculated constant for the
(inches) selected.
formula.
- 8 ­
Example: Assume SO-degree flat-fan nozzles spaced on 20-inch centers, a
20-GPA application rate and operating speed of 3 MPH. Substituting these values
in the formula you get:
20 GPA x 3 MPH x 20 inch
= GPM
5940
GPM = 0.2 gallons per minute per nozzle.
Once nozzle flow rate has been figured, you then select the nozzle with
For our
comparab1e fl ow rate when operated at the pressure you selected.
example calculation we would look for a nozzle with a GPM figure close to 0.2
at an operating pressure around 25 or 30 psi. With extra heavy or thick sprays
you will have to compensate for the viscosity.
Herbicide Application
A flat fan type nozzle should be used for applying broadcast herbicides.
Flat fan nozzles produce an elliptical pattern, where the edges are light and
heavy in the center. These should be spaced on the boom for 30 - 40 percent
overlap. When it becomes necessary to band apply herbicides use a even fan or
flood nozzle. These nozzles produce an uniform pattern across the area sprayed.
The fan nozzles should be operated at 20 - 40 psi. Flood nozzles are designed
to operate at lower pressures 5 - 15 psi. The capacity of both type nozzles
should be 15 - 20 gpa when operated at 21/ 2 - 4 miles per hour.
Insecticide, Fungicide and Foliar Colorant
When applying insecticides, fungicides and foliar colorant solid or hollow
These two patterns can be produced by
cone type nozzl es shoul d be used.
different tip configurations. One type tip disc-n-core consists of two parts.
One being a core (swirl plate) where the fluid enters and is force through
tangential openings. Then a disc-type harden stainless steel orifice (opening)
is added. Another type tip that produces the same patterns is of one piece
construction (nozzle body). Liquid is passes through a precision distributor
with diagonal slots which produce swirl in a converging chamber. The resulting
pattern of both tip configurations is either solid or hollow cone. Under normal
conditions, nozzle tips should be approximately 6 - 10 inches from the foliage.
They should have the capacity to apply 20 - 50 gallons per acre operating at
60 - 400 psi depending on the density of the foliage and age of trees.
Generally, ground speed should be 21/ 2 - 4 miles per hour.
Boom Configuration
Figure 5 illustrates one method for setup for applying insecticides,
fungicides or foliar sprays to trees via hydraulic sprayer. The sprayers should
be a maximum of 42 -48 inches at its widest point. This will allow operation
between rows of trees without damage to them. The boom should be constructed
so that a clearance height of 7 - S feet can be obtained. Also, boom height
adjustment should made easily from the operators position. In production of
Christmas trees, growers will have several different age plantings. Therefore,
the ability to adjust boom height during application would be time saving.
- 9 ­
Winch to lift boom up and down
Nozzles
Spaced
12 inches
________.
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L,__~
f-42-4811
Figure 5.
.
-1
Sprayer boom configuration and nozzles set-up for christmas trees.
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10 ­
This setup can be modified easily to apply herbicides. Place blanks in
the nozzles along the slanted boom. Then add one or two nozzles at the end of
the slanted boom for drop nozzle herbicide application.
Sprayers should be calibrated often. Calibration should be conducted
every eight to 10 hours of operation to ensure proper pesticide application.
A good calibration procedure to follow is "Calibration Method for Hydraulic Boom
and Band sprayers and other Liquid Applicators" circular 683. Contact your
County Extension Agent.
APPLICATION EQUIPMENT MAINTENANCE
All equipment must be checked thoroughly before the beginning of each
season and on rout i ne bas is duri ng the season to keep equ i pment in good
mechanical condition.
Give special attention to valves, nozzles, tubing,
connections, and other components that may leak. Replace parts promptly when
they show signs of wear or malfunction.
Equipment Care
For the safety of the applicator and efficiency of application, the
equipment needs to be calibrated accurately to dispense the pesticide in the
prescribed amounts. The label must be strictly followed. An overdosage could
be a prime cause of illegal residues, as well as a potential source of human
i nj ury.
An agitator should be the right size to insure efficient mixture of the
chemical.
The agitator must be checked periodically to make sure it is
operating correctly.
All washers and gaskets should be checked before each seasonal use, and
on a routine basis during the operating season to prevent leakage.
Hose Care
A worker w"ill not use his mouth to siphon or blowout nozzles and clogged
lines on any pesticide equipment. A siphon bulb, pump or other type mechanical
device should be used for these repairs.
Sprayer hoses are subjected to high pressure and they present a definite
hazard to the operator should the hose burst. Through proper maintenance and
storage this hazard can be minimized.
The following safety checks and precautions are recommended:
1.
Hoses should be inspected under high pressure by using plain water before
each seasonal use and periodically during the use season.
2.
Store hoses when not in use, this should be in a dark area to prevent U.V.
breakdown of the rubber.
-
11 ­
3.
Do not hang hose over a nail or other sharp objects, as this can cause a
weak-spot- in the hose.­
4.
Hoses can be wrapped around a metal drum or other suitable objects to
prevent creasing.
Cleaning Sprayers
Herbicide residue in a tank loaded with insecticide could seriously damage
susceptible plants; also, insecticide residue in a herbicide tank could result
in high toxicity to humans if the chemicals are incompatible.
The suggested cleaning procedures are as follows:
1.
Thoroughly flush the tank with warm water and a detergent. Then fill it
with a solution of one part household ammonia in 100 parts of water. Run
some of the solution through the sprayer boom and nozzles. Allow the
solution to remain in the equipment for 12 to 24 hours, then remove it and
rinse the equipment with water.
2.
Rinse the tank for about 2 minutes with a 0.25 percent suspension of
activated charcoal (1/4 pound of activated charcoal in 10 gallons of
water) to which has been added a small quantity of household detergent.
Run some of the suspension through the boom and nozzles. Empty the tank
and rinse with clean water.
3.
Neither of the above methods is always completely effective. To test the
equipment for herbicide residue fill the tank with water and spray
seedlings of a sensitive plant such as bean, tomato, or a sensitive weed.
If the plant is not affected within 2 days, the equipment is safe for
further use.
Cleaning According to Types of Formulations:
1.
Wettable Powders - rinse the tank with water containing a wetting agent
or detergent; then rinse with plain water.
2.
Emulsions - Flush the tank with large quantities of water, with agitator
running.
Rinse once or twice with an oil solvent (paint thinner or
herbicidal naphtha). Flush again with water and drain.
3.
Solutions - Rinse with the same kind of solvent used in the formulation
previously contained in the tank; if this was an organic solvent, you may
use paint thinner, herbicidal naphtha, or fuel oil. Drain the tank and
rinse with soapy water. Rinse again with plain water.
- 12 ­
THIS PUBLICATION WAS PREPARED WITH FUNDS MADE AVAILABLE FROM OIL OVER­
SETTLEME.NT$ At::JP WITHIN THE GUIDELINES OF THE U.S. DEPARTMENT OF
ENERGY. HOWEVER, ANY OPINIONS, FINDINGS, CONCLUSIONS, OR RECOMMENDATIONS
EXPRESSED HEREIN ARE THOSE OF THE AUTHORS AND DO NOT NECESSARILY REFLECT
THE VIEW OF DOE.
_CI:iABGE~COURT
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Paur E. Sumner, Extension Engineer
The Cooperative Extension Service, The University of Georgia College of Agriculture
offers educational programs, assistance and materials to all 'people without regard to
race, color, national origin, age, sex or handicap status.
AN EQl)AL OPPORTUNITY EMPLOYER
Sept. 1989