Home' Grower : August 2010 Contents 10
The South Australian Grower – August 2010
❏ By DAVID EAST
THERE is no doubting that the availabil-
ity of chemicals (herbicides, pesticides,
insecticides and fungicides) to control
pests and diseases is one of the most valuable
management tools available to growers.
When used appropriately and properly
• Maximise crop yields
• Save time and money, and
• Significantly increase profits.
When used inappropriately or incorrectly,
they can lead to problems such as food con-
tamination, environmental pollution (drift
and run-off), the development of resistance
and the elimination of beneficial predator y
Safe, efficient and effective spray applica-
tion is all about using the right chemical in
the right place at the right time and at the
Effective chemical control of pests and dis-
eases can be achieved with most types of spray
equipment currently available, if they are well
set up and the operator has a clear under-
standing of how best to target the sprays.
Generally, the spray target (pest or disease)
will dictate the best type of spray equipment to
use, but unless the sprayer is in peak working
condition and is properly adjusted and calibrat-
ed, it will not operate efficiently in ensuring the
correct dosage of chemical is being applied.
Sprayer performance can vary considerably
with different pump pressures, travel
speeds, application volumes (rates), wind
velocities and with different nozzle types.
It is perhaps ironical that one of the criti-
cal keys to the whole spraying process cen-
tres around the smallest component on all
spray machines – the spray nozzle.
Modern day nozzles are made from
advanced plastic materials although ceramic
nozzles are still available, and can be bought as
drip-proof, with swivel multi-heads and types
that can be safely changed while the spray tank
and lines are full of chemical mixture.
It is important to remember, however,
that all types of nozzles wear with use and it
necessary to check them regularly.
Worn nozzles will produce increased flow
rates and uneven spray patterns.
They may also produce too many wasteful
large droplets or, conversely, too many drift
prone small droplets.
The use of air – air assist and air shear –
nozzles has increased quite dramatically in
recent years as a means of sprayers being
more target specific with more accurate
These machines incorporate both a pump
and a compressor that must be well matched.
Generally speaking, the air is used to
atomise the liquid, either inside special noz-
zles or at the nozzle outlet, and direct the
droplets to the target.
The greater the volume of air, the smaller
the droplets generally are.
Another factor that af fects droplet size is
the spray pressure created by the pump – it
is the other side of the droplet equation.
For more accurate and target-positive
spraying with minimum drift and run-off
wastage, it is generally recommended that
pressures at the lower end of the range spec-
ified by the nozzle manufacturer be used.
When using tractors with multi-speed
power-take-off drives, always check the
drive speed is that recommended by the
The wrong PTO speed equates to the
wrong pump speed, incorrect pump pres-
sure and the wrong size spray droplets.
Proper sprayer set-up involves maximising
spray coverage and minimising chemical
waste by adjusting and optimising:
• Tractor speed.
• Air volume, velocity and direction, and
• Nozzle type and size, number and direction.
Sprayer calibration is the measurement of
the flow rate of liquid from the sprayer noz-
zles in conjunction with the intended travel
speed to establish the volume of liquid that
is required or best suited to the job.
The efficient application of chemicals has
become increasingly essential in pest and
The smallest component of the sprayer –
the spray nozzle – is one of the most
■ Spray target determines correct equip-
■ Many variants affect performance
■ Follow manufacturer’s recommenda-
☛ AT A GLANCE
Correct equipment for
more effective spraying
Enviromist spray system saved PJ & PA Hawe’s
macadamia farm in Electra, Bundaberg
Queensland in excess of $29 per hectare
on every application.
Using the Enviromist combo, Pat uses his ATV to spray 12.5km of
macadamia tree rows with just 80L of mixture using 8 litres of glyphosate in
2.5 hours. Previous to buying his Enviromist, Pat used a tractor, 3000 litres
of mixture, 30 litres of glyphosate and took 8 hours to do the same job.
Benefits using an Enviromist spray system:
• Huge gains in productivity AND reduction in costs
• No drift, use in windy conditions that may stop standard
• Operate at faster speeds, fewer fill-ups – more spraying
• Operating costs of ATV much lower than for tractor
Contact us to see how we can help reduce your input costs!
Telephone 1800 624 044 or 08 8582 4077 | E. email@example.com
Links Archive July 2010 September 2010 Navigation Previous Page Next Page