Many operators choose to have the optical spot sprayer as a standalone unit which is only used for ‘spot-spraying’, while others choose to have the system integrated with a conventional boom so that ‘blanket spraying’ and ‘spot-spraying’ can occur at the same time, from one machine.

Standalone set-ups

There are many benefits to having a standalone optical spot sprayer, in terms of size, weight and horsepower of the machinery required to get the sprayer across the paddock.

Having two sprayers, a standalone optical sprayer and a conventional boom, offers the ability to have both the conventional boom and the optical spot sprayer operating at the same time in different paddocks, however historically this has meant the need for two drivers.

In recent years it is becoming increasingly common to set up the standalone optical sprayer on a lightweight autonomous platform.

It is possible to run a single line optical sprayer with all nozzles turned on to apply a blanket application if required. However, if the optical spot sprayer is being used regularly to apply full blanket applications then operators should consider the additional weight being carried on the boom and the potential risk of damage to the sensor/camera system that may occur when the optical spray system is not required.

Integrating a optical spot sprayer with a conventional boom set-up

When mounting two spraying systems on a single boom, it is best to have two completely separate plumbing systems, one for the conventional boom system and another for the optical system.

While the sensors may be physically able to be mounted onto a single boom or toolbar, having two independent systems means having two tanks, two pumps and two separate plumbing systems.

This is particularly important as optical systems require the use of a pressure accumulator, typically a Ramsay valve, which is difficult to integrate into the conventional boom’s plumbing set-up as the pressure may need to be limited to a maximum of about 3 bar for the optical system.

The benefit of having two separate plumbing systems far outweighs the benefits of trying to use one system.

Some benefits of separate plumbing systems include:

• being able to have two different products, rates or tank mixes for each application, while still allowing either system to be used independently, or together, when required;

• having a smaller tank for the optical spot sprayer, which is important to ensure adequate agitation and to avoid product potentially ‘going off’ if it remains in the tank too long (as it may in larger tanks);

• ease of decontamination of two separate systems, particularly where one tank may only require a water flush while the other may need a full decontamination; and

• ease of troubleshooting or isolating a system if a problem occurs with one of the systems.

Commonly, having dual line systems allows for a blanket residual herbicide to be applied at the same time the optical spot sprayer targets any weeds which have already established. Some users also elect to apply a blanket application of a lower herbicide rate to target small weeds that have just established, while utilising the optical sprayer line to apply additional herbicide to the larger weeds that are detected.

Some more recent systems are being fitted with ‘quick release’ fittings to allow for relatively simple removal of the optical detection system when the boom is to be used in full blanket spray mode. This may protect the optical spray system from damage when it is not required to be used.