Increasing droplet size is key in reducing spray drift, according to Mid North-based consultant Peter Cousins, Crystal Brook.

Peter says increasing water rates and choosing the right nozzles are important in increasing droplet size. He also encourages growers to keep the boom height low and reduce ground speed to help them reduce the risk of spray drift.

“One thing I encourage growers to do is to get someone else to operate your system for a run, then you can get out in the paddock and assess how your spray rig is operating,” he said.

“Critically assess what your spray pattern looks like, you should be making sure your spray is hitting the ground and ensuring that there is no drift behind the boom. If there is, make adjustments to reduce drift, recheck the weather and operating conditions and stop if necessary.”

“If weather conditions are suitable for spraying and you still have drift you need to change your operating and rig set up.

“First, look at what type of nozzles you are using, making sure the nozzles are operating at the correct pressure or as per the manufacturer or label recommendations. Also look at the droplet size and increase if necessary.

“Then look at the boom height, best practice is to sit the boom 50 centimetres above the target.

“Operating speed is also important. As a general rule of thumb, aim for 14 to 22km per hour. But first and foremost, keep an eye on changing weather conditions and stop if in doubt, especially if at risk of an inversion.”

Peter encourages growers to educate themselves about temperature inversions and their effects on spray drift.

“Reading inversion conditions can be difficult, but if growers can get some information such as what is provided by the GRDC then that will help them to get a better idea as to when they should or should not be spraying,” he says.

“Inversions occur on most nights 1.5 hours before sunset and up to 1.5 hours after sunrise, unless there is a continuing wind speed of over 11km per hour through the night or if it’s overcast.

“Do not spray when there is no wind, you need at least 3km per hour at all times. You can continue to spray up to 18km per hour. Using your own, or regional specific, real-time weather systems is also recommended to ensure spray decisions are based on the best available information.

“Take the weather conditions in the paddock continually throughout the spray operation, growers should check at least once every hour and are encouraged to use both a hand-held device and a reliable online weather forecasting service. These details should be recorded in a spray diary.”

Along with fellow Mid North-based consultant Mick Faulkner, Peter has been instrumental in getting funding from the State Government to set up a network of weather stations across the Mid North.

The network, to be established at 40 locations across the region, will give growers access to weather data, such as temperature, wind speed and even when temperature inversions are developing.

This specific combination of data will help growers make informed decisions and minimise the risk of spray drift.

“Once it is established, the network will provide ongoing data to growers 24 hours a day so they can make decisions about whether or not to spray,” Peter said.

“We hope to eventually get to a point where the technology can automatically send an alert to growers’ smartphones when conditions get too risky for spraying, like during a temperature inversion.”

Peter says there is an onus on growers to self-regulate when it comes to spraying, similar to how they have in regard to the grassland fire danger index (GFDI) during harvest.

“Essentially, growers need to recognise that they have a responsibility to hit their target and reduce spray drift,” he said.

“It is also important to stress the importance of following the crop protection product label so their application technique meets the legal requirements.”

Details: Peter Cousins, 0408 210 893,

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