Effective spraying is critical for successful pest and disease management, but with orchard systems rapidly evolving, ensuring every spray pass delivers maximum coverage, productivity and efficiency is more critical than ever.
Spray optimisation has been a core feature of Smart & Sustainable for the last two years, with the research translating smoothly through to extension and adoption by growers.
Access to science-backed recommendations for modern orchard systems is vital to improve spray performance, reduce costs and get more from agrichemicals and equipment, says NZAPI R&D Programme Manager Rachel Kilmister.
“New Zealand is a world leader in horticultural innovation. Research like this delivers the practical gains that matter on orchard, helping growers increase efficiency, improve productivity and maintain sustainable production systems.”
Why the Research Was Needed
Spraying has an important role in the sector’s systems-based approach to pest and disease management.
However, over the past decade, growers have increasingly adopted smaller, narrower and more open canopy structures. At the same time, a wider range of sprayer types and application technologies have become available.
“This raised an important question: are current spray volumes, application rates and operating practices still optimised for modern orchard systems?” says Kilmister.
“We did not want growers relying on assumptions developed for large dense tree canopies when orchard architecture, equipment and grower expectations have evolved significantly.”
The research was therefore designed to answer practical questions that matter on-orchard, including:
How much spray reaches different parts of the canopy?
Do spray volumes need to change for different canopy structures?
How to set up different sprayer types for different tree canopies.
What impact do travel speed, wind and sprayer settings have on coverage?
Can growers reduce agrichemical use while maintaining effective pest and disease control?
Taking a Closer Look at Spray Performance
Over two years, researchers examined spray application across a range of orchard systems and management approaches.
Year One: Understanding Coverage
The first year focused on understanding how sprays move through modern orchard canopies and where improvements could be made.
Researchers measured how much spray reached different parts of the tree across a range of canopy types and sprayer setups. They tested tower and airblast sprayers, different application volumes, and droplet size.
The team also investigated whether spray rates should be adjusted based on tree size, shape and density rather than applying a one-size-fits-all approach across orchards.
“The work has demonstrated that the total spray target size across modern intensive canopies on different row spacings is relatively uniform per hectare,” says project researcher David Manktelow. “While easier to spray than more traditional 3D trees on wider row spacings, modern hedgerow canopies require no less than 70% of what traditional canopies do.”
Ground-based and aerial application methods were compared, while practical techniques for assessing spray coverage were tested. Importantly, the work generated a substantial field dataset that support future grower guidance, industry extension efforts and digital modelling tools.
Year Two: Optimising Efficiency
The second phase expanded testing across a wider range of modern orchard systems.
Researchers examined how factors such as wind conditions, travel speed, air output and sprayer setup influence coverage and spray deposition throughout the canopy.
“The diversity of canopy training systems and sprayers creates a ‘too many variables’ problem,” says Manktelow. “We are addressing this by developing sprayer setup and optimisation guides for different sprayers and canopies.”
The goal was not simply to understand the science, but to develop practical recommendations for growers.
By identifying how different operating conditions affect spray performance, the research helps growers better match spray volumes, sprayer settings and application techniques to their specific orchard systems.
What This Means for Growers
One of the strongest themes from the research is that efficiency and efficacy can work hand-in-hand.
“One of the most interesting things we discovered was how variable current spraying practices are across the industry, and how much room there is for optimisation and greater efficiency,” says Manktelow.
Matching spray volumes more closely to canopy structure creates opportunities to reduce unnecessary agrichemical use while still achieving effective coverage. For growers, that has multiple benefits.
Using only the volume required for a particular canopy can reduce input costs, improve work rates and decrease the number of tank refills needed during spraying operations. Fewer refills mean less downtime, greater operational efficiency and more hectares covered in a working day.
The research has also highlighted the importance of sprayer setup. Factors such as air output, travel speed and equipment configuration can significantly influence how effectively sprays reach their target.
In some situations, relatively small adjustments could improve coverage throughout the canopy, allowing growers to get better performance from equipment they already own.
“After two seasons of practical deposit studies, we are at the point of understanding what good looks like for sprayer and spraying optimisation,” he says. “Now comes the role of the extension programme over the next three seasons.”
Building Capability for the Future
The value of this research extends beyond today's orchard systems, says Kilmister.
“Data helps build the foundation for future technologies,” she says. “Digital spray modelling, LiDAR-guided spraying and variable-rate application technologies have the potential to further improve precision, reduce wastage and increase productivity in the years ahead.”
The work is also considering how emerging application methods could fit safely into orchard systems. “The safe, effective and practical integration of drone spraying into orchard spray programmes is an exciting challenge with a lot of potential, however it needs to be well tested and guidelines developed,” says Manktelow.
The research also helps ensure on-orchard decisions are based on New Zealand evidence and growing conditions, which could mean improved coverage in some situations, reduced chemical use in others and opportunities to improve productivity and profitability.
Delivering Value Beyond the Orchard Gate
This project demonstrates why investment in industry-led research remains so valuable.
By identifying practical improvements that can be implemented on-orchard today while also laying the groundwork for future technologies, spray optimisation research can help New Zealand's apple and pear industry remain at the forefront of innovation, productivity and sustainability.
As orchard systems continue to evolve, this research gives growers the confidence that their spray programmes can evolve with them to deliver better outcomes from every hectare, every season and every spray pass.