How Target Zoning Can Help You Save an Additional 20% on Chemicals with Your Single Spot Sprayer

With the introduction of Target Zone rates for Optical Spot Spraying Technologies (OSST)-labeled chemicals, there’s now a more efficient way to set up your single spot sprayer than using the commonly recommended even fan nozzles. This approach could lead to significant savings on chemical use and improved spraying efficiency.

Below is an explanation of Target Zoning from The Spot Spray App.

How Target Zoning Came About

Target Zoning is a concept recently developed by myself (Dave Young) and Dan Skerman, an agronomist and farmer based in Dalby. Dan had been working with his WeedSeeker, a well-known single spot sprayer using 50 cm nozzle spacings with 80° nozzles, attempting to maximise its performance compared to local WeedIt sprayers, which use 25 cm nozzle spacings. The wider spacing presumed to be a key factor affecting the performance difference between the two systems.

The Concept of Target Zoning

Our collaboration started with field tests using water-sensitive papers to measure spray patterns. The traditional approach for single spot sprayers requires measuring the spray width (or footprint) of the nozzle on the ground. Although we began with theoretical calculations, real-world results were variable, leaving the water-sensitive paper method as a subjective guide, not a reliable measure of rate per hectare.

We then moved to a more controlled testing environment: Dan's shed. We used a patternator with a simulated travel speed of 16 km/h, generated by a large electric fan, to mimic real-world field conditions, including natural and variable crosswinds. While not perfect, this method provided results much closer to actual field performance.

Key factors during testing included nozzle angle and height. We tested Wilger and ARAG 80° nozzles at both 70 cm and 80 cm heights. While Dan’s WeedSeeker was set at 80 cm, many of my customers using See & Spray, WEEDETECT, or AiCPlus systems typically operate at 70 cm, so we gathered data for both setups. We also tested Wilger 40° and 60° nozzles to expand the analysis.

It’s important to note that a single spot sprayer nozzle must be calibrated as if it operates in isolation, meaning overlap isn’t factored into the rate calculation for either the full spray width or the Target Zone rate.

Another critical development since our testing is that all ARAG/ASJ 40° and 80° CFLD nozzles are now factory tested in Italy to verify their Target Zone volume distributions.

APVMA’s Stance on Target Zoning

Once we completed the testing, I reached out to Gary Dorr at the APVMA. His official response confirmed that Target Zoning is label-compliant. He stated:

I would consider that choosing the smaller nozzle calibrated for the target zone and limiting the total amount of product applied so the correct rates were being applied to the target is actually following the label.

For the full conversation, visit: OSST Label Rate Compliance.

How Target Zoning with Tapered Fan Nozzles Reduces Chemical Use

An even fan nozzle must be calibrated based on its entire spray width, or you risk underdosing in the target zone. Tapered fan nozzles, however, have a thicker spray pattern in the middle, allowing for precise calibration within the Target Zone. By using a smaller nozzle and focusing on the critical area, you can achieve the required rate while using less chemical overall.

For instance, at a rate of 90-100 liters per hectare, a speed of 18 km/h, and pressure of 3 BAR at 70 cm nozzle height, you can save around 20% in active product by switching to a tapered fan nozzle. In this setup, the even fan 08 nozzle would require a flow rate of 3.2 liters per minute, whereas the tapered 06 nozzle would only need 2.4 liters per minute—resulting in over 20% savings on top of your existing savings.

Potential Downsides of Target Zoning

Brendan Williams from Rometron Australia (WeedIt importer and distributor) has noted potential drawbacks of using spot sprayers equipped with forward-looking cameras. You can explore his thoughts and further commentary on my X (Twitter) timeline: @nozzlesonline.

Additionally, a See & Spray user reported "hollowing out" in the center of the spray pattern when using 80° even fan nozzles. This observation, along with the advantages of tapered fan nozzles, aligns with Tom Wolf's findings at Sprayers 101. Read more here: Spray Patterns for Spot Sprays.

Explore Target Zoning Further

That’s all for now on Target Zoning. If you’re interested in seeing how this approach compares to traditional spray width calculations, I invite you to try our online Spot Spray Calculator.

Visit the calculator here: Spot Spray Calculator

Be sure to read the disclaimer carefully, as it provides a summary of the information discussed here.

Best regards,
Dave
30/09/2024

P.S. I’m pleased to report that Dan, who always says "water is cheap," is now using his Wilger DR8010s with better results and cost savings, thanks to Target Zoning and accurate batching.

PPS… That Dan is using 8010’s where 8005’s or 06’s will do 100 l/ha TZ rates just goes to show that using more water with bigger nozzles still allows you save on chemicals. All he does is divide his TZ application rate of 177 /ha at 16km/h into his tank size to establish the number of doses per tank thus reducing the chemical concentration to achieve the correct dose of active. (OSST rates require you to batch up X lit / per 100 lit of water).

It's working sweet now we’ve got a few things sorted, and I know exactly what rate I'm putting out. - Dan Skerman