TECHNICAL
increase the water volume but, as a result, will tend to increase the number of small droplets and therefore the risk of drift, especially with traditional flat fan nozzles. Syngenta trials have
demonstrated that even a small increase in pressure, from three to four bar for example, can
dramatically increase the proportion of drifty fine droplets, with some nozzles.
Conversely, reducing the pressure will reduce the driftiness of a nozzle, but can compromise the spray pattern and the velocity of droplets to hit and stick on the target. Most nozzles are designed to work most efficiently at two to three bar.
The effects can be particularly apparent with auto rate controllers. Increasing forward speed automatically increases pressure to maintain a consistent application rate; that will alter the spray droplet pattern, and can inadvertently produce more small droplets susceptible to drift.
The tip is to mark an optimum two to three bar zone on the pressure gauge, and always moderate speed to stay in the zone. Forward speed also has an effect on the water volume physically applied. Reducing the speed from six to four km/h, for example, will increase the water volume and, therefore, the product application rate. This is a factor to consider when spraying greens, for example, where there is a tendency to slow down at the start and end of each run.
Whilst one nozzle size can deliver different water volumes by adjusting speed and pressure, you can be more efficient and precise in your accurate application of the most appropriate water volume by selecting the most appropriate nozzles size.
Size options
A good selection of nozzles to have available for consistent application in most turf situations, at two to three bar, would be a set of:
• 025 nozzles for greens, delivering a water volume of 200- 300 l/ha at four to five km/h - targeting foliar treatments
• 04s applying 220-380 l/ha at five to seven km/hr on fairways for foliar and crown target treatments
• 08s that will deliver 450-770 l/ha at five to seven km/hr for soil target treatments
That is simple if you have a sprayer nozzle holder that accepts three or four bayonet housings, where you can fit the required types and simply
twist around to the required nozzle. If not, it is easier if you buy additional sets of nozzle bayonet holders, which are relatively cheap, and make them up in the workshop with the seals fitted. Store each set in a separate clear plastic box, with the name and size written on the top, and simply swap over the bayonets to change nozzles, rather than the time consuming and messy job of changing individual nozzles. Always keep a record of the spray output charts for each of your nozzle sets, as these will be invaluable when calibrating the sprayer and establishing the optimum performance for your individual sprayer.
Calibration check
Calibrate your sprayer accurately for each set of nozzles, and check regularly for signs of wear or uneven patterns. Some liquid fertilisers, especially iron, can be especially abrasive and lead to high levels of nozzle wear. Once you get in the routine of checking calibration, it will only take a few minutes.
The rule of thumb is that if any nozzle output is +/- 5% from the average, then change the whole set of nozzles. The cost of nozzles is relatively inexpensive, given the value of treatments being applied, and the importance of getting the best possible results from them. Machinery maintenance is crucial - including checking tyre pressures, the seals on pumps and valves and inspecting pipes for signs of wear or cracking. An annual National Sprayer Testing Scheme (NSTS) MOT is extremely good practice as a sprayer health check, but needs to backed up with a routine look around the sprayer before every use.
Water sensitive paper test using 04 XC nozzles
Water sensitive paper test using 025 XC nozzles
Water sensitive paper test using 08 XC nozzles
Application Academy
Syngenta’s stand at BTME (21-23 January, Harrogate) features a practical demonstration unit to fully explain the fundamentals of spray application - including how to select nozzle types, water volume and sprayer pressure to give the best chance of hitting the target.
Visit the stand to register for a chance to join an unrivalled education opportunity at the pioneering Syngenta Application Academy. Get the opportunity to learn the science behind spray technology from leading industry specialists, along with in-depth practical skills required to become a top sprayer operator.
Application Academy tutorial videos
To watch Glenn Kirby’s advice for targeting turf applications, scan the QR Code or visit
https://www.greencast.co.uk/syngenta-art-application-videos
PC December/January 2020 123
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