It’s all about striking the best balance on the day between spray quality, speed, volume and drift control to suit the target and conditions.
That’s how Andrew Myatt, 2009 winner of the Syngenta Farm Sprayer Operator of the Year Award sums up his approach to crop protection work.
“In an ideal world, we’d all be spraying at a good pace on flat ground using simple flat fan nozzles and wouldn’t have to contend with drift-inducing wind,” he jokes. “In practice, of course, it’s the task of every sprayer operator to balance the different factors that affect spraying to do the best possible job on the day.”
With his 3000-litre/24m Bateman RB16 facing a total workload of some 10,000ha (24,710 acres) a year, output is a major consideration – hence the shift in recent years to nozzle sizes that allow faster working speeds without compromising spray quality or distribution pattern.
But so, too, is drift control – not only to prevent pesticides heading into neighbouring crops where they do not belong, but also to ensure even coverage of the crop being treated.
“Fortunately, we’ve seen some useful developments in nozzle design and the way we use them which helps us do a good job while working faster and keeping drift in check,” he points out. “Air induction nozzles, in particular, are brilliant for drift control compared with a conventional flat fan. The development of air induction nozzles that produce a less coarse spray means we can use them for a much wider range of applications.”
As foreman on the Stowell Park Estate in Gloucestershire, Mr Myatt handles all spraying operations across an arable rotation that this year comprises oilseed rape, winter wheat, spring wheat in place of spring barley, rye for a second year, oats and some spring beans.
Hilly ground limits spraying speeds in some fields and Mr Myatt prefers to refill the tank back at the yard at Yanworth near Cheltenham where facilities have been installed to add chemical direct from the store. All of which means it’s essential to capitalise on a lively work rate in the field when possible.
|Being able to quickly switch between two sets of different nozzles on the one spray line makes it easier to maintain pressure and flow consistency at different working speeds.|
Mr Myatt’s boom set-up helps in that respect by providing easy access to two sets of different nozzles on one spray line. With pneumatic nozzle body on-off control, selecting either set – or both in the case of high volume treatments such as pre-harvest glyphosate at 200-230litre/ha – involves nothing more than the press of a button.
“It’s a versatile set-up that’s put to good use in the autumn for grass weed control and in the spring and summer when it gives me more output during a busy fungicide spraying schedule,” he says.
For grass weed control, the sprayer is fitted with two different nozzles – a conventional 03 flat fan delivering the fine spray quality needed for maximum interception of the target weeds and an 03 air induction tip for situations where more emphasis has to be put on drift control.
“I use the air induction nozzles for the first pass around the field to make sure the spray stays where it’s meant to be and then switch to the conventional flat fan nozzles to get maximum target coverage,” Mr Myatt explains. “I’ve tried the Hawk tip with its angled spray, but found it a bit too drifty. My solution was to put a standard nozzle in a Billericay angled cap and get the advantages of an angled fan that way.”
Last autumn, he put Syngenta’s new Defy nozzle to the test as a potential alternative to the 110deg flat fan. It’s available in size 03 – with 035 and 04 to follow – and, unusually, is designed to produce an 83° fan angled 40° from the vertical.
For pre-emergence use, the recommendation to fit the nozzles alternately facing forwards and backwards follows trials comparing vertical and angled sprays lifting blackgrass control from 50% to 75% and more even coverage each of side of “shadowing” soil clods.
A combination of 03 and 035 Hypro Guardian Air induction tips are used for fungicide treatments with pressure used to tweak spray quality according to the target and conditions on the day.
Although Syngenta’s application specialist Tom Robinson says the Defy nozzle works best at 50cm (1.6ft) boom height, it is just as effective at 70cm (2.3ft) – which provides a bit more boom-dip clearance when spraying fast and accommodates sprayers that can not get their boom down this low.
At the same time, the slightly coarser spray quality produced by the narrower fan partly explains the 50% drift reduction recorded at The Arable Group’s Silsoe Spray Application Unit with a standard flat fan nozzle.
“First impressions in the field were that it was certainly less drifty than the 03 110° flat fan I’ve been using,” says Mr Myatt. “It may help that having the nozzles facing forwards and backwards leaves spaces for the air in front of the boom to get through, rather than being forced under or over in a wave and taking spray droplets with it.”
In any event, Mr Myatt plans to give the new nozzles another chance to impress this spring: “I’ll probably try them in situations that push the boundaries a bit and see how they perform on larger grass weed plants,” he says.
Once the fungicide spraying season gets underway, the Bateman will be kitted out with two sets of Hypro’s Guardian Air 110° flat fan tips.
“When I first put the Guardian Air nozzles side-by-side on the boom with the air inclusion nozzles I used previously, the difference between them was obvious,” says Mr Myatt. “Pattern tests using water-sensitive paper and the results we get from our fungicides have confirmed that they are perfectly acceptable for disease control.”
Guardian Air 03 tips suit the Bateman’s 12-13kph spraying speed capability on hilly ground while the recent addition of 035s to the spray line has lifted working speed on the flat to 16-17kph at the same 100-litre/ha and a little over two-bar pressure targets,
“Being able to switch between these two nozzles makes the system tremendously versatile,” says Mr Myatt. “I can stick to my preferred volume for output and my target pressure to maintain a good pattern, but still shift up to a faster spraying speed when field conditions allow.”
Within that broad approach, speed and pressure will be adjusted slightly depending on where the target disease occurs. Foliar diseases call for a slight coarsening of the spray by easing forward speed and pressure to get droplets down into the foliage whereas an increase in pressure – typically to three-bar – will produce a finer output with a better chance of delivering ear wash sprays to the intended target.