Ice-cold, hard water that can affect the performance of some crop treatments is just one of the issues that top sprayer operator George Sargent has to manage on 610ha of Lincolnshire cropping.

But at least a whittled down choice of spray nozzles is making life easier. “I used to have quite a selection of nozzles for different treatments and situations,” he says. “Now I’m down to just three that I use most of the time because we’ve got better designs doing a better job.

“It’s a lot less complex in that sense – but you do have to understand what the nozzles can do and how to use them,” Mr Sargent emphasises.

The Syngenta Farm Sprayer Operator of the Year 2013 title holder operates a SAM Vision 3.0 self-propelled sprayer for arable farming enterprise JG Fisher. The 610ha of winter wheat, winter and spring barley, winter oilseed rape and spring beans provide a varied workload, and with many of the crops grown for seed, good weed and disease control is especially important.

The sprayer works across two units – 486ha at Stallingborough, six miles west of Grimsby, and 202ha due south at Hatcliffe on the Lincolnshire Wolds where water for spraying is drawn from a borehole.

“It’s hard water and it’s very cold – you wouldn’t need to add ice for a drink,” says Mr Sargent. “The water can affect some treatments – for example, I’ve had to re-spray glyphosate at Hatcliffe when it’s worked perfectly well here at Stallingborough, trace element tank mix compatibility can be adversely affected and there’s more foaming from some products when I’m working on the chalk.”

A water softener and anti-foaming agent tackles the water hardness issue, but as far as water temperature is concerned, the only practical solution is to fill the dark-coloured bowser and take advantage of any sunshine to warm it up a degree or two.

Simple design

With no liquid fertiliser applied other than a foliar feed, the sprayer has a simple single line configuration with triplet nozzle bodies typically carrying three tips – an 03 size Syngenta Defy and two sizes of Hypro’s Guardian Air low-drift design. An 035 delivers for 100-120-litre/ha applications and an 05 is used for treatments warranting volumes of 150-200 litre/ha.

An 08 conventional flat fan gets an occasional look-in for applying a 20% N foliar feed to oilseed rape, partly for the 250-litre/ha application volume involved, but also because the large orifice helps deliver the high-viscosity product.

See also: Syngenta Farm Sprayer Operator of the Year 2013 collects his trophy

At the start of the annual crop spraying workload in the autumn, the triplet nozzle bodies are rotated to deploy the Defy nozzle when applying 100-litre/ha pre-emergence treatments against blackgrass and broad-leaved weeds.

“Blackgrass isn’t a widespread problem here, but there are some bad patches, which we’re trying to contain by any means possible – very late drilling to allow time for an effective stale seed-bed, and higher seed rates with good tillering varieties to crowd out the grassweed.”

The Defy nozzle was purpose-designed for pre-emergence treatments. Its 83deg flat fan is a little coarser than is typical for a non-low- drift nozzle, which helps minimise drift, and although it still works best at 50cm boom height, good results are achieved at up to 70cm, says Syngenta applications specialist Tom Robinson.

That means wide booms can be set high enough to minimise the risk of ground impacts when working at speed on undulating fields.

Mr Sargent settles on a 60cm height setting for the 30m non-self-levelling boom on his Vision sprayer and follows Syngenta’s recommendation of installing the nozzles so that the 40deg inclined fan is projected alternately forwards and backwards.

This follows tests showing more even spray coverage to each side of soil clods compared with nozzles set vertically, which led to an improvement in pre-emergence blackgrass control from 50% to 75%.

“I’ve used the Defy nozzle ever since it first came out – it works very well for us,” says Mr Sargent. “I also use it for post-emergence blackgrass treatments, but with all the nozzles facing forwards.”

Forward movement

For this treatment, the objective is to maintain forward movement in the spray as the droplets lose momentum, in order to hit the very thin vertical target presented by a young blackgrass plant.

“But if I see a bit of drifting in a particular direction, which would result in less even coverage, I’ll change the nozzles to alternating again because the change in airflow tends to keep the spray on target,” he points out. “At just over 2 bar pressure, the 03 Defy allows a comfortable 12kph working speed, but it’s flexible enough when I’m working on our hillier ground to go down to 10kph at 1 bar and 14kph at 3 bar without any problems.”

The nozzles remain in place when it’s time for T0 fungicide treatments, with the Defy design’s fine but positively placed spray paying dividends in terms of even coverage.

Thereafter, the triplet bodies are rotated to bring the Guardian Air tips into play, reflecting a Syngenta recommendation to switch to an air induction (AI) tip that produces an output fine enough to provide good leaf coverage, but with sufficient mass to get down into the crop to tackle stem base disease.

“The 035 gives me 100-120 litre/ha at 2.5 bar and a target speed of 16kph, while the 05 delivers 150 litre/ha if it’s needed,” says Mr Sargent. “Again, there’s great scope for slowing to 14kph at 2 bar on the hills and speeding up again without affecting the spray pattern.”

The Guardian Air does produce a coarser spray than a conventional flat fan nozzle, which is why it is valued for opening up marginal spraying opportunities by minimising drift. But as Mr Sargent correctly identifies, its output is the finest of any single-outlet air induction nozzle, as the HGCA’s nozzle selection chart illustrates.

“Yet it still gives brilliant penetration and drift control if you reduce pressure to 2 bar to make the spray a bit coarser,” Mr Sargent points out. “Arranging the nozzles angled forward and back also seems to help when you’re wanting coverage up and down the plant, but later, when the target is the upper foliage, angling them all backwards to counteract forward movement allows the spray to settle into the top of the crop.”

It’s back to the Defy nozzle for T3 treatments because the finer spray and an alternating rearward- and forward-facing nozzle configuration should guarantee good all-round coverage of emerged ears to protect against fusarium ear blight on wheat while topping up protection against foliar disease infection.

Both nozzle types also have a part to play in non-cereal crops, starting with the finer Defy tip in an alternating arrangement for pre-emergence treatments, but with an all-forward layout to intercept hard-to-hit targets when applying graminicides post-emergence.

The 05 Guardian Air and 200-litre/ha volume helps get residual herbicides through a flourishing canopy, and the same nozzle delivering 150 litre/ha will be used to get fungicides deep into an oilseed rape canopy when necessary.

The 035 Guardian Air and 03 Defy share duties for the next part of the programme, depending on where the target lies; the Guardian Air for combined fungicide and insecticide treatments and the Defy nozzle for its upper plant coverage when combating sclerotinia infection before petal fall.

Finally, the 035 Guardian Air is Mr Sargent’s nozzle of choice for desiccating oilseed rape and winter beans.

“At 3 bar to produce a slightly finer spray, the Guardian Air gives us intensive coverage and a spray that will work its way through the crop to hit any blackgrass that may be lurking underneath,” he says.

“We’ve used this approach for the past two years on the winter beans and our agronomist has brought growers to see the results for themselves because it’s been so effective.”