Technology Spraying solutions

Big and small spraying solutions

Effective agrichemical spraying is a necessary part of vineyard management for any table grape grower.

If you could reduce chemical waste, reduce financial outlay, reduce your vineyard’s carbon footprint, improve coverage and reduce your time – or your workers’ – on the job, that would be the definition of utopia. Wouldn’t it?

Growers might think these are grape expectations, but they are achievable. Here we explore both minor and major changes you could make to your vineyard spray practices, and take a look at how these might benefit you.

Recycling sprayer

Growers who attended the Australian Table Grape Association’s first event in the “AgTech Sessions” series in July would have seen a recycling/ recirculating sprayer in action.

“The main purpose of a recycling sprayer is to capture and recover what wasn’t deposited on canes (early in the season) or on canopy later in the season, and then filter it and return it to tank for re-use,” said Cam Clifford.

Cam is the managing director of AME Group, who manufacture recycling sprayers available for use on Australian table grape vineyards. “The ‘revolving vortex’ of air produced by the FMR recycling sprayer creates an air curtain at the front and back of the recovery shroud, which not only strongly assists the recapture, but also reduces off-target drift,” Cam said. “At the start of the season, this means huge chemical savings. Recycling rates can be up to 70 per cent early season. As foliage density increases, recovery rates obviously diminish, to below 10 per cent, as expected. You can still expect an average of 30 per cent chemical savings across the season.” “In a wide table grape trellis the shrouds are obviously quite widely spaced, which does impact on the potential recapture efficiency,” weighed in Alison MacGregor, ATGA extension team member, about the impact of a recirculating unit. Alison has had a career-long interest in optimising spray applications for growers. “Any spray that doesn’t land on the canopy is wasted. In spring it is hard to avoid a lot of wastage using a conventional sprayer,” she said. “Recirculating units can reduce that wastage significantly.” Both Alison and Cam agree the benefits are substantial. The advantages go beyond minimising drift and chemical waste – recapturing overspray means that you get across more rows before you empty the tank, saving on not only chemical product, but re-fill time, tractor operation and labour costs.

“The recycling sprayer also enables enhanced spray window opportunity due to the ability to continue spraying in wind conditions, when conventional sprayers would need to stop due to drift,” Cam said.

Alison said that current recirculating vineyard sprayers had shrouds that hang over the row, which was suitable for most table grape trellises. An over-row design would not be suited to linked trellises common in Western Australia, however.

Using the tools in your toolbox

Whether you have the latest model sprayer or an old traditional sprayer, there is a lot you can do to optimise the coverage and operational efficiency of any sprayer. Growers might respond to the question “Do I still need to calibrate nozzles if the sprayer has a controller in the tractor cab? ” with “No need! My sprayer tells me how much I applied!” So why do sprayer and nozzle manufacturers still recommend that you check nozzles and calibrate your sprayer? “Their reason is simple,” according to Alison. “A spray controller regulates the total output per distance travelled – brilliant for maintaining output if your travel speed varies. It also keeps track of total amounts applied, for your spray diary. “But a controller doesn’t tell you whether individual nozzles are blocked or damaged, or are appropriately oriented to hit the target. “So, assessing nozzle outputs still remains an important part of sprayer and spray coverage optimisation.” Alison said that calibrating a traditional airblast sprayer, with only six or eight nozzles per side, used to be a relatively quick and easy process. “You could quickly identify if any nozzles are under-performing, and calculate total output per hectare,” she said. “It’s much harder to use that approach now, because calibrating a modern sprayer can involve testing more than 90 nozzles”.

David Manktelow, a spraying expert based in New Zealand, insists that “spray nozzles are precision parts”. David said spray nozzles required servicing and occasional replacement and it was sensible to remove and clean all nozzles on a sprayer at least once per season. “While nozzles are off the sprayer, you have an ideal opportunity to also check nozzle outputs on a simple test rig,” David said. “This service is offered by sprayer service agents in New Zealand and would be great to see in Australia.” As well as checking nozzles, David added that it was important to check pressure in the booms or manifolds. “Use a simple pressure gauge with an adaptor that fits onto the nozzle body to test for differences in operating pressures in different sections of the sprayer,” he said. “Another way to check output of different boom sections is to operate the electronic controller in manual mode while you measure output from each boom separately. “Differences of more than 5 per cent in output or pressure between sections indicate a plumbing fault or obstruction that you should identify and fix.

“Once you have checked nozzle outputs and checked for differences between boom sections you can trust your rate controller or monitor to reliably deliver your target application volume.” v

HERE IS A PRE-SEASON OR WET-DAY MAINTENANCE JOB TO MAKE THE SEASON RUN SMOOTHLY

STEPS

1

2 Remove and soak all nozzles and filters in tank cleaner or detergent.

Remove gunk gently with a soft brush or with compressed air. A portable ultrasonic cleaner (available for $100$400, designed to wash jewellery) is ideal for cleaning nozzles

TIME-SAVER TIPS

Test flow (L/min) of each nozzle to make sure there are no blockages or nozzle wear. Output should be within 10% of the specs. Ask your local sprayer dealer to set up a benchtop flow metre to test all your nozzles before you reinstall them.

3 Check outputs of different boom sections. Operate the electronic controller in manual mode, at a constant pressure, and run each boom separately to find differences in output (L/min) between sections.

4 Check different sections of the sprayer for differences in operating pressures across the sprayer. Use a simple pressure gauge with an adaptor that fits onto the nozzle body to check pressure in that section. Repeat on each manifold or boom.