Agrovista believes Syngenta’s potato nozzle might be the best compromise for blackgrass control and for covering ground quickly.

Agrovista trials to find the best combination of nozzle and workrate for blackgrass control with Atlantis applications suggest the angled VP04 “Gold Potato” nozzle from Syngenta is best for spraying at faster speeds.

In the trials, Atlantis + Firebird + Biopower was applied after a half-rate Trooper pre-emergence base using several combinations of nozzles, water volumes and forward speed, the firm’s Mark Hemmant says. “The aim was to find out what the best practical solution is for customers.”

Previous trials had shown that nozzle choice could have a big impact on the performance of Atlantis, he says. “From the best to worst nozzle we’d seen, you could get twice as much out of Atlantis by applying it right.”

But growers also want to drive at reasonable forward speeds, and use lower water volumes, so the firm wanted to see what effect adding those factors made to the performance of each nozzle. “They don’t want to use a nozzle that requires you to drive really slowly, or only go when there is no wind.”

Perhaps not surprisingly, the results showed a strong trend for slower forward speeds to give the best results. For example, travelling at 19kph and using 100 litres/ha with a red 04 flat fan nozzle gave 7% less blackgrass control than going 12kph with 150 litres/ha of water.

In past trials, angled nozzles had also improved coverage and, therefore, control over flat fan nozzles. “They give better coverage of the small, vertical target that blackgrass presents at that time,” says Mr Hemmant

But in this year’s trials, the Hawk nozzle, a VP03 nozzle angled forward 40°, gave only moderate results, surprisingly poorer than in past years. Drift could be to blame, Mr Hemmant suggests. “The wind speed was 6-8kph when we applied the sprays, and looking at the plots, there was some evidence of drift in neighbouring plots. So we think that some of the finer sprays, which in theory should have given the best results, suffered.”

But the other angled nozzle in the trial, the Gold Potato, a VP04 nozzle angled forward 30°, which gives a less fine spray than the Hawk nozzle, performed best in the trial, giving 95% control at 12kph using 150 litres/ha water volume.

“It was the only nozzle that gave good results at 12kph,” Mr Hemmant says. “If there was no or low wind the Hawk nozzle might be best, but maybe it would be better to have the Potato nozzle in the boom for when it is more windy. Let’s face it, when you’re spraying in the autumn, wind speeds of 6-8kph are not uncommon.”

This is the first year the Potato nozzle has been included in the trial, Mr Hemmant notes. “We’re going to continue looking at it this year, along with other methods of angling nozzles, such as using twin caps.”

Atlantis application

• Nozzles tested at varying speeds/water volumes
• Slower speeds favour better control
• Angled nozzles tend to help, but beware excessive drift
• Syngenta Gold nozzle allowed faster speed and gave best control

Active ingredients

• Atlantis – mesosulfuron-methyl + iodosulfuron methyl sodium
• Firebird – diflufenican + flufenacet
• Trooper – flufenacet + pendimethalin