Sprayer setup essential for successful weed control

Spring is a key time for weed control in winter crops, and ahead of spring sowing. Herbicides and targets vary, but proper sprayer maintenance and setup, along with correct nozzle selection ensure e ective weed control in all situations.

In partnership with independent application specialist Tom Robinson (right), Bayer commissioned trials to assess how nozzle choice and boom height a ect drift and e cacy of Roundup (glyphosate). “We wanted to have better information on Roundup application to help farmers improve stewardship and performance,” says Bayer’s Roger Bradbury (left).

careful attention to spray quality. Too ne and it drifts away; but too coarse and it lands on the soil instead.

The trials tested four nozzles at two boom heights (0.5m and 1m) spraying 100-litres/ha Roundup to a eld of spring wheat, which was used to simulate a stubble. The poorest performing nozzle was the 110 fanjet, which is the standard label recommended nozzle. It caused more drift without improving weed control.

Although the focus was (mesosulfuron + iodosulfuron

Although the focus was glyphosate in stubbles, the results are also relevant for other contact acting herbicides such as Atlantis Star (mesosulfuron + iodosulfuron + thiencarbazone). Here are the main ndings.

“If you are spraying with lots of drift, you will get a worse result,” says Tom Robinson. “Drift is bad for compliance and for the image of the farmer, but it also shows that application is less than ideal.” Contact acting herbicides need to land and settle on the target leaf which needs

The other three nozzles were the 3D, Hypro Guardian Air 75% drift reduction, and Lechler ID3 90% drift reduction. “The other three nozzles performed roughly in line with expectations,” says Mr Robinson. “The 3D gave the best control, but is prone to drift. The Lechler ID3 was continued over…

•Broad spectrum weed control

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New biological e cacy data shows no loss in performance for tank mixes of Atlantis Star with fungicides. The optimum timing for Atlantis Star is in early spring when weeds are small but weather and workloads could see post-em applications pushed back towards the T0 timing.

Damage was the least 'drifty' nozzle. The surprise result for the 3D nozzle at 1m is probably because of a temporary drop in wind speed during application.

…from previous page the least 'drifty', but this resulted in slightly lower weed control. The Hypro Guardian is a good compromise option.

“In ideal conditions, up to force 2 winds with few stronger gusts, the 3D is the best option. At higher windspeeds, the Hypro Guardian or the Lechler are probably a better choice.”

Check boom height

Boom height is the single biggest factor in levels of drift; setting the boom to 0.5m above the crop is the most important thing to do regardless of nozzle choice. Setup and maintenance are important here because the boom must be stable to apply this low down. If it is unstable, the easiest x for the operator is to increase the height causing more drift and poorer spray coverage (see Graph).

“Angling nozzles helps when hitting small upright targets such as grassweeds because more of the target is hit directly by the spray. For the 3D, the angle is set to 38 degrees, but other nozzles can be angled in a similar way to improve coverage,” says Mr Robinson.

The trial took place at 12kph in good spraying conditions against an easy target; but on farm, things can be more di cult, points out Mr Bradbury. “The di erences between nozzles and height were small but we have to consider the implications on farm. Any di erences would be magni ed at higher speeds, in more di cult conditions and aiming for a more challenging target – all of which might be true when farmers go out to spray this spring.”

He emphasises that forward speeds should be at a maximum of 12kph; any faster risks poorer coverage and control. Targets in spring can also be challenging, over-wintered broad-leaf weeds and perennials both need high rates of glyphosate (1,440–1,800g) to get control. FG

Trials tested mixes at the T0 timing in early April with Arizona (folpet), Arizona + Variano Xpro (bixafen, PTZ, Fluoxastrobin), Arizona + Boogie Xpro (bixafen, PTX, spiroxamine), Aviator Xpro (bixafen + PTZ) and Ascra Xpro (bixafen + PTZ + uyopyram). All applied at the full label rate. For every combination, there was no reduction in weed control compared to straight Atlantis Star.

“Biological compatibility means there is no drop in performance, this is a step up from the standard physically compatible tank-mix guidance which is about safety,” says Bayer’s Tom Chillcott.

“These results will reassure farmers who decide to combine the T0 with weed control if there is a delay to the post-em. But it doesn’t change the overall advice to apply Atlantis Star as soon as conditions allow.”