A sprayer nozzle has been launched that will provide growers with improved control of problem grassweeds, along with a reduction in spray drift.

In 2004, Syngenta introduced its Hawk nozzle, developed to get the most out of the post-emergence cereal grassweed herbicide bearing the same name.

The concept was simple – aim the spray directly at the target and you give yourself a better chance of hitting it, whether it is a small upright blackgrass plant or the back of a soil clod.

See also: New Defy 3D nozzle: Sprayer operators give their verdict

Such accuracy was achieved by taking a standard 110deg flat-fan nozzle and shifting the trajectory of the spray from vertical to a forward-facing angle of 38deg.

Regulators banned the trifluralin component of Hawk (clodinafop + trifluralin), but Syngenta was left with the nozzle concept which, after a slight redesign, evolved into the 83deg, 40deg inclination Defy.

Alternating backwards and forwards along the width of the boom, it was specifically designed to apply residual-acting herbicides to bare soil and attack clods from two angles.

Defy nozzles not only improved grassweed control, but also cut drift and had the ability to work effectively at higher boom height and faster ground speeds.

The ‘rugby ball’ effect of the old Defy nozzle (left) is eliminated with the new 3D version (right).

Syngenta application expert Ben Magri says the Defy nozzle has now been trumped by the new Defy 3D, further improving coverage and reducing drift by a huge 60-75% over the standard flat fan, depending on nozzle size.

“Although the Defy was very good, the coefficient of variation – or evenness of spray – along the boom when alternating forward and backwards wasn’t as good as it could be.

“You would get the “rugby ball” effect, whereas the new 3D nozzle gives perfect 50-50 distribution between front and back and was the main reason for the redesign,” explains Mr Magri.

In Syngenta trials the improved nozzle performance has equated to a 6% improvement in blackgrass control when using a Liberator + Defy pre-emergence herbicide stack in 100 litres/ha of water.

Environmental benefit

Mr Magri says that achieving the improved drift reduction of the new nozzle while maintaining the appropriate droplet spectrum to maximise soil-applied residuals has been very difficult.

He explains that a droplet spectrum is like a sliding scale – taking away the fine “drifty” droplets at the smallest end of the spectrum, increases the larger droplets at the other end and worsens distribution.

The 3D design has gone some way in eliminating this effect and has resulted in the least drifty flat-fan nozzle on the market.

“It’s important that we avoid off-target contamination and the new nozzle is designed to deliver drift reduction to a level we haven’t had for grassweed control before.

“Less drift also means a greater number of spray days, which will help in the timely treatment of grassweeds such as blackgrass,” adds Mr Magri.

The original Defy nozzle didn’t have a Lerap rating so aquatic buffer zones on category B product labels could not be reduced.

It is expected the 03, 035 and 04 Defy 3Ds will have a Lerap two-star rating, with the 05, 06 and 08s likely to have a three-star rating, which means both will enable a buffer zone reduction to maximise the treated area.

The Defy 3D will be available from most nozzle distributors by 21 August. Growers can pre-order by calling Syngenta on 0800 652 4216