“But it also offers potential environmental benefits from reduced drift, and could help growers improve results by boosting work rates for more timely spraying, he adds.

“Trial results using a tank mix of the pre-emergence herbicides 4 l/ha Defy + 0.4 l/ha flufenacet/diflufenican showed black-grass control was boosted to 97% using the new Defy 3D nozzle,” explains Mr Magri. “That compared with 91% from an equivalent-sized conventional flat fan nozzle. Both were operated at a 75cm boom height.

“Similarly, at a 50cm boom height, control levels were 96% from the Defy 3D nozzle versus 93% from the conventional.

“The significance of 97% control is that this is often considered the minimum threshold needed to stop black-grass populations increasing,” he adds.

In common with the previous Defy nozzle from Syngenta, Mr Magri says the new Defy 3D nozzle produces a spray that is angled from the vertical and is designed to be used alternating backwards and forwards-facing along the boom to treat targets from both sides, not just above.

However, the key point with the new nozzle is that it has also been engineered to produce very little variation in spray coverage along the boom length, says Mr Magri – something that testing has confirmed. Further tests have also shown improved spray coverage over the front, top and back surfaces of simulated soil clods versus a conventional fan nozzle, he adds, and it is this better coverage in all directions that gives the new nozzle its 3D name.

“It is the combination of various factors that contributes to its overall efficacy. The droplet spectrum of the new nozzle has also been tailored for grass weed control, and to give fewer small drops in order to reduce drift. Depending on size, the new nozzle offers 60-75% less drift compared to a conventional flat fan nozzle.

“It also gives excellent performance at a 100 l/ha water volume – since the effect of the angled spray outweighs the need for extra water to improve coverage. Compared with higher volumes, 100 l/ha increases the proportion of time spent spraying versus downtime spent travelling and filling. This can also help improve results by treating more black-grass in available spray windows and therefore on time.

“Also, as well as environmental benefits, less drift can mean a greater number of spray days. And we know that timely spraying is critical with black-grass,” he adds.

Syngenta technical manager, Jason Tatnell,  agrees that timeliness of sprays and correct application are important with black-grass herbicides. As resistance to post-emergence herbicide chemistry has increased, he says maximising results from pre-emergence herbicides has become even more crucial.

“Trial results show that control from a post-emergence treatment has roughly halved over the last seven seasons,” explains Mr Tatnell. “So growers have to stack all the odds in their favour.

“We know from trials that mixing or stacking different pre-emergence herbicides increases overall control level. For example, adding Defy to a flufenacet base treatment boosted control by an extra 13% in trials last autumn.

“However, as we have seen with the new Defy 3D nozzle, by paying attention to nozzle choice, the efficacy of a popular Defy + flufenacet-based pre-emergence tank mix can be improved even further.

“We have a clear goal at Syngenta to help growers fight back against this problem grass weed, and application is one of the techniques we are exploring,” Mr Tatnell adds.

When spraying, Mr Magri says the new Defy 3D nozzle has been optimised for use at boom heights of between 50cm and 75cm above the target.

Spray pressure for the new nozzle should be between 0.7 and 3 bar, and it works most effectively at sprayer speeds of between 12kph to 14kph, he says. It will be available in sizes of 03, 035, 04 and 05, he adds.

The new Defy 3D nozzle
• Engineered to deliver more even spray coverage
• Black-grass control boosted by up to 6% compared with conventional nozzle
• Potential environmental benefits from reduced drift
• Could help with treating more black-grass on time

Click here for more information and advice on managing black-grass and details on the new DEFY 3D nozzle >>