Alternating nozzles boost application of herbicide Defy

Winter wheat and winter barley growers looking to boost application of the new pre-emergence herbicide Defy against black-grass can do so using 40 degree angled Hawk nozzles, but alternating them forward and backward facing along the spray boom, trials by Syngenta suggest.

Conducted over two seasons, the trials showed that the fore and aft facing nozzles gave amongst the highest level of control in comparison with a range of alternative nozzles when used to apply the new herbicide.

In particular, on a cloddy seedbed last autumn, control was boosted anywhere from 2-10% when using them to apply a recommended black-grass tank mix of Defy + trifluralin.

According to Syngenta application specialist Tom Robinson, this is likely to have been due to improved herbicide coverage around all sides of the clods.

"We believe that the forward facing Hawk nozzle effectively covers the front face of the clod as the sprayer approaches it, while the rearward facing nozzle effectively deposits spray on the opposite side.

"In reality, good performance from Defy was achieved whichever nozzle type was used in the trials. It's just that if you want a step forward with application, particularly on a cloddy seedbed, then the alternating fore and aft nozzles would be our favoured approach."

Originally designed to boost performance of the post-emergence herbicide Hawk on difficult-to-hit black-grass at the 1-2 leaf stage, the Hawk nozzle works by producing a special 40 degree angled spray pattern to deposit chemical on the target from the side.

With all nozzles pointing forward, as recommended for Hawk, this has been shown to more than double the amount of spray deposited on the target compared with a vertical spray for this post-emergence timing. In addition, a survey of users revealed that nearly two thirds rated the Hawk nozzle as 'better' than standard nozzles against black-grass – with over ninety percent saying they would use them again.