CEREAL GROWERS could reduce the rate of a key autumn herbicide without compromising weed control, according to Syngenta trials.

As part of the Voluntary Initiative (VI), growers in some river catchments* are being advised to cap rates of isoproturon (IPU) at 3 litres/ha, compared to a maximum label rate of 5 litres/ha, explained the firm’s Iain Hamilton.

But he believes this needn’t compromise weed control.

The Syngenta trials compared treatments of 5 l/ha IPU + trifluralin against 3 or 4 l/ha IPU + Hawk (clodinafop-propargyl + trifluralin) and found little difference in blackgrass control.

“For growers in these catchment areas and even elsewhere this news offers the opportunity to reduce the amount of IPU they’re using without compromising control.”

The 3 l/ha rate appeared optimum, he added. “It could prove a very useful holding spray this autumn.”

*The VI advice applies to growers in parts of South Staffordshire, Oxfordshire, Northamptonshire and Warwickshire