Use of full label rates vital to protect new herbicide

Author: Natalie Lee | Date: 18 Apr 2013

AHRI Roberto Busi

Grain growers gearing up to sow crops are urged to resist any temptation to use below label rates for the newer pre-emergent herbicide Sakura® (pyroxasulfone), with research highlighting the risks if rates are cut.

They are also encouraged to rotate the use of the product with different mode-of-action herbicides, and use integrated weed management tactics, including crop competition and harvest weed seed control.

The advice comes from Grains Research and Development Corporation (GRDC) supported research conducted by the Australian Herbicide Resistance Initiative (AHRI).

The unique and pro-active research, which tested the propensity of ryegrass to evolve resistance to Sakura®, was conducted for five years before the commercial release of the herbicide in Australia in 2012.

AHRI postdoctoral fellow Roberto Busi said the Group K herbicide Sakura® provided growers with a valuable, alternative pre-emergent herbicide option to control ryegrass populations, many of which had evolved resistance to several herbicides.

Dr Busi said that in the trials, a ryegrass population initially susceptible to Sakura® evolved resistance to it after only three generations of exposure to below label rates of Sakura®.

“Our trials found that the use of below label rates of Sakura® posed a high risk for the rapid development of herbicide resistance,” he said.

Dr Busi said the research reinforced the message that rates for all herbicides should never be cut, and that growers should use a diverse range of weed control strategies.

“There is a danger of over-reliance on Sakura®, with this research showing that ryegrass could rapidly evolve resistance to it,” he said.

“Judicious use of this herbicide will delay the evolution of herbicide resistance in the field.”

Dr Busi said growers should rotate Sakura® (Group K) with other herbicides including the pre-emergent herbicides Boxer Gold® (Group J & K) and trifluralin (Group D).

More information on the Sakura® research is contained in an article published in the March-April edition of the GRDC magazine Ground Cover at, and in the GRDC Herbicide Resistance Supplement to be included with the May-June edition of Ground Cover.

More information about Australian research programs targeting herbicide resistance can be found at the AHRI website at

For information on herbicide sustainability and harvest weed seed control practices, visit the WeedSmart information hub at


AUDIO DOWNLOAD: Click here to download an audio grab for this release. Audio is of Roberto Busi

PHOTO CAPTION:  AHRI postdoctoral fellow Roberto Busi says the use of below-label rates of Sakura® poses a high risk for the rapid development of herbicide resistance in weeds.

For interviews:

Roberto Busi
(08) 6488 1423, 0415 185 553


Natalie Lee
Cox Inall Communications
(08) 9864 2034, 0427 189 827

GRDC Project Code UWA00146

Region West