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 proactive 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®.

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.

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 www.grdc.com.au/

groundcover, and in the GRDCHerbicide 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 www.ahri.uwa.edu.au

For information on herbicide sustainability and harvest weed seed control practices, visit the WeedSmart information hub at www.weedsmart.org.au