July 3, 2012
Western Australian research investigating herbicide control of wild radish in cereal crops has highlighted the importance of good spraying conditions to maximise chemical uptake by the weed.
It has also shown the importance of combining herbicides with different modes of action to maximise wild radish control, especially where herbicide resistance is suspected.
The findings were made by Synergy Consulting under a Grains Research and Development Corporation (GRDC) funded ‘Western Agribusiness Trial Extension Network’ project.
“Spraying conditions at the three sites – west of Dowerin, east of Dowerin and at Bolgart – were ideal last year in relation to weed size, weed density, crop stage and good growing conditions resulting in ‘soft’ weeds,” Synergy Consulting’s David Pfeiffer said.
“The outcome was good herbicide uptake and resulting control, regardless of the treatment tested.
“The effectiveness of the spraying treatments was in contrast to conditions and results achieved by WA growers in the very dry season of 2010.
“It is critical that, where possible, growers take advantage of good spraying conditions to maximise wild radish control to not only grow grain but also prevent radish seeds returning to the seed bank and further compounding the problem.”
Mr Pfeiffer said the herbicides tested in 2011 included contact, systemic and a combination of contact and systemic herbicides, applied with different water rates and spray nozzles.
He said combining herbicides with different modes of action was shown to be more critical than the choice of contact or systemic herbicides to maximise wild radish control, particularly where growers suspected there were herbicide resistance issues.
“Combining modes of action is achievable via tankmixes or commercially available formulations,” Mr Pfeiffer said.
The trial indicated that increasing spray coverage – via higher water volume and nozzle selection - increased the efficacy of herbicides on wild radish, but this trend was not statistically significant.
“As expected, increased spray coverage was more effective with contact herbicides than systemic options such as MCPA LVA,” Mr Pfeiffer said.