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New application window for glyphosate-resistant kochia

June 6, 2013 – A University of Alberta-led research study has found that post-harvest herbicide applications significantly reduce kochia seed set. The findings provide growers with new ammunition in the fight against glyphosate-resistant kochia.

In 2012, University of Alberta, with the support of BASF Canada Inc. and Natural Science and Engineering Research Council of Canada (NSERC), initiated trials to look for alternate ways to control glyphosate-resistant kochia in Western Canada. The research looked at the efficacy of post-harvest applications to specifically reduce the seed set of glyphosate-resistant kochia and add a different herbicide into crop rotations.

"Herbicide-resistant weeds are spreading, but we're also getting more and more resistant species and have seen the first occurrence of herbicide resistance to glyphosate," said Linda Hall, Lead Research at University of Alberta who conducted the study. "With the research, we were trying to determine whether there is a post-harvest treatment that can reduce the seed set of kochia."

Kochia is a unique weed with the ability to germinate at low soil temperatures and can produce between 10,000 and 25,000 seeds per plant. It emerges very early and matures very late, which means using multiple modes of action to control kochia at post-harvest could be an alternative action to combat the noxious weed.

"To investigate the post-harvest control window, we went in after harvest and applied a range of herbicides. In those trials we measured the amount of seed left on the plant and the amount that had fallen onto the ground. We found two herbicides that were effective at reducing seed set, and very dramatically. Fifty per cent reductions were seen with DISTINCT and paraquat," said Hall.

The research findings open a new opportunity for weed management. With more in-depth research coming, post-harvest applications with products that have additional modes of action like DISTINCT are likely to result in fewer seeds on the soil and will help combat glyphosate resistance.

Growers concerned about glyphosate resistance should visit www.weedtool.com. The website is an online weed resistance risk assessment that allows users to measure the risk of glyphosate resistance developing and it also contains valuable agronomic advice to manage resistance.