Grains Research and Development

Date: 02.05.2016

Weed resistance maps help navigate herbicide options

Author: Catherine Norwood

A new mapping tool gives growers the ability to identify herbicide resistance in their local area. It will incorporate results from University of Adelaide research looking at herbicide use strategies for preserving effective chemicals and managing emerging resistance.

Photo of mature ryegrass in barley

Mature ryegrass in barley.

PHOTO: Nicole Baxter

Thousands of weed-resistance test results conducted over more than two decades have been collated into a unique mapping tool that tracks the development of herbicide resistance across Australia. More important than the history, the maps record options for future control of the weeds they highlight, says Craig White, leader of the Bayer integrated weed-management program in Australia.

Screenshot showing information on the spread, location of herbicide resistance at a glanceOnline screen grabs showing the spread, and location, of herbicide resistance can be seen at a glance. These examples (above and below) show annual ryegrass resistance to Dim (Select®) herbicide in Victoria in 2004 and 2014.

The mapping tool, which is built on the Google Maps platform, has been developed by Bayer using resistance data from Australia’s two commercial herbicide-resistance testing laboratories, at Charles Sturt University in New South Wales and Plant Science Consulting in South Australia. Most of the findings relate to tests from farms conducted between 1993 and 2014, and more data including results from 2015 tests will be added to the maps as it becomes available. Mr White says in recent years an increasing number of roadside weed-seed test samples have also been included in the results.

Screenshot showing information on the spread, location of herbicide resistance at a glance

SOURCE: www.diversitycantwait.com.au/iwm/maps/mapdata.asp

Through Bayer’s Crop Science website growers and advisers can create and view maps down to postcode level showing weed species, mode of action, herbicide and year. Mr White says the maps provide an objective analysis of herbicide resistance that can help growers and advisers identify which chemistry options may still be open to them as part of an integrated weed management (IWM) program, which should integrate chemical and non-chemical weed-control tools.

“There may be herbicide choices still working (or not working) in a particular region, but which have been discounted because of assumptions about resistance. That has the potential to cost growers a lot of money. I think there are still great opportunities for growers in many areas to enhance their weed-control choices, and the mapping tool can help identify these.”

He says the maps offer a starting point for discussions about emerging issues and the extent of resistance for particular plants and herbicide chemistry, and also about where more information might be needed. The mapping tool also clearly identifies areas where no resistance data is available. Mr White says growers and advisers in these areas might consider testing to generate this information.

The mapping tool has been developed specifically for Australian growers to support IWM practices.

“Weeds represent a major threat to global food production systems, and we can’t just rely on herbicide chemistry for control,”

Mr White says. “Australia has been among the first countries to experience widespread herbicide resistance, but this also means we are well advanced in finding solutions involving integrated weed-control strategies.”

Bayer has a mode-of-action tool that can be accessed through its Crop Science website. This compares available products by registered name and chemistry to help growers identify whether they really are changing their chemistry when they rotate products.

More information:

Craig White,
0427 339 470,
craig.white@bayer.com;

Bayer Crop Science

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