Herbicide resistance levels increasing in wild radish
A survey of farmer paddocks across the Western Australian grainbelt has confirmed a big increase in the level of herbicide resistance in wild radish to commonly used Group B selective herbicides.
But other herbicides such as glyphosate, atrazine and Velocity® (bromoxynil and pyrasulfotole) are still providing good control of WA’s worst cropping weed, in most cases.
Details of current levels of herbicide resistance in wild radish will be outlined at this month’s Agribusiness Crop Updates, which are supported by the Grains Research and Development Corporation (GRDC) and the Department of Agriculture and Food (DAFWA).
In his opening address to the Updates in Perth, GRDC Chairman Keith Perrett said that the GRDC was committed to long-term research into herbicide resistance.
“We are currently investing $8.2 million a year in weed management research.
“A major component of this investment is our ongoing partnership with the Australian Herbicide Resistance Initiative (AHRI) to tackle herbicide resistance. It’s also funding research into non chemical weed control options such as the Harrington Seed Destructor,” Mr Perrett said.
In providing details of the survey, AHRI senior researcher Mechelle Owen said 84 per cent of 96 radish populations tested had some level of resistance to the Group B herbicide chlorsulfuron (such as Glean®).
“Almost half (49 per cent) of these populations also displayed resistance to imidazolinone (another Group B herbicide),” she said.
“Most populations tested had resistance to the Group I herbicide 2,4-D amine (76 per cent) and diflufenican (49 per cent) although only a small number of plants within each population were resistant to diflufenican.”
Ms Owen said that while glyphosate, atrazine and pyrasulfatole/bromoxynil (Velocity®) were still effective in most cases, growers should not rely on herbicides alone to manage wild radish and other weeds, and should also consider the use of non-chemical methods for weed control.
The survey of herbicide resistance in the WA grainbelt was conducted in late 2010 by AHRI and funded by the GRDC, with analysis of the results progressively completed for the weed species collected.
Weed samples were taken from 466 paddocks from Binnu in the north, to Esperance in the south, including 362 samples of annual ryegrass, 96 of wild radish, 128 of wild oats, 47 of barley grass and 91 of brome grass.
The 2013 Agribusiness Crop Updates, held in Perth on February 25 and 26, will be followed by a series of Regional Crop Updates, aimed at growers, in March.
PHOTO CAPTION: (right) Wild radish plants that have survived an application of herbicide.
PHOTO CAPTION: (above) Wild radish in a barley crop.
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