Spray early, spray twice: local wild radish research by GRDC western regional panel member Paul Kelly

Wild radish

As a grain grower near Mingenew in the Geraldton port zone I’m well aware of the threat posed by wild radish to the financial viability of growers in my region.

Due to its resistance to many major herbicide groups, farmers are being forced to spend increasing amounts of money to adequately control this worst local weed.

Recognising the problem, collaborative local research has been conducted investigating herbicidal control of wild radish, and the results will provide guidance to Western Australian growers this season.

The trials were initiated through the Grains Research and Development Corporation (GRDC) Geraldton port zone Regional Cropping Solutions Network (RCSN), of which I’m one of about a dozen local representatives.

After identifying wild radish as the main priority for funding in 2012, the research – involving a number of researchers and farm advisers – set about trying to find new herbicide tankmixes for wild radish control as an alternative to using the newer herbicides such as Velocity® (bromoxynil and pyrasulfotole) twice in a growing season.

There are concerns that over-reliance by farmers on newer herbicides could heighten the risk of wild radish developing resistance to them.

The research results were unexpected.

Coordinated by agricultural consultancy Planfarm and the Department of Agriculture and Food (DAFWA), the trials found that timing and application were more important than product choice for control of the weed.

Conducted at trial sites containing the worst, hardest-to-kill wild radish populations, the research found that if small weeds – the size of the top of a beer can – were sprayed twice with good coverage, some very resistant wild radish could be killed using a range of herbicide combinations.

There were many two-spray strategies that gave 100 per cent control of wild radish, but only one, one-spray strategy that provided this level of control.

Given growers need a diverse range of herbicide options for wild radish control, two sprays are therefore best.

There were many effective combinations that used older herbicides as part of the two-spray strategy and will pave the way for farmers to reduce reliance on the newer chemistries.

The success of the various combinations was highly dependent on timing and application.

One of the implications of the research results is that growers can move the whole spraying window forward, avoiding late herbicide sprays that could result in chemical residues in grain.

Those involved in the trials – including Planfarm’s Andrew Sandison and former DAFWA weeds researcher Peter Newman, now with the Australian Herbicide Resistance Initiative (AHRI), based at Planfarm – stress that chemical control methods should be used in combination with non-herbicide weed control practices.

To further test herbicide sequencing options, and the hypothesis that timing and application of both new and old herbicides is critical for maximum control of wild radish, further field trials will be conducted in the Northern Agricultural Region (NAR) this year.

These trials – supported again through the Geraldton RCSN - will be conducted in different sites on grower farms in the region.

Best practice management guidelines for wild radish management in cereals are also being developed and communicated to NAR agronomists for application in 2013.

The information coming out of the Geraldton RCSN wild radish trials is an example of how the RCSN initiative is helping to ensure that growers get the information they need, when they need it, so they can make good decisions about farming practices.

As well as initiating smaller projects, RCSNs feed issues into the standard GRDC investment process which leads to bigger projects.

People who want to become a RCSN representative are encouraged to express their interest. More information about the RCSNs can be found at www.grdc.com.au/rcsn

Paul Kelly

Paul Kelly

More details about the RCSN wild radish research results will be contained in an article in the May-June edition of the GRDC magazine Ground Cover, which will be available from www.grdc.com.au/groundcover

Information about the trials can also be obtained from Mr Sandison on (08) 9964 1170 or andrew@planfarm.com.au; Mr Newman on 0427 984 010 or petern@planfarm.com.au; or Geraldton port zone RCSN facilitator Cameron Weeks on 0427 006 944 or cameron@planfarm.com.au

To find out more about Australian research programs targeting herbicide resistance and resistance management to encourage sustainable cropping systems, visit 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

ENDS

PHOTO CAPTION: Collaborative research initiated through the Geraldton port zone RCSN has found that timing and application are more important than product choice for control of wild radish. Photo courtesy of DAFWA.

PHOTO CAPTION:  Paul Kelly.

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