Harvest weed seeds to curtail wild radish

HWSC an option to manage wild radish

Cropping
ALL FACETS: A new fact sheet from the GRDC outlines wild radishs ecology, resistance status and management options.

ALL FACETS: A new fact sheet from the GRDC outlines wild radishs ecology, resistance status and management options.

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CROPPERS are encouraged to implement a multi-faceted integrated weed management strategy, particularly to get the upper hand on wild radish.

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GRAINGROWERS are encouraged to implement a multi-faceted integrated weed management strategy, which includes harvest weed seed control in order to gain the upper hand on wild radish.

Wild radish (Raphanus raphanistrum) is one of the most widespread broadleaf weeds affecting almost all grain-growing regions in Australia.

It is becoming increasingly resistant to multiple herbicide modes of action, costing growers about $53 million in lost revenue per year.

GRDC Weeds manager Jason Emms says management of wild radish is a long-term prospect, with the aim to drive seedbanks down and maintain them at low levels.

"Wild radish is such a difficult weed to manage and is quite variable in its biology," he said.

"It holds onto its pods and does not shed a large proportion of those on the ground, making it a great candidate for HWSC.

"Wild radish pods are also generally set high enough to be collected by the harvester.

"The key to management is preventing seed return to the seedbank and harvest weed seed control can help achieve this."

Harvest weed seed control has been proven to be an excellent non-herbicide tactic to reduce wild radish numbers when applied to paddocks over multiple years.

Weed seeds can be collected and removed from the paddock using chaff carts, concentrated into a windrow for burning in autumn, delivered into a seed impact mill and destroyed or moved to narrow chaff lines via chaff lining or chaff tramlining.

Dr Emms encouraged growers to inspect paddocks in order to determine areas of weeds which had survived herbicide applications throughout the growing season.

An integrated program of herbicide and non-herbicide tactics is needed to reduce (wild radish) herbicide resistance and provide long term control. - JASON EMMS

"Right now, growers should be able to see what has survived herbicide application and it is important to carefully consider how to manage these remaining plants," he said.

"Patch management can be tackled using knockdown herbicides and hand pulling remaining plants can be effective.

"For larger infestations of wild radish, late season in-crop herbicide application can be a useful management tool where registrations exist. However, harvest weed seed control can help in long-term prevention."

As wild radish is so persistent and hard to manage, Dr Emms said adopting a diverse and integrated control strategy will be most effective.

"Herbicides remain an important tactic to manage wild radish," he said.

"However, an integrated program of herbicide and non-herbicide tactics is needed to reduce herbicide resistance and provide long term control.

"Each farm is different, so the management strategy needs to be tailored to suit each situation."

Wild radish seed samples can be collected during harvest and sent away for resistance testing to help with weed management in following seasons.

"It is critical to understand which herbicide options remain available for effective management in the future," Dr Emms said.

A new fact sheet from the GRDC outlines wild radish's ecology, resistance status and management options.

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