News Archive

WA growers are likely to face another late break this year. Whilst parts of the state received significant early rainfall, the majority of wheat belt farmers are anxious for a decent rainfall to enable crop seeding.

Adding to the challenges of low grain prices in 2010 are that in 2009 many paddocks were weedy, meaning high weed burdens in 2010.

Based at UWA and funded by GRDC, the Western Australian Herbicide Resistance Initiative (WAHRI) is led by Director Stephen Powles, who is urging growers to think about the implication of dry sowing crops, especially into high weed burden paddocks.

“Weedy paddocks were widespread last year and unless weed control tactics were employed to prevent weed seed from entering the seed bank, there will be a lot of paddocks with high weed burdens this year” Prof Powles said.

“A late break may force growers to dry sow crops without any knockdown. Dry conditions reduce efficacy of pre-emergent herbicides and consequently in-crop herbicides will be heavily relied upon for weed control”

Prof Powles pointed out that ryegrass and wild radish are resistant to many post emergent herbicides, making in crop control of these weeds difficult. Therefore, where possible, growers are encouraged to delay seeding to enable a good knockdown, especially in high weed burden paddocks. Rotating between available pre-emergent herbicides is also important.

Department of Agriculture Weed Researcher Peter Newman is advising growers to think wisely when choosing which knockdown products to use this season.

“Once the season breaks there will be an influx of small weeds and often these are quite difficult to kill” Mr Newman said.

Previous research conducted by Peter demonstrated that neither glyphosate nor paraquat type products will give reliable control of half leaf grasses on their own.

“Time is precious when the season break is late, and farmers want to spray as early as possible, often targeting small weeds.  In a situation such as this I would advise to use Spray.seed or paraquat” he said.

“These products work really well when applied in overcast or dark conditions and when mixed with trifluralin will give better grass control than applied alone.”

“They also have a comparative advantage over glyphosate on small cotyledon broadleaf weeds and provides an opportunity to give glyphosate a rest for resistance management.”

Media references

Professor Stephen Powles; Director, WAHRI  Tel 08 6488 7833, Mobile 0418 927 181,
Mr Peter Newman; Weed Researcher, DAFWA Tel 08 9956 8563 or
Ms Neree Martinez, 08 6488 7872 or email [email protected]