Double knock to preserve glyphosate

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock.

Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a herbicide followed by a non-herbicide tool (e.g. the ‘Canola Combo’ – crop top followed by harvest weed seed control). All that really matters is any resistant survivors to the first herbicide are hit with another control measure so that the weeds don’t set seed.

And then there is the double knockdown. Glyphosate followed by paraquat (or paraquat + diquat). Glyphosate resistance is such a big deal it gets its own, specific weed control strategy. Glyphosate is the world’s most important herbicide and nothing else comes close as a low cost, reliable knockdown, so we really need to look after it.

Australian Glyphosate Sustainability Working Group

With investment from the Grains Research and Development Corporation, the Australian Glyphosate Sustainability Working Group was established. 

After guiding growers and agronomists through a critical 15 years of managing glyphosate resistance in Australia the AGSWG has been disbanded, however the work of advising farmers and other weed managers continues. Find key factsheets on glyphosate management.

Articles

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How does crop competition support other weed control tactics?

Crop competition is a quiet achiever in weed control that also has a synergistic effect when applied with other tactics. Read More...
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News

Tickle those weeds this autumn

An autumn tickle of the weed seed bank can stimulate a flush of weed germination allowing for efficient control of the weed seedlings. Read More...
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Plan your attack on the weed seed bank

Here we summarise the key components of the WeedSmart Big 6 strategies and the principles that underpin them. Read More...
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Summer weed control in a high input cost year

WeedSmart’s western extension agronomist Peter Newman says yes; spraying summer weeds is one of the greatest returns on investment in modern agriculture – preserving soil nitrogen and moisture reserves for the following crop. Read More...
Case Study
Case Study

I’Anson Family Farms, Marrabel SA

Kym and Katie I’Anson are treating the serious soil constraints on their farms to grow more even crops and squeeze out the weeds. Read More...
Article
News

Invest in the weak link crop to avoid weed blow-out

South Australian farmers, Kym and Katie I'Anson, have added multiple tactics to control ryegrass in wheat, their weakest link crop. Variable rate lime, gypsum and seed has increased crop competition and the double knock and impact mill keep the fields clean. Read More...
Article
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What can I do to control large FTR grass in fallow?

Feathertop Rhodes grass is a major weed in chemical fallows in Australia, and is notoriously hard to kill with glyphosate, but there are other options. Read More...
Case Study
Case Study

Jamie and Susie Grant, Jimbour Qld

Proactive use of automated optical weed detection technology, allows continuous spraying and treating smaller and smaller weeds. Read More...
Article
Ask an Expert

What strategies will rein in wild turnip in the northern region?

Wild turnip steals crop yield and requires additional control measures that together cost over $10 million every year across Australia. Read More...
Article
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What’s the benefit of a double paraquat knockdown?

A double paraquat application can be used to great effect to avoid a serious blow-out of glyphosate resistant annual ryegrass. Read More...
Case Study
Case Study

Elton and Pam Petersen, Moonie Qld

The Petersens have rapidly regained control of glyphosate-resistant summer grasses using automated spot-spraying technology. Read More...
Article
Ask an Expert

How can I maximise grass weed control using hybrid canola?

For a competitive canola crop to halve grass weed seed set, use a vigorous variety, robust pre-em herbicide and the best agronomic package. Read More...
Case Study
Case Study

Single family, Coonamble NSW

The Singles gain good weed control year round using crops and fallow in both winter and summer on their farm near Coonamble. Read More...
Case Study
Case Study

Kurt Mayne, Rolleston Qld

Kurt Mayne is impressed with the benefits that have come with the addition of an optical sprayer to their weed control program. Read More...
Case Study
Case Study

Jason Rogers, Moree NSW

Keeping weed numbers down, managing patches and minimising weed seed set has been a high priority for Jason Rogers, Moree. Read More...
Article
News

Keeping glyphosate resistance rare

WeedSmart is now the home to key information from Australian Glyphosate Sustainability Working Group (AGSWG). AGSWG was oringally was set up under the CRC for Australian Weed Management (Weeds CRC) to bring together commercial and research expertise from around the country with a determination to ‘keep glyphosate resistance rare’. Read More...
Article
Article

Alternative second knock herbicides for broadleaf weeds in fallow

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Article
Article

Big 6 winter – 3. Double-knock to protect glyphosate

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Case Study
Case Study

Tim Rethus, Horsham Vic

Wimmera grower Tim Rethus and his family are taking an integrated approach to the weed management with a strong focus on weed-free crops. Read More...
Case Study
Case Study

Lance Wise, Bowenville, Qld

An optical sprayer and disc chain combination has proved to be very effective in keeping weed numbers low on the Wise family farm at Bowenville, on Queensland’s northern Darling Downs. Read More...
Article
News

Confirmed resistance to the double-knock tactic in tall fleabane  

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Case Study
Case Study

John Stevenson, Lockhart NSW

At Warakirri Cropping Trusts’ ‘Orange Park’, manager John Stevenson has set up a crop rotation that is profitable and able to combat herbicide resistance in weeds. Read More...
Case Study
Case Study

Aaron McDonald, Horsham Vic

Hay production is a central component of Aaron McDonald’s mixed farming operation and is helping to keep herbicide resistance in weeds at bay. Read More...
Article
Ask an Expert

Can I retain stubble and keep weeds under control?

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Case Study
Case Study

Daniel Fox, Marrar NSW

Marrar farmer Daniel Fox is chasing higher yields across his 2100 ha cropping program while also driving down weed seed numbers. Read More...
Article
News

Resistance risk to eliminate herbicides on irrigated farms

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Case Study
Case Study

Karl Raszyk & Robert Hughes, Scaddan WA

Karl Raszyk saw potential in the chaff tramlining system to help manage herbicide-resistant weeds. Read More...
Case Study
Case Study

Colin McAlpine, WA

Colin has thrown everything he can at reducing the weed burden on his farm while taking all precautions to protect the available herbicide modes of action. Read More...
Case Study
Case Study

Greg Martin, VIC

Greg Martin believes resistance had evolved due to a lack in rotation of chemical groups and not enough importance given to controlling survivors. Read More...
Article
Ask an Expert

How can I get the best bang for my buck with a double knock?

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...

Podcasts

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Audio
Podcast

S07E21: Innovation in selective spray technology opening up growers’ options

On this podcast episode, we welcome our latest WeedSmart Partner, Hardi! We catch up with Hardi Innovation Manager, Heath Thompson to discuss the partnership and their selective spray technology, GeoSelect. Read More...
Audio
Podcast

S07E10: Regional Update – Giles Kearsley, Agronomist, Eyre Peninsula, South Australia

Giles provides an update on how floods in January have impacted growers and an overview on how pre-emergent herbicides have performed. Read More...
Audio
Podcast

S07E06: Regional Update – Lance Turner, Farmer, East Pingelly, WA

East Pingelly grain farmer Lance Turner joins us on the Regional Update podcast and says it's a great time to consider a double knock. Read More...
Audio
Podcast

S07E05: Adapting spray tactics from summer to autumn pays off

On this edition of the podcast, we’re focusing on getting spraying right. As we move from Summer to Autumn, it’s a good time to consider what spray practices are being implemented and to consider what practical changes might be worthwhile. Read More...
Audio
Podcast

S06E40: Regional Update – Bernie Quade, Agronomist, Wyalkatchem, WA

In this Regional Update, we catch up with Nutrien Agronomist, Bernie Quade who is based in Wyalkatchem, Western Australia. Read More...
Audio
Podcast

S06E17: Group G tips and lucerne as a fence line weed control tool

We've got new info on Group Gs and nitrogen placement. Also, have you thought about growing a crop to compete with weeds in non-cropped areas? Read More...
Audio
Podcast

S06E13: Benefits of continuous spraying when weeds are small and Terrad’or explainer

On this podcast we look at good spraying practice with WA farmer Tim Critch learn about Nufarm's new Group G herbicide, Terrad'or. Read More...

Case Studies

View all
Case Study
Case Study

I’Anson Family Farms, Marrabel SA

Kym and Katie I’Anson are treating the serious soil constraints on their farms to grow more even crops and squeeze out the weeds. Read More...
Case Study
Case Study

Jamie and Susie Grant, Jimbour Qld

Proactive use of automated optical weed detection technology, allows continuous spraying and treating smaller and smaller weeds. Read More...
Case Study
Case Study

Elton and Pam Petersen, Moonie Qld

The Petersens have rapidly regained control of glyphosate-resistant summer grasses using automated spot-spraying technology. Read More...
Case Study
Case Study

Single family, Coonamble NSW

The Singles gain good weed control year round using crops and fallow in both winter and summer on their farm near Coonamble. Read More...
Case Study
Case Study

Kurt Mayne, Rolleston Qld

Kurt Mayne is impressed with the benefits that have come with the addition of an optical sprayer to their weed control program. Read More...
Case Study
Case Study

Jason Rogers, Moree NSW

Keeping weed numbers down, managing patches and minimising weed seed set has been a high priority for Jason Rogers, Moree. Read More...
Case Study
Case Study

Tim Rethus, Horsham Vic

Wimmera grower Tim Rethus and his family are taking an integrated approach to the weed management with a strong focus on weed-free crops. Read More...
Case Study
Case Study

Lance Wise, Bowenville, Qld

An optical sprayer and disc chain combination has proved to be very effective in keeping weed numbers low on the Wise family farm at Bowenville, on Queensland’s northern Darling Downs. Read More...
Case Study
Case Study

John Stevenson, Lockhart NSW

At Warakirri Cropping Trusts’ ‘Orange Park’, manager John Stevenson has set up a crop rotation that is profitable and able to combat herbicide resistance in weeds. Read More...
Case Study
Case Study

Aaron McDonald, Horsham Vic

Hay production is a central component of Aaron McDonald’s mixed farming operation and is helping to keep herbicide resistance in weeds at bay. Read More...
Case Study
Case Study

Daniel Fox, Marrar NSW

Marrar farmer Daniel Fox is chasing higher yields across his 2100 ha cropping program while also driving down weed seed numbers. Read More...
Case Study
Case Study

Karl Raszyk & Robert Hughes, Scaddan WA

Karl Raszyk saw potential in the chaff tramlining system to help manage herbicide-resistant weeds. Read More...
Case Study
Case Study

Colin McAlpine, WA

Colin has thrown everything he can at reducing the weed burden on his farm while taking all precautions to protect the available herbicide modes of action. Read More...
Case Study
Case Study

Greg Martin, VIC

Greg Martin believes resistance had evolved due to a lack in rotation of chemical groups and not enough importance given to controlling survivors. Read More...

Videos

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Video
Video

Rod Birch on how the Big 6 is keeping weeds at bay at Catalina Farms

Rod Birch (Coorow, WA) gives an overview of what Big 6 principles are working for them. He also explas how they're approaching weed control at new property acquisition, 'Koobabbie', which hadn't changed hands for 115 years. Read More...
Video
Video

WeedSmart Week Forum Day Videos

Watch all the videos from our Esperance WeedSmart Week Forum Day! Read More...
Video
Webinar

What’s next in the North for weed control?

Agronomists Peter McKenzie and Angus Dalgliesh discuss the weed control tactics their clients have been using to deal with their weed challenges.  Read More...
Video
Webinar

You don’t know what you don’t know about managing weeds

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Video
Webinar

WeedSmart in HRZ – practical options for dealing with ryegrass

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...
Video
Video

Double knock applications: extent of herbicide resistance in the north

What’s better than an attack on weeds? A second one. Come at them with a different strategy and any survivors left over don’t stand a chance, that’s the beauty of the double knock. Controlling herbicide-resistant weeds is essentially all about double knocks. This can be one herbicide followed by another, or it could be a […]...

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