Stop weed seed set

Take no prisoners! Stop Weed Seed Set.

It sounds a little obvious, but annual weeds must set seed if the species is to persist, so stopping weed seed set is a critical strategy to manage herbicide-resistant weeds. Stopping seed set does two things, 1. It reduces the size of the weed seed bank, and 2. It acts as a second knock to clean up survivors to other selective herbicides, preventing resistance evolution and prolonging the life of the selective herbicides.

One comment that you will hear time and time again from successful grain growers is, ‘we never miss an opportunity to stop seed set’. Sure, the opportunity does not always present itself, but when it does we owe it to ourselves to stop seed set at all costs and take no prisoners.

Some of the key seed set control options include

  • Crop top canola and pulses in weedy paddocks;
  • Consider hay, brown manure or long fallow in high-pressure paddocks;
  • Spray top/spray fallow pasture prior to the cropping phase.
  • Check out the GRDC’s latest fact sheet on pre-harvest herbicide use (including crop topping) here.

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Make seedbank management your priority this year

You can listen to the article being read above!

We all know that old saying – ‘one year seeding, seven years weeding’ or some variant of it, and know it is true. But it is easy to overlook just how important weed seedbank management is, until herbicide resistance begins to reduce the efficacy of previously reliable tools.
For a few decades herbicides really took the focus away from seedbank management because the chemical options were so effective at killing weeds that they appeared to be a complete solution to weed management.
But all along, growers, agronomists and researchers have known it was too good to last. The WeedSmart Big 6 strategy has struck a chord because it is a useful check list that can be used to prompt growers to consider using a selection of the many available weed control tools.

No one tool will do the job – just as herbicides alone have failed, so too will harvest weed seed control or crop competition if they are not part of a planned and multi-pronged assault on the weed seedbank. This is the underlying principle for integrated weed management.
In economic simulations conducted using the RIM and WeedRisk models in 2006, agricultural economists Randall Jones and Marta Monjardino showed that although many things impact on the economic assessment of weed management practices, there is strong evidence that when seasonal risk is taken into account, and the economic assessment is for a period of 20 years, integrated weed management consistently out-performs herbicide-only systems, regardless of the weed in question.
Herbicides provide high level control and are considered an essential component of broadacre cropping systems, however, other tactics that specifically target weeds that have escaped herbicide control are what make IWM systems more profitable in the long-run (see Table 1).
For weeds like wild radish, which produce large quantities of seed that can remain viable in the soil for many years, taking a non-integrated approach of using post-emergent herbicide only has the potential to ‘crash the system’, from an economic point of view.
It will always be a numbers game and IWM consistently wins, usually by a considerable margin, primarily due to lower weed seedbank numbers and conservation of the highly effective herbicide resource for tactical use over time in integrated weed management systems.
TABLE 1 The economic impact ($/ha) of different crop and IWM systems on meana annualised discounted returns for wild oats, wild radish and annual ryegrass in a southern New South Wales cropping system (4-year crop phase followed by 3-year perennial pasture phase).

 

Economic return ($/ha)a

 

Wild oats

Wild radish

Annual ryegrass

Continuous cropping
 
 
 

No IWM

268 (± 35)

-9 (± 27)

284 (± 34)

IWM

332 (± 38)

315 (± 37)

335 (± 38)

Crop + pasture rotation

No IWM

288 (± 29)

157 (± 25)

284 (± 28)

IWM

319 (± 32)

300 (± 30)

320 (± 31)

a The shown in brackets following ± are the standard deviation.
Source: Jones R, Monjardino M and Asaduzzaman Md (contributors) (2019). Section 1: Economic Benefits of Integrated Weed Management, in: A.L. Preston (Ed) 2019. Integrated weed management in Australian cropping systems. Grains Research and Development Corporation.
Use the WeedSmart Big 6 to prepare an IWM plan for your farm
To develop an integrated weed management plan (IWM), it is useful to collate some historical information about past weed control activities, test weeds for herbicide resistance and use the WeedSmart Big 6 to match opportunities and weeds with suitable and effective control tactics, remembering that there are many weed control tools at your disposal.
With your agronomist’s assistance, aim to create a plan that maps out when each tactic will be applied. Ideally, try to include three or more of the Big 6 tactics in each crop, fallow or pasture phase.
Diversity is key. Some people prefer to have a set cropping sequence while others choose the crops in response to seasonal or market conditions, but either way it is important to look for ways to add as much diversity to your farming system as possible and to keep downward pressure on weed numbers at every opportunity.
While preventing weed seed production completely is unrealistic in the real world, a focus on the weed seedbank will pay dividends in the long run.

Article
Article

Harvest tips, crop topping + trifluralin resistance

Development Officer at Merredin Research Station Glen Riethmuller gives some useful insights into harvesting low, crop lifters and also discusses crop topping. We also hear from Meckering farmer Darren Morrell. He recently received resistance test results which showed one of the farms he is leasing has 80% trifluralin resistance. Darren talks about what tactics he’ll be using to get on top of the weed problem he is now facing.
Listen to the podcast below.

Glen Riethmuller at Merredin Research Station 

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Article

Crop topping, using Sharpen & getting ready for harvest

In the podcast this week, we focus on crop topping and the relatively new herbicide, Sharpen. In our last podcast, Andrew Messina talked to us about Case IH harvester set-up. This week farmer Lance Turner gives us the rundown on John Deere gear.
AHRI and WeedSmart Agronomist Greg Condon talks to us about the benefits of crop topping and what to do if you suspect you’ve got herbicide resistance.
We also hear from BASF Technical Services Manager, Phil Hoult, about the herbicide Sharpen. It’s now registered as a harvest aid in winter pulses, for winter cleaning of Lucerne and for wild radish seed-set control in winter cereals, so we’ll find out in more detail about its applications for broadacre croppers.

Article
Article

Spray drift & crop competition

Join your hosts Jessica Strauss and Peter Newman in the first podcast for March! Spraying weeds and choosing seeds are the hot topics this podcast. We chat with Nufarm Australia Spray Application Specialist Bill Gordon, who gives some great tips and insights on correct set-up. Rohan Brill also joins us for insight on choosing canola seeds and the benefits of crop competition!
Our webinar series is also kicking off for 2017 next week! If you’d like to register for the March 7 webinar with Rohan Brill, who will be going into more detail on crop competition, click here!

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155: Why crop topping is a great tool to prevent weed seed set

It’s hard to believe that harvest is just around the corner! In light of this fast approaching reality, we wanted to talk about crop topping and spray topping.
Each of our WeedSmart Extension Agronomists provide a rundown on what to look out for in their cropping regions in regards to crop topping, swathing and desiccation.
WeedSmart Southern Extension Agronomist Greg Condon guest co-hosts for this podcast.

Paul McIntosh, Northern Region: crop topping or swathing/windrowing winter pulses, e.g. faba beans – jump to listen at 18:00
Jana Dixon, High Rainfall Zone:  crop topping barley and spray topping pastures – jump to listen at 30:00
Chris Davey – desiccation and crop topping pulses – jump to listen at 41:30
Greg Condon – crop topping canola – jump to listen at 55:00

Dr Chris Preston, University of Adelaide, also joins us to explain the mode of action classification system changes from a letters system to numbers system and what it’ll mean for growers.
Dr Chris Preston explains the changes to MoA classification for herbicides in Australia from letters to numbers.
Helpful links

GRDC Pre-Harvest Herbicide Use Fact Sheet
Global Herbicide Classification Look-Up
Recent WeedSmart Content

News Article: Chaff carts were made for feeding livestock
Ask an Expert Article: How can I set up my summer crops to help manage weeds?  Our expert is Belinda Chase, who is an Agronomist with Dalby Rural Supplies
Webinar recording: Mixed farming – does it really help control resistant weeds? Greg Condon hosts and Agronomist Craig Drum is our guest presenter.

Bonus
I promised a holiday picture of sea lions, and I’m going to deliver. Here’s a playful sea lion who hung out with me when I was snorkelling in Jurien Bay.
Sweet sea lion in Jurien Bay (Jessica Strauss).

Audio
Podcast

Crop topping, using Sharpen & getting ready for harvest

In the podcast this week, we focus on crop topping and the relatively new herbicide, Sharpen. In our last podcast, Andrew Messina talked to us about Case IH harvester set-up. This week farmer Lance Turner gives us the rundown on John Deere gear.

AHRI and WeedSmart Agronomist Greg Condon talks to us about the benefits of crop topping and what to do if you suspect you’ve got herbicide resistance.
We also hear from BASF Technical Services Manager, Phil Hoult, about the herbicide Sharpen. It’s now registered as a harvest aid in winter pulses, for winter cleaning of Lucerne and for wild radish seed-set control in winter cereals, so we’ll find out in more detail about its applications for broadacre croppers.

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

Catalina Farms is approximately 13,000 ha of 100% cropping, with 65% wheat, with the other 35% comprising of 20% canola and 15% lupins. The longterm rainfall is about 330ml per year and around 250-280ml of growing season rainfall.
Taking on a new property usually has its challenges, but there can be upsides too. Some of the challenges at Koobabbie were related to the fact it had been a livestock property and cropping machinery had never having been run through it. However, Rod explained that they have had some great news about the herbicides they are able to use.
Through the University of Western Australia’s resistance testing service, run by Dr Roberto Busi at AHRI, they found out some older chemistries were still effective, which was a pleasant surprise. Daniel Birch explains below in the Regional Update Podcast what they found out and how they used this information in their planning.

Video breakdown

1:10 Crop rotations – Rod’s favourite rotation is Lupins – wheat – canola – wheat. It provides a lot of diversity for Modes of Action, as well as allows for nitrogen to go back into the soil through the lupin phase.
2:10 Crop Competition – the Birches are big fans of crop competition and it’s an essential part of their approach to controlling weeds.
3:00 Double knock – conditions haven’t been suitable for a double knock since 2016, but when the opportunity arises, it’s an important tool.
4:21 Mix and rotate herbicides – the crop rotations used at Catalina allow for really diverse chemical groups to be used, which is a great tactic to keep resistance at bay.
5:52 Stopping weed seed set – the Birches are trying to eliminate as many weeds in the crop as possible. Crop topping is a tool that they employ, as well as late spraying where necessary.
6:49 Harvest weed seed control – seed destruction is on the horizon at Catalina, but logistically has been a bit tricky.
7:21 Acquiring Koobabbie – it has been exciting for the Birches to be able to introduce more diverse rotations. They’ve been able to use Modes of Action which have never been used before.
9:48 Soil amelioration  – liming has been a really beneficial tool for Catalina Farms. They also put out pot ash and gypsum. Deep ripping has also been a great tool to remove the compaction layer.
11:29 Big 6 benefits  – controlling weeds is such an important strategy at Catalina Farms. Rod Birch said “We’ll never have a ceasefire on the war on weeds!”.

 

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Video

WeedSmart Week Forum Day Videos

List of videos

Interviews with the Esperance Pioneers. Chair: Lisa Mayer, interviewing Neil Wandel & Theo Oorschot
Rotating buys you Time, mixing buys you shots
Efficacious use of the new pre-ems, Brent Pritchard
Delivering regionally focused research
Crop competition in wheat and canola, Hugh Beckie
Summer weed control
Strategies for control of ryegrass, marshmallow, fleabane, portulaca, Greg Warren
Farmer Experience
Rotations to stop seed set and preserve chemistry, Tom Longmire
Soil Amelioration, Tom Edwards
Crop competition: Reduced row spacing, higher seeding rates, east-west sowing, precision seed placement & competitive varieties, Theo Oorschot
Farmer Experience – Utilising crop competition strategies and the Big 6, Mic Fels
Weed control – farmer systems discussion panel – Chair: Peter Newman, with Mark Wandel and Laura Bennett
What’s next in spray technology? Andrew Messina
What’s next in spray technology 2? Guillaume Jourdain
Innovation Panel – Chair: Ben White, with Guillaume Jourdain, Andrew Messina
Stacking the Big 6 in farming systems in WA presented by Greg Condon, with Peter Newman

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