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Using your harvester to destroy weed seeds

Collecting and destroying weed seeds as part of the harvest operation is recognised as the most efficient and effective way to implement harvest weed seed control (HWSC) within an integrated weed management system.

Acknowledged as the ‘holy grail’ of the WeedSmart Big 6 tactics to manage herbicide resistance, HWSC was implemented on over 40 per cent of Australian grain farms in 2014 and adoption is expected to increase to 80 per cent by 2020.


Chaff impact mill machines render the weed seed unviable, causing the destruction of over 95 per cent of the weed seed that enters the mills.

There are currently six HWSC methods being used in Australia, all of which have been invented, adapted and adopted by Australian farmers. When choosing between these methods growers must consider the set-up cost, nutrient removal costs and labour requirements.

Most agree that the ultimate HWSC tool would complete the weed seed control in one pass at harvest, retain all stubble and nutrients and not require any follow-up work such as marketing hay or burning chaff. There are currently two machines that meet these requirements – the iHSD (Integrated Harrington Seed Destructor) and the Seed Terminator.

These two chaff impact mill machines render the weed seed unviable, causing the destruction of over 95 per cent of the weed seed that enters the mills. In 2017 harvest, both the iHSD and Seed Terminator machines were in commercial operation on farms around Australia and both experienced the teething problems that can be expected for new technology moving into the real-world. They have since been in field trials overseas – the Seed Terminator in Canada and the iHSD in France – where both machines completed around 200 hrs work without a hitch.

Kondinin Group Manager of Research and Development, Ben White interviewed 20 growers using either the iHSD or Seed Terminator during the 2017 harvest and reported that their observations suggested both brands were achieving over 95 per cent reduction in seed viability.

“Both types of impact mills ran into the same real-world problems of handling high flow rates of chaff, choking on green crop or weed matter and significant damage to the mills from any sand or soil that is picked up by the harvester,” he said. “Both machines also caused a reduction in harvester capacity of between 12 and 20 per cent in wheat, even though the harvesters had been remapped. This is a significant cost that growers must allow for through machine depreciation and base hourly operating costs, as more hours are needed to harvest the same area of crop.”

Over 70 per cent of the growers that the Kondinin Group engineers visited had remapped their harvesters to improve the harvest capacity.

Operators should note that chaff impact mill technology pulverises the entire chaff fraction, which generates significant levels of dust during the harvest operation. This means that more frequent machine clean-down may be required to minimise fire risk, as well as increased frequency of filter cleaning or replacement.

“Although the problems outlined here are important, they are all likely to be resolved as this technology matures in the commercial world,” said Ben. “There is enormous interest in this method of harvest weed seed control and this will ensure that the problems are solved.”


Seed Terminator, WA.

Australian Herbicide Resistance Initiative’s cost comparison of HWSC methods suggests that the chaff impact mills cost $16-17/ha compared to $22/ha for narrow windrow burning and $6-7/ha for chaff tramlining and chaff lining, depending on crop yield and area. In addition to the weed control benefits achieved through the use of any HWSC method, the chaff impact mill option also reduces crop volunteers.

Research into the efficacy of impact mills is an ongoing process, particularly while the two types of machines are undergoing rapid developmental changes. Recent research by Michael Walsh (AHRI and Sydney University) with help from John Broster at Charles Sturt University (CSU), shows that despite the problems that have been experienced with the new machines, iHSD mills are passing the research tests with flying colours.

Their research concluded that:

  • The iHSD achieved 96–99% destruction of the seeds of 11 weed species when processed in wheat chaff.
  • Weed seed destruction varied by about 10% depending on crop chaff type – ryegrass seed kill was greatest in lupin (98%) > wheat (92%) > canola (90%) > barley (88%).
  • Weed seed kill dropped by about 4% when chaff moisture increased above 12%.
  • Weed seed kill increases with mill speed and 3000 rpm is the accepted optimal speed for the iHSD.

SAGIT funded research conducted by Trengove Consulting in 2017 found similar results for the Seed Terminator:

  • Ryegrass weed seed kill was 93% at 2250 rpm and increased to 98% or greater at normal operating speeds (2500–3000 rpm).
  • Greater than 99% control of several other species including wild radish, brome grass, wild oat, bifora, bedstraw and tares.
  • Increasing chaff flow rate (harvest rate) did not reduce control of these species.
    Samples analysed in 2018 by the Weed Science Research Group, at The University of Adelaide showed that the Seed Terminator could consistently kill 96% of weed seeds when operated at 2750 rpm.

These kill rates refer only to the weed seed that enters the impact mills. To achieve high level of weed control it is essential that all efforts are made to ensure the weed seed enters the front of the header and is then separated and directed into the mills.


iHSD, WA.

Timing, cutting height, operating speed, weed and crop type and harvester set-up all play a part in achieving maximum harvest weed seed control. As is recommended for all HWSC methods that treat the chaff fraction, separation of the chaff and straw through the harvester often requires the addition and fine-tuning of a baffle plate to achieve greater efficiency.

Setting up and operating harvesters to achieve the best weed control outcomes often involves some modification and compromise. By taking the time to get things right, growers usually find that they end up with more grain in the bin and a better sample, making the extra effort worthwhile.

WeedSmart has secured the rights to distribute an electronic version of Kondinin Group’s Research Report: Residue Management at Harvest, which is available in the Resources section of www.weedsmart.org.au. WeedSmart encourages growers and advisors to support Kondinin Group’s independent research through subscription to Farming Ahead.

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What to expect at WeedSmart Week 2021

Big 6 at WeedSmart Week 2021 – Double knock to protect glyphosate
The WeedSmart Forum is set for Tuesday 17 August, 2021 at the Civic Centre in Esperance WA. The program features growers, agronomists and researchers discussing ways to use the BIG 6 to beat crop weeds. You can register for the 3-day WeedSmart Week event here.
Greg Warren from Farm and General in Esperance will be sharing his thoughts on the control of weeds like summer-germinating ryegrass, marshmallow, fleabane and portulaca.
He says the growers around Esperance are tackling glyphosate resistance in annual ryegrass, along with brome and barley grass and other emerging weeds using a range of integrated control tactics. The double knock plays a key role in preserving glyphosate (and soil moisture) and providing a clean seed bed for planting crops.

 
Big 6 at WeedSmart Week 2021 – Increase crop competition
WeedSmart Week 2021 is set for Tuesday 17 to Thursday 19 August, 2021 in and around Esperance WA. The last two days feature local growers hosting visits to their farms and discussing how they use the BIG 6 to beat crop weeds. You can register for the 3-day WeedSmart Week event here.
One of the farms hosting a visit during WeedSmart Week is Warrakirri’s 12,800 cropping operation at Condingup. Farm manager Con Murphy has implemented a variety of tactics to combat their main weeds – annual ryegrass and wild radish. Since 2015 the farm has undergone an intensive soil amelioration program to improve the drainage and ameliorate the sandy soils across the farm.
Con says the benefits have been seen in better germination and establishment that sets their cereal, pulse and canola crops up to compete strongly with weeds. There is also a benefit at the end of the season where rain in August or September enters the soil profile without causing waterlogging, and providing a better finish for their crops.
Since 2016-17 about 80% of the farm has been ripped and a portion has been ripped 2 or 3 times because the sandy soils tend to slump after substantial rainfall events, recreating the hardpan.
Con will be showing the WeedSmart tour group how their ripping, drainage, liming and spading program has helped grow more crop and less weeds!
Listen to the podcast with Warrakirri’s Con Murphy talking about the impact of improved drainage on crop competition

Big 6 at WeedSmart Week 2021 – Implement harvest weed seed control
The WeedSmart Week machinery display is set for Wednesday 18 August, 2021 at Dave Campbell’s shed near Esperance WA. The 3-day WeedSmart Week program features growers, agronomists and researchers discussing ways to use the BIG 6 to beat crop weeds. You can register for the 3-day WeedSmart Week event here.
We’ve saved the harvest weed seed control discussion for the machinery session on Wednesday 18 August. Ben White from Kondinin Group will host the machinery session with spray and harvesting gear on display including impact mills from Seed Terminator, Redekop and iHSD (both hydraulic and belt-driven), Emar chaff deck, and spray technologies including Goldacres’ G6 Crop Cruiser series 2, and weed detection technologies using drones and weed identifying cameras (green on green).
Ben White, Kondinin Group (Photo: Melissa Powell, courtesy of GRDC)
Growers doing the WeedSmart Big 6
WeedSmart Week 2021 is set for Tuesday 17 to Thursday 19 August, 2021 in and around Esperance WA. The last two days feature local growers hosting visits to their farms and discussing how they use the BIG 6 to beat crop weeds. You can register for the 3-day WeedSmart Week event here.
One of the growers who will open up their farm for a visit is Adrian Perks who farms at Condingup, 70 km north-east of Esperance. Adrian runs a continuous cropping program on his 4300 ha property, growing canola, wheat, barley, faba beans and lupins. This diverse rotation allows him to mix and rotate both chemical and non-chemical weed control tactics. Over half of Adrian’s farm is sandplain, on which he has implemented a soil amelioration program to address non-wetting to increase the competitiveness of his crops. He currently uses chaff decks for harvest weed seed control and is introducing an impact mill this season. Adrian monitors the tramtracks for weed growth and if he feels the weed pressure is too high, he uses a shielded sprayer to reduce seed set. The bus tour will include four farm visits and a machinery display.
Listen to Adrian on the Regional Update podcast.
Adrian Perkins, Condingup WA
 

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WeedSmart agronomist set to tackle high rainfall zone weeds

Every locality has its own spectrum of weeds, and growers face different opportunities and challenges regarding the control tactics they can employ.
The WeedSmart Big 6 approach is a practical way to ensure that an integrated weed management program is put in place that disrupts weed seed production and the evolution of herbicide resistance.
Commencing in January 2021, Jana Dixon has joined the WeedSmart team of extension agronomists, with a focus on applying the Big 6 to manage weeds in the high rainfall cropping systems of southern Australia – from Esperance in WA to south-eastern SA, Tasmania and south-western Victoria.
Jana will add to the dedicated and experienced extension agronomists on the WeedSmart team with Peter Newman in the Western region, Chris Davey in the South, Greg and Kirrily Condon in the East and Paul McIntosh in the North.
Jana Dixon has joined the WeedSmart team of extension agronomists, with a focus on applying the Big 6 to manage weeds in the high rainfall cropping systems of southern Australia – from Esperance in WA to south-eastern SA, Tasmania and south-western Victoria.
Jana hails from the Mid North of SA, and began working at Pinion Advisory (previously Rural Directions) while she was studying agriculture at the University of Adelaide. She has been employed full-time at Pinion Advisory since January 2019 as an agribusiness consultant, based in Clare, and spends most of her time delivering agronomy and farm business advice to clients from a wide range of cropping regions in South Australia.
Pinion Advisory is a foundation WeedSmart sponsor and Jana has been involved in two WeedSmart Week events already – the first as a participant and grower group organiser at the Horsham event in 2019 and then as the local organiser for WeedSmart Week 2020 in Clare.
In welcoming her to the WeedSmart team, program manager Lisa Mayer says Jana brings energy, commitment and insight to deliver communications focussed on the southern region’s high rainfall regions.
“Growers in the southern high rainfall zones are facing some serious issues with herbicide resistance influencing their farming decisions,” says Ms Mayer. “Jana will be engaging with agronomists, growers and researchers in each of the distinct high rainfall zones to understand the complexities and look for practical ways to apply the WeedSmart Big 6 in various cropping scenarios.”
“We plan to deliver WeedSmart Week in Esperance, part of Western Australia’s high rainfall cropping zone, in August 2021 and Jana will play a key role in the planning and delivering of our annual 3-day flagship event.”
Jana says her experience with the WeedSmart program has been very positive and she has been particularly impressed with the support the program has from all sectors of the grains industry.
Newly appointed WeedSmart extension agronomist, Jana Dixon (green cap) leading discussions with farm visit host, Ben Marshman, Owen SA, and growers and agronomists attending WeedSmart Week 2020 in Clare.
“I have spoken to many growers and agronomists who have found real value in the information that the WeedSmart program delivers,” she says. “For many it is as much about considering another operator’s philosophy on dealing with weeds, and taking a fresh look at their own systems, rather than just learning about a new tactic or the traits of a new herbicide in isolation from the big picture.”
She says the high calibre of industry people who contribute their time and expertise to the program is testament to the value WeedSmart has to agribusiness, growers, agronomists and researchers alike.
In taking on the responsibility for delivering information tailored for the high rainfall zones Jana says she is pleased to have an extensive network of contacts through Pinion Advisory, with offices in a number of high rainfall areas to provide easy access to local agronomists and growers. She is also aware that there are major differences in weed spectrums and farming systems in each high rainfall zone and plans to take full advantage of the opportunity this role presents to expand her understanding of different approaches to weed management.
“The long and favourable growing season and the associated prolonged periods of weed germination, is a key factor that I see potentially impacting on a grower’s weed management strategies in these regions,” she says. “On the other hand, access to highly diverse rotations and a focus on crop competition are two strategies that can play an important role in achieving excellent weed management in these regions.”
“I am keen to engage with anyone working and farming in the high rainfall zones to build my knowledge and understanding,” she says. “And to create opportunities to develop and extend the WeedSmart Big 6 strategies, both herbicide and non-herbicide, that work in each area and in different situations.”
WeedSmart is the industry voice delivering science-backed weed control solutions with support from the Grains Research and Development Corporation (GRDC), major herbicide, machinery and seed companies, and university and government research partners, all of whom have a stake in sustainable farming systems.
You an follow Jana on Twitter and keep up to date with the HRZ here.

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Never cut the herbicide application rate

Scientific studies have demonstrated that resistance can rapidly evolve in weeds subjected to low doses of herbicide. Some weeds can develop resistance within a few generations.
Full rates when mixing herbicides too!
When mixing herbicides it is important that each product is still applied at the full label rate to ensure high mortality.
Applying different chemicals in one mix can provide an additive advantage. It is important to understand the mode of action of each herbicide on the plant when preparing a herbicide mix. This is just as important for pre-emergent grass weed mixes as it is for post-emergent mixes aimed at broadleaf weed control. ALWAYS READ THE LABEL.
Surrounding weed seeds with a combination of pre-emergent herbicides with different modes of action can give a high level of control and help extend the useful life of all the chemicals used. The high level of control must be supported with additional control measures for all survivors. All products with different modes of action must be applied at full label rates for this to be an effective strategy.

 
Mixing two chemicals with the same mode of action can achieve some additional efficacy, however, the mix should deliver the combined full rate to ensure a lethal dose. The amount of stubble present and crop safety are all important considerations when mixing chemicals. For example, when using a tank mix of Avadex® and trifluralin to control ryegrass in wheat, the rates used will vary depending on the sowing system and level of stubble retention. Be sure to get good advice.
Many herbicides on the market are a combination of two or more modes of action within the one product. These products must be applied at the full label rate to be effective. Having dual action does not negate the need to change herbicide products and rotate modes of action. Repeated use of any single strategy will reduce the effectiveness of that strategy over time.
 

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Ryegrass management in the High Rainfall Zone – What have we learnt?

This webinar was hosted by Jana Dixon, WeedSmart’s High Rainfall Zone extension agronomist.

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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

Video
Webinar

Ryegrass management in the High Rainfall Zone – What have we learnt?

This webinar was hosted by Jana Dixon, WeedSmart’s High Rainfall Zone extension agronomist.

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