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Windrow burning: it’s got to be hot

Growth Farms Australia manager, Chris Bunny, knew that the company was buying a property with herbicide resistant weeds when they purchased ‘Glaisnock’ near Young in 2008.

“The ryegrass on the property was known to be resistant to both Group A and Group B herbicides,” he said.

Chris and Elise Bunny, ‘Glaisnock’, Young believe narrow windrow burning is an effective non-chemical tactic to add to their weed control strategy.

“Twenty-five years of continuous wheat-canola cropping had taken its toll and changes to the farming system were obviously required.”

Over the last few years Mr Bunny has implemented drastic changes—reintroducing livestock into the system, changing herbicide application tactics, modifying the rotation and adopting narrow windrow burning—all to address the problem of herbicide resistance in weeds.

The 970 ha red earth property, ‘Glaisnock’, located between Young and Temora is well suited to cropping but continuous cropping practice has generated an unsustainable level of weed pressure. Mr Bunny is in the process of fencing paddocks and installing stock waters as they move around the property planting lucerne for stock grazing.

“About 20 percent of the property is under lucerne in any one year,” he said. “Lucerne gives us the opportunity to earn income off these paddocks while also winter cleaning with heavy grazing and paraquat in at least 3 of the 5 years of pasture.”

They run trade stock, either steers or prime lambs, so they are able to be flexible with the timing and stock density. The lucerne is also breaking up the hard pan that had developed over so many years of continuous cropping.

Triazine tolerant canola and wheat are currently sown 50:50 across the remaining farming area. Mr Bunny said the triazine-tolerant canola had proven to be a useful way to introduce different modes of action to the assault on resistant weeds. He hopes eventually to reduce the area sown to canola but for now it is playing an important part in their integrated weed management program.

During the summer fallow Mr Bunny employs double knock herbicide applications at every ryegrass germination. “Generally there are two double knock applications in the fallow,” he said. “The timing of the operations is determined by the weed size and the extent of the germination.”

“The staggered germination pattern of ryegrass can make it difficult to know when to spray,” he said. “It is also tempting to not do the second knock when the first spray appears to have worked well, but we have seen the benefits when a strip has been left un-sprayed and it is clear that the second application is essential.”

To round off their integrated weed management strategy Mr Bunny has also implemented narrow windrow burning of canola chaff as a non-chemical harvest weed seed control measure.

This year is the third year of narrow windrow burning on the property and Mr Bunny is convinced of its effectiveness in reducing the weed seed bank. “The only real problem with narrow windrow burning is the chance of the windrows getting wet before you are allowed to burn,” he said. “We try to start burning as soon as permits are available. So far we have had successful burns in 2 out of the 3 years.”

A hot fire is the key to effective narrow windrow burning to kill weed seeds.

A hot fire is the key to effective narrow windrow burning to kill weed seeds.

Mr Bunny had previously used stubble burning as a weed control measure but had found that burning the whole paddock was ineffective and there was the associated loss of stubble.

“Burning the narrow windrows is a much safer operation and for negligible cost it is possible to modify the header and introduce another weapon against resistant weeds.”

The canola chaff easily generates the required 400 degrees Celsius required to kill ryegrass seed. The next challenge for Mr Bunny is to implement the strategy in harvested wheat paddocks. The main difficulty with taking this step is the need to cut the wheat lower than usual and the timing of harvest compared to when the ryegrass seed begins to fall.

“We will be working on lowering the header, aiming for ‘beer can height’, and adjusting the chute to make the windrows as narrow as possible without causing blockages,” he said.

Being able to effectively burn chaff in every paddock, every year is the aim and Mr Bunny is determined to solve any problems that stand in the way.

Mr Bunny said two people can easily burn 400 ha of narrow windrows in one afternoon. Each windrow is lit every 400 metres or so, starting soon after midday. The windrows burn quite quickly and most are burnt out by late afternoon. Mr Bunny checks the paddocks again late in the afternoon and extinguishes any that are still alight.

“With the wheat we anticipate the need to burn off smaller areas at a time and that there will be more risk of the fires spreading across the paddock,” he said.

Summer rains can cause problems with the wet windrows tending to only burn along the top where the chaff has dried off. Mr Bunny has found that even in years where the effectiveness of the burn is reduced there is still a benefit in concentrating the weed seed into narrow bands in the paddock where germinations can be more easily and cost-effectively targeted.

Growth Farms Australia recently hosted researcher Michael Walsh from the Australian Herbicide Resistance Initiative and a group of growers from Western Australia with extensive experience with herbicide resistant weeds, including annual ryegrass. Growers from the Young district were invited to meet the visiting experts and to see narrow windrow burning demonstrated.

Delta Agribusiness consultant David Crowley and GRDC funded, Charles Sturt University researcher John Broster arranged field days at Young, Griffith and Lockhart to give local growers an opportunity to meet the West Australian expert panel to discuss their experience with harvest weed seed control methods, including the Harrington Weed Destructor, chaff carts and narrow windrow burning.

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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


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.


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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