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Taking a single shot at weeds

Detect, then spray. Two phase weed control.

As farmers get their hands on fast and accurate weed mapping technology, the frequency of blanket herbicide spraying can be greatly reduced. With an accurate digital map that shows where the weeds are right now, most boomspray rigs can become low-cost spot sprayers.

For the past two years John Single and his son Tony have been using the air-borne weed sensor, Single Shot, developed by John’s other son Ben, to rapidly detect and map weeds on their dryland cropping property, Narratigah, near Coonamble, NSW.



John Single with a drone carrying the Single Shot weed sensor. By separating the weed mapping and weed spraying tasks the Singles can take a planned approach to their weed management throughout the year.

Ben saw the benefits of separating the weed detection and weed spraying tasks and set about building the platform and working with Robotic Systems to bring the idea to reality.

“The main aim is to stay ahead of herbicide resistance,” says John. “Ten years ago we started work on developing drone-mounted sensors that could take over the task of detecting weeds in a green-on-brown situation. Many sprayers, particularly later models, do not require any modifications and there are many benefits in having the weed mapping done separately rather than on-the-go.”

Weed maps enable growers to take a planned approach to their weed management throughout the year and to build a historical record of weeds in a paddock. The Single Shot sensor maps green-on-brown but are not limited to fallow situations. The sensors can be used in newly sown crops to map weeds that emerged on the planting rain or were missed in a previous application.

These patches, or individual weeds, can be treated in-crop or a pre-emergent can be applied to the patches at the end of the season. The sensor can also be used in-crop to identify high biomass areas within a paddock where high weed density requires more drastic action, such as cutting for hay, and in wide-row crops where the canopy does not fully close and weeds can be detected between the rows.

Screen shot of the Trimble guidance screen in operation with a Single Shot spray map.

The Singles have used the Single Shot technology in several different management scenarios already and the possibilities seem endless. John says they have used the sensor to identify survivor marshmallow and milk thistle plants in fallow and then spot spray them with a high rate of Starane to prevent seed set. They have mapped feathertop Rhodes grass in wheat to generate a map for applying pre-emergent herbicide post-harvest and have filtered data to segregate weeds based on size, giving them the option to apply a blanket spray on smaller weeds and a herbicide spike to treat larger weeds, or to use a second boom to apply two different products or rates. Where pre-emergent herbicides are used, a perimeter determined by the user can be added to cover the seed distribution area of the mother plant.

Another important role for Single Shot at Narratigah is to scout for survivor weeds after herbicide applications. The Singles crop 4500 ha and can map the farm at a rate of up to 300 ha per hour. This is one of the most important tasks in a herbicide program and yet it is generally not done effectively due to the time required. Having ‘eyes in the sky’ makes routine and accurate scouting practical after every spray treatment.

The sensor is capable of covering 300 ha/hr under continuous flight or targeting weeds greater than 5 cm diameter. Under normal operating conditions, and including battery changes, the Singles achieve a work rate of around 200 ha/hour. Critically, data processing can be done in the field, if the internet is available at the site, and is done at a speed 1.7 times faster than flight time.

Once a weed map has been created, the drone can be sent out again to take high resolution imagery of plants in specific locations in the paddock for identification purposes, allowing John and Tony to plan a herbicide program with their agronomist, based on exactly what’s in the paddock.

When it comes to spraying, having the weeds mapped before the spray operator gets in the cab means that the job can be done when conditions are suitable, including at night.

The real power of the Single Shot system is the ability to run simulations and to re-process the data to fine-tune a herbicide program based on weed size or density. The sensor requires just a 1 cm ‘brown’ perimeter around a weed to be able to detect the weed size.

The weed maps are built from images that are ten thousand times higher resolution than satellite images, giving a 1 cm sampling size. Every part of the paddock is photographed twice so obstacles such as stubble occlusion can be significantly reduced. The drone flies at a height of 75 m, following a pre-determined path, and can also be flown lower and or slower if necessary to collect specific data. The sensor also accurately identifies stressed weeds.

“Information is power and this has really put us back in control of our weed management,” says John. “We know how much chemical to buy to do the job at hand, we know the costs and can alter the chemistry to suit a budget if necessary, we can choose to blanket spray or spot spray, and our ability to apply the double knock tactic is greatly improved.”

Ready for unmanned aerial vehicle (UAV) spraying

In a bid to be one step ahead of the game, the Single Shot software will also calculate the shortest path for the sprayer, which is most useful when doing spot spraying on an ATV, or in the future, to deliver herbicide via a drone-mounted sprayer (UAV) or autonomous vehicles.

“We ran a scenario for treating about two thousand survivor weeds in a 125 ha paddock using a spray drone,” says Ben. “To apply a blanket spray to the paddock, the spray drone would need to travel about 310 km. Using the Single Shot software we determined the shortest path to reach all the weeds, which cut down the time required to do the job to just two and a half hours. The sprayer would only be applying herbicide for 16 km of the 54 km flight, and just 5 per cent of the paddock would have herbicide applied.”

Left: Actual weed coverage in a 125 ha paddock (blue line is the boundary, and purple is weed). Right: The path that the UAV would travel using the shortest route computation.

Weed mapping using tools and systems like Single Shot are putting growers back in the driving seat to cost-effectively and consistently implement the WeedSmart Big 6 tactics that underpin sustainable herbicide use and maintain productivity gains through no-till farming systems.

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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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