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Vertical iHSD maintains the brand’s 98% weed kill rate

Whether you have a horizontal iHSD impact mill or are looking to get into this technology with the newly-released vertical configuration, you can rest assured that the kill rate of both configurations has been independently proven to be 98 per cent for annual ryegrass.

Dr Michael Walsh, Director Weed Research, Faculty of Science, The University of Sydney has been testing the efficacy of impact mills on weed seeds since the early days of development of the Harrington Seed Destructors.

Left: Without harvest weed seed control. Right: With iHSD harvest weed seed control.

“The vertical configuration of the iHSD mills could change the direction of the chaff flow through the mills and this could affect the processing of the chaff and potentially the efficacy of weed seed destruction,” he says.

“Having previously shown that the horizontal iHSD impact mill can achieve at least 98 per cent weed seed kill, we were keen to repeat the test for the vertical mill configuration.”

During the 2018 harvest, a wheat crop at Broomehill was used to test the vertical mill. Twelve 20 m strips were marked out in the wheat crop where there was no annual ryegrass present. These plots were used to test the efficacy of the vertical mill at three different harvester speeds – 4, 6 and 8 km/hr.

Weed seed destruction was 98% or better at three operating speeds (4, 6 and 8 km/hr).

As each plot was harvested, 5000 dyed annual ryegrass seeds were introduced into the chaff stream directly above the inlet to the righthand side mill. The processed chaff from each plot was collected in large, fine-mesh bags attached to the righthand side outlet chute.

To determine the weed seed survival rate from each plot, Dr John Broster’s team at Charles Sturt University, Wagga Wagga processed subsamples from each of the 12 bags of chaff. The chaff was thinly spread on trays, covered lightly with potting mix and watered every day for four weeks to stimulate the germination of any surviving annual ryegrass seed. Each day annual ryegrass seedlings present were counted and removed from the trays.

“The result of this testing was a weed seed kill rate of at least 98 per cent for the vertical iHSD impact mill, regardless of the harvester operating speed of 4, 6 or 8 km/hr,” says Dr Walsh. “This level of weed seed destruction is equivalent to that of the horizontally mounted mills that we have tested previously.”

“From this result we can be confident that provided the harvester is set up to efficiently collect annual ryegrass seed at harvest, growers using either configuration of the iHSD can expect to achieve this very high rate of weed seed destruction.”

Peter Newman, Western Extension Agronomist with the Australian Herbicide Resistance Initiative (AHRI) and WeedSmart, says there is keen interest amongst Australian growers in harvester-integrated weed control solutions.

“Growers are looking at price and weed seed control efficacy,” he says. “This new configuration of the iHSD provides several new features that will benefit growers, including the ability to easily check for grain loss by opening a rear hatch and disengaging the iHSD belts, the large cavity under the sieves effectively prevents bridging and the stone trap will help to prevent any foreign objects from entering and damaging the mill.”

New features include mechanical drive, vertical configuration, rear hatch and stone trap to reduce costs and improve reliability.

“The vertical configuration uses the same cage mill for seed destruction as the earlier horizontal version but is mechanically-driven rather than hydraulic, significantly reducing the cost, making the iHSD more attractive to growers.”

Following the invention of the HSD by WA grower Ray Harrington and development by UniSA with investment from GRDC, the iHSD has undergone further development by SKF Engineering and DeBruin Engineering, together with national distributor, McIntosh Distribution.

McIntosh & Son dealer principal (southern branches) Devon Gilmour says the vertical, mechanical iHSD’s direct-drive system is easy to use and maintain, can be retro-fitted on a wide range of harvester models and is easy fitted on-farm. Impact mills have a proven high weed seed kill rate, making them a very effective, non-herbicide tool in the fight against herbicide resistant weeds.

Harvesters fitted with impact mills can spread crop residue more evenly, reducing the loss or redistribution of nutrients, making them an attractive proposition for growers.

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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

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Spray well – correct nozzles, adjuvants and water rates

Spray application is a technical field and growers need to make sure their equipment and application techniques are spot-on. The GRDC Spray Application GrowNote provides detailed information and about 80 videos to demonstrate key skills. Prevent spray-drift The focus of spraying herbicide needs to be on doing the job right so the weeds receive the correct dose and die, and this includes reducing the air borne fraction to a bare minimum. Bill Gordon’s 10 Tips for Reducing Spray Drift Choose all products in the tank mix carefully. Understand the product mode of action and coverage requirements. Select (and check) the coarsest spray quality that will provide effective control. Expect that surface temperature inversions will form as sunset approaches and will likely persist overnight and even beyond sunrise on many occasions. DO NOT SPRAY. Use weather forecasts to inform your spray decisions. Only start spraying when the sun is about 20 degrees above the horizon and when the wind speed has been above 4–5 km/hr for more than 20–30 minutes, and clearly blowing away from any adjacent sensitive crops or areas. Set the boom height to achieve a double overlap of the spray patterns. Avoid higher spraying speeds. Leave buffers unsprayed if necessary and come back. Continue to monitor conditions, particularly wind speed, at the site during the spray operation High water rates don’t have to slow you down Some growers are concerned that increasing the water rate when applying herbicide will slow down their spray operation and cost them money. However, the biggest financial loss during spraying usually comes from a failed spray job. To keep your spray operation as time efficient as possible when using more effective and reliable application volumes, you can: Use nurse tanks around the farm to reduce the time spent travelling back to a central re-fill point. Use a larger pump, e.g. 2.5 inch, to make re-filling quicker. Pre-mix the batch while the sprayer is operating. Many mixes can be held in the mixing tank for up to 6 hours. However, wettable granules and suspension concentrates will need agitation to keep them in solution. For pre-emergent herbicides in high stubble situations, carrier volume has a large effect on the level of control achieved. Across four trial sites Dr Borger’s research demonstrated that ryegrass control with trifluralin or Sakura® increased from 53% control when the carrier volume was 30 L/ha to 78% control when the carrier volume was increased to 150 L water/ha in high Water quality and mixing order Water quality is often overlooked as a possible contributor to herbicide failure and can lead to confusion over the herbicide resistance status of weeds on a property. Water should be considered as one of the chemicals in any mix, given that water quality varies markedly depending on its source. Getting the mixing order right is essential for effective spray results. Don’t start mixing until the water quality is right Podcast – Mixing herbicides Adjuvants Sometimes adding an adjuvant is beneficial and sometimes it is detrimental; and there is an art to knowing how to best deploy these additives. When weeds are susceptible to the applied herbicides, the effectiveness of adjuvants generally goes un-noticed. Correctly applied adjuvants can reduce the impact of low level herbicide resistance by helping to maximise the amount of herbicide taken up by the plant.

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