Harvest weed seed control

Capture weed seed survivors at harvest using chaff lining, chaff tramlining, chaff carts, narrow windrow burning or weed seed impact mill. There are currently nine Harvest Weed Seed Control (HWSC) tools being used by Australian grain growers. All remove weed seeds at harvest but they come at a different capital cost, running cost and cost of nutrient removal. To compare these tools we must first consider the running cost, and then add the nutrient cost to get a realistic comparison.

WeedSmart’s Peter Newman has also put together a model on HWSC so you can calculate the cost of different HWSC options on your farm. You can download the model here.

You can access two of the Kondinin Group’s Research Reports on mill technology by clicking on the images below.

Articles

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Stacking the Big 6 in a strip and disc system

High residue farming with a stripper front and a disc seeder efficiently captures and stores soil moisture, and growers are finding the system can be tweaked to also improve weed management. An increasing number of growers in the northern region are seeing early confirmation that the system works and there is building scientific evidence that they are on the right track with the adoption of narrow row sowing with single disc planters, combined with a stripper front and either a chaff deck or chaff line at harvest. Peter and Kylie Bach, Kurilda Ag, Pittsworth use a Shelbourne harvester front and Emar chaff deck to conserve stubble and put weeds in their place. AHRI and WeedSmart agronomist Greg Condon says this system is providing growers in the northern grains region with opportunities to plant and grow crops that would otherwise not be possible. “Harvest weed seed control is a useful tactic against many of the key weed species in the northern region,” he says. “We now have scientific data to show that, with correct harvester set-up, stripper fronts and drapers can be equally effective at collecting weed seeds at harvest. The advantage of the stripper front is that the vast majority of the crop residue remains as standing stubble in the paddock. This means the harvester does not have to deal with enormous amounts of plant material and there is so little straw going through the machine that choppers and spreaders have much less work to do.” “When a chaff deck or chaff line chute is attached to the harvester, the weed seed is separated from the grain with a small amount of chaff, and deposited either on the controlled traffic wheeltracks or in a narrow band behind the harvester. These weeds can then be subjected to targeted control tactics applied to a very small percentage of the paddock area.” A chaff deck attached to the harvester separates the weed seed from the grain, along with a small amount of chaff, which is deposited on the controlled traffic wheeltracks. For some growers, like Peter and Kylie Bach farming at Pittsworth on the Darling Downs of Queensland, using the stripper front and chaff deck combination in their cereal crops has gone a long way toward solving their problems with volunteer crop plants from previous seasons. “The standing stubble has given us planting opportunities for summer crops that would not have been possible after a conventional harvest,” says Peter. “Barley stubble provides an excellent environment for planting mungbeans and when the mungbeans are harvested, the paddock has much better ground cover with the previously-standing cereal stubble being retained on the soil surface.” The stripper front leaves most of the stubble standing in-situ, meaning much less material needs to be processed in the harvester. Peter and Kylie find that the barley stubble can persist for a few seasons after the growing season, providing soil moisture conservation benefits in their summer cropping program. The ‘strip and disc’ system ticks off three of the WeedSmart Big 6 tactics for managing herbicide resistance – crop competition, harvest weed seed control and diverse rotations. “When weed control is integrated into an agronomic package it is possible to achieve some real synergies in the system – achieving more than just the cumulative benefits associated with each of the parts,” says Greg. “After a few years, there is a combination of standing and residual stubble in the field and stubble load is managed through the sequencing of different crops, without ever leaving the soil bare.” The ground cover benefits of cooler, moist soil opens up the possibility of sowing early and growing longer season crops, and even double cropping is some environments. There is also better nutrient cycling and improved soil biota activity. Tall stubble left after the stripper front harvests the crop and a line of chaff left behind the harvester concentrates any weed seed collected during harvest in this narrow and well-shaded band. While the stripper front has several benefits and efficiencies over the conventional draper, these benefits are not likely to support a change-over until existing machinery is due for replacement, according to an economic study by John Francis, Holmes and Sackett. A draper can achieve many of the same standing stubble benefits and harvest efficiencies as the stripper front if the harvest height is set at 40 to 60 cm. For both options to be effective for weed seed collection the crop competition must be strong to force weeds to set seed high in the canopy. Without strong crop competition, harvest weed seed control generally relies on cutting as low as possible at harvest. Grower experience suggests that stripper fronts have a distinct advantage when it comes to picking up fallen or lodged crops and weeds.
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News

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.
Article
Case Study

Bruce family, Alford SA

Keeping pressure on brome grass with HWSC Brothers Gary, Paul and Bronte Bruce farm at Alford on the Yorke Peninsula, SA have used harvest weed seed capture as an important tool in their weed management program to bring down grass weed numbers in their continuous cropping business. For the last 15 to 20 years the Bruce family has followed a 3-year rotation of wheat – barley – legume, having exchanged field peas for lentils in the legume phase in recent years. They found that producing export hay on grassy paddocks was a very effective way to manage grass weed seedbank, to the point where they had only one paddock of hay in 2016 and no hay in 2017. Gary Bruce, together with the family’s agronomist Chris Davey, YP-AG sets out a plan for the season, including our weed management program, with different strategies used depending on whether there is a wet or a dry start. “Hay production is hard work and now that we don’t have much of a grass weed problem we are taking hay out of the rotation for a while,” says Gary. “The hard work was certainly worth it in terms of regaining control over herbicide resistant weeds on the farm. Now we’d like to keep more crop residue on the paddocks to improve the hardsetting nature of the soil here.” Having used a chaff cart for many years, the Bruce’s were well aware of the benefits of capturing weed seed in the chaff stream but Gary was very interested to hear HWSC advocate and WA grower, Ray Harrington, speak at a field day about chaff lining. In 2017 harvest they used chaff line chutes on two headers for the first time. As usual they learnt a lot in their first harvest and have plans to make even better use of the system this season. Gary is very aware of the fact that there is very limited research on the long-term impact of chaff lining on weed management. “Our farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run,” he says. “We found starting the harvester on a spray track at the edge makes the best use of the wheeltracks. If we go to a full CTF system we will probably change to using a chaff deck system but the chaff lining chute is certainly a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble.” Gary’s farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run. So far they have found using the chaff lining chute is a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble. HWSC and late germination Brome grass is the most problematic weed on the Bruce’s farm with limited options for control in the cereal phase. There are limited chemical control options to kill early germinating brome grass before seeding and so Gary relies on HWSC to take care of late germinating cohorts. They recognise that hay making has played an important part in keeping this weed in check and acknowledge this could be more difficult if they get out of hay production altogether. All crops are sown to achieve greatest crop competition possible using 25 cm row spacing and cultivars that are well suited to the different soil types. Two-thirds of the farm is inter-row sown while paddocks with hardsetting topsoil generally follow the same furrow as the previous year. As the soil improves through increased residue retention Gary hopes most of the farm will eventually be sown in the inter-row. Generally they find, Scepter wheat yields better than Mace, Compass barley produces the most straw, PBA Bolt lentils give salt and boron tolerance where it’s needed and PBA Hurricane lentils offer Group B herbicide tolerance. “Early in April we usually speak with our agronomist, Chris Davey, about a plan for the season, including our weed management program,” says Gary. “For example, wet and dry starts need different strategies such as ensuring there is sufficient moisture to activate metribuzin and propyzamide before sowing lentils. We have also experienced more summer rainfall recently and often need to do two sprays for summer weed control.” Other resources: Implementing the WeedSmart Big 6 on the Yorke Peninsula
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News

Going for the Big 6 on Yorke Peninsula farms

Chris Davey, partner and director of YP AG at Kadina has worked with growers on the Yorke Peninsula of SA for over 20 years, assisting them to devise weed control programs that reduce the impact of herbicide resistance. His group of 20 clients farm between Port Broughton and Arthurton with annual rainfall ranging from 300 to 500 mm and very diverse soil types. Chris initiated the Northern Sustainable Soils farmer group in 2007 to provide growers with the opportunity to research farming system tactics and discuss their ‘fit’ for the highly variable soils found on the Peninsula. YP-AG partner and director, Chris Davey works with his grower clients including Gary Bruce (left), to plan integrated weed management programs that include as many of the WeedSmart Big 6 tactics as possible. “The soils here range from shallow sheetrock and limestone to grey calcareous loams, dune and swale systems to heavy red fertile clay,” he says. “This variability drives many management decisions and has a direct relationship with many of our weed problems.” Chris has used resistance testing services to keep track of herbicide resistance in the main weeds, with growers managing resistance in annual ryegrass, brome grass and wild radish for some time and more recently finding milk thistle, Indian hedge mustard and prickly lettuce increasingly problematic. Annual ryegrass and brome grass on the Peninsula are known to have resistance to herbicides in Groups A (fop and dim), B, D and M and wild radish is resistant to Groups B, F and I. “This area was the home of ryegrass resistance and growers are trying hard to avoid the same blow-out situation with brome grass,” says Chris. “Growers are well aware of the potential consequences if resistant brome grass gets out of hand so most are using some form of patch management and even chemical fallow in blocks where the brome grass has out-competed the crop.” In response to increasing herbicide resistance, 85 per cent of Chris’ clients have adopted some form of harvest weed seed control within their weed management program. “Sixty per cent of my clients are using narrow windrow burning and 25 per cent are using either a chaff cart or chaff lining chute,” he says. “In the 2017 harvest there was also one iHSD and one Seed Terminator operating here.” Chris is a strong supporter of all the tactics in the WeedSmart Big 6 and actively promotes the inclusion of all tactics in his clients’ integrated weed control programs. 1. Crop and pasture rotation The close lentil – wheat rotation that has dominated farming systems on the northern Yorke Peninsula in recent years is acknowledged as a weak link in terms of weed control. This rotation has led to an increase in broadleaf weeds such as milk thistle and prickly lettuce, with bifora, tares and medic also exploding in the lentil phase in some years, leaving a high weed seed bank for the following year as well as increasing the risk of herbicide resistance evolution. Chris says the economic drivers for the rotation can make weed control decisions difficult and there is a need for other profitable rotation options that can assist in reducing weed pressure. The main problem with the short rotation is that weeds are exposed to the same herbicide modes of action every two years. Although imi-tolerant (Clearfield) varieties have been very useful, particularly PBA Hurricane lentils, allowing the use of Group B herbicides in the crop or in previous seasons, the alkaline soils on the Peninsula have expedited the more rapid evolution of Group B resistance in wild radish, mustard, milk thistle and ryegrass. Lentils have provided several economic and weed control benefit to farming systems on the Yorke Peninsula but the short lentil / wheat rotation is a definite weakness when it comes to managing herbicide resistance.   2. Double knock to protect glyphosate Glyphosate resistant ryegrass is widespread on the Yorke Peninsula, primarily along fencelines but as fences are removed to form larger paddocks, there is a significant risk that the resistance gene will be spread by headers. In 2013, the Peninsula had the dubious honour of having the first confirmed case of glyphosate resistant brome grass on a farm near Maitland, and this season, glyphosate resistance in barley grass was observed for the first time on northern Yorke Peninsula. An annual double knock application before seeding is considered very important to help protect the efficacy of glyphosate and is widely practiced on the Peninsula. Sowing earlier to achieve a yield advantage and dry sowing can impact on the use of double knock. Chris advises his clients to avoid early or dry sowing in weedy paddocks and to hold off sowing until the double knock has been implemented, even though there could be a yield penalty. Under dry, dusty conditions most growers will choose two contact herbicides such as paraquat or paraquat / diquat rather than glyphosate / paraquat for the double knock. 3. Mix and rotate herbicide groups There is a heavy reliance on pre-emergent herbicides on the Yorke Peninsula and in weedy paddocks growers need to use additional shots to drive down weed numbers to preserve yield. In cereals, the Boxer Gold and Sakura applications are often spiked with triallate to strengthen the pre-emergent efficacy because there are no in-crop herbicide options in wheat and barley crops. Pre-emergent herbicides are also very important in lentils as the main break crop to reduce ryegrass numbers so there is less pressure on the clethodim / Factor mix in crop. Trifluralin susceptibility in ryegrass has been very low since the late 1990s and so is not a tank mix option, unless targeting broadleaf weeds like wireweed or three corner jack. 4. Stop weed seed set Chris says Yorke Peninsula growers generally use their late fungicide application in August or September to scout for weed escapes in crop. Taking a nil tolerance approach, growers might hand pull small areas, or spot spray. Using paraquat or paraquat / diquat, growers can avoid using glyphosate on potentially resistant individuals when chemically fallowing areas of their crop. The permit for Weedmaster DST use to crop-top in barley provides a useful control tactic for radish and ryegrass at the end of the season, but is often too late for brome grass, which has usually already set seed by this stage of the crop. In blow-out situations Chris often advocates for the ‘short-term pain for long-term gain’ of a chemical fallow using paraquat or Spray.Seed. Chris suggests that the chemical fallow is the best tool to use if brome numbers are building up in a paddock. In his experience, the performance of the following crop usually makes up for the one-year sacrifice due to increased nutrients and moisture availability. He says some growers plan for the inclusion of a small portion of the rotation to be sown as a chemical fallow, while a larger number would use chemical fallow only in a failed crop or for a weedy portion of a paddock as a patch management option. 5. Crop competition Where the soil type allows, Yorke Peninsula growers have readily adopted east west sowing having seen the benefits of this row orientation promoted through AHRI and WeedSmart. Some soil types, such as the sand swales around Port Broughton, dictate sowing direction but it is an option in other areas. Barley is the most competitive crop grown across the Peninsula and growers usually consider choosing the most competitive cultivars available. This is coupled with high sowing rates and narrower row spacing of 22–30 cm (9–12″) spacing, although there is local research that suggests there could be benefits of even narrower row spacing. 6. Harvest Weed Seed Control (HWSC) Chris’ trial work with HWSC shows the importance of getting the weed seed into the header. He says brome grass can be difficult as its flexible stem doesn’t always get cut and can flick back up once the harvester has passed. Wild radish generally stands up well with 70–80% of seed entering the header. Even with a 50 to 60% capture of brome grass, depending on the season and how early harvest occurs, HSWC is still an important part of any weed management program. Capture of ryegrass seed is seasonal with the ryegrass lodging in some years and not picked up by the header, while it will stand up well and achieve 80% capture in other years. Once weed seed is in the header, Chris’ research has shown that it doesn’t matter what HWSC method is used – all are effective. Chaff carts and narrow windrow burning have been widely adopted for many years but Chris expects that chaff lining and chaff decks is likely to increase while NWB will decrease in use. Chaff lining was widely adopted in 2017 harvest as an economical and easy way to manage weed-laden chaff. He also expects some growers with larger areas and some contractors to purchase iHSD and Seed Terminator modules, with one each of these operating in 2017 harvest on the Peninsula. Chris Davey’s trial work with various harvest weed seed control methods has shown that the amount of weed seed entering the header can vary, but once in the header all methods are equally effective at reducing the weed seed bank for the next season.

Podcasts

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Podcast

Farmers share their harvest weed seed control experiences with Planfarm Agronomist Dani Whyte

We have a special guest co-host this week, with Planfarm Agronomist Dani Whyte joining Jessica Strauss, providing insights on farmer interviews she conducted last harvest. Dani has been working on a GRDC RCSN project, looking at harvest weed seed control practices in the Kwinana East port zone. She conducted 10 farmer interviews in total. In this podcast, we hear from three of the farmers who participated in the project. Farmer Ty Kirby runs chaff decks on his property. Farmers Clint Della Bosca (pictured at the top), Stephen Dolton and Ty Kirby all share their HWSC experiences. Planfarm Agronomist Dani Whyte in the field. The focus of this project is getting the weeds in the front of the header in low yielding crops.  The core messages are: Harvest low – 10-15cm (this means paddocks need to be clean of rocks/stumps and staff need to be trained accordingly) Coreflute attached to finger tyne reel Knife extensions/crop lifters on the front of the harvester Farmer Stephen Dolton  
Audio
Podcast

Harvester set-up and implications of hay crossing borders

In the podcast this week, we’re focusing on harvester set-up and we also discuss how to capture weed seeds in the chaff fraction. John Broster from Charles Sturt University gives us some insight into the research he and Michael Walsh (University of Sydney) did on capturing weed seeds. A few years back, they measured how many weed seeds were entering the chaff fraction in a modern harvester. We learn what this means for growers. We also hear from WA farmer Andrew Messina about setting up Case harvesters. Finally, with the terrible drought conditions in Queensland and NSW, many farmers have had to source feed from totally different parts of the country. We chat with Grains Farm Biosecurity Officer for Biosecurity Queensland Kym McIntyre about the implications. A candid shot of WA farmer Andrew Messina. Andrew has been practising HWSC for more than two decades We also talked about a great opportunity being offered by the GRDC in the podcast. Did you know your group can apply for the GRDC “Grower Development Awards – Study Tours” to potentially help fund your trip to WeedSmart Week next year? Applications close Oct 9. Get the details here.
Audio
Podcast

HWSC Workshop overview and sowthistle management update

With the help of GRDC, Planfarm recently held Harvest Weed Seed Control (#HWSC) workshops in Western Australia. All the current approaches to HWSC were discussed in detail. In this podcast, Jessica Strauss is joined by two co-hosts, Peter Newman (AHRI, WeedSmart, Planfarm) and Nick McKenna (Planfarm) where they provide an overview of the learnings from the workshops. We hear from Goomalling farmer John Even who attended one of the workshops. He talks about his approach to weed control, including his reasoning behind choosing chaff lining as his primary HWSC management tool this season. The Cropping and Resistance Forum is also coming up in Dalby on December 6. Northern Grower Alliance CEO Richard Daniel is going to be presenting at the forum on sowthistle and wild oat management. He gives an overview of the current issues facing the northern region and gives some details on what he’ll be presenting at the forum. You can get all the information and tickets for the forum here. Take a listen to the podcast. Music: bensound.com

Case Studies

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Article
Case Study

Bruce family, Alford SA

Keeping pressure on brome grass with HWSC Brothers Gary, Paul and Bronte Bruce farm at Alford on the Yorke Peninsula, SA have used harvest weed seed capture as an important tool in their weed management program to bring down grass weed numbers in their continuous cropping business. For the last 15 to 20 years the Bruce family has followed a 3-year rotation of wheat – barley – legume, having exchanged field peas for lentils in the legume phase in recent years. They found that producing export hay on grassy paddocks was a very effective way to manage grass weed seedbank, to the point where they had only one paddock of hay in 2016 and no hay in 2017. Gary Bruce, together with the family’s agronomist Chris Davey, YP-AG sets out a plan for the season, including our weed management program, with different strategies used depending on whether there is a wet or a dry start. “Hay production is hard work and now that we don’t have much of a grass weed problem we are taking hay out of the rotation for a while,” says Gary. “The hard work was certainly worth it in terms of regaining control over herbicide resistant weeds on the farm. Now we’d like to keep more crop residue on the paddocks to improve the hardsetting nature of the soil here.” Having used a chaff cart for many years, the Bruce’s were well aware of the benefits of capturing weed seed in the chaff stream but Gary was very interested to hear HWSC advocate and WA grower, Ray Harrington, speak at a field day about chaff lining. In 2017 harvest they used chaff line chutes on two headers for the first time. As usual they learnt a lot in their first harvest and have plans to make even better use of the system this season. Gary is very aware of the fact that there is very limited research on the long-term impact of chaff lining on weed management. “Our farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run,” he says. “We found starting the harvester on a spray track at the edge makes the best use of the wheeltracks. If we go to a full CTF system we will probably change to using a chaff deck system but the chaff lining chute is certainly a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble.” Gary’s farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run. So far they have found using the chaff lining chute is a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble. HWSC and late germination Brome grass is the most problematic weed on the Bruce’s farm with limited options for control in the cereal phase. There are limited chemical control options to kill early germinating brome grass before seeding and so Gary relies on HWSC to take care of late germinating cohorts. They recognise that hay making has played an important part in keeping this weed in check and acknowledge this could be more difficult if they get out of hay production altogether. All crops are sown to achieve greatest crop competition possible using 25 cm row spacing and cultivars that are well suited to the different soil types. Two-thirds of the farm is inter-row sown while paddocks with hardsetting topsoil generally follow the same furrow as the previous year. As the soil improves through increased residue retention Gary hopes most of the farm will eventually be sown in the inter-row. Generally they find, Scepter wheat yields better than Mace, Compass barley produces the most straw, PBA Bolt lentils give salt and boron tolerance where it’s needed and PBA Hurricane lentils offer Group B herbicide tolerance. “Early in April we usually speak with our agronomist, Chris Davey, about a plan for the season, including our weed management program,” says Gary. “For example, wet and dry starts need different strategies such as ensuring there is sufficient moisture to activate metribuzin and propyzamide before sowing lentils. We have also experienced more summer rainfall recently and often need to do two sprays for summer weed control.” Other resources: Implementing the WeedSmart Big 6 on the Yorke Peninsula

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