Case Studies

Case Study

Neek Morawitz, Comet Qld

‘2 + 2 and No Survivors’ to protect RR technology
At the junction of the Comet and Nogoa Rivers, 40 km east of Emerald in central Queensland, Neek and Robyn Morawitz grow a range of irrigated and dryland crops.
One third of the 990 ha irrigated area is under four centre pivots and the rest is flood irrigated from their on-farm storages and the Emerald Irrigation Scheme. An additional 350 ha is operated as a minimum tillage dryland system.
Neek Morawitz grows a range of irrigated and dryland crops adjacent to the Comet River in Central Queensland. His herbicide and crop program aims to keep weed numbers low to minimise the risk of herbicide resistance.
Roundup Ready Flex cotton with Bollgard 3 technology for helicoverpa control is central to the Morawitz’ business. As such Neek is keenly aware of the importance of keeping ahead of herbicide resistance.
“To reduce the risk of glyphosate resistance we implement as many other weed control strategies as we can across the crop rotation,” he says. “In the fallow after an irrigated cotton crop we normally don’t use glyphosate at all, choosing to use paraquat, diquat and synthetic auxins such as 2,4-D early in the summer and then we also cultivate a few times to kill weeds, incorporate stubble and prepare the land for the next crop.”
“Occasionally we will do a double knock mid-season in the fallow using synthetic auxin followed by paraquat, or glyphosate followed by paraquat. Applying MCPA in wheat crops is another opportunity to use synthetic auxins, however we restrict our use of these herbicides because of the risk of contamination of spray equipment and the potential for crop damage, particularly in cotton.”
“We aim to implement the ‘2 + 2 and no survivors’ strategy of two non-glyphosate controls in-crop and two non-glyphosate controls in the fallow to extend the life of the Roundup Ready technology,” he says. “In-crop we are using inter-row cultivation, crop competition plus pre-emergent herbicide and in the fallow we use cultivation and alternative knock-downs such as paraquat and synthetic auxins.”
In the following chickpea crop Neek also applies a different pre-emergent herbicide mode of action to keep weed numbers low in-crop.
Cotton, sorghum and maize are grown on beds that are 960 mm apart, while wheat and chickpea crops are planted in four rows, 375 mm apart, across 2 m CTF beds. Neek pays close attention to achieving an even plant stand through precise seed placement and even germination. He says the use of GPS technology at planting has made a real difference to the competitiveness of crops by avoiding misses and overlaps.
PBA Pistol, PBA Kyabra, PBA HatTrick and PBA Seamer chickpeas have all performed well in rotation with cotton, generally only requiring a pre-water and then one irrigation early in the flowering phase.
“By using cultivation and strategic application of residuals along with sowing clean seed from our own farm we are getting a good even stand and very few weeds growing in our chickpea crops,” he says.
Cover crop
One of the centre pivot blocks has quite sandy soil that is prone to wind erosion. While soil loss is a real concern, so is the sand-blasting damage done to cotton seedlings on windy days.
“We use cover crops such as wheat to protect the soil surface and the young cotton crop,” says Neek. “In fact the only wheat we have planted this winter is the cover crop on this block. Last summer we grew peanuts and baled the peanut crop residue after harvesting then planted the wheat cover crop, using a spinner, to provide surface cover for the next cotton crop.”
This wheat cover crop was planted with a seed spreader to protect the sandy soil surface and conserve moisture prior to planting cotton.
The cover crop was sown in mid-June after a glyphosate / paraquat double knock. In mid-September Neek brown manured the wheat with another double knock and left the crop in-situ until the cotton crop was direct drilled in late September. In addition to physical protection of the cotton seedlings Neek has seen other benefits to cover cropping, including better crop establishment and more even water distribution through the soil.
Crop and herbicide rotation
Much of Neek’s crop rotation centres on planning around plant-back periods for residual herbicides. On the irrigated portion of the property he chooses a mix of cotton, sorghum, maize, mungbean and soybean in summer. Neek doesn’t usually sow a summer crop on their dryland area, however, when the opportunity has arisen he has had success with dryland cotton, sorghum and mungbean.
Since the introduction of Bollgard 3 cotton Neek has been taking advantage of the opportunity to plant as soon as the window opens on 1 August, particularly on the irrigated blocks. This means the crop can be harvested by late January, making both the dryland and irrigated crops more moisture efficient. The early plant also means land is free for double cropping into mungbean or sorghum if the opportunity arises.
In winter, the whole farm is sown to either chickpea or wheat, if sufficient water is available. This simple rotation in winter maximises the effective use of cereal stubble for soil moisture conservation. Neek generally expects to produce three crops within a two-year timeframe, which allows for some double cropping and some fallow breaks.
If necessary, Neek has the option to use irrigation to activate pre-emergent herbicide and help manage herbicide breakdown in periods of extended dry weather.
“Our herbicide choices are based on balancing the expected impact on weeds and the crop safety of the following crop,” he says. “Our mix of crops allows us to be using a wider range of herbicides in both summer and winter.”
“We grow some sensitive crops and so it is very important that the herbicides we apply hit their target and any drift is kept to an absolute minimum,” says Neek. “We don’t skimp on water rates and choose spray nozzles best suited to the herbicide and the conditions at spraying.”
Non-crop areas and infrastructure
To date, Neek has not identified any herbicide resistant weeds on the property however he has participated in a Department of Agriculture and Fisheries weed survey and is interested in seeing the results when they are released.
“Feathertop Rhodes grass is our main concern here and it has the well-known tendency to establish on crop borders and non-crop areas around the farm,” he says. “To prevent movement of FTR into the cropped areas we are diligent with both herbicide and non-herbicide control methods, including using a flame-thrower to kill larger plants along irrigation channels and the like. With herbicide treatments we try to mix that up as much as possible, changing between glyphosate, paraquat, diuron and metsulfuron.”
In non-crop areas such as around irrigation channels Neek has found that a flame-thrower is a good way to kill established FTR plants and prevent seed set.
Other resources:

Bollgard3 Roundup Ready Flex Cotton Weed Resistance Management Plan

Case Study

John Stevenson, Lockhart NSW

Orange Park is an 8200 ha corporate dryland cropping operation with eight main blocks, all within a 30 km radius of Lockhart, NSW where John introduced the use of the double break from cereals 10 years ago.
To get the best result possible from OP canola, ‘Orange Park’ manager John Stevenson (left) has their seed professionally graded and only plants seed sized over 2 mm diameter. Karl Grocke (right) has joined the team at Orange Park on their graduate program, making the most of the opportunity to learn from great operators like John.
“Our rotation is driven by herbicide resistant weed management,” he says. “A double break, such as hay/canola, pulse/canola, fallow/canola, is implemented once in a 7-year rotation. The rotation is flexible but we do what we can to avoid growing three cereal crops in a row because the result is inevitably a weed blow-out.”
The main weeds on Orange Park are annual ryegrass in-crop and fleabane in summer, which has been increasing since 2005, particularly in wet years. Wild oats is a lesser but persistent weed.
“We have low level glyphosate resistance and varying levels of Group A resistance to contend with,” says John. “We don’t use much Group B chemistry either, except occasionally in imi-tolerant crops, partly because of decontamination issues with canola, but mainly because of poor efficacy.”
The wettest September on record in 2016 saw about 10% of the crop across the Orange Park operation inundated – compromising their weed control and nitrogen management.
“Essentially we lost a year of weed control with ryegrass blow outs due to poor crop competition and not being able to do timely herbicide applications,” says John. “We also saw a shift in the weed spectrum with more carryover of weeds that thrive in wet conditions, such as toad rush and lesser loosestrife.”
Crop rotation and double break cropping
The rotation that is working well on Orange Park since 2008 consists of two cereals followed by canola, then another two cereals and finally a double break before returning to cereals.
John incorporates as much diversity within the system as possible to maximise returns and keep pressure on weed numbers. Canola, wheat, barley, pulses (including faba bean, lentils and vetch hay), oaten hay for export, and strategic fallowing to conserve moisture, all feature in the list of options. The diversity in crops enables the rotation of herbicide groups, including pre-emergent herbicides ahead of each crop.
Imi-tolerant crops such as Hurricane lentils, IT-canola, possibly barley in the future add to the mix although John often grows hybrid IT-canola conventionally simply for its inherent yield advantage.
“The price of lentils is attractive however logistics are difficult, as grain needs to get to Horsham, over 6 hours away,” he says. “Realistically, canola and feed grain for poultry and feedlots are our mainstay crops.”
To maximise the competitiveness of canola crops John grows some hybrid crops and also grades OP canola to 2 mm diameter as a cost-effective way to improve crop establishment and early vigour that also suppresses early weed growth.
John uses TT canola when weeds become a problem issue and Clearfield canola in low weed population paddocks where he can also apply atrazine on volunteer faba beans.
This year John planted 650 ha trial of lentils in a block that would normally have been fallowed. “There was good residual soil moisture from last year’s wet winter and we tried a late planting system to reduce the density of the lentil crop to keep air flowing through canopy, hopefully reducing the incidence of disease,” he says. “Weed control in the Hurricanes XT lentils has been exceptional although the crop has demonstrated the need for better pH amelioration at depth.”
“Including lentils will spread the workload and we can target a different weed germination cohort,” he says. “Having a different group of herbicides available will also help add diversity to our control program.”
Row spacing, CTF and stubble management
John manages Orange Park as eight 1000 ha management units, where a unit may consist of several blocks in close proximity. He is looking at opportunities to implement east–west sowing in suitable blocks to maximise yield and reduce weed pressure.
While on a Nuffield Scholarship trip to New Zealand, John saw crops grown on 125 mm (5 inch) row spacing where farmers were able to include ryegrass as a crop in their rotation, without concern over future weed problems.
“Historically, our seeding has been on a 300 mm row spacing but we are in the process of investing in a full disc seeding system, which will allow us to narrow the row spacing to 175 mm (7 inches),” says John.
The disc seeder will enable John to retain stubble from their 1.7 t/ha pulses, 3.4 t/ha wheat and 4 t/ha barley crops within their 18 m system with 3 m CTF tramlines.
Harvest weed seed control
John and his team have been narrow windrow burning for three years. Having tried this harvest weed seed control tactic in canola, wheat and barley crops they have found the safest and best results are achieved in canola.
“Realistically, narrow windrow burning is not very compatible with the council’s fire regulations so we are looking at alternatives,” says John. “Cereal stubble burns for 4 or 5 hours, and whirlwinds can easily shift burning chaff 300 m into a neighbour’s stubble.”
A downside to narrow windrow burning is that more moisture is stored under the narrow windrows, which can cause uneven crop germination the following season.
John has been successfully using narrow windrow burning in canola for several years. Twelve days after sowing, this Lancer wheat crop shows the variability in germination where the rows under the narrow windrow have access to more moisture.
John is looking into other options for harvest weed seed control and will probably phase out narrow windrow burning over the next few years. Chaff deck systems suit CTF and although John thinks they have merit, there are limitations on the options available when using contract harvesters. Chaff lining seems easier to implement and is likely to feature in the near future.
“Narrow rows help push weed seed heads to the top of the canopy,” says John. “Two plants per m2 is too many, especially if the weed is able to adopt a prostrate habit and evade collection at harvest. The big challenge is getting inexperienced header drivers to harvest low, even though we pay the contractor a premium to have this happen.”
John uses spray topping in canola, and sometimes wheat and barley, along with hay production to take out late germinating weeds.
Fallow management
Over summer, John uses a contractor with an optical (camera) sprayer to treat survivors with paraquat following a broadacre spray of glyphosate. He says the optical sprayer is also a valuable tool to help manage cud weed, which is becoming more prevalent.
There is no routine cultivation in the system however John does incorporate lime with a speed tiller before planting and a full tillage using a flexicoil is done when there is levelling work required.
“When we change over to the disc seeder we will probably need to cultivate to remove the ridges left by the tined system,” he says. “The disc seeders can’t handle too much chaff on the ground either, so burning is still an option for weed control, or when slugs and mice are a problem.”
Soil fertility and weeds
Across the Orange Park operation John has acidic (pH 4.5) red soil ridges and some sodic vertosols to contend with. He is using variable rate technology (VRT) to apply lime to the red ridges using rates ranging from 1 to 3 t/ha to lift the pH to 5.5.
“We saw an immediate response of lower ryegrass population in low pH blocks after lime application due to stronger crop competition,” he says. “Variable rate application and soil testing has been very cost effective for us and has helped reduce weed numbers and improves herbicide efficacy. Fixing soil pH gives the best return on investment through improved nutrient availability, which supports higher yield and better weed control.”
John is also using soil sensing and VRT to address constraints in nitrogen and phosphorus.
The red soil ridges on ‘Orange Park’ are acidic (pH 4.5) so John is using variable rate lime applications to lift the average pH in these soils to 5.5. In doing so he has observed an immediate reduction in ryegrass numbers due to the improved crop competitiveness.

Case Study

Aaron McDonald, Horsham Vic

Farming with his parents, Greg and Leanne, Aaron runs 5500 ewes for wool and prime lamb production, utilising pastures, hay paddocks and crop stubble on their 4050 ha property.
The McDonalds are finding a rotation of canola, wheat, canola, wheat, then a double break of canola followed by faba beans or clover hay, is profitable and enables them to keep weed numbers down.
In barley crops the straw is also often baled after cutting the crop low, allowing sowing without stubble burning.
Aaron does most of their oaten hay production on the poorer soils but also uses oaten hay as an effective means to clean-up paddocks that have a higher infestation of ryegrass. Their clover hay is sold locally, predominantly as cattle feed, while their oaten hay is exported most years.
“Annual ryegrass and wild radish are our main problem weeds,” says Aaron. “We test for herbicide resistance every couple of years and so far the results have come back as ‘susceptible’ for most of the major groups. The main challenge we have with wild radish is the fact that it germinates all year round. With ryegrass it’s all about keeping plant numbers low.”
Although the testing is not showing herbicide resistance, Aaron is seeing evidence of Select not working as well as it did in the past. To add more mode-of-action diversity to their system the McDonalds are using pre-emergent herbicides Sakura and Boxer Gold in cereals with good success and grow both hybrid (RR and 650TT) and open-pollinated (TT) canola cultivars.
“The RR canola enables extra knocks with glyphosate in-crop to clean up paddocks where we are concerned over the efficacy of Select,” says Aaron. “All our other in-crop herbicides are still working well but we are trying to rotate as much as possible with Select and Edge, and using paraquat ahead of canola and glyphosate or paraquat ahead of cereals.”
The McDonalds have always sown their crops on fairly narrow rows, 250 mm spacing, and use high sowing rates (wheat and oats sown at 100 kg/ha and canola at 3.6 kg/ha) to provide strong crop competition to help with weed control.
The sheep grazing stubbles provides quite good control of summer weeds but some herbicide is always required. Aaron’s main summer weed concerns are melons and self-sown crop. In autumn or pre-sowing he occasionally double-knocks but often there are no survivors so the second knock is not needed.
Hay making and harvest weed seed control
Aaron has implemented narrow windrow burning for the last 4 or 5 years in their canola crops as a harvest weed seed control tactic to capture late germinating weeds. This is supported with strategic crop topping of the canola to desiccate and then windrowing 80 per cent of the canola area each year.
In their cereals, crops are cut low and stubble is burnt on about 75 per cent of the cropped area to allow easier sowing operation, and has the added benefit of destroying some weed seed. In barley crops the straw is often baled after cutting the crop low, allowing sowing without stubble burning. Grazing stubble and burning also helps reduce mice and slug numbers.
“Oaten hay production enables us to apply a desiccant over the top prior to cutting for hay,” says Aaron. “This gives us the opportunity to implement a herbicide plus non-herbicide double knock on in-crop herbicide escapes.”
Aaron McDonald is using oaten hay and clover hay production as weed management tools within their mixed farming operation south of Horsham.
“We graze the cereal stubble and canola narrow windrows after harvest but don’t leave the sheep on the paddocks for long,” he says. “We find that the cereals provide better feed value than the canola windrows but we also put lambs on the canola regrowth for a little extra green pick.”
Each year about 5000 lambs move through the on-farm feedlot, where the McDonalds feed out gradings from the barley grain and the straw. “Feeding the grain gradings out in the feed lot also brings weed seeds into the confinement area where we can control them quite easily,” says Aaron.
The feedlot adds value to the straw and grain gradings, turning off about 5000 lambs per year. Weed seeds that are brought back to the feedlot are easily managed if they survive being eaten.

Case Study

Eagle family, Horsham

2020 mini update – Sam and Emily Eagle have introduced sheep containment yards to their operation as a means of managing weeds and optimising pasture and fodder crop production. They use sheep to graze paddocks sown to Moby barley and clover, then double knock, to make money from their cover and brown manure crops.
Having used narrow windrow burning in canola for six years, Sam and Emily invested in a seed impact mill in 2018 as their harvest weed seed control tool. They spray-top their legumes, make hay and silage for on-farm use and their contract windrower sprays canola under the cutter bar, all to stop weed seed set.
The Eagles continue to use herbicide resistance testing to better inform their herbicide choices and use multiple chemical groups in a broad rotation.
Watch Sam’s presentation at the Horsham WeedSmart Week forum in 2019.
2017 case study:
Sam and Emily Eagle run 2500 merino ewes on their 3000 ha mixed farm near Horsham, Victoria. They say the livestock and cropping activities complement each other, keeping their pastures and crops performing at their best.
Herbicide resistant annual ryegrass is their main weed challenge with one test revealing resistance to glyphosate (65 per cent) and clethodim (80 per cent), and full susceptibility to chlorsulfuron (Group B, Glean).
Sam and Emily Eagle run a mixed farming enterprise near Horsham, Victoria where grazing and cropping are mutually beneficial for weed management.
“We test annual ryegrass from two or three paddocks each year to monitor any changes in susceptibility to the herbicides we use,” said Sam. “Knowing which herbicides are effective makes it easier to plan our herbicide use without relying solely on the products that still work. Every year we have at least one tactic in place specifically to reduce the weed seed bank.”
Knowing that the tested weeds were susceptible to Glean gave Sam an opportunity to regain control of a potential blow-out situation, using a herbicide that is much cheaper than alternatives that he might have chosen if he had to make the decision without the herbicide resistance test results.
The Eagle’s agronomist usually collects the seed for testing and the results are considered to be representative of the whole paddock, each one being around 35 to 70 ha.
“We can fairly safely assume that all our weeds have some level of resistance so we concentrate on managing survivors, mostly treating with a double-knock whenever possible,” he said. “Annual ryegrass is our main problem weed however we are keeping a close eye on brome grass that is present on one of our lease blocks.”

Triazine resistance on one block precludes the use of TT canola so the Eagles grow conventional canola on this block, aiming for the most competitive, highest yielding crop possible.
Along fence lines Sam uses a 2-year program where he slashes in spring in one year and then sprays a knockdown + residual herbicide mix the next year. “When we slash, we know that the weeds will still set seed. We keep the slasher low to the ground to ensure any seed heads present at harvest are below header height so they won’t get spread,” said Sam.
The pasture paddocks are de-stocked over summer with the sheep grazing on the stubble. If the stubble runs out early the sheep are returned to the containment area where they are fed screenings, hay and grain until the pastures are ready. The ewes return to the pastures to lamb in autumn.
Sam and Emily use narrow windrow burning in the canola as their harvest weed seed control tool. They have had trouble using this tactic in cereals, where the fires often don’t burn right to the ground, leaving weed seed concentrated in bands. On the other hand, the canola burns well, destroying the weed seed, and Sam is able to safely burn several paddocks on the one day. Grazing the canola narrow windrows has not caused any problems with burning or with weed seed being spread.
Narrow windrow burning in canola has worked very well for Sam, driving down herbicide resistant ryegrass numbers.
“Canola actually gives us a few opportunities to control late germinating weeds,” said Sam. “Firstly with an over the top spray to desiccate the crop, secondly windrowing the crop early and third, using the narrow windrow chute at harvest in preparation for narrow windrow burning in autumn. We also spray top wheat and barley, with the sheep providing the second knock for any survivor weeds.”
Growing faba beans, canola, wheat and malt barley enables them to use a different pre-emergent herbicide each year of the rotation. At the end of this 4-year program any paddocks that are carrying a weed burden are thoroughly cleaned using a pasture and a 3-year hay program. Moby forage barley sown with clover gives a nutrient boost to the perennial ryegrass pasture phase, which may last up to ten years.
“We supply hay for export and generally grow two oat crops and one vetch,” said Sam. “Any failed crops or additional production is stored as silage in underground pits to drought-proof our breeding flock. Silage is a particularly good way to clean up weeds because we spray out when the crop is actively growing and not under any moisture or heat stress, then cut in early September.”
At the end of a 4-year cropping program any paddocks that are carrying a weed burden are thoroughly cleaned using a pasture and a 3-year hay program. The Eagles supply hay for export and generally grow two oat crops and one vetch.
The 2017 seeding represents the beginning of the Eagles’ fully aligned controlled traffic farming (CTF) system. The transition to 12 m wide CTF has taken several years but Sam and Emily are convinced that the efficiencies gained will be well worth the investment.
They sow all crops on 300 mm row spacing and aim to achieve the most competitive crops possible. Although Sam knows 380 mm row spacing would make some management operations easier, they pick up extra yield and suppress weeds with the narrower spacing.
In the seven years that Sam and Emily have been managing the farms they have seen the benefits of the rotation in keeping weed numbers low. “All of our worst paddocks have now had the ‘rotation treatment’ and we have avoided weed blow-outs,” said Sam. “Two wet years in a row could potentially challenge our weed management but having the sheep in the system gives us more options while still earning income from each paddock.”
Related links

10 Point Plan – Test for resistance to establish a clear picture of paddock-by-paddock farm status
Plant Science Consulting herbicide resistance testing
CSU Herbicide resistance testing

Case Study

Paul Slack, Moree NSW

Bringing pre-emergent herbicides back into cotton systems
The new rules for managing Bollgard 3 cotton include changes to the requirements surrounding pupae busting. Dryland cotton farmer Paul Slack is considering his options but is cautious about the ramifications of a fully no-till cropping rotation on his farms east of Moree, NSW.
“Weed management in cotton has seen several transitions in the last 20 years,” he said. “Before Roundup Ready cotton we applied pre-emergent herbicide in a band behind the planter and relied on chippers or shielded sprayers to remove any survivors or late emerging weeds. With the adoption of Roundup Ready Ingard, then Bollgard II cotton across the industry, growers started using less and less pre-emergent herbicide and in the last eight to ten years or so we have been heavily reliant on glyphosate.”
Dryland cotton and grain grower Paul Slack (right) and his agronomist Tony Lockrey (AMPS) have been working on crop rotation options to deal with herbicide resistance in weeds.
With the only real cultural control measure being used being cultivation for the purpose of pupae busting, which also helped reduce the weed burden, there has been an over reliance on just one herbicide group. Although there is less cultivation required in Bollgard 3 production, there is still a recommendation to kill the cotton crop and any green bridge weeds or volunteers.
“Cultivation may still feature in our weed management program. We would never cultivate after corn or wheat but cultivation after cotton or chickpea is a good option to fix wash-outs or deep wheel tracks while there are lower levels of stubble in the paddocks. Uneven landform presents significant challenges for spraying, especially with optical sprayers, so it is important to repair damage as soon as possible,” said Paul.
“We have grown cotton every year since 1989 and know that no-till and stubble conservation in the grain phase of our dryland system is worth an additional half to one bale of cotton per hectare,” he said.
Longer rotation
“We got into trouble with herbicide resistance as a result of the short wheat / chickpea / wheat rotation that we used for 15 years or more, like many others in the district,” Paul said. “The legacy of this routine is our ongoing battle with Group A resistant black oats.”
One strategy Paul and his agronomist Tony Lockrey, AMPS Moree have put in place is a longer rotation with summer and winter crop options across the 4850 ha of cropping land. Cotton and corn are the best fit for summer with wheat and chickpea in winter.
Growing cotton and corn in summer and wheat and chickpea in winter has lengthened the crop rotation and added more options to diversify herbicide use.
“Usually we can double crop from corn into chickpea and possibly also from cotton to chickpea,” said Paul. “Wheat follows chickpea before returning to cotton or corn, providing a profitable mix of commodities.”
“Currently we are using a 3-year rotation and could consider lengthening this more,” said Paul. “Disease management and nematode levels influence crop rotation choices and then we plan our use of residual herbicides keeping plant-back restrictions and chemical MOA rotation in mind.”
Canola and barley are both options to lengthen the winter rotation but can only slot into the rotation under certain circumstances. Barley stubble lasts longer than wheat stubble, providing better moisture conservation for the next cotton crop however there are fewer herbicide options available for grass control, putting additional pressure on Group A chemistry and risking a blow-out in black oats. Canola offers more options for nematode and black oats control.
Protecting knock-downs
Herbicide resistance is evident in populations of annual ryegrass, liverseed grass, barnyard grass and black oats on the property. Depending on the size of the patches Paul’s strategy includes optical spray technology and or cultivation to stop seed set.
Paul is looking at ways to diversify his herbicide and non-herbicide tactics to regain control of herbicide resistance in weeds.
Summer fallow sprays targeting grass weeds are usually double knocked with paraquat, and Paul rotates fops and dims (between Verdict and Select) within Group A because these active ingredients have slightly different resistance profiles.
“It can take as few as seven applications of Group A herbicide to initiate resistance so this chemistry is a very short lived option if efforts are not made to control survivors,” said Tony. “To reduce this risk we have tested the use of Paratrooper (paraquat + amitrole) and paraquat + Group G herbicides (Sharpen and Sledge) this summer for ‘one shot’ control of glyphosate resistant grasses and rosette or early elongation fleabane. In some cases this was applied with other fallow residual herbicides to again take pressure off glyphosate and group A chemistry. With this approach it is essential to achieve excellent coverage so we used water rates in the range of 100–200 L/ha.”
Results were very encouraging so Paul and Tony have confidence that this brings another option, albeit another herbicide option, that does not involve glyphosate and Group As.
Pre-emergent resurgence
In fallow prior to the summer crop, Paul is re-introducing the pre-emergent use of Terbyne (Group C). Once the crop is sown he then applies a PSPE diuron + metolachlor (Group K) mix in cotton and atrazine + metolachlor in corn for grass and broad-leaf weed control. A recent registration also allows in-crop application of Bouncer (metolachlor) in cotton.
Flame is sometimes used in the fallow following chickpea and prior to the wheat crop. Balance (Group H) applied to chickpea provides effective pre-emergent grass control into the following summer as well, complementing the Flame. Balance also provides good control of volunteer cotton plants.
Metolachlor, one of the pre-emergent herbicides, requires incorporation with sufficient rainfall within two weeks of application. To hedge the risk, Paul applies one shot in August prior to planting rain for cotton and corn then follows up with a second shot applied PSPE in fields with problem summer grasses.
Paul currently grows conventional corn varieties however he is considering the use of imi-tolerant corn, and the soon-to-be-released IT sorghum or sunflower varieties, in the future as this would enable him to plant these crops after using Flame in the fallow without causing crop damage due to residual activity.
“The release of these crops will heighten the need for growers to carefully implement the imi herbicide stewardship measures,” said Tony. “With imi tolerant options for several winter and summer crops it is essential to observe the requirement to limit Group B (imi) applications to two sprays in a 4-year period.”
Crop competition
Using the crop to compete with weeds is often difficult in this drier cropping zone where much of the crop growth relies on limited stored soil moisture and row spacings are often wide.
Corn sown on 1-metre rows provides good shade and an opportunity to plant before the summer grasses germinate. “Corn is planted and a pre-emergent herbicide applied in August when the soil temperature hits 12 degrees C,” said Paul. “This gives the crop a competitive advantage over the summer weeds, which don’t germinate until the soil temperature reaches 14–15 degrees C. Corn also provides good canopy shade to suppress weed germination and growth as the season progresses.”
“Corn also leaves more residual soil moisture for the following chickpea crop,” he said. “This is a good combination for us, generating a yield benefit of 0.4 t/ha in the chickpea crop.”
In cotton, Paul is considering a change from a double skip planting configuration to a single 2.4 m wide row to better suit picking and the 3 m controlled traffic farming configuration, giving 5 rows in 12 m. Although he knows this will open the crop up to increased weed pressure the single row will favour better quality cotton and the picker will operate more efficiently.
Paul is considering a change from the double skip planting configuration to a single 2.4 m wide row to better suit picking and the 3 m controlled traffic farming configuration. Although Paul knows this may open the crop up to increased weed pressure the single row will favour better quality cotton and the picker will operate more efficiently.
Paul is a member of the local Dryland Cotton Group, and is hosting the group’s trial looking at the benefits of using cover crops to improve moisture conservation across the rotation. This is really a test of whether a cover crop is a viable way to improve the fallow efficiency across 5 to 7-year rotations. The group is trying different summer and winter cereals and legume species and species mixes to investigate the potential benefits of cover cropping. They are just part-way through a 3-year trial but the field pea is showing the most promise for retaining stored moisture and boosting yield in the following crop. Weed management is not the focus of this trial however there may be implications from this trial that Paul may use as he continues to fine-tune their production system.
“In our hot, dry environment, organic matter in standing stubble is mostly lost to the atmosphere rather than contributing to soil organic carbon,” he says. “More nutrients and carbon return to the soil when stubble is incorporated. We will need to determine when to leave stubble standing and when to do light incorporation of the cover crop residues to maximise the benefits of both.”
Related links

Eradicating herbicide resistant barnyard grass
Best way to protect herbicide tolerance technologies
Soil behaviour of pre-emergence herbicide manual (GRDC)
Pre-emergent herbicide fact sheet (GRDC)

Case Study

Clemson family, Ardlethan NSW

As the 2013–2016 drought bit harder in NSW’s Riverina, Ardlethan farmers Lou and Charlie Clemson were thinking about ways to better utilise more of their property, particularly the 200 ha of non-arable country.
Using a NSW State Government drought assistance grant to supplement their own funds they have installed a laneway through the middle of their property, Wongajong, to link the hilly paddocks with the stockyards and provide easy access to all the cropping paddocks between.
Lou Clemson says the laneway allows easy movement of stock through the cropping area and also provides an excellent confinement area with troughed water and creep feeders. The timbered hill paddock is key to the system’s success, providing native pasture for the breeding herd.
Lou says the changes to their business and their weed management have been amazing. “We now have another income stream, and cattle have been very profitable since the drought,” she said. “And we are using less herbicide to manage weeds.”
The re-introduction of livestock to Wongajong started in 2010 when the Clemsons bought 300 steers to make use of a frosted wheat crop. “We fed the steers for 5 months and made good money out of what would have otherwise been a failed crop,” said Lou. “After that we fenced off the hill and added the central laneway and watering points. We are really happy with how well this system is working and see benefits across our whole cropping operation.”
“Growing early varieties is the key to maximising the feed benefit of fodder crops such as Moby barley and Brenan and Naparoo feed wheats, which we plant in February or March,” she said. “In paddocks where we have some annual ryegrass pressure we have sown feed barley in February–March, weaned calves onto it in May and grazed until September. This 73 ha paddock alone turned off 200 prime yearlings.”
With some welcome rain in December, the Clemsons sprayed out the barley and took the opportunity to sow cowpeas over summer. “This year we weaned part of the herd in January and the calves went straight onto the cowpeas where they remained until late April. The cowpeas even podded up and we could have stripped them but decided to just continue grazing. The added nitrogen will also boost the next crop and build soil fertility.”
Cowpeas planted opportunistically on some December rain provided perfect feed for newly weaned calves from January until late April. In addition to the feed value the cowpeas have also provided a boost to soil fertility.
With two back to back seasons of crop competition and sustained grazing pressure, the ryegrass is well under control and the Clemsons have sown Condo grain wheat this winter. After removing the young stock from the cowpeas the Clemsons introduced them to creep feeders offering hay, feed barley and a magnesium calcium supplement in the central laneway.
Lou said their system relies on the 200 ha of hilly country where they run their breeding herd. The cows calve in the hill paddock in July then have access to crop stubbles straight after harvest until January when the cows return to the hill paddocks and the calves are weaned onto feed.
“In this system, Wongajong can carry 200 breeding cows and 50 replacement heifers but no more,” she said. “This is working so well that we are keen to build our herd and will replicate the laneway and fodder cropping system on a second property nearby. We have been expanding our area for both cropping and livestock with additional land purchased and leased.”
Looking across Wongajong, the top paddock grew cowpeas that were grazed over summer, the next paddock down the hill has feed barley ready for grazing and then the laneway where the young cattle are introduced to hay and grain once their rumens are mature. The Lemken speed tiller will be used to prepare the cowpea paddock for sowing the high yielding, short season Condo wheat.
“We identify paddocks that need a spell from cropping and also look at the weed burden,” said Lou. “Grazing barley is our go-to crop for weedy paddocks. It does a good job competing with annual ryegrass and gives us several options such as making hay or grazing and then spraying out.”
Canola has been a mainstay crop for the Clemsons along with barley for grazing, hay and feed grain, and wheat for grazing and feed grain.
The cattle strip graze the fodder crops at a density of 2 head/ha to maximise the feed value and weed control benefits. Electric fencing is used where necessary to manage the grazing intensity and provide fresh feed. Most of the fodder crops will be grazed out and sprayed in spring to clean-up for the following winter. The Clemsons are now planning to extend their fodder cropping program to hay and silage production.
Forage barley has proven to be the most useful crop for livestock production and weed control.
Charlie and Lou use a Lemken Helidor speed tiller to lightly cultivate paddocks that have been sprayed out after grazing. Paddocks are then rested for seven months, from late spring through summer, before they are re-sown. The combination of several non-herbicide weed control tactics such as strip grazing, fodder conservation and the speed tiller have resulted in an overall reduction in herbicide use.
“Sowing early gives us the greatest number of choices,” said Lou. “Some years we would expect about 10 per cent of our crops to be frost affected, but by sowing early we can achieve higher yields and this can make up for losses to frost.”
Lou said there has been a noticeable change in their attitude towards weeds with Charlie being much less stressed. Having the canola and wheat sprayed on time is important while there is more flexibility with spraying times for the grazing crops.
“If there are weeds visible in the paddock we can stay relaxed knowing that once the cattle have finished grazing and been sold, the paddock will be sprayed out before the ryegrass sets seed, and any survivors will be killed with the Lemken Helidor,” she said.
The Clemsons use a Lemken speed tiller straight after harvest to manage stubble and weeds. Provided there is some soil moisture present the cultivation to a depth of up to 10 cm or so causes about 80 per cent of the weed seeds to germinate, allowing a very effective spray opportunity.
Cultivation with the Lemken Helidor machine stimulates weed germination and breaks up the stubble.
Operating at 15–16 km/hr, the 12 m wide cultivator also breaks up and spreads the stubble and throws soil over some of the stubble to aid decomposition. The cattle still have access to valuable feed in paddocks where the Lemken has been used. This light cultivation means there is no need to burn stubble and seeding the next crop is easy.
“Summer cropping opportunities seem to be more common in recent years and we have had success with both cowpeas and sorghum,” said Lou. “The Supa Sudan sorghum we grew this past summer came back three times and provided excellent feed value but it also used too much soil moisture and might limit our immediate cropping choices for that paddock.”
“In winter, forage barley is followed by TT canola then a grazing wheat with the option to graze, make hay or harvest the grain.”
In addition to annual ryegrass incursions the Clemsons have also seen black oats, wild radish and brome grass populations cleaned up through this combination of grazing and cropping.

Case Study

Daniel Fox, Marrar NSW

For a few years Daniel has been adding components to his system to conserve moisture and keep herbicide resistant weeds at bay.
“A series of drought years got us started down this track of better soil moisture conservation,” he says. “We have been able to store more water than we expected really and this has been converted into better yields.”
Daniel (left) and David Fox are pleased with the chaff lining chute they have introduced as a harvest weed seed control method on their Marrar farm near Wagga Wagga.
The long-term average rainfall at Marrar, north of Wagga Wagga, NSW is 500 mm and although last year was extraordinarily wet, the 15 years prior to this were relatively dry. This long dry stretch made growers like Daniel and his father David think more about conserving soil moisture over summer and using stubble to protect the soil moisture from evaporation.
As they add more strategies to their management system they are seeing yields rise from an average 2.5 t/ha for wheat to 4 t/ha in years that would have seen the crop suffer due to a lack of spring rainfall.
To tackle increased pressure from annual ryegrass Daniel and David started narrow windrow burning but found that a combination of cutting the crop low at harvest and burning much of the crop residue was impacting on yields. To investigate, they participated in a trial run by Grassroots Agronomy to see if cutting the crop higher, at 30 cm rather than the recommended 15 cm for narrow windrow burning, would still be an effective harvest weed seed control measure.
“The results showed a half-tonne difference between cutting barley low and cutting higher,” he says. “It seems that the taller stubble provides better protection for the soil surface and the trial with the taller stubble had better conserved moisture, which was needed to finish the crop that year, where we had no rain from early September to mid October.”
Highly competitive crops, like this barley, tend to hold annual ryegrass seed heads up high in the canopy where they can be easily collected by the stripper front on the Fox’s harvester.
To maintain the effectiveness of harvest weed seed control Daniel has recently purchased a Shelbourne stripper for the header to collect the grain, and weed seeds, while leaving most of the stubble standing. “Using the stripper we are putting less material through the harvester but still collect grain and weed seed in the crop canopy,” he says. “This means we are picking up yield and reducing the weed seed bank without compromising harvesting efficiency.”
Having used narrow windrow burning for a few years and seeing the benefit of capturing seed from late germinated weeds at harvest, the Foxes have now built a chaff lining chute for the header and are delivering the chaff component, including weed seeds, into a 250 mm chaff line in the middle of the 12 m CTF lap. This maintains most of the crop residue evenly across the paddock and avoids the need for burning. “Having the weed seed concentrated in a narrow band reduces the amount of seed that germinates and also reduces the chance of weed seed being buried and ‘stored’ underground at planting now that we are using a disc seeder,” says Daniel.
Daniel has had no problem sowing through the chaff and is also able to apply more herbicide to the tramlines if the weed numbers appear to be increasing. He is also keeping an eye on the developments of microwave weed control technology as a potential non-herbicide method to treat the tramlines in the future. “We realise that there might be an impact on soil microbes and earthworms but if the microwave is only treating the chaff lines then it could still be a good option,” he says.
Croptopping in non-malting barley, canola and pulses provides an additional opportunity to stop seed set with the chaff lining providing an effective, non-herbicide second knock to support the herbicide.
The cereal stubble persists across the four-year rotation of two cereal crops followed by two break crops, providing more shade and wind protection, and keeping the soil surface cooler.
Daniel Fox has implemented a double break crop system where the cereal stubble is maintained on the soil surface across the 4-year rotation, conserving soil moisture and improving crop yields.
The double break cropping rotation enables Daniel to have a two-year shot at both grass and broadleaf weeds using a combination of herbicide and non-herbicide tactics. “With herbicides we are using robust pre-emergent and in-crop applications and double knocking our knockdown herbicides,” he says. “The non-herbicide tools are collecting weed seed at harvest with the chaff lining chute, strong crop competition from narrow row spacing and haymaking if required. In just three years we have seen a huge reduction in the ryegrass population on the farm.”
During the 2000s David stayed with the canola / wheat rotation they had in place even though it meant that they had a few failed crops, which they converted into silage. “By resisting the temptation to go with a long cereal rotation we avoided the weed blow-out that occurred on some farms,” he says.
The Foxes grow wheat and barley in the cereal phase with an option for oats on their frost-prone paddocks. “Wheat is our mainstay on the higher paddocks where we sow early and the crop flowers in cooler weather, which can make a 2 t/ha difference in yield compared to sowing later,” says Daniel. “We are wanting to raise our average wheat yield from 2.5 t/ha to 3 t/ha, even in lower rainfall and lower radiation years. Likewise, for barley we are confident that significant yield gains are possible in the system we have developed.”
In the broadleaf phase they grow canola and a pulse, usually lupins, and are considering faba bean and lentils as alternative pulse options. They are also investigating whether winter cover crops followed by a summer crop might have a fit in their system to give them the opportunity to use different chemistry at different times of the year to combat weeds.
“No-till and glyphosate generated a big jump in productivity on this farm and now we are seeing another big improvement with new gear such as the chaff lining chute, stripper front and high clearance sprayer,” says Daniel. “We could not have got through last season without the sprayer. It has allowed us to get onto weeds when they are small and cover a big area in the best conditions.”
Doing their own spraying and planting gives Daniel and David the opportunity to monitor their paddocks during the season to keep an eye on weed numbers, which also helps when they go around the farm with their agronomist to plan the weed control program.
A new disc seeder has also made stubble management easier and allowed Daniel to move to 6.5 inch (165 mm) row spacing for all crops. The single disc seeder has 72 units over the 12 m span which, like the sprayer, fits within the controlled traffic system.
Daniel is conscious of brome grass and black oats entering the farm from the roadside so he is spraying through the external fences with a mix of glyphosate and residual herbicide to help minimise the risk of weeds moving into the cropping areas. “We sow right up to the fence to maintain competition and if we need to, we bale the outside lap of the crop,” he says. “After harvest we plough along the fencelines as a firebreak, which is a council requirement.”
The Foxes look for crop traits that provide a competitive edge such as hybrid canola over open-pollinated types and taller wheats such as Spitfire, while still maximising yield and profit from the available moisture. “The 29 year row spacing trial in WA demonstrated that narrow rows produce more crop and less weeds, and we have seen a 400 to 500 kg/ha benefit through less tiller deaths and more heads here too,” says Daniel. “To achieve this it is essential that the soil fertility is able to support the increased production. Our granite soils tend to leach nitrogen in wet years and that has a big impact on yield.”
Related information

Getting weed seeds into the header’s chaff stream
Michael and Marnie Fels grower case study – chaff lining

Case Study

Ben and Emily Webb – Kojonup, WA

2020 mini update
Ben is still using a chaff cart for harvest weed seed control but he now burns the chaff heaps after they have been grazed. The Webbs now have an higher component of legumes, including faba beans, in their cropping program. They generally keep the cropping and livestock paddocks separate but graze the stubbles (including the chaff heaps) in summer and crop some pasture paddocks to use up excess nitrogen. From time to time they grow oats or vetch within their cropping program and defer graze these paddocks over winter, then spray top the crop. 
Ben puts the sheep into confinement areas in autumn to allow the pastures and fodder crops to get away while he concentrates on the cropping program. 
Any weedy patches in cropping paddocks are cut for hay or silage and Ben has also started to mow and bale two laps around cereal crops as another non-herbicide control tool to reduce weed infestation from crop borders and minimise the risk of producing herbicide resistant weeds. 
Watch a short video about the Webb’s weed control program.
Weed seeds have great feed value (2017 case study)
For mixed farming operations like ‘Marbarrup’, west of Kojonup, WA there are a stack of good reasons not to light up chaff heaps — they are just too valuable.
Ben and Emily Webb farm 2150 arable hectares and run 4500 dual purpose Merinotech ewes and their offspring on crop stubble and 935 ha of non-arable pasture. Their recent investment in a chaff cart to provide non-herbicide weed control also provides them with a valuable feed source over summer and better livestock production.
Ben Webb and his consultant Kent Stone are pleased with the efficacy of the chaff cart system to collect weed seeds at harvest.
“In a trial that Ed Riggall at AgPro Management ran on our property in the summer of 2015–16 the sheep gained more weight when they had access to canola chaff heaps compared to grazing a similar paddock without chaff heaps,” said Ben. “The sheep grazed the canola for six weeks over December and January, gaining an extra 3.8 kg/head over the gains made by sheep just grazing stubble.”
Liveweight of sheep grazing canola chaff dumps compared to grazing paddocks without chaff dumps at ‘Marbarrup’, Kojonup WA. Note: 18 mm of rain fell at the two-week stage of the trial and a further 97 mm of rain fell eight weeks into the trial.
The nutrient analysis of the canola chaff heaps showed the feed value was 7.3% crude protein and 6.1 MJ/kg DM metabolisable energy. Not only did the sheep gain additional weight, the Webbs also saved time and money on supplementary feed that would be required to achieve the same weight gain.
Ed Riggall calculated the benefit of grazing chaff heaps for a typical, model farm of 2000 ha with 50% crop and running 9.5 DSE/ha would be an average saving of over $29,000/annum and an internal rate of return on investment (ROI) on a chaff cart of 36% per annum over 20 years. This is averaged across livestock weight gains achieved on canola, barley, wheat and oats chaff heaps in a detrimentally wet season.
“In addition to this considerable benefit, we also saw a 25 per cent improvement in lambing percentage in the ewes grazing the canola heaps compared to those just grazing stubble,” said Ben. “This is a direct consequence of the higher productivity from heavier ewes in higher body condition.”
Ben has found that the sheep do a good job of knocking down the heaps, particularly when a large mob is given access to the paddock for a short time. Prior to seeding grazed chaff heaps Ben often runs over them with a scarifier to spread the residue more evenly. This makes it easier to seed through the heaps and reduces the need to burn in autumn.
“Ungrazed heaps definitely shed rainfall better but under the right conditions the grazed heaps still burn very well if we decide that’s the way to go,” he said. “The sheep do best on the canola stubble so that is our priority for grazing. The canola heaps don’t generally need much done with them after grazing but I often burn the wheat, oat and some barley chaff heaps after grazing because they can be a pain to seed through.”
“We have trialled narrow windrow burning here a few times but find that it is often too wet to achieve a good result. Moving to the chaff cart and grazing the heaps has been working better for us.”
Not burning the chaff heaps does allow more weeds to persist but as this photo shows, the chaff cart does a good job of cleaning up the whole paddock and concentrating the weeds in a very small area.
Scientific studies have shown that sheep do not spread weed seeds as the seeds are destroyed as they pass through the sheep’s gut. A study by CSIRO scientists in 2002 concluded that less than four per cent of annual ryegrass seeds consumed could survive passage through a sheep’s digestive system and similarly a 2010 international study showed both annual ryegrass and wild radish seeds were destroyed after two days in the rumen.
The Webbs use the chaff cart on all their cropping land and have seen a reduction in herbicide use across the whole farm. In addition to harvest weed seed control with the chaff cart, the Webbs have also been including as many high biomass, competitive crops in their rotation as possible. Their current program includes canola, barley, lupin and wheat, with trial paddocks of faba bean.
Ben has found that growing RR and RT canola has provided excellent biomass production and allows them to restrict the use of clethodim to the lupin phase of the cropping program only.
Hyola 600 RR canola (pictured) and RT canola provides a high biomass crop that competes well with weeds and produces high quality chaff heaps for the Webb’s Merinotech sheep.
Frost is a concern every year and the Webbs have been heavily impacted in the last few years. One of the greatest difficulties being the unpredictability of frosts – early one year and late another. Ben sows Calingiri, a noodle wheat, and Trojan, a bread wheat as early as possible to minimise the risk of frost damage.
Annual ryegrass, brome grass and wild radish are the Webb’s top-3 weed challenges and to-date the herbicide resistance status is low. A ‘quick test’ performed last year indicated that resistance to clethodim was building and this was a significant motivator for Ben and Emily to invest in the chaff cart. Prior to sowing Ben applies a double knock of glyphosate followed by paraquat mixed with a pre-emergent herbicide.
Ben applies in-crop herbicides as required and hand rogues any surviving wild radish plants. To reduce seed set they also crop top lupins and spray glyphosate under the swathe when windrowing canola. Ben has also been trialling windrowing in wheat and barley, primarily as a harvest management tool that also has benefits for late frost avoidance and to reduce seed set in late germinating weeds. On the rare occasions that weeds have got out of hand the Webbs have also used hay production as a way to reduce seed set and drive down weed numbers.
Planting on 229 mm (9 inch) row spacing and paired rows, Ben opts for higher end seeding rates for all crops to maximise yield and competition with weeds. Cutting the crop as low as possible and utilising the stubble as fodder makes planting on narrow rows easier to achieve.

Other resources:

AHRI Insight Chaff carts good for the crop and the sheep
Grazing chaff heaps solved two problems
Grazing chaff dumps over burning webinar

Case Study

Gary Lang – Wickepin, WA

A significant shift into continuous cropping in the Wickepin area south-east of Perth started about 10 years after the same change in the northern cropping regions of Western Australia. For Wickepin grower Gary Lang, this 10-year delay has given him the opportunity to listen and to learn about herbicide resistance.
“Hearing growers talk about the trouble they had run into with herbicide resistance made me sit up and take notice,” he said. “Aside from the more regular threat of frost damage, herbicide resistance represents the most significant threat to profitability if you are forced to take country out of production, so we have tried to get on the front foot with our weed management. We want to continue making crop choices that are not dictated by herbicide resistance in weeds.”
Wickepin grower, Gary Lang uses a 12 inch seeder with splitter boots, making the row spacing 250 mm (10 inches) wide. Combined with higher seeding rates and competitive cultivars he is achieving good weed control through strong crop competition.
Across the 3780 ha cropping enterprise Gary grows 25 per cent canola, 15 per cent each of oats and barley, 10 per cent lupin and 35 per cent wheat. An additional 380 ha is utilised for prime lamb production. Ryegrass is the most challenging weed with wild radish posing a problem in some paddocks. While most of the wild radish is still susceptible to all chemistry, there is resistance to Group B and Group A fops in annual ryegrass.
“Wild radish is a less aggressive weed for us here but we take it very seriously due to the experience of growers further north,” he says. “While wild radish is still susceptible to herbicides it is possible to clean up a blow-out that may occur in years where the weather has prevented the application of the usual herbicide program. It will normally take three to four years to bring the weed numbers back down, but it is manageable.”
Frost has been a major limiting factor for the Langs for many years so they are making changes to their cropping program to reduce the risk of losses to frost. Wheat is becoming a less important part of the cropping system and Gary tries to avoid wheat on the frost-prone paddocks, where he can grow oats or barley more reliably. Although barley provides another option for frost prone paddocks, La Trobe barley is not overly competitive against weeds compared to some other barley cultivars, due to its short stature and slow early growth rate.
They also look to oats as a good crop choice for weedy paddocks for greater crop competition and sowing early means they can make use of trifluralin to provide pre-emergent weed control until the crop canopy closes. Growing oats for human consumption has not been common practice around Wickepin but it is proving to be a good option if the crop is sown early enough, taking advantage of the crop’s resistance to frost. Williams oats can be sown as early as the end of April to produce a very competitive, dense crop.
Frost has been a major limiting factor for the Langs for many years. Williams oats is proving to be a good option if the crop is sown early enough, taking advantage of the crop’s resistance to frost, and is a very competitive, dense crop. Sowing early also means the Langs can make use of trifluralin to provide pre-emergent weed control until the crop canopy closes.
The Langs delay sowing wheat to manage their frost risk and use a pre-sowing double knock operation of glyphosate followed by paraquat to give the crop a clean start.
Crop competition is achieved through narrow row spacing, higher seeding rates and crop cultivar choice. Gary uses a 12 inch seeder with splitter boots, making the row spacing 250 mm (10 inches) wide and does a blanket burn of cereal stubble at the end of the rotation before planting canola.
The Langs use higher seeding rates, such as sowing cereals at 90 kg/ha instead of the usual 60–70 kg/ha, in weedy paddocks or patches using variable rate technology to increase crop competitiveness.
On the western side of the farm the Langs usually grow canola–cereal–cereal and on the eastern side where the soils are lighter and the rainfall less, the rotation is commonly lupin–cereal–canola–cereal–cereal. Gary chooses to grow mostly triazine tolerant (TT) open pollinated and Roundup Ready (RR) canola cultivars for their herbicide traits and the higher biomass from the RR hybrid. Gary is pleased to have seven profitable crop options to work with when planning his program each year to minimise financial and frost risk while maximising profit and making the most of a wide range of herbicide and non-herbicide weed control tactics.
High biomass Hyola 404RR canola is very competitive against weeds and along with open pollinated TT canola offers alternate herbicide use patterns within the rotation.
In wet summers such as 2015–16 and 2016–17, melons, caltrop, fleabane and even some ryegrass and radish will necessitate two or three summer sprays.
Stopping seed set by croptopping lupins and spraying glyphosate under the swathe in canola, and implementing harvest weed seed control are critical components of Gary’s weed management program. Gary tried narrow windrow burning 1000 ha of canola in both 2013 and 2014 and found that the movement of potassium into the narrow windrow caused serious nutrient deficiency across 2000 ha that was still evident in 2016, prompting him to look at other harvest weed seed control tactics. For the last three harvests he has used a chaff deck system to channel chaff into the tram lines within his controlled traffic farming system.
“The chaff lining also relocates nutrients but there is much less material shifted in the chaff only,” he says. “Ultimately we’d like to have a weed destructor in our next header but in the meantime the $9000 investment in the chaff deck was easier to do than $70,000 for a chaff cart, which also requires more work.”
“In our environment we don’t seem to get the rotting down of the chaff in the tramlines that is observed in wetter districts but there is certainly fierce competition in the tramlines and we could spray the weeds in the tramlines if we felt it was necessary,” he says. “For now, we have added extra jets to the boom to apply more herbicide behind the wheels where there are generally more survivors. We have also added outer wing nozzles to ensure the tramlines under the wings get the full application rate.”
The chaff deck system delivers annual ryegrass seed into the tramlines where it competes with itself in a tough environment.
Gary is keen to avoid over-spraying the crop and compromising the benefit of crop competition. He occasionally brings the sheep on to graze the crop stubbles but is concerned that they may be shifting some weed seed out of the tramlines. So far there doesn’t appear to be a problem with the sheep concentrating their grazing efforts to the tramlines and adding a trampling effect to the chaff in the tramlines. Having the available dry feed – grain and weed seeds – concentrated into the tramlines, making grazing more efficient.
It is clear that Gary’s weed management program is working well and that he is ‘calling the shots’, not being dictated to by herbicide resistance. Much of his success could be attributed to the fact that he saw the potential risk early and started taking positive action to keep his weed numbers low.
Relevant resources

Webinar about managing frost and weeds
Podcast featuring Gary Lang

Case Study

Curry family – Junee, NSW

A desire to minimise the build-up of herbicide resistant weeds on their Junee property in southern NSW is a driving force behind the Curry family farming operation.
Brothers Glenn and Brian Curry use their livestock and cropping enterprises to great effect in their weed management plan. Each winter they revisit their rotation plan with their agronomist, Greg Condon and fill in the details according to the seasonal outlook and their assessment of the weed burden in each paddock.
“We have a farm plan for the coming five years or so that provides the general direction for the business, and weed management is a key component of that plan,” says Glenn. “The farm’s financial sustainability relies on effective weed management so we have firm strategies in place while remaining very flexible about how the strategies are implemented.”
Glenn, Tim and Brian Curry review their weed management plan each winter and make any changes necessary to ensure weed numbers are kept low and the risk of herbicide resistance is minimised.
“When we sit down to make detailed plans for the next 12 to 18 months we look at what has worked well in the previous season and where we might have more weeds than expected,” he says. “We are not afraid of making changes as the season unfolds either and having livestock in the system really gives us more options, like cutting a paddock for silage or turning it out to pasture earlier if we feel the weed pressure is getting ahead of us.”
Glenn and Brian have successfully farmed together all their adult lives and are now joined by Brian’s son, Tim. Their weed management program is planned well in advance to ensure the most effective use of crop rotation and chemical group rotation to minimise the build-up of herbicide resistant weeds on the property.
A disciplined rotation is followed in their 12 m controlled traffic farming (CTF), no till, stubble retention system, maintaining a high level of break crop area across the 2600 ha of farmed land.
“Generally we have one-third of the arable area under pasture and the rest is cropped,” says Brian. “We have used mainly canola as the break crop until recently when we have started to incorporate albus lupin in the rotation to gain more soil fertility benefits and aid in grass weed control. Break crops comprise about 40 to 45 per cent of the cropped area each year.”
The rotation commences with low grass weed numbers after the lucerne pasture is sprayed out and fallowed in spring. TT canola is sown the following growing season then wheat, wheat, barley, albus lupin and back to lucerne/clover pasture for grazing. The pasture is maintained for 5 or 6 years by which time it has become grassy and is returned to cropping.
This crop rotation allows the Currys to use a diverse herbicide program including atrazine, propyzamine and clethodim in TT canola, Sakura and trifluralin in wheat, Boxer Gold and Dual Gold in barley and finally, simazine, Factor, clethodim and paraquat in lupins.
In weedy paddocks, a double knock of glyphosate followed by paraquat is used prior to sowing. Narrow windrow burning is used in canola to control any weed survivors. Cereal crop areas that have higher ryegrass density are cut strategically as baled silage or ensiled in underground pits for use as stored fodder, killing the weed seeds in the silage process.
Livestock in the weed plan
The Currys moved out of cattle some years ago and now run 3800 merino ewes comprised of 1600 ewes in a self-replacing merino wool production and breeding program and 2000 ewes producing cross-bred lambs. They find sheep easier to manage than cattle and they are a good fit in their cropping program.
The sheep graze the crop stubbles and long growing season canola hybrids provide valuable feed in autumn and winter for the merino wethers. Dual purpose crops can be a weak link in the system where grass numbers can build up due to the early sowing dates, but these crops are needed to fill the winter feed gap and also provide the opportunity to use different herbicide groups to target grass weeds.
Crop paddocks that have become dirty with herbicide resistant annual ryegrass are sown out to lucerne and clover to reduce control costs and build soil fertility.
Dual purpose canola, stubble grazing, strategic silage making and a 5-year pasture phase are all part of the Curry family’s integrated weed management plan.
Crop competition and stubble management
In the medium to high rainfall environment of Junee, NSW, crop competition plays an important role in suppressing weeds. The Currys use a flexicoil air seeder with tines and press wheels on 225 mm (9 inch) spacing to sow their crops, usually into a high stubble load.
Brian says they had to move out from 175 mm (7 inch) row spacing to 225 mm when they began full stubble retention a few years ago. “Wheat crops here generally yield around 5 t/ha and that is a challenging amount of stubble for tined planters to operate in,” he says. “The slightly wider row spacing and the additional stubble cover seems to still provide acceptable suppression of weeds in the establishment phase, however we are looking at changing to a disc seeder in the future.”
Malting barley and spring wheat provide strong competition for weeds when sown at target plant populations that also optimise yield and quality. Lancer and Beckom wheat varieties are preferred for their shorter stature and lower stubble volume.
Spray application
The Currys recently upgraded to a 36 m Case Patriot boomspray to suit their CTF system. The sprayer has the latest application technology including AIM Command, which enables section control of individual nozzles and improved drift management.
“Our farming system relies on effective herbicides and so we put a huge emphasis on spraying weeds when conditions are ideal so we can expect the best result possible every time,” says Glenn.

Case Study

Karl Raszyk & Robert Hughes, Scaddan WA

The wet winter in 2010 led to a blow-out of annual ryegrass numbers at Dolany Farms but this also coincided with the introduction of chaff tramlining, using the Emar Chaff Deck at harvest. Although the consequences of the seasonal conditions in 2010 took about four years to clean up, Robert believes that using the chaff deck that year, and ever since, enabled them to ‘nip the problem in the bud’.
Convinced of the value of harvest weed seed control, Karl and Robert wanted to avoid the additional labour required to burn chaff heaps. They also felt that the chaff deck system would be easier to manage at harvest, particularly when they rely on a high number of casual workers, including harvester operators, during the harvest period.
Robert Hughes, operations manager at Dolany Farms north of Esperance says the introduction of the chaff deck system in 2010 has helped them regain control over herbicide resistant ryegrass.
“With the chaff deck installed there is nothing else for the operator to do other than keep an eye on the header height,” says Robert. “The harvester cuts at a height of 100–125 mm, or lower if necessary, to put as much biomass through the harvester and onto the chaff deck as possible. The chaff component containing a high percentage of the weed seeds present at harvest is delivered directly onto the controlled traffic (CTF) tramlines while the rest of the material is chopped and spread by the spreaders.”
The chaff in the tramlines composts down and minimal weed seeds germinate in the hostile environment. Having the rest of the crop residue spread across the paddock avoids some of the potential problems associated with nutrient removal or relocation that occurs with some other harvest weed seed control options. The system is well suited to both wheat and canola crops so is used across the whole 9700 ha cropping program every year.
The chaff deck delivers the chaff component into the CTF tramlines behind the header, confining the weed seeds to a very small portion of the paddock. The chaff composts away and very few weed seeds germinate.
“The chaff deck has not enabled us to reduce our herbicide usage but it has avoided blow-out years and our herbicide program is aimed at maintaining low weed numbers,” says Robert. “One unexpected benefit from this system is that the chaff layer in the tramlines prevents dust being stirred up, making subsequent spaying operations more effective.”
“Although the chaff deck was a great addition to our weed control program we also benefitted from the release of Sakura and Boxer Gold herbicides at around the same time,” he says.
All crops are sown using a Morris contour drill on a 27 m toolbar suited to controlled traffic, on 302 mm (12 inch) row spacing. The planter enables precise placement of seed and fertiliser in the most efficient parallelogram formation to maximise crop competition.
The planter performs well in full stubble retention systems and Robert runs a disc on either side of the tramlines using a razor module that bolts onto the standard bar of the planter. This overcomes the problem of potential blockages caused by the chaff.
“We sow in the tramlines to avoid having a gap in the crop that might encourage weed growth,” he says. “The crop plants don’t perform particularly well in the tramline but the more shading we can provide to reduce weed growth the better. With ryegrass now confined to the tramlines we apply herbicide across the whole paddock, to maintain our low weed numbers. If necessary the tramlines are sprayed out using a shielded sprayer, but this is usually only done to be certain the paddock is clean enough to be harvested for seed.”
The tramlines are sown mainly to provide some shade to suppress the growth of any weeds that establish from the chaff.
Seed is taken from the cleanest paddocks and cleaned on-farm by a Hannafords contract seed cleaner to remove as much weed seed contamination and small grains as possible to ensure the best results the next year.
Crop and herbicide rotation
The crop rotation is generally two wheat crops followed with canola. Robert says they have also tried to include barley but find it difficult to achieve the quality standards required for malting. Round-up Ready RT 425 canola hybrid was sown in paddocks with the highest level of herbicide resistant ryegrass in 2016 to reduce their reliance on clethodim. This hybrid is taller than many other hybrids, providing greater weed competition, and allows two in-crop applications of glyphosate.
All crops are sown in paired rows with Flexi N applied at planting. This system has seen an improvement in canola establishment, particularly in early sown crops and on non-wetting sands. This configuration is well suited to inter-row sowing using a 150 mm offset with an auto-steer control on the bar to maintain accurate row alignment.
Herbicide resistant annual ryegrass was a major problem weed on Dolany Farms but it is well under control now, however wild oats and brome grass are providing new challenges. Having previously managed farms in other districts in WA, Robert is surprised that wild radish is not really of great concern in the Esperance area, perhaps due to the wetter and milder growing conditions.
The end of harvest in mid-November marks the beginning of the summer spraying program. Robert uses a mix of glyphosate and 2,4-D ester to manage broadleaf weeds such as fleabane, milk thistle and melons, usually with three sprays applied over summer. In wetter seasons he often uses a double knock treatment on fleabane and marshmallow, which can be more difficult to manage.
The double knock is then implemented seven to ten days before sowing, usually glyphosate followed with a paraquat and a relevant pre-emergent mix as the second knock. Pre-emergent herbicide is applied in front of the seeder – Sakura in wheat, Boxer Gold in barley and treflan in canola.
Diflufenican (e.g. Jaguar) is used for broadleaf weeds in cereals, where Robert finds marshmallow to be their most difficult in-crop weed. No selective post-emergent herbicides are used on ryegrass in the cereal crops. Most of the canola sown is an open-pollinated TT hybrid that usually yields around 1.5 t/ha. A combination of atrazine, clethodim and Targa is used to manage grass weeds in TT canola.
“With low weed numbers we now have more management options to choose from and can avoid the higher risk chemical options,” he says.
Soil acidity is a constraint to crop production in the Scaddan district, allowing weeds a competitive advantage. Karl and Robert use variable rate technology (VRT) maps to identify areas on the farm that require lime.
“We apply 1.5 to 2 t/ha of lime and see a response in weed numbers and also a better response to herbicide,” says Robert. “In other paddocks we have heavy clay soils where we need to manage boron toxicity using gypsum at rates of 500 kg/ha up to 3.5 t/ha to improve the yield and competitiveness of cereals.”
Other resources
Chaff lining (a variation on chaff tramlining)
Chaff decks and chaff lining discussion with inventor, Mark Wandel

Case Study

Michael and Marnie Fels, WA

Placing an emphasis on cultural weed control has been a major focus for Mic and Marnie Fels on their Wittenoom Hills property, 50 km north of Esperance WA.
The resulting low weed numbers means they can still use a wider range of ‘older’ off-patent herbicides, which helps keep herbicide costs to a minimum.
“We have tried to use herbicides as a back-up for our cultural practices, rather than the other way around,” says Mic. “Narrow rows, stacked rotations, burning windrows in canola and chaff lining all crops at harvest are the central components to our weed management, taking the pressure off our herbicide program.”
Noticing the early stages of triazine resistance was a significant motivator in implementing their weed management program, and Mic is pleased that the actions they have taken have ‘saved’ this valuable option.
“We bought this farm in 2002 having always farmed in the district, and although some of the older Group A and B herbicides are gone we have all other options, including triazine, and still get good results using the ‘old rates’.”
The Fels have recently ‘purchased potential’ in the form of a 4500 ha property at Three Springs, WA to expand their current 6500 ha operation at Wittenoom Hills. “The yields are less consistent at Three Springs due to the more fickle rainfall but we are finding that the farming systems we have developed at Wittenoom Hills are working well, with minimal modification, in the Three Springs environment,” says Mic.
Mic and Marnie’s farming system is a great example of the Weedsmart 10 Point Plan in action – incorporating both herbicide and non-herbicide weed control strategies.
Mic and Marnie Fels have developed a farming system where herbicides are used to back-up their cultural practices, rather than the other way around.
Stacked rotation
What started as an effective disease management system, stacked rotations have also had long lasting effect on weed management and the Fels believe this strategy will be the key to improving the profitability of their new farm at Three Springs, WA.
“Our stacked rotation involves growing each of our three crops – canola, wheat and barley – for two consecutive years each rather than spreading them out in the rotation,” says Mic. “We grow canola for two years, then wheat for two years and barley for two years.”
This rotation provides a four year break for the diseases that affect each crop, namely black leg and sclerotinia in canola, crown rot in wheat and net blotch in barley. Mic says the system has eliminated crown rot, which was once a significant challenge on the farm.
At Three Springs Mic is planning to implement the same strategy but using lupins on the soils that are not as well suited to canola.
“In the canola phase we use an open pollinated TT hybrid in year one and an RR hybrid with a different and high blackleg resistance rating in year 2,” says Mic. “In the wheat phase, we have used Mace on Mace but will be moving to the newer ‘all-rounder’, Scepter. In the barley phase it’s Hindmarsh followed by La Trobe or Capstan in year 2.”
In the canola Mic aims for 100 per cent ryegrass control to set up the rest of the rotation with very low weed numbers. To achieve this, and to remove the excess biomass that accumulates in the chaff lines over five years, the Fels have introduced windrow burning in the second canola crop on top of all the other cultural and herbicide practices.
Canola plays an important part in the Fels’ weed management program. In the 2-year canola phase they implement strong crop competition, a broad range of different herbicide MOA, windrow early to collect as much weed seed as possible, concentrate the weed seed to a narrow line and burn the windrow in year 2, just to be sure!
Mic and Marnie sold the last of their cattle in 2012 and as a result stopped growing lucerne in their crop rotation. They were previously undersowing lucerne with Clearfield canola, which gave them solid stands of the perennial legume for very little cost. Mic would love to still have a legume in the system, but the economics currently don’t stack up on their Esperance properties.
Chaff lining compost
Mic has used a modified version of chaff lining as their harvest weed seed control strategy. The idea is that the chaff component is funneled into a narrow strip in the middle of the CTF runs behind the header.
In a controlled traffic system this means that the weed seeds collected through the header are concentrated into the same zone every year and any seeds that germinate through the mulch are subject to the full force of crop competition. Similar to the experience of growers using a chaff deck to channel the chaff into CTF permanent wheeltracks, Mic finds that the chaff and the weed seeds simply rot away and there is no need to burn the chaff to gain the benefits of this weed control measure.
The $200 plastic chute fitted to the harvester funnels the chaff containing the majority of weed seeds present into a narrow band in the middle of the CTF run.
Mic views chaff lining as ‘an incremental tactic’, accepting the fact that a portion of the annual ryegrass seed will already be on the ground at harvest. Over time though he says the results are obvious when harvest weed seed control is implemented in every paddock every year.
“For us, chaff lining is working well. It only cost $200 for a plastic chute for the harvester and there are no moving parts to break or slow us down,” he says. “While early cutting is important it can’t be done across the whole farm, especially in wheat, so you have to accept that some paddocks will be harvested too late for optimal weed seed capture.”
“Even so, every year more and more weed seed is captured and composted in the chaff lines,” he says. “And you can still drop the header that bit lower when harvesting a grassy section of a paddock.”
In the second canola crop the Fels have started to burn the chaff lines to really tidy up the paddocks and avoid the possibility of weeds spreading out from the chaff line. Canola burns easily and provides a hot fire suitable for maximum seed destruction. This is particularly useful if they are planning to make changes to tramlines or are removing fences.
The chaff composts over time, killing most if the weed seed and any seedlings that do germinate are subject to stiff crop competition.
Narrow row, high residue seeder
In 2011 Mic changed the row spacing from 30 cm (12 inches or ‘ryegrass heaven’) to 18.75 cm (7.5 inches). Whenever there is a gap in the crop Mic is reminded of what a big difference narrower row spacing has made to their weed control.
In changing to narrower row spacing Mic wanted to change from a tined to a disc seeder but was not 100 per cent happy with the disc seeders available. Being an engineer he set about modifying a John Deere seeder, which has since been commercialised after field testing in SA, WA and on his own farm.
“Finding a suitable bar was the most difficult part,” he says. “The seeder units have a single rippled disc rather than a flat disc and we have removed the gauge wheel to achieve better soil throw into the inter-row and eliminate blockages. This feature is very important for using pre-emergent herbicides on non-wetting soils.”
“The result is a simpler machine with less components – just the disc and the press-wheel,” says Mic. “Planting is a smoother operation with far less downtime or choking up with stubble.”
“Setting the harvester choppers to spread the stubble evenly is very important and can be difficult to do on older harvesters,” he says. “But accurate seed placement relies on even stubble spread so it is worth doing what you can to achieve this at harvest.”
Mic has invented and commercialised the Alpha Disc, a narrow row disc seeder that can operate very effectively in stubble, has fewer components and effectively throws the soil into the inter-row.
Wet years not so scary
The 2016 season was unusually wet and the Fels compare it to 2003, their second season farming at Wittenoom Hills, but they have been pleased to notice a big difference in the effect of wet weather on weed numbers.
“In 2003 we had such a large area infested with ryegrass that we were forced to salvage paddocks to hay,” says Mic. “This made us realise that weed management had to be a priority and we have put as many cultural practices in place as possible to lessen the effect of wet years where herbicides are not enough to cope with the ryegrass pressure.”
“Our system was thoroughly tested in 2016, another cold and wet winter, and the only areas where the ryegrass was an issue were where the crop basically died from waterlogging. Crop competition is just so important in this environment. After 13 years we still have most of the older chemistry available and all the new chemistry options up our sleeve.”
The Fels are now working on building soil nutrition to complement the narrower row spacing. They have increased phosphorus rates to support strong early growth to achieve the best crop competition effect, and are looking at going back to nitrogen application ‘down the tube’ for similar reasons.
“With full stubble disc seeding there is a greater risk of nitrogen applied on the soil surface being tied up in the breakdown of stubble,” says Mic. “I hate having to handle nitrogen fertilisers at seeding, but with our residue levels these days it may be the best way to get it into the plants early in the season.”
Something extra: How many consecutive cereal crops can you safely grow?
Mic’s farming system has been tested using the RIM (Ryegrass Integrated Management) analysis tool. The scenario tested was a double stacked canola rotation to control ryegrass and then growing four consecutive cereal crops (2 wheat then 2 barley) before rotating back to canola. The question being considered was ‘is this crop rotation plus herbicides sufficient to control annual ryegrass?’.
This RIM analysis result, and a similar one done in a low rainfall cropping environment, indicates that a grower can choose the crop rotation that best suits their farm, provided sufficient weed control measures are in place to prevent a blow out in ryegrass numbers. In these analyses, using harvest weed seed control every year was enough to beat ryegrass and keep the rotation going.
Peter Newman, Communication Lead at the Australian Herbicide Resistance Initiative says even on a farm where there is no weed resistance to glyphosate or pre-emergent herbicides, and using the best herbicides available, a blow out in ryegrass numbers would be expected in the fourth wheat crop following two consecutive canola crops if there is no harvest weed seed control.
“If the grower adds harvest weed seed control to their management every year then it is possible to grow at least four consecutive cereal crops while also maintaining ryegrass numbers at or near zero,” he says. “Returning to the two seasons of canola with ryegrass numbers still low is the ideal outcome for managing weeds and herbicide resistance risk.”
“It doesn’t matter what harvest weed seed control system you use, all that matters is that it happens every year. With all the weed control measures that Mic has in place, the system even works in the face of Group A and glyphosate resistance.”

RIM scenario for Mic’s stacked rotation, chaff lining, narrow row system
RIM scenario for stacked rotation system in a low rainfall environment

For more information
Webinar discussing the use of a chaff deck system, similar in principle to Mic’s system.

Chaff tramlining in action – Karl Raszyk and Robert Hughes case study

Case Study

Kohlhagen Family, NSW

A changed attitude to weeds has been driving brothers Malcolm and Des Kohlhagen to implement a comprehensive management program on their farm near Wagga Wagga in southern NSW.
Fifteen years ago the Kohlhagens assessed their weeds in terms of their likely economic impact but their mindset has changed to a much lower tolerance of weeds and they aim to keep numbers low year in, year out.
Brothers Malcolm (left) and Des (rear) Kohlhagen along with Malcolm’s son, Adrian (centre), have developed and implemented a comprehensive weed management program for their 100 per cent cropping operation in southern NSW.
The sheep have all gone from their 1600 ha operation and the family has expanded their cropping program to include a wider range of crops. The winter program now includes wheat, barley, canola, albus lupin and, most recently, faba bean.
Malcolm and Des use break crops to introduce a different range of herbicides into the rotation and a double break of a pulse followed with canola provides two years of grass control so the cereals are sown into clean paddocks. The Kohlhagens have stuck to their crop rotation even when many other growers in the district reduced their canola hectares during the 2000s.
They grew field peas many years ago but gave them away due to harvesting difficulties, and now find lupin and faba bean are a better fit in the rotation, providing a definite nitrogen boost for the following canola crop.
Triazine tolerant (TT) and Clearfield canola are used to rotate chemical modes of action. The Kohlhagens don’t currently consider RoundUp Ready canola an option for them due to delivery point and marketing issues.
Harvesting weed seed
Canola crops are windrowed to aid in harvest management and, from this season, will be crop topped under the cutter bar to capture any late escaping weeds. The Kohlhagens also plan to crop top their pulse crops in years where late escapes are a problem.
A narrow windrow chute is used on the harvester to collect weed seed in the pulse and canola crops and the narrow windrows are burnt to kill any seed present. This means over 40 per cent of their cropping area is subject to this very effective non-herbicide weed control method, particularly for annual ryegrass.
A double break crop of a pulse crop followed with canola provides excellent grass weed control, including narrow windrow burning, before returning to cereals in the rotation.
The brothers do not narrow windrow burn their cereal crops because of the high stubble load from barley and wheat crops yielding up to 6.5 t/ha and 5 t/ha respectively. When grown back to back these cereal crops generate too much stubble to effectively confine the fire to the narrow windrows.
Getting the right conditions for burning is not always easy but the Kohlhagens believe it is worth doing and are looking forward to when they can justify investing in an integrated Harrington Seed Destructor so they can avoid burning, a practice that is not popular in town!
In years where weed populations increase for any reason, haymaking is an effective method to stop weed seed set. The Kohlhagens find their heavier soil types are more likely to be challenged with weed blow-outs so they target these areas for haymaking as a salvage operation when necessary, giving great weed management benefits in poorer seasons.
Malcolm and Des currently contend with ryegrass that is resistant to Hoegrass (Group A, fop) and are aware of similar resistance arising in wild oats and possibly wild radish on the farm. To keep wild radish numbers as low as possible they hand rogue plants in spring, to avoid any seed going through the header.
Competitive cropping
Further narrowing their row spacing to create greater crop competition is currently on the table for the family but until they have decided on the best option they are using high seeding rates, especially in the already-competitive barley crops. Blockages in the seeder and slug and slater damage to seedlings can create gaps in the rows, which provides the opportunity for weeds to flourish, and wider rows also allow more weeds to grow between rows.
Changing the seeding setup is quite an expense so the family is considering whether to reduce the spacing on their current tined seeder to 250 mm or to change to a disc seeder.
Even at 300 mm they are having trouble managing the stubble load so are hesitant to narrow the spacing much further, however the tined seeder allows them more herbicide options than can be safely used with disc seeders. On the other hand, they have been impressed with a 150 mm disc seeder they have seen operating in high stubble environments in South Australia.
When the Kohlhagens first moved to controlled traffic, wheel tracks were left bare.  However, the gap left by the wheel tracks in the controlled traffic system lets more light into the adjacent rows, allowing more weeds to establish. To reduce this effect the Kohlhagens now seed their wheel tracks using a mid-row banding disc to provide increased crop competition and reduce weeds.
Residual herbicides
Pre-emergent herbicides are applied in all crops for grass control. While clethodim is still providing effective control in canola the Kohlhagens are well aware that it may not continue to be an option in the future. To support the pre-emergent herbicides the Kohlhagens are sowing their canola and pulse crops early to encourage better establishment and more rapid canopy closure, reducing the opportunity for in-crop weed germinations after the residual effect has diminished.
Changed farming system; changed weed spectrum
Since moving from a mixed farming operation to 100 per cent cropping, Malcolm and Des have seen a change in the weed spectrum present on the farm, with less capeweed present and less movement of weed seed around the farm.
Not having livestock however has increased the need for more vigilance over summer to prevent weeds using precious soil moisture that may be the difference between finishing a crop and crop failure as the October rainfall is now less reliable. Fleabane is of particular concern in summers with higher rainfall seeing explosions in fleabane populations, which may require double knock treatments.
Hairy panic is another persistent weed that must be sprayed when small to achieve effective and economical control. To manage broadleaf weeds the Kohlhagens use a low volatile 2,4D ester spike in glyphosate sprays applied over summer. Milk thistle is another emerging weed that is taking advantage of the no-till farming system.
Clean seed a priority
Prior to harvest Malcolm and Des inspect their paddocks to identify the cleanest areas of each variety suitable to harvest for retained seed. They then use a low capacity seed grader to remove small or damaged seed and as much weed seed as possible from their seed before storing on-farm.
A mobile grader is contracted to grade the pulse grain for marketing and to thoroughly clean the pulse seed retained for sowing.
Malcolm and Des are clearly on top of their game with their weed management program but they are also full of praise for their agronomist, Greg Condon from Grassroots Agronomy, who provides excellent agronomic advice and keeps their herbicide program up to date.

Case Study

Robert Gollasch, NSW

Narrow windrow burning for maximum effect in less time
Narrow windrow burning to destroy weed seed has been widely accepted as a useful tool, however there are risks and it can be time consuming.
Robert Gollasch has been burning narrow windrows for a few years now and has found ways to minimise the time commitment while still gaining the benefits in his weed control program.

Robert and Liz run a mixed farming operation at Wallacetown, north of Wagga Wagga, NSW. For the last 40 years they have continuously cropped most of their 2000 ha farm and currently run 1100 first cross ewes.
In the early 2000s the Gollaschs noticed increased weed burden across their cropping area and that herbicide resistance was reducing their control options. In response, Robert reassessed his cropping system and introduced more diversity in the crops grown and the weed management tools used.
“Implementing narrow windrow burning was not difficult but it did take a couple of years for us to really refine the practice on our farm,” said Robert. “Preparing for narrow windrow burning is fairly simple – the chute only takes a few hours to make and fit – and then it is down to cutting the crop short so that everything goes through the header. Although cutting short can be difficult in canola we have found that it is worth persevering with.”
Robert designed and built a chute for his Claas harvester and uses a custom-made trailer to safely and easily remove the spinners. The chute is fitted with small trolley wheels so it can be maneuvered into place and only lifted a short distance. The opening of the chute is 500 mm wide, which creates a suitable windrow without causing blockages in the header.
Simple innovations such as trolley wheels on the narrow windrowing chute and a customised trailer for the spinners off the harvester makes it easier to swap and go between crops at harvest.
After harvest the sheep are allowed to graze the narrow windrows left after harvesting cereal and lupin crops. Robert finds that the sheep don’t damage the windrows, in fact they help aerate the windrows to give a good hot burn.
“We use a low stocking rate on the crop stubble and the sheep just pick over the windrows looking for grain,” he said. “We don’t see any measurable benefits from sheep grazing the windrows but they don’t seem to spread the seed and it is making use of a resource on the farm.”
If overgrazed, sheep can create many small fire breaks in windrows. making them difficult to burn so it is important to monitor closely and remove sheep from the paddock before this occurs.
It is important not to leave the windrows sitting in the paddock for too long. Robert has found that an inch or two of rain on the windrows in autumn can make them very difficult to burn. He tries to burn the windrows as soon as permits are available in autumn and conditions are safe.
“One thing we have learned is that narrow windrow burning is most effective when you tackle a smaller area and do it well, rather than trying to windrow and burn every crop, every year,” he said. “If weed numbers are increasing in a paddock we will usually try to narrow windrow burn in that paddock for two or three years in a row to really drive down the weed seed bank.”
Robert aims to narrow windrow burn about 200–300 ha a year, usually in lupin and canola crops and finds two successive years of windrow burning in a paddock is very effective in driving down weed numbers.
Robert usually windrow burns about 200–300 ha each year, primarily in the canola or lupin phase of the rotation. To burn the windrows safely and effectively, he usually starts lighting the rows at midday and aims to have the job complete by 5 pm that day. Lighting the rows every 100 m or so produces a slow hot burn that is known to kill 99 per cent of annual ryegrass seeds present. Using a motorbike and burner, Robert lights windrows across about 50 ha a day, which takes only a few hours to burn out. He also takes into account the fact that narrow windrows in canola tend to burn slower than those following cereals and lupins.
The usual rotation Robert uses is TT canola, wheat, albus lupins, wheat and barley, then in older paddocks he establishes a lucerne pasture for five years for the sheep. The Border Leicester x Merino first cross ewes are crossed with Dorset rams and all progeny are sold.
Robert finds that ryegrass numbers tend to build up the most in cereal crops so in years where the weed numbers have increased he often bales the cereal crop rather than harvesting the grain. “Two successive years of windrow burning in the canola and lupins and then hay baling cereal crops is a very effective way to run down weed numbers,” he said.
Robert has implemented most tactics recommended in the Weedsmart 10 Point Plan to maximise the pressure on weed numbers across his farm and cropping rotation.
The barley is usually followed with a lucerne pasture phase and when Robert brings a paddock back into cropping he usually starts with canola to enable more grass weed control options followed with narrow windrow burning before planting cereals.
“We have used broadleaf cropping in our rotation for a long time, which has enabled the use of different herbicide chemistry, including pre-emergent herbicides, particularly in the lupins,” he said. “Our time with chemicals is running out so anything we can do to lessen our reliance will lengthen our use of chemicals and make our system more sustainable. We are relying heavily on clethodim for ryegrass control at the moment so being able to use Factor on lupins gives us some extra diversity in our herbicide program.”
The Gollaschs make the most of grazing livestock for weed control during the pasture phase and also use paraquat to control young grass plants toward the end of the pasture phase.
“The sheep keep the pasture short and reduce grass seed set. Each spring I spray for barley grass then ryegrass control begins in earnest in the last few years of the pasture phase,” he said. “Paraquat and simazine are applied in the second last year of the pasture to treat annual ryegrass and silver grass and then a glyphosate and paraquat double knock is used to kill the pasture in preparation for a return to cropping.”
Robert and Liz Gollasch make the most of grazing livestock for weed control after harvest and during the pasture phase on their mixed farming operation near Wallacetown, NSW.
Robert has also reduced the crop row spacing from 12 inch to 10 inch to improve yields across the farm and apply more pressure to emerging weeds. Their Bourgault Paralink seeder with hydraulic tynes works well at 10 inch row spacing but relies on the stubble either being cut shorter or burnt as inter-row sowing is harder to achieve with 10 inch row spacing. A move to narrower rows and full stubble retention would require changing to a disc seeder.
The combination of increased crop competition and harvest weed seed control go hand in hand. In competitive crops, weed seed set is reduced and weeds that do set seed tend to have seed heads held high in the canopy where they are easier to capture at harvest.
Simple innovations such as trolley wheels on the narrow windrowing chute and a customised trailer for the spinners off the harvester makes it easier to swap and go between crops at harvest.
After more information on narrow windrow burning?

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Case Study

Mark Sandow, SA

Using technology to put pressure on weeds
Herbicide resistant annual ryegrass has been an on-going challenge for grain producers in the Mintaro area of South Australia since the 1980s.
Agricultural consultant Mick Faulkner has worked alongside growers as they tackle the problem and has been impressed with the tenacity of some growers in the area as they adopted a new attitude toward weed control.
“The growers that changed their attitude to a ‘no tolerance’ approach to weeds are the ones that have been able to gain the upper hand with herbicide resistant weeds,” he said. “This approach works because if you have no weeds you have no trouble with herbicide resistance.”
When developing a weed control plan with growers Mick looks for tactics that have at least a 92 per cent control rate. The aim being to bring weed density right down and preventing any survivors from setting seed to keep reducing the weed seed bank.
One grower who has fully embraced this no-tolerance policy is Mark Sandow, and in doing so he has almost eliminated herbicide resistant annual ryegrass, wild oats and wild radish from the 1900 ha of cropping land he owns and leases in the 500–600 mm rainfall zone of South Australia.
“There are paddocks on Mark’s property where annual ryegrass covered 17 per cent of the area to begin with and this is now down to one per cent or less by doing everything possible to stop weed seed set,” said Mick. “Having low density and knowing where those weeds are in a paddock helps keep chemical costs right down as you are treating known problem areas, not the whole paddock.”
Annual ryegrass was the first herbicide-resistant weed on the property and its resistance was confirmed 35 years ago. In the early days Mark used haymaking to manage weedy paddocks. Although he found it difficult to successfully make hay in their high rainfall conditions it did help with the weeds until better options came available.
Over the last five or six years Mark has used GPS capability in his tractors to map and manage weeds. “We started using GPS to mark the location of weed patches and this gave us a better understanding of the scale of the problem,” he said. “It actually showed that the weed density was probably less than we first thought and gave us more confidence that the problem was manageable.”
Mark makes the most of the technology available in the tractor to map where weeds are in the fields. When he started out he would ‘drop a flag’ but now he prefers to ‘mark lines’ to better illustrate the spread of weeds.
Since then the Sandows have upgraded to the more accurate RTK GPS system and rather than ‘dropping a flag’ Mark now marks lines from one side of a weedy patch to the other.
“This provides a much better weed map and we have no doubt about where the weeds are in a paddock,” he said. “When we treat these patches we use more expensive herbicides but on a much smaller area. I also check for any misses after a spray and pull out any plants that have survived.”
Mark has found that most apparent ‘survivors’ have been due to reasons other than a chemical failure, but he recognises the need to physically remove older plants to prevent them setting seed.
The Sandows direct drill all crops to save time and avoid erosion on some steeper areas of the farm. While not using a fully controlled traffic system Mark is still seeing benefits of keeping the most frequent traffic—the sprayer and urea spreader—on permanent tracks. “In a weedy patch the elimination of weeds is the highest priority and I am not overly-concerned if removing the weeds in that area also causes some crop losses,” he said. “Overall the crop losses are less now than they were simply because we keep to the permanent tracks and less crop is knocked down during spraying.”
A very significant benefit of low weed density in a paddock is that cropping choices are much wider than if the grower is having to consider weed control as part of the rotation decisions. Mick said that with more choice, growers are able to sow crops that are likely to be the most profitable that season without being bound by weed control concerns.
The Sandow’s farming system includes wheat, faba bean and canola in rotation on 2.5 m wheeltracks and sheep graze the stubble after harvest. The main soil type on the farm is red-brown earth over limestone with smaller areas of black clay. The crop rotation works well across the whole cropping area giving the Sandows more options to rotate chemical groups between cereals and broadleaf crops.
“We lease some cropping land from my cousin and the sheep belong to him,” said Mark. “Having the sheep graze the stubble helps keep weeds under control over summer and provides some extra feed for the sheep. In years that we don’t have sheep on a paddock it is clear to see the increase in weeds over summer. There is no doubt that they are doing an effective job.”
Mark also uses narrow windrow burning in the canola crops as another weed control tactic. If there is a particularly high stubble load after back-to-back wheat Mark may also burn the stubble, although this is fairly rare. “I have tried cutting the straw under these circumstances but have noticed increased disease pressure so find burning is a better option in these paddocks, which will also help reduce the weed seed bank,” he said.
Farming in a high rainfall zone means Mark is faced with several germinations of weeds over summer and autumn. He treats pre-seeding germinations as they occur using a one-off spray to remove weeds such as volunteer cereals, potato weed, salvation Jane and wild radish. “Having a clean field to sow into is essential to conserve moisture and to minimise in-crop weed pressure,” he said. “Our attitude to weeds has always been ‘if you see it, try to fix it’ and I am also willing to sacrifice a small area in a crop if that is the best way to reduce weed numbers.”
After the autumn break Mark does the first spray of the season applying Sakura prior to sowing wheat and following up with Boxer Gold post-emergence in the known problem areas. “This is where the weed maps in the GPS system really show their worth,” he said. “I know that I am applying the herbicide where it is needed while keeping a lid on the cost.”
Mark uses crop competition as another way to combat weeds in-crop. He and Mick choose the most competitive variety and increase the seeding rate to keep the crop density high. Mark sows all crops using a flexicoil bar with narrow point tines. The tines are set at 25 cm (10 inch) to keep the crop rows as narrow as possible while still managing the stubble and minimising the risk of herbicide damage to the crop from pre-emergent herbicides. “We find we can sow in all conditions—wet or dry—and get sufficient trash clearance using this set-up,” he said. “We plant the crops on narrow rows to increase their competitive ability without compromising yield.”
Mark is also very conscious of the potential for glyphosate resistance to evolve in non-crop areas such as along fencelines. He sprays glyphosate initially, follows up with Spray Seed for any misses and then uses a hoe or pulls out any remaining weeds. Mark has removed most of the internal fences and has incorporated the land into the crop area where he keeps a close eye on any weeds that grow where the fences once were.

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