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
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
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
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.
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
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
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.
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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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.
Andrew Boultbee, WA
Grazing chaff heaps solved two problems For many growers burning crop residue to kill weed seeds collected at harvest goes against the grain. Along with the loss of nutrients and ground cover there is significant risk, stress and discomfort associated with burning, even in autumn. Andrew Boultbee wanted to stop burning chaff heaps. His solution: first graze the chaff heaps, then lightly scarified before seeding right across them. Andrew and Marjorie Boultbee run a predominantly cropping operation near York, Western Australia, with land they own and lease spread across their district. As annual ryegrass became increasingly difficult to control with herbicides the Boultbees adopted narrow windrow burning as a harvest weed seed control method. They soon saw how effectively this technique drove down weed seed numbers on their farm and decided to invest in chaff carts. Andrew has seen many growers in his district adopt the use of chaff carts only to stop using them because of the costs and dangers associated with burning the heaps. “We soon found that burning the chaff heaps consumed all our attention and the smoke was unpopular with our neighbours,” he says. “Having properties spread out also caused logistic difficulties and with the heaps smouldering over several days we had a few close calls and sleepless nights.” To keep the weed control benefits without all the problems Andrew and Marjorie decided to stop burning and to start using the chaff heaps as a feed resource for their sheep over summer. Andrew has found canola and wheat chaff heaps to be very effective for weed control, even if the heaps are not burned. He allows sheep to graze on the heaps first which makes use of the feed resource while also knocking down the heaps to allow him to seed through them the following autumn. This works very well in canola however Andrew has found that running the scarifier lightly along the cereal heaps prior to seeding helps to spread the heaps more and minimises the chance of blockages at planting. “The sheep eat down and flatten the canola heaps to the point where we can pass through with the seeding equipment and the crop grows through the remaining residue,” says Andrew. The cereal chaff heaps are also well grazed, however Andrew always runs a scarifier along the row of heaps, knocking them down to about 30 cm in height. Doing this at right angles to the sowing direction means the seeder is able to seed through the chaff zone without blocking up. “It is important to seed across the line of chaff heaps, not along them,” he says. “We make a habit of creating the heaps in a line across the paddocks at harvest.” It takes a couple of years for the heaps to disappear altogether and return to full production but the heaps cover only about 1 per cent of the total cropping area. Once the heaps have disappeared there is a noticeable increase in the crop production in those patches, more than compensating for the small loss of production in the first year. “The remaining residue in the 30 cm deep cereal chaff layer slowly composts during the winter rains,” Andrew says. “Two years after grazing a chaff dump we can notice the difference in that part of the paddock, with stronger crop growth and few weed issues.” The Boultbees also choose crops and cultivars that they are confident will perform well within their weed management program. Andrew says they look for cultivars that are high yielding, very competitive in the early growth stages and have hard grain that is not damaged by the harvest settings that remove the most weed seeds. “It pays to set everything up well before attempting to use harvest weed seed control tactics like chaff carts,” he says. “The paddocks must be free of rocks so that there is no impediment to cutting low to the ground and the header must have sufficient power and the correct settings so that weed seeds are taken in the front and end up on the sieve.” Cutting low is particularly important for soft-seeded weeds like annual ryegrass that do not stay dormant in the soil for many years. Andrew says that leaving low growing or lodged weeds in the paddock in the first year effectively selects for the trait that exposes the weakness of this weed control method. “It is important to harvest as low as possible right from the start and to have other strategies to deal with weeds that ‘survive’ collection,” says Andrew. “The next step is to make sure the header is set up for optimal performance and to collect as much seed as possible in the chaff.” It is important to run at high rotor speed and to open the back of the concave up so that seed and straw is efficiently separated. The harvester needs to have the capacity to handle the increased amount of straw and must be set up so weed seeds end up on the sieve and not out the rotor. Andrew also avoids harvesting on cold damp nights where separating the harvested material efficiently is more difficult. Annual ryegrass and wild radish no longer dictate the Boultbee’s cropping rotation as they once did. The chaff carts keep weed pressure low and allow the Boultbees to take advantage of seeding or marketing opportunities for their crops, with spin-off benefits for their sheep enterprise. Australian Herbicide Resistance Initiative leader of communications, Peter Newman, says chaff carts capture about 75 to 85 per cent of annual ryegrass seeds and 85 to 95 per cent of wild radish seeds that are present in a crop, without slowing harvest operations. In a cost comparison of harvest weed seed control methods, WeedSmart estimated that running a chaff cart, including the cost of nutrient removal, costs $14/ha (assuming 2000 ha wheat at 2 t/ha), or even less is a second-hand chaff cart is used. In Andrew’s situation there is less nutrient removal costs and less costs associated with burning. He identifies rock-picking the paddocks as one of the major costs in his operation but estimates the cost of running the chaff carts is only $8/ha. A few years after grazing, improved growth and crop productivity can be easily observed with the chaff heap zones growing larger crops. Better results in barley Barley crops play an important part in the Boultbee’s weed management program. Andrew chooses the most competitive barley varieties available to suppress weed germination and growth in-crop. When sown on 260 mm row spacing the tall dense stand lessens lodging in the annual ryegrass, keeping it erect and protecting the seed heads from shedding in the wind. Swathe first By swathing the barley they introduce more diversity into the rotation so that every few years each paddock will be cut early rather than later. Barley windrows maintain their shape well and are easy to pick up with the header. There is less shedding of barley grain and weed seed due to the early swathe timing. “Swathing barley means there is a greater proportion of the cropping area that is cut early,” says Andrew. “With harvest potentially extending through to the end of December the weeds have quite a long time available to mature and shed their seed and so evading capture through any harvest weed seed control measure.” Then graze and burn in-crop There are some challenges that arise when barley chaff heaps are not burned. Barley chaff heaps are prone to thatching, which helps protect seeds on the soil surface from getting wet and composting during winter. “Even after grazing, the soil under the chaff heaps stays dry enough to preserve both barley seed and weed seeds,” says Andrew. “Volunteer barley growing in our wheat crops became a problem that we had to solve and so we have tried in-crop burning of barley chaff heaps in winter.” From their previous experiences with narrow windrow burning and burning chaff heaps, the Boultbees knew that burning was an effective way to drive down weed numbers quickly but they did not want to go back to the traditional autumn burning method. “We are seeing good results from in-crop burning of barley chaff heaps when the winter crop has reached the mid-tillering growth stage,” Andrew says. “Unlike burning chaff heaps before sowing, these in-crop burns are very safe, with virtually no risk of escape. Because of the minimal risk involved, one person can easily set fire to heaps across 1000 ha in one day.” The small fires are well contained and burn out within a day or two rather than continuing to smoulder for several days. Burning in winter makes it easier to predict the wind and Andrew takes the wind direction and location of their neighbours into consideration when burning. “There is no stress or urgency associated with burning in winter and there is much less smoke,” he says. The Boultbees are using the same idea in high weed density wheat paddocks and Andrew thinks it could also work well in paddocks with a high burden of wild radish in canola. In-crop burning of the barley heaps after grazing is very safe and has proven to be very effective in destroying the weed seed that can evade grazing and composting. Extracting the feed value from chaff heaps Grazing the chaff heaps over summer fills a feed gap for the Boultbee’s 3000 sheep, and has lifted the lambing percentage of the flock to over 100 per cent—quite an achievement for Merino ewes. The ewes are put in to graze the canola heaps first and on mating they are moved onto the barley heaps. After mating the ewes are moved onto the wheat heaps where they will stay until planting. Once the lambs are weaned they remain on the cereal paddocks with access to barley in a lick feeder to finish them. The grazing value of the chaff heaps enables the Boultbees to run more sheep over summer and the sheep do better than those that don’t have access to this resource. Andrew says that there is an opportunity to use the chaff in a lot-feeding situation but he has not done this as yet. Sheep selectively graze the most digestible portion of the chaff heaps including fine leaf material, whole and broken grain and weed seeds, chasing the seeds to the bottom of the heaps. Annual ryegrass, wild radish and wild oats seeds along with some broken cereal grains constitute about nine per cent of the material in the chaff heaps. The sheep seek these seeds and fragments out and spread the remaining plant material as they feed and trample the heaps. The nutrients from the heaps are then redistributed in the paddock via the manure, particularly when the chaff heaps are located some distance from watering points. To gain maximum nutritional benefit, the Boultbees put the sheep in to graze the chaff heaps soon after harvest, and move them to new paddocks when they have extracted all the feed value from the chaff heaps and stubble. Providing a protein-rich feed such as barley seed in a lick feeder is a great way to finish the weaners very cost-effectively. The chaff heaps provide an additional feed resource and allow the Boultbees to increase the number of animals they can run over summer, especially in difficult years when there is more small seed left in the paddock at harvest. There are risks associated with feeding chaff to livestock that farmers should be aware of. High levels of toxins such as the bacterium associated with annual ryegrass toxicity, phomopsin in lupins that cause lupinosis and ergot, which can cause illness and even fatalities in sheep and cattle. Monitoring the health of the animals while they are grazing, and testing for toxicity in the chaff will reduce the risk of disease. Research has shown that less than three per cent of ryegrass seeds that the sheep consume from chaff heaps will survive digestion. In contrast, almost one-third of ryegrass seeds ingested by cattle remain viable in the faeces. Research has shown that less than three per cent of ryegrass seeds that the sheep consume from chaff heaps will survive digestion. The sheep shown in this image are not grazing on the Boultbee’s property. Want more? You can also watch the recording of the webinar where Andrew and Peter discuss the value and practicalities of grazing chaff heaps and stubble.
Colin McAlpine, WA
Delayed planting pays off Badgingarra grain grower, Colin McAlpine, avoids dry seeding like the plague and reckons that has been the key to his success with regaining control of herbicide resistant weeds on the 4000 ha of cropping land he owns and leases. Starting with a mainly-livestock enterprise with a high weed burden Colin has greatly reduced the weed numbers in his mainly-cropping enterprise in less than ten years, taking advantage of the fact that herbicide resistance levels were still quite low. He has used a variety of tactics to protect the herbicide modes of action available while hammering down the weed seed bank every year. Twelve years ago Colin moved from the eastern wheatbelt to the Badgingarra district in the central-west wheatbelt where the incidence of frost is lower and the annual rainfall higher, averaging 550 mm. He soon found that the higher rainfall and non-wetting soils presented significant management challenges in the form of staggered germination of weeds. Colin does no dry sowing, and believes that the practice puts too much pressure on pre-emergent herbicide, often leading to a blow-out in herbicide resistant weeds. “It takes real determination to leave the seeder parked in the shed when other growers in the area are out seeding their paddocks,” he says. “Instead, we wait for rain and the subsequent germination of weeds. We do a double knock of glyphosate followed with either Spray.Seed or paraquat, always at full rates. The aim is to germinate and kill as many weeds as possible before we seed.” “I never use glyphosate on its own and always follow through with the double knock,” he says. “In just eight years we brought resistant populations of radish, brome and silver grass under control on our home farm.” Resisting the urge to start planting earlier takes a high level of confidence in the value of the double knock to clean the paddocks up before sowing, reducing the number of weeds that the pre-emergent herbicides need to control at seeding. “We have seen the results and although the crops may sometimes seem a bit behind other crops in the district we have much less in-crop weed pressure,” he says. “The profitability of our crops is higher because we have consistently solid yields and our costs of production are no greater than average.” Annual ryegrass and wild radish have been the main problem weeds on his farms and Colin has taken on the challenge of running down the weed seed bank without allowing herbicide resistance to evolve. “We have thrown everything we have at weeds and have been testing weed seed for resistance every year so that we are always ahead of the game,” he says. “We only have a small number of herbicide modes of action available so we can’t afford to lose any of them.” Colin has thrown everything he can at reducing the weed burden on his farm while taking all precautions to protect the available herbicide modes of action. Colin grows noodle and prime hard wheats and malt barley, as well as canola and lupins. He chooses sowing rates at the upper end of the range to achieve strong crop competition and finds barley is the best competitor against weeds. To further favour the crop over weeds, Colin has moved from 30–33 cm (12–13 inch) row spacing to 25 cm (10 inches) on one seeder and the second seeder is set to sow paired rows at 23 cm (9 inch) spacing. Colin has used narrow windrow burning in some years but has also had success using a ‘cold burning’ technique. “We cut the crop short and spread the residue, then after it rains we burn off the residue and find that we destroy a large portion of the weed seed present,” he says. “Having less crop residue allows better soil contact for the pre-emergent herbicides, improving their efficacy, and the weed seed numbers are less of a challenge.” Colin’s overall weed management program has been so successful that he has not needed to do any burning in the last two years. Sheep also feature in the weed management program with 2500 breeding ewes and their prime lambs graze on crop stubble over summer. “The adult sheep remove any weeds growing after harvest and also stir up the soil, helping to stimulate new germinations of weeds,” he says. “They also breakdown the stubble and improve the water penetration into these non-wetting soils.” Colin manages the farms in 600–800 ha blocks and once he has used a mode of action in the block he does not use it again in that block for three years. In the 800 ha canola block each year Colin uses as many weed control strategies as possible to clean the block up ready for the cereal phase. At harvest Colin sprays glyphosate under the swathe and puts the ewes in straight after harvest. Roundup Ready canola is used just one in every four canola seasons to avoid the risk of glyphosate resistance. In recent years Colin has reduced the row spacing from 30–33 cm (12–13 inch) to 25 cm (10 inches) on one seeder and the second seeder is set to sow paired rows at 23 cm (9 inch) spacing to increase crop competition while maintaining strong yields. On the sandier soils Colin grows lupins as the break crop, using crop topping as another tool to target late germinations of weeds and any survivors. He times the crop topping spray to suit the maturity of the weeds present and accepts any yield loss that might cause. “Short term economics does not always support weed control strategies,” he says. “I believe we have to play the long game and do things now that will limit the cost of weed control in the future.” Colin believes there are distinct advantages in owning and operating your own spray equipment to make sure herbicide is always applied at the best time. “Getting good advice from an agronomist is also very beneficial,” he says. “Some herbicides have very specific requirements to meet when it comes to timing or optimal conditions. Having a technical advisor helps make the most of every application.” He has invested heavily in liming to raise the soil pH and in improving the soil nutrition and biological activity across the clay loam and sandy soil types. “Every four years we apply lime to keep the pH around 5.8 to 6.2,” he says. “This improves plant growth and also makes the pre-emergent herbicides more effective.” Completing a double knock within 10 days of rain and before seeding means Colin needs to cover a lot of ground very quickly with the sprayer. Using a nurse tank in the field he is able to cover an additional 30–50% larger area than if he had to fold up the sprayer and return to the shed each time the sprayer needed refilling. Using modern spray equipment he is also confident that he is applying the right droplet size at the right pressure for the particular herbicide. “High water rates are critical to achieve good results,” he says. “The aim is always to be treating actively growing weeds when the soil is moist. Dusty conditions are not good and it helps to have some crop residue on top of the soil.” Colin usually has 1800 to 2000 ha of wheat, 800 ha barley, 800 ha canola and 500 to 600 ha lupins in each year. He finds the longer rotation helps preserve herbicides and avoids using the same herbicide two years in a row. “When we came here the property had only a small area of cropping and the weed numbers were very high from the predominantly grazing use,” he says. “In our early years our wheat crops were yielding around 2.5 t/ha as they struggled under poor soil health and high weed conditions. Since then yields have steadily increased to average 4–5 t/ha and I can confidently market the wheat knowing that we can achieve the yields required.” Watch Colin’s video!
Greg Martin, VIC
Take no prisoners to combat resistant wild radish! University of Adelaide Early detection of herbicide resistant weeds, a focused management strategy and being fastidious about controlling survivors is helping Victorian Mallee farmer Greg Martin get the better of herbicide resistant weeds. Mr Greg Martin is currently attacking Group I herbicide resistant wild radish (Raphanus raphanistrum) that was found growing in a single paddock on his 5500 hectare farm located at Nandaly in the Victorian Mallee. In 2013, a suspected patch of herbicide resistant wild radish was identified and live plants surviving herbicide treatment were tested for resistance. The results confirmed low level resistance to 2,4-D and MCPA. Mr Martin believes resistance had evolved due to a lack in rotation of chemical groups and not enough importance given to controlling survivors. Mr Martin’s dryland property features sand/sandy loam soils and a typical annual rainfall of 300-400 mm on average. Grain production is the main enterprise and he has made a conscious effort over the past few years to diversify the cropping mix. This broadacre cropping approach provides farmers with a greater tool kit to battle weed resistance problems, creating more opportunities to use varied weed management tactics. Over the past 10 years Mr Martin’s enterprise has changed, moving to a no till system that involves a lot more cropping. Whilst this typically requires a greater reliance on chemical management of weeds, for wild radish it keeps the seeds closer to the surface – reducing their longevity and allowing faster management and eradication of a resistance problem. Mr Martin and his agronomist Matt Elliott (Dodgshun Medlin) developed a 5 year targeted and integrated weed management plan to combat the herbicide resistant wild radish. Mr Martin believes consulting with his agronomist will be key for him to successfully eradicate resistance: “They have a proven record of dealing with this problem on other farms so we consulted with them and formulated a plan to get on top of the problem.” He expects it will take a minimum of five years to get the resistance problem under control. Control may occur sooner but he is mindful to not relent too soon. Since the discovery of herbicide resistant wild radish on Mr Martin’s farm there is now an emphasis on herbicide chemical group rotation, managing survivors and integrated weed management. Making use of alternative cultivation practices where possible, such as narrow windrow burning and spray toping in the legume phase, has also been included in the management plan. These tactics have been selected as the farmer feels it is important to use as many different control options as possible. “Mindset is important; test and identify the scale of your problem, get a plan and get stuck in! Maybe with hindsight we danced around the problem for too long” said Mr Martin. Incorporating Triazine Tolerant (TT) canola into the crop rotation is the primary strategy in place to defeat the resistant wild radish. “There was a heavy reliance on Clearfield cereals in the rotation and another chemical group was needed to control radish in the break crop phase of the rotation” said Mr Martin. “Radish has also shown group B resistance so the use of Atrazine (group C) has given us a greater level of weed control within the crop.” Finding paddocks without a history of group B herbicide use in which to grow TT canola can be a stumbling block for this approach and here accurate farm management records are advantageous. In the season after resistance was confirmed, TT canola was grown in the problem paddock. This proved to be a good first step for Mr Martin’s management program with the group C herbicide providing effective control of all wild radish growing in the paddock that year. “We are entering the second year of a five year management plan and the new strategies appear to be successful in getting the resistance problem under control” Mr Martin also carefully considered his approach to harvesting his canola, creating narrow windrows of straw and chaff to burn. It is not surprising he chose this narrow windrow burning strategy considering how well it has worked in WA to reduce wild radish seed banks and overcome resistance problems. Tactics to combat spread of the resistance by preventing seed set are also in place. “To kill any late germinating radish plants that may emerge after the first spray we are using a Double Knock strategy; killing every plant that germinates that year equals a reduction in numbers and reducing their spread” said Mr Martin. In 2015 the paddock will be returned to wheat and the control of wild radish monitored vigilantly. Wild radish invading a cereal crop (Photo: Peter Boutsalis). “We are also taking a no prisoner approach to any seed that hits the ground by controlling weeds in non-cropped areas, including fence lines. This reduces their numbers using chemistry that is not used in the crops” Mr Martin highlighted. The main complication with this tactic is timing of herbicide applications as radish can germinate at all times of the year. As the resistance problem was localised to one paddock the management plan was specific to that area. However, dealing with this problem has increased Mr Martin’s awareness and positively altered his attitude towards weed management for his entire enterprise. The lesson was to make weed management a high priority; vary the control tactics, monitor treatment performance and be prepared to make management changes early. Mr Martin also points out that all of his resistance control measures have come at a greater financial cost. “Economic circumstances are an issue that should not be underestimated. Realising you are developing a problem yet having the means to act accordingly could be an obstruction.” However, he deems the additional expenses incurred from a comprehensive weed management strategy are justified. Mr Martin declares “We can see that controlling our problem is going to come at a cost to the business but also realize that for us to do nothing, and let the problem intensify, is going to eventually lead to a problem that is so massive it could ultimately make us unviable. Short term pain for long term gain!”
Grant Wilson, VIC
Their no-till cropping rotation, which includes wheat, lentils, canola, barley, lupins and field pea, is governed by disease and weed management considerations, proving that integrated weed and disease management can go hand in hand. “There was a time when we just ignored summer weeds, but not now,” says Grant. “We are very conscious of weed management all year round and the potential for herbicide resistance to really limit our options if it gets out of hand.” Following a ‘no cereal after cereal’ policy, Grant usually tries for a two year break between cereal crops. “We also rotate between different wheat cultivars to make the most of their disease management traits,” he says. “Following a cereal we would be looking to plant a legume, usually a lentil crop, but if we were faced with a broader weed problem we would choose an ‘imi’ tolerant lentil or possibly decide to grow field pea instead of lentils to take advantage of the wider range of selective herbicides registered in field pea.” Grant usually keeps a two year break between cereal crops to maintain effective control of diseases. Pulse crops sown into standing stubble offer the best combination of tactics to tackle ryegrass in-crop using grass selective herbicides and desiccation. Being in a lower rainfall zone (325 mm or 13 inches), the Wilsons find a conservative rotation is safer in the long run and gives them more options to manage annual ryegrass. Pulse crops offer the best combination of tactics to tackle ryegrass in-crop using grass selective herbicides and desiccation. Recently Grant started using pre-emergent herbicides such as Boxer Gold® and Sakura® to reduce their reliance on trifluralin in wheat. “So far we have had mixed results, especially in dry weather, when there was insufficient moisture to properly activate the herbicide, on top of poor crop competition due to the seasonal conditions,” he says. “It is an expensive option but when it works it provides good control across the paddock.” Grant prefers to use Boxer Gold® before sowing with knife-points and press wheels on the seeder. The heavier soils are in a fallow rotation to conserve soil moisture. Most fallow paddocks will usually be sprayed once or twice, depending on rainfall, over the summer. The Wilsons grow vetch as a green manure crop on their lighter soils to improve soil health and control weeds. When the vetch reaches maximum biomass Grant sprays it out to gain maximum benefit from the high biomass production. All other crops are left as standing stubble and this year they will be moving into inter-row sowing. “We now have RTK guidance fitted to the seeder and expect to see some real improvements in crop establishment,” he says. “With a more even sowing depth we should get more uniform germination and that will increase the crop’s ability to out-compete weeds.” The soil type across the Wilson’s farm ranges from sand to loam and varies in pH. Kate, an independent agronomist, takes production-limiting factors such as soil pH and boron levels into account when planning the rotation, particularly with lupins being more sensitive to higher pH and lentils being sensitive to boron levels. The potential for herbicide residues to still be present after a dry summer is also a consideration, particularly on higher pH soils. The Wilsons crop between 4000 and 5000 ha a year and generally do not have livestock, however they do fatten lambs on stubble as the opportunity arises. Annual ryegrass has some resistance to Group A ‘fops’ but so far ‘dim’ herbicides are still effective. Kate customises their herbicide mixes to preserve the effectiveness of the dim herbicides by avoiding unnecessary usage. They have also resisted a move into glyphosate tolerant varieties because they are concerned about the potential over-use of glyphosate that may lead to glyphosate resistance in weeds. However, they do grow some herbicide tolerant crops that utilise different herbicide modes of action. Annual ryegrass on the Wilson’s property has some resistance to Group A ‘fops’ but so far ‘dim’ herbicides are still effective. Kate customises their herbicide mixes to preserve the effectiveness of the dim herbicides by avoiding unnecessary usage. The Wilsons choose not to grow imi-tolerant cereals because they believe this would lead to an over-use of Group B chemistry, which is known to lead to herbicide resistance in weeds such as brome grass. They use imi-tolerant Clearfield canola to a limited degree as another option to control annual ryegrass using imazapic/imazapyr (Group B) products and rotate herbicides as best they can in an attempt to stave off herbicide resistance in grass weeds. “We use crop desiccation to stop weed seed set to avoid the need for narrow windrow burning to destroy weed seeds after harvest,” says Grant. “Desiccation seems most effective in legumes, particularly lentils. In cereals we have also used herbicides to croptop weeds according to product label instructions.” “Fleabane is a new weed in this area having become noticeable for the first time during the wet summer in 2010,” says Grant. “A double knock treatment has been recommended for fleabane control and we will also introduce cultivation if required in some situations.” The Wilson’s tread a fine line between maximising crop competition and conserving soil moisture. “Plant health is our main interest and we use a range of tactics to reduce weed pressure in-crop,” says Grant. “With legumes in the rotation we avoid applying much starter-N fertiliser and we make an effort over summer to get the paddocks as clean as possible before seeding.” The Wilsons plant their crops as narrow as possible using a standard cereal seeding rate of 60 kg/ha on a 250 mm row spacing. They find this row spacing narrow enough to provide early crop competition and not be too rough, while still being able to inter-row sow. Taking a thoughtful and long-term view of herbicide use within their cropping system has kept a lid on herbicide resistance on the Wilson’s farms so far and preserved a wide range of herbicide chemistry. Herbicide use is supported with non-herbicide tactics and the rotation of modes of action within and between crop types.
Case Study News
Keeping the farm clean using tactics
Case study: Graham Clapham A diversified cropping system requires great attention to detail and offers many opportunities to implement several tactics in an integrated weed management strategy. Spray application technology like these multiple-nozzle fittings make it quick and easy for the operator to change the nozzle type if environmental conditions change during the spray operation. The Claphams have placed the nozzles on their spray rig close together (250 mm apart) to maximise coverage and minimise drift. Graham Clapham started his farming career straight out of school at 15 years of age. Even then he was clear about his desire to own a black soil farm on the Darling Downs. Graham grew up on his parent’s 200 ha mixed cropping farm, growing irrigated and dryland crops including corn, soybean, wheat, sorghum, onions and pumpkin. With help from his parents, Graham realised his first goal when he was 18, purchasing a farm of his own at Norwin, west of Toowoomba. He now grows mostly irrigated cotton, corn and wheat and dryland cotton, wheat and sorghum on the family’s 1840 ha aggregation in the Brookstead–Norwin district. On the 700 ha that is usually irrigated each year Graham has two main rotations—irrigated cotton or corn followed with irrigated wheat then a long fallow before returning to cotton or corn. In the corn–wheat rotation there is no cultivation but Graham has different herbicide options available and an opportunity to provide a disease break to combat fusarium wilt. Rainfall dictates the dryland crop rotation on the rest of the cropping area. Minimum till is practiced to conserve soil moisture with occasional cultivation only to renovate the tramtracks. Graham is aware of the risk of herbicide resistance, particularly in weeds like flaxleaf fleabane and feathertop Rhodes grass, which have always been hard to kill with glyphosate, and milk thistle is a new concern for the business. Since the introduction of genetically modified cotton in 1996, the Claphams have practiced pupae-busting cultivations to manage resistance in helicoverpa. This has had the spin-off benefit of keeping hard to control weeds like flaxleaf fleabane and feather-top Rhodes grass under control. “Pupae busting is a robust cultivation to a depth of 100 mm and is required to remove all large soil clods,” he says. “It must be done before the end of July following the cotton harvest in April–May.” The deep cultivation after cotton buries weed seeds deep in the profile where they can’t germinate. Unfortunately flaxleaf fleabane seeds remain viable for longer when they are buried than when they are close to the soil surface. This means cultivation in subsequent years can bring viable seed back to the surface where it can germinate so it is not a complete solution but another useful tactic in the farming system. The cultivation leaves the soil dry and prone to erosion so the Claphams aim to sow a wheat crop after cotton to provide ground cover over winter and stubble for the following summer. Soil moisture and irrigation water availability govern the sowing rates used although the Claphams have two options when it comes to row width in their dryland crops. When sowing wheat into cultivated soil after cotton they can use an air seeder to plant rows 150 mm apart rather than the single disc planter used in minimum till planting to sow 500 mm rows. Sowing in narrow rows has several benefits for weed control in the dryland system. To begin with sowing is a full tillage operation that removes any weeds present at the start of the season. The increased shading of the inter-rows suppresses weed germination and after harvest there is more stubble left on the ground, again suppressing weed germination. Infrastructure such as channels and pump sites are kept clean throughout the year to avoid the risk of weeds spreading throughout the farm in irrigation water. Graham has not noticed a yield difference between crops sown at the narrow and wider spacing although the air seeder does dry the soil out more than the single disc planter. “The wheat crop is often not great, especially if winter rain is scarce,” he says. “But it provides good cover and we can use different chemistry to control weeds, especially to achieve a residual effect on flaxleaf fleabane.” Graham says the chemistry available for use in wheat is very effective, keeping the wheat crops quite clean. Corn can experience some late grass germinations, which they have previously treated with glyphosate at harvest and then burnt the stubble. When there is additional water available for irrigation early in the year the Claphams often take the opportunity to plant soybeans. Having this as an option they are conscious of the residual action of the herbicides used in the previous wheat crop. “We use herbicides with no residual effect to control broadleaf weeds such as thistles and turnip in the wheat so we don’t need to worry about the plant back period for soybean,” says Graham. So far the Claphams have not experienced any spray failures that have raised concern about herbicide resistance. Graham is very conscious of the potential risk and is mindful of the experience in the USA with widespread glyphosate resistance in their cotton industry. “Glyphosate-ready cotton has been a positive innovation for the industry, making it more sustainable and ending the use of environmentally-harmful herbicides,” says Graham. “However, glyphosate does not give 100 per cent control of weeds in cotton. Vines particularly can survive a spray and so we use inter-row cultivation and hand chipping to remove vines as needed.” Inter-row cultivation in cotton, corn and sorghum also helps maintain the furrow profile and to conserve moisture before the canopy closes. Graham occasionally uses an inter-row shielded sprayer to apply glyphosate in corn and sorghum crops. The Claphams recently purchased a neighbouring farm with a very heavy weed burden. They have used cultivation and herbicides to drive down the weed seed bank and to treat weeds they have never seen in the area before. The Claphams do all their own spray operations, mainly so they can control when they spray. “The Darling Downs region is closely settled and there are not many trees across the cropping area. It can be very difficult to find suitable times to spray without the risk of off-field impacts. Having our own gear and labour available means we can spray as soon as suitable conditions prevail.” Spot spraying larger weeds that have escaped earlier treatment is the last operation before plating clean seed into clean paddocks with clean borders (#8 in the 10 Point Plan). Graham’s son-in-law, Jonathon Mengel, is responsible for the spraying operations across the farms. They have found that having a person with the designated responsibility to have the chemicals in stock and be looking for spray opportunities has been very beneficial to their operation. “We have very few weed escapes after a herbicide spray,” says Graham. “On the rare occasion that it does happen we prevent seeding using tillage or a follow-up application of a knockdown like paraquat.” “In the fallow we look for opportunities to do a double-knock treatment but it can be very difficult to get favourable conditions for two sprays close together,” he says. “Glyphosate, Starane®™ and MCPA®™ are relatively easy to apply using air induction nozzles to splash the product on with minimal risk of spray drift. The second application of paraquat 10 days later is more difficult, especially given the need to apply a fine droplet size.” The Clapham’s Case Patriot sprayer, with its 36 m boom and 4 m wheel base, fits perfectly into their on-farm control traffic system. They have doubled the number of nozzles on the boom, placing a set of nozzles every 250 mm instead of the traditional 500 mm, allowing greater coverage and helping to extend the tight spraying window. “This gives us a double overlap so we can consistently use coarse droplet nozzles and still get coverage, and it also enables us to operate lower to the ground,” he says. When necessary Graham will spot spray or hand rouge weeds prior to planting the next crop to ensure the paddocks are as clean as possible going into the season. The Claphams are also careful to keep irrigation infrastructure such as head ditches, supply channels and tail drains weed free. They use residual herbicides at high rates to effectively sterilise the soil in these non-cropping areas. “The risk of distributing weeds throughout the farm is of great concern and maintaining weed-free infrastructure is a year-round priority for us,” says Graham. “We also pay attention to planting clean seed each year, buying in cotton, sorghum and corn seed, and grading the wheat seed we keep the next season.” “Black oats has been a bad problem in the winter cropping program but we seem to have won the battle with a consistent approach to planting clean seed.” Throughout the crop rotation the Claphams are looking for ways to manage weeds to achieve the best possible productivity and profitability in the long term from their cropping operation. Watch Graham’s video below!
Tom Murphy, NSW
Aggressive and innovative approach tackles resistant weeds An aggressive and innovative approach to weed control is helping northern NSW farmer Tom Murphy win the war on herbicide resistant weeds. Mr Murphy manages the 10,000 hectare North Star Aggregation for the Sustainable Agriculture Fund, which purchased the property four years ago. Unknowingly, they inherited populations of glyphosate resistant barnyard grass, Group A-resistant black oats (wild oats) and Group B-resistant phalaris, as well as ‘herbicide tolerant’ populations of fleabane and feathertop Rhodes grass. “A lot of this was discovered purely when we went and did the first spray of a fallow with a reasonably robust rate and found that the barnyard grass would still remain in the paddock – we knew straight away we had a problem,” Mr Murphy said. “The same year we put a Group B herbicide across a winter crop and the phalaris just did nothing, and that was with little or no Group B history on the farm as well. “So we sent that seed away for testing and came up with a plan to deal with it.” As a result of his subsequent success in tackling resistant weeds, Mr Murphy has been chosen as a WeedSmart Champion. WeedSmart is an industry-led initiative managed by the Australian Herbicide Resistance Initiative (AHRI) aimed at enhancing on-farm practices and promoting the long term sustainability of herbicide use in Australian agriculture. “We got involved in the Weedsmart program purely because we’ve been through the tough lessons,” he said. “We encountered the problem and had to be very quick on our feet to try and get around it. “If I can share those lessons with other farmers so they can get on top of their problem weeds sooner then that’s a win for industry. “WeedSmart also allows me to meet people who have tackled these problems differently. If I can find a different way of doing something that’s more cost effective then that’s great for the business that I run.” The dryland North Star Aggregation property features about 8500 arable hectares under rotation, with 75 per cent each year sown to winter crops of wheat, barley, canola and chickpeas, and the remainder to sorghum and cotton in summer. The Brigalow-Belah country features highly productive, grey self-mulching soils, which can store 150-180mm of soil moisture, with most of the 620mm average annual rainfall arriving in winter. Despite the productive potential of the country, the added work and chemical required to control the range of problem weeds was loading $40/ha in costs to the bottom line. Mr Murphy devised an aggressive integrated weed management plan, featuring crop and chemical rotation, very precise herbicide applications and double-knock treatments, as well as non-chemical methods such as strategic tillage and windrow burning. “One thing we’ve definitely done is be really aggressive with these weeds,” Mr Murphy said. “It does cost more and while you might not win all of your battles, with that aggressive approach you will win the war. “The other feature of the plan has been a willingness to think outside the square. If someone told me that windrow burning was the way to go around here I would have laughed at them a couple of years ago. “But we’re giving it a crack and if it doesn’t work then at least we know. And if it does work and it’s a winner for us then we’re ahead.” Mr Murphy’s strategy features a strict, managed approach to chemical use. “We’re managing our use of herbicides through a couple of options. One is the double knock approach, which we’re finding is working very well; the other is mixing up the chemistry – we try not to be too reliant on one active group too much. “It’s also very important to get your spray rig set up right and to use the correct rates. “We’ve taken a very aggressive approach to our resistant weeds so we use nothing but the top rates. We found out the hard way that if you try and reduce your rates with any resistant weeds you’ll run into trouble again.” The ability to grow summer crops as part of the rotation has also delivered benefits to herbicide rotations as well as non-chemical treatments. “For example, for cotton you have a long fallow leading into it; you’ve got a crop period where you can use different chemistry; and you’ve got a long fallow after it, as well as a mandatory cultivation,” he said. “Having sorghum in there as well also changes the fallow period and introduces new residual chemicals, so the summer rotation is really key to what we’re doing.” The non-chemical control method of windrow burning is also being trialled, and although early signs are it may not be suited to the environment, Mr Murphy is maintaining an open mind. “At this stage I don’t see that it’s a great fit for our circumstances because a lot of our weeds have lost their seed come harvest time or they’re not a problem in crop, but we are looking at it and we are trialling it. “It’s really important that when you’ve got a herbicide resistance problem that you don’t stick your head in the sand – you need to be proactive about it.”