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Lance & Erin Turner, Pingelly, WA

HWSC underpins continuous cropping

Lance and Erin Turner first encountered herbicide resistance soon after switching to continuous cropping on their home farm at East Pingelly, WA, in 1990.

Having relied on low rates of chlorsulfuron (e.g. Glean, Group 2 [B]) to control annual ryegrass, resistance was confirmed in 1993. Five years later, Lance attended a Ryegrass Integrated Management (RIM) workshop, which prompted the purchase of their first chaff cart for harvest weed seed control in 1998.

“At the RIM workshop, it was clear that simply rotating our crops and herbicides was not going to be enough to stay ahead of the weeds long-term in a continuous cropping program,” says Lance. “Since introducing harvest weed seed control in our system, we have never left a paddock out of crop because of weeds.”

Lance is a long-standing supporter of WeedSmart and has adopted all the WeedSmart Big 6 tactics in various ways on their three properties across three different rainfall zones. RIM analysis confirms that their current farming system has a long future from a weed burden and herbicide resistance standpoint.

Weed program on an expanding aggregation

In 2009, the Turners purchased a predominantly sheep property east of Corrigin and established a continuous cropping system. The long history of spray-topping pasture on this property had resulted in a huge population of glyphosate-resistant ryegrass. Fortunately, the ryegrass was susceptible to several other chemical options. Using a suite of older chemistries and a chaff cart, the Turners vastly reduced the weed seed bank to the point where the weeds no longer dictate the rotation on this property.

The latest expansion of the Turner’s cropping operation occurred in 2019 when they took on a leased farm at Goodlands, on the eastern edge of the Wheatbelt. Their 7000 ha aggregation now includes three farms in the medium and low rainfall zones of Western Australia, ranging from 340 to 350 mm at Pingelly down to 250 mm at Goodlands. They are also contending with very different soil types. Across the farms, annual ryegrass is the main weed, along with a small amount of wild radish, which is effectively controlled with harvest weed seed control.

The Turners have a dedicated campaign to keep weed numbers low using the power of crop and herbicide rotation, competitive cropping tactics and harvest weed seed control. Lance has a talent for machinery modification and innovation and maximising the value of second-hand equipment.

Maximising crop diversity

The Turners have been continuous-cropping since 1990 when they sold the last of their sheep. Their 2700 ha home farm, Glenmorrell, at East Pingelly, is 100 per cent cropped in a lupins, barley, canola and barley rotation.

Being in lower rainfall zones, the farms at Corrigin and Goodlands are now half fallow, half crop to maximise returns and lower input costs in these areas with lower yield potential. At Corrigin, it is barley, fallow, barley, fallow, and similarly, at Goodlands, it is wheat, fallow, wheat, fallow. Barley suits their Pingelly and Corrigin farms, which have an increased frost risk compared to the Goodland farm.

“We grow imi-tolerant Chief CL Plus wheat and Maximus CL barley, but we don’t use imi herbicides in-crop because we have other, cheaper options,” says Lance. “We budget for feed barley quality, but Maximus CL barley has malting potential, which is a bonus in some years.”

The Turners introduced Roundup Ready (RR) canola to get glyphosate into the cropping phase when clethodim (e.g. Select, Group 1 [A]) at 0.5 L/ha was no longer effective. Lance uses the canola phase to reduce the pressure on pre-emergent herbicides, particularly in dry-seeding years.

Lupins are a valuable part of the rotation, giving the Turners several opportunities to apply pressure to the weed population. Starting with a double knock tactic (usually double paraquat) if it rains before planting, then in-crop applications of simazine and clethodim (and butroxydim, e.g. Factor, if the season requires it). They aim to maximise crop competition, then crop-top the lupins and apply harvest weed seed control. This gives six or seven different weed control tactics in one crop.

“We try not to miss any opportunity for weed control,” says Lance. “Having a clean farm gives maximum flexibility – allowing us to seed by the calendar and make last-minute changes to the rotation if we see an opportunity.”

For example, because their weed numbers were low, when ex-cyclone Seroja delivered 30 mm of rain on the Goodlands property in April 2021, they could start seeding immediately without needing to double-knock first. Similarly, in 2023, the areas designated for lupins and canola were too wet for these crops, so one week into seeding, the Turners swapped to sow oats in those areas instead.

“We chose oats to provide the nematode break that lupins usually supply in the rotation,” says Lance. “This was the first crop of oats we had grown for 20 years, and it yielded well. Being the third successive cereal crop in that paddock it has resulted in high ryegrass numbers, which we plan to control with a hot stubble burn to destroy the seed bank.”

Mixing and rotating herbicide MOA and double-knocking

Keeping their weed numbers low is central to maintaining access to a wide range of herbicide options, which also means they can keep their costs down by using mainly older chemistries.

“There is some indication of rate creep for some older chemistry, but they are still broadly effective, and we only use the new chemistry on small areas of the farm,” says Lance. “In the last few years, we have engaged an agronomist to help us keep up with the newer chemistry options.”

Keeping the fallows clean on the lower rainfall properties at Corrigin and Goodlands is a high priority. Margins are small on these farms, especially in low rainfall years, so there is no room for a weed blow-out in the budget. Lance ‘throws everything’ at the ryegrass on these properties and doesn’t let any get through the fallow. He has found that Voraxor (Group 14 [G], saflufenacil + trifludimoxazin) has been a valuable addition to their chemical program, particularly at Goodlands, to reduce broadleaf weed and ryegrass numbers in the winter fallows.

“We haven’t used Sakura (pyroxasulfone) yet and only some Boxer Gold (prosulfocarb) in the last few seasons and, in the cereal phase, we just apply trifluralin up front and no in-crop herbicide at all,” says Lance. “Using all the tools we can to keep weed numbers low allows us to plant what we want, when we want and to keep our costs down.”

Lance rotates herbicide modes of action as much as possible, but there are limitations within their cropping program.

Their double-knock program uses glyphosate followed by paraquat plus diuron (except where canola is the next crop) for broadleaf weeds like radish, volunteer canola, water weed and capeweed in fallow. Diuron plus paraquat also works well for broadleaf weeds in cereal. Lance might use some imi herbicides to tidy up those paddocks if barley grass or brome grass is present. When targeting ryegrass in fallow, Lance applies a paraquat double knock.

Spray efficacy

Lance has added a spray line to the front of his seeder bar to apply trifluralin, unlocking the self-propelled boom spray from the seeding operation. If it rains, the boom spray can go to any farm to double knock without interrupting seeding, and if the seeder gets bogged, the trifluralin application stops too, so there’s no wastage and no slowing down another machine.

To maximise spray efficacy, Lance operates the self-propelled boom spray at slow ground speed, uses high water rates (90–100 L/ha), and low-pressure air inducted (no drift) nozzles.

“Spray technology is in the nozzles and the set-up, not in the machine,” he says. “We use a John Deere 4930 self-propelled boom spray with over 14,000 hours on the clock at Pingelly and Corrigin and a Westspray trailing boom at Goodlands. An optical sprayer is on our wish list for fallow and summer spraying.”

Where possible, Lance targets small weeds with applications at the lower end of the recommended rate range for the herbicide. A higher label rate is used if the weeds are larger and more mature.

Stopping seed set

To stop weed seed set in-crop, Lance crop-tops their lupins and canola and follows up with harvest weed seed control.

In their RR canola crops, Lance uses high water rates and slow ground speed to ensure the herbicide reaches the weeds underneath the crop canopy. In 2022, it was too wet to apply the late in-crop glyphosate spray, which allowed ryegrass to set seed, adding extra seed burden going into 2023. Fortunately, the cold, wet start in 2023 resulted in good weed germination and allowed for a double knock before seeding.

The Turners could incorporate hay into their rotation to address a weed blow-out if required.

Crop competition boosts crop yield and weed control

Lance aims to maximise crop competition through increased seeding rates, selecting competitive varieties and crop types and sowing early. He prioritises paddocks with emerging weed issues for early sowing and may choose to plant barley as their most competitive crop option to suppress weed germination.

Up to 100 per cent of their program is dry-seeded each year. If any areas are missed at seeding, Lance will reseed to ensure strong crop competition across the paddocks.

The Turners use 12-inch (30 cm) row spacing across all their farms for stubble management at sowing and to conserve moisture to finish the crop. This is especially important on their lower rainfall farms at Corrigin and Goodlands – where they also use lower seeding rates of 55–60 kg/ha for barley and 40 kg/ha for wheat.

Their fertiliser rates are set to match yield expectations, and they often bump up rates after a high-yielding year on the Corrigin or Goodlands properties.

The Turners use stubble burning for disease management in a double cereal phase, to reduce the allelopathic effect of barley stubble on canola germination, and cultivation for wheel-track renovation after a wet season or to incorporate lime. These practices also impact survivor weeds and the weed seed bank.

Lance says trials have shown a 300 to 400 kg/ha yield response in the year lime is applied and incorporated due to mineralisation plus the longer-term benefit of the lime. They have applied trace elements every year for 30 years.

“We would like to cultivate once every five to seven years to move the trace elements lower in the profile where there’s more soil moisture to make the nutrients more accessible to the plants,” he says. “But it is hard to find time to cultivate, and our soils are not suited to mouldboard ploughing.”

Harvest weed seed control is a key strategy

The Turners began harvest weed seed control (HWSC) in 1998 after purchasing a second-hand Cole chaff cart. Soon after, Lance modified the cart from a blower type to an elevator system.

While elevators were not new at the time, Lance modified his elevator to catch only the chaff while chopping and spreading the straw. This innovation maintained the integrity of any short straw in the chaff and solved all the issues with blockages in the blower and with smashed-up straw smouldering instead of burning properly in the chaff heaps.

Burning the chaff heaps would take a month, and after the livestock were removed from the system, the Turners were keen to change to a less time-consuming HWSC system. After 14-15 years of using chaff carts, they moved to a seed impact mill six years ago. They now have three headers and two single-mill seed destructors. If one header breaks down, they swap the mill onto the spare header and keep harvesting.

Lance designed the custom single-mills during a project with de Bruin Engineering to build a mechanical drive single-mill suitable for smaller harvesters such as his John Deere 9750 STS machines. He also designed the horizontal mechanical drive for the iHSD for the mills that de Bruin adopted initially, but they have since moved to a vertical drive for the iHSD.

“We get the same result with the mills as we did with the carts,” he says. “We still cut at beer can height and use the same baffle system to separate the straw from the chaff stream. It doesn’t matter which harvest weed seed method you choose, but adding something at harvest does make a difference to weed burdens the following year.”

The Australian Herbicide Resistance Initiative (AHRI) developed the Ryegrass Integrated Management (RIM) tool that Lance used over 20 years ago to test his farming system, and the results convinced him of the value of harvest weed seed control.

“Herbicide resistance, particularly glyphosate resistance, was going to take us out of cropping if we didn’t start using harvest weed seed control,” he says. “We started doing it, and more than 20 years later, we are still using the cheaper herbicides for wild radish and annual ryegrass control and still have many of the newer herbicide products up our sleeve.”

Growing competitive crops makes weeds like ryegrass grow tall and not go under the cutter bar at harvest, thus improving the HWSC result. Wild radish is an easy target for HWSC and separates easily into the chaff. Lance finds that the mills don’t slow harvest down in their barley crops up to 3–4 t/ha, but they need to go slower in wheat.

Cutting all crops at beer-can height also makes seeding easier in the following season. In the lower biomass crops at Goodlands and Corrigin, it is more difficult to capture weed seeds in the header front as the seed heads are not held up as well in the crop. There is no doubt that the tactic is worthwhile, as demonstrated in the only time that Lance removed the mills for harvest and faced the consequences the following year.

“Harvest weed seed control on our farm for 20 years has applied selection pressure to our weeds, and I expect to see a shift to early shedding of seed eventually. I think we are starting to see this with wild radish in crops now often dropping their pods before harvest – so they have selected for early pod drop,” says Lance. “After 30 or 40 years of early weed control in-crop, I have certainly seen a shift to later germination in weeds.”

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