Control the controllables in mixed farming systems

Andrew returned to the family farm at Lake Cargelligo in 2016, where he and his wife Kirsty assist his parents with their cropping and lamb trading business at Wilga Park and run an independent agronomic consulting business.

Andrew accumulated extensive experience working as a commercial agronomist and then cropping and senior manager with Paspaley Pearls Properties based at Kurrajong Park, Coolah in NSW, before returning to the northern Riverina low rainfall zone. As chairman of Grains Orana Alliance (GOA), he is keenly interested in conducting and evaluating field research that addresses information gaps as they emerge at the local level.

“At Wilga Park, we have a mixed farming system that suits the two generations involved and provides good weed control options,” says Andrew. “Ryegrass and black oats are the most challenging weeds in our cropping system, with resistance, mainly to glyphosate, being very common across the region.”

While working at Coolah and on the Liverpool Plains, Andrew had seen patches of grass weeds surviving glyphosate applications, and started sending samples for herbicide resistance testing, then discussing management tactics to manage this emerging problem.

“Within my client group we are now doing the same – testing suspect plants and sharing experiences and management results within the group to raise awareness and keep one step ahead,” he says.

Lake Cargelligo is in the northern Riverina low rainfall zone, which has an annual average rainfall of 425 mm distributed evenly throughout the year. The region has experienced a string of unusually wet years from 2023, including significant flood events.

There is a farming system and soil type effect from north to south in the region. To the north, the soils are heavier, and annual ryegrass is becoming increasingly difficult to manage in the mostly continuous cropping systems. To the south, the soils are lighter textured and feathertop Rhodes grass is the most challenging weed in cropping paddocks.

The Mallee sands with red clay (sometimes sodic) subsoils typical of the Lake Cargelligo area present some management challenges for weed management, pre-emergent herbicides, and crop germination. Andrew uses the WeedSmart Big 6 framework to build a program to suit the grower, selecting a suite of tactics that the grower can implement within their farming system.

At Wilga Park, the McFadyens crop 30 to 40 per cent of the aggregation and run trade lambs on the remaining area. Their cereal-dominant rotation is in place for three to four years, with the final crop undersown with lucerne and the sheep returning to the paddock after harvest.
Within his client group, there is a broad mix of cropping systems, including irrigated cotton and some forage sorghum in summer, and wheat, barley, canola, lupin, chickpea and vetch (brown manure and hay) in winter.

“On mixed farms like ours, a lucerne and pasture phase has similar outcomes to growing vetch in continuous cropping systems,” he says. “Both build soil nitrogen, and combat problem weeds, either with grazing and alternative herbicide modes of action, or through brown manuring or making hay to eliminate weed seed set.”

Within his client group, the average scale of operation for cropping is 3000 ha total area (2000 ha crop, 1000 ha sown chicory, fescue, lucerne pasture), along with larger mixed farms of 5000 to 30,000 ha that include large sections for extensive grazing that are not cropped.

Many farms in the Lake Cargelligo area are intergenerational businesses where profitability is the key driver for decision-making.

“When working with clients and within our own operation, we try to ‘control the controllables’,” says Andrew. “By keeping focus on the things we can control, like crop rotation, product choices and spray application logistics, the uncontrollables, like seasonal conditions and existing herbicide-resistant weeds, tend to have less impact. Every decision has trade-offs, so the best you can do is work towards the goals for the business.”

Andrew uses the WeedSmart Big 6 framework in his own business and with clients to ensure each integrated weed management strategy includes as much diversity as possible to keep weed numbers low.

Speaking in a panel session at WeedSmart Week 2026 in Griffith, Andrew said the crop and pasture rotation should underpin the farming system to manage weeds, pests and diseases, and drive profitability in mixed farming operations.

A typical mixed farming rotation includes a 3 to 5-year cropping phase (growing wheat, barley, and canola), with the final year commonly oats, under sown with lucerne, to begin a 3 to 5-year pasture phase. Lucerne or lucerne plus oats provides additional protein for lamb growth, along with opportunities for alternative weed management tactics, including strategic cultivation.

“The lucerne phase needs to be at least two years long to provide effective weed control,” says Andrew. “We can implement a range of tactics in this phase, including pasture topping with paraquat, hay making, grazing, grass-selective herbicides, such as clethodim targetting ryegrass and barley grass mainly, and strategic cultivation.”

Andrew says the double-knock effect of pasture topping followed by heavy grazing pressure using large flocks of sheep is an excellent way to stop weed seed set.

In a minimum-till, continuous cropping system, the most common rotation is wheat, canola, wheat, but growers also need another option if there’s insufficient soil moisture at planting for canola. Vetch has proven to be a good break crop that growers are willing to plant. Growing vetch enables weed control options similar to those used in a pasture phase. Andrew says controlling grass weeds is particularly important to conserve the nitrogen fixed in the soil during the legume phase.

Adding herbicide-tolerant crops to the rotation has many benefits, provided that they are part of a well-planned rotation. Andrew says he is always discussing scenarios within his grower group, to avoid panic decisions when things don’t go to plan.

“In this area, we can use several imi-tolerant Clearfield crops to manage grass weeds, provided we are intentional about avoiding being caught in an imi-spiral,” says Andrew. “We plan as far ahead as possible to ensure effective weed control, minimise resistance risk and protect crop safety. For example, an imi might be applied in Clearfield canola, then no imi herbicide applied in the following Clearfield wheat crop, and an imi applied in the following Clearfield barley.”

Each of these crops also offers other weed control options to suppress germination and stop weed seed set.

In continuous cropping systems, wheat is the pillar crop with barley providing a good alternative in drier years. Andrew says grower interest and confidence in canola has grown in the last five or six years, since the establishment of National Variety Trials (NVT) for canola in the local area. These trials have demonstrated canola’s ‘fit’ for weed and disease management, and profitability in different seasons. Growers are also gaining experience and confidence using pre-emergent herbicides with canola, which is expanding the weed control value of this crop in the rotation.

“Canola is a great option in the Lake Cargelligo area when there is good soil moisture at planting, and a favourable forecast,” says Andrew. “Heat and low humidity in spring can impact canola crops here. Our spring is generally very short, ahead of a prolonged summer. Sowing early is critical to achieve rapid growth in winter and early spring. For us, hot days during flowering is of more concern than frost.”

Andrew says that having an overall rotation with built-in flexibility is beneficial. For example, being aware of the possible implications of using particular residual products, such as Lontrel, that have long residual effects under some conditions.

“In the fallow, maintaining stubble cover and eliminating weeds are very important, particularly on our lighter soils, to conserve soil moisture,” he says. “Every 1 mm of water conserved equals 15 to 20 kg of grain per ha in this region.”

In mixed farming systems, sheep need to follow the spray rig after harvest. Andrew says more growers are retaining stubble to conserve soil moisture and only burning when the stubble load is likely to interfere with planting equipment. Growers are generally harvesting at increasingly lower heights. There is also slow adoption of stripper fronts that leave tall standing stubble to provide maximum shade of the soil surface, which conserves moisture and suppresses weed germination.

“The stripper fronts work very well in cereals, but some growers are concerned about canola stubble not providing enough protection of the soil,” says Andrew. “Some cut canola crops short, while others slash, graze, or leave the stubble standing.”

Once the crop and pasture rotation is mapped out, the other strategies of the WeedSmart Big 6 can be added – crop competition, mix and rotate herbicides, stop weed seed set, spray effectively and consider harvest weed seed control options.