Aclonifen Herbicide Helping Win The Numbers Game In Cropping Programs

03 March 2026, AU: “It’s a numbers game!” This catch cry is often heard for annual ryegrass control, including of herbicide-resistant populations, putting the focus on reducing the weed seedbank in cropping programs, and long-term trials are showing it’s important to have the ideal chemistry combination to maximise reduction of weed numbers.

Bayer Technical Solutions Agronomists have continued to undertake trials with the company’s pre-emergent and early post-emergent (EPE) herbicide, Mateno® Complete, and, similar to independent trials, they have confirmed that its EPE application is the industry benchmark for annual ryegrass control.

Mateno Complete contains aclonifen, pyroxasulfone and diflufenican, and its use EPE, following an effective pre-emergent herbicide, helps achieve improved and extended control across the entire soil surface, including of weeds in the furrow.

“There are various strategies that can help manage your weed seedbank, including harvest weed seed control, good crop competition, optimised spray application and the use of knockdown herbicides pre-plant, but it’s critical to keep the weed seedbank as low as possible at all times without letting up,” said Matt Willis, Technical Solutions Agronomist with Bayer in Western Australia’s northern agricultural region.

Matt Willis, Technical Solutions Agronomist with Bayer in Western Australia, says the aclonifen active ingredient in Mateno Complete herbicide provides both foliar and root uptake of the herbicide, adding robustness to early annual ryegrass control. Matt says trials have shown an average 5% increase in control with early post-emergent applications of Mateno Complete compared with the next best performing treatment in the trials, and this can result in 50% fewer weed seeds getting through to weed seedbanks.

Over the past five years, Matt has coordinated a dozen trials throughout the northern region and the EPE application of Mateno Complete, compared to other herbicides and tank mixes applied by farmers following pre-emergent use of trifluralin, has achieved an average 5% increase in annual ryegrass control compared to the next best performing treatment.

“Mateno Complete EPE following trifluralin recorded an average 90.4% reduction in ryegrass panicles across all the trials, compared with 85.2% for a typical on-farm herbicide tank mix which does not contain aclonifen applied EPE,” Matt said.

“Application of Boxer Gold® or Arcade® EPE following trifluralin both achieved about 82.5% reduction in ryegrass panicles across these trials.”

He said the combination of the three active ingredients in Mateno Complete, and particularly the aclonifen component, was responsible for the 5% improved control.

“The pyroxasulfone in Mateno Complete provides a very high level of annual ryegrass control with lengthy residual activity, but the aclonifen provides multiple pathways of herbicide uptake and so adds robustness to that initial control, particularly when conditions at application are not perfect.”

“Pyroxasulfone has to be washed-in by rainfall and taken up by plant roots and ideally needs to be moved 1-2 centimetres down the soil profile, below germinating weed seeds. By itself, there is a risk of weeds getting too big prior to activation by this rainfall. Aclonifen uptake is a combination of foliar and root uptake. After application, it will sit on the soil surface and be taken up by emerging ryegrass shoots, providing that extra robustness for control.”

Matt said achieving 5% less control with other herbicides and tank mixes applied EPE was effectively allowing 50% more weed seeds to get through to the weed seedbank – and this was what the aclonifen was preventing.

“In an untreated scenario, as an example, there might be 1000 ryegrass panicles per square metre, and whereas the Mateno Complete EPE treatment is allowing 100 to get through in this case, the on-farm herbicide tank mix treatments are letting 150 of them through – 50 extra panicles. So, the Mateno Complete is reducing the seedbank and providing that benefit for future cropping seasons.”

He said where broadleaf weeds featured in populations with annual ryegrass, the improved weed control provided by the aclonifen in Mateno Complete then increased considerably.

“The combination of active ingredients delivers a complementary benefit, so when targeting problem broadleaf weeds such as wild radish, the aclonifen and diflufenican really becomes a case of one plus one equals three. The performance of Mateno Complete on broadleaf weeds can sometimes be underestimated due to the focus on grasses, but it has shown consistently how strong it is in the field.”

“Tank mixes applied EPE would require a broadleaf herbicide to be included, adding cost and also the potential for increased crop phytotoxicity.

“As a result of the excellent broadleaf weed control benefit with EPE applications of Mateno Complete, there have also been many cases where growers have not had to undertake another broadleaf herbicide application.”

Matt said, importantly, the aclonifen was also offering a different herbicide mode of action for early season grass and broadleaf weed control, effectively taking the pressure off other commonly used herbicides.

Meanwhile, ongoing independent, “showpiece” trials being coordinated in WA, investigating the best upfront herbicide strategies put forward by crop protection companies against annual ryegrass, have once again underlined the EPE Mateno Complete application as the best strategy to achieve optimum annual ryegrass control.

The EPE application of Mateno Complete following pre-emergent use of trifluralin resulted in significantly improved annual ryegrass control and yield gains compared to the industry standard application for ryegrass control, involving a tank mix of trifluralin and Sakura pre-emergent herbicides.

Mateno^® is a Registered Trademark of the Bayer Group.

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