Last week at the International Weed Science Congress in China, a world-leading Queensland researcher presented findings of trials demonstrating breakthroughs in managing a costly weed - Phalaris - across Asia and Australia.
The trials reveal that combining targeted herbicides, innovative crop competition and specific planting systems delivers effective control.
The findings will help Australian grain growers manage Phalaris (Phalaris paradoxa) more economically and sustainably. They are also attracting strong international interest.
The research, funded by the Grains Research and Development Corporation's (GRDC) Weed Management Initiative, is led by University of Queensland (UQ) weed researcher Professor Bhagirath Chauhan. He is challenging long-held approaches to eliminating weeds in crops with new findings on the integrated management of Phalaris.
Professor Chauhan leads the Queensland and northern NSW node, one of four nodes across Australia, of the $47 million Weed Management Initiative. He said the findings of trials across northern NSW confirm that sustainable weed management depends on combining herbicides with good agronomy.
The management of Phalaris has traditionally been through the sole use of post-emergent herbicides, however Professor Chauhan and his team are combining different pre-emergent herbicide use with crop competition, specifically through optimal seeding rates and row spacing, while using tyne sowing rather than discs to sow the seeds.
Professor Chauhan said that rather than just one line of attack against Phalaris using chemicals, he found using multiple methods was delivering outstanding results, particularly as the weed had developed resistance to many post-emergent herbicides.
"In 3 of 4 on-farm trials in 2024, our strategies to manage Phalaris outperformed the industry-standard single post-emergent herbicide approach. We recorded yield increases of up to 27 per cent in wheat and clear weed suppression advantages in chickpea," Professor Chauhan said.
As part of GRDC's Weed Management Initiative, we are repeating these trials to make sure what we observed once is in fact repeatable and could become part of northern cropping programs.
Northern NSW grower, Matt Langfield got involved in the Weed Management Initiative trial off the back of an increased presence of Phalaris that he was keen to understand and get on top of.
"We have a bit of an issue with resistant Phalaris in our winter cereals, mainly wheat. And we struggle to control Phalaris purely with in-crop herbicides," Mr Langfield said.
"So, we're working with Bhagirath in this trial to try and understand how we can use plant density in conjunction with herbicides in our system."
In a field at his Bellata property, Mr Langfield showed how the team had been testing how plant density, varying the number of seed per square metre sown, had produced different rates of competition with the Phalaris.
We've also worked on sequential herbicide applications, applied before the weeds emerged and then followed by post-emergence spraying. It's provided consistent and near-complete Phalaris control - this is a new approach for us, and we were keen to test its impact.
The research is also looking at the significance of using a tyne planter, rather than a disc, with pre-emergent herbicides to prevent crop toxicity. The tyne throws treated soil out of the furrow and prevents damage to the crop.
"We're looking at how different herbicides can be rotated or used in sequence, and how non-chemical strategies like crop competition can work alongside them. Ultimately, the goal is to reduce the weed seed bank and identify the best integrated weed management program for growers," said Professor Chauhan.
GRDC Senior Regional Manager - North, Rebecca Raymond, said Australian weed research was respected globally, with Professor Chauhan leading the Scientific Program Committee and GRDC Manager Weeds, Sarah Morran, attending the upcoming International Weed Science Congress in Nanjing, China.
"Australia isn't the only country to struggle with Phalaris in grain crops. The first herbicide-resistant Phalaris minor occurred in India in the 1990s, and it is now a problem across other Asian countries' winter crops as well," Ms Raymond said.
"Australian research and innovation is sought internationally to help with this weed, and it's great to share our knowledge about non-chemical methods to help manage it.
Relying on one herbicide mode of action is not sustainable. By integrating herbicide programs with competitive crops, we can protect yields now and preserve our chemistry options for the future.
GRDC's Weed Management Initiative, is a 5.5-year program bringing Australia's leading researchers and communications and extension specialists together to work on innovative, cutting-edge weed management research, development and extension.
It aims to provide sustainable and effective weed management strategies through the four nodes across Australia, ensuring both national collaboration and regional specificity.
A key component of the initiative is capacity building, with UQ establishing three PhD positions and one postdoctoral position to develop the next generation of weed science experts
