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A reveals that Australian grain and cotton growers are achieving productivity gains by investing in smarter, long-term weed management strategies, proving weeds can be beaten.

A decade on from the last national estimate, new CSIRO research has found that weeds cost the grain and cotton industries an estimated $4.43 billion per year.

Taking into account inflation and adjusted values, this is a 7% increase in costs for grain growers. However, despite this increase in costs, growers are reaping the rewards of their investment.

Through proactive management and innovation, the impact of weeds on crop yield has fallen, from 2.8 million tons in 2016 to 1.2 million tons in 2025, translating into higher production and income.

"Weed control remains one of the biggest annual costs for growers, but the investment is paying off," said Rick Llewellyn, CSIRO Research Scientist who co-authored the report led by Jackie Ouzman.

"By staying ahead of the weed seed bank, resistance and adopting smarter, more targeted practices, growers are protecting long-term profitability and enabling flexibility in their system."

Australian growers lead the way with integrated weed management, combining pre-emergent herbicides, harvest weed seed control, crop rotation and new precision technologies such as camera-guided spraying.

One of the biggest gains comes from improved summer fallow weed control, which helps conserve valuable soil moisture and supports better crop establishment in drier seasons, an essential part of farming in a changing climate.

"Effective weed control is a critical part of climate adaptation," said Dr. Llewellyn. "With increasingly variable rainfall and larger cropping programs, growers need to sow crops when conditions are right without delays for weed control."

The 2025 study also includes cotton production for the first time, offering a fuller picture of weed impacts across Australia's two largest cropping sectors.

Weeds cost producers on average $4.3 billion ($203 per ha) in grain crops and $145 million ($445 per hectare) in cotton crops—with cotton growers shown to invest heavily in keeping weed densities exceptionally low.

"Australian growers are showing global leadership in weed management, but the cost increases are real. We need to keep supporting research and find ways to stay ahead of evolving weed challenges while also reducing these costs," said Dr. Llewellyn.

The study reaffirms continued investment in weed management research, not just for reducing losses, but for unlocking gains in productivity, climate resilience and sustainable land use.

"The only reason we're not seeing widespread yield losses from weeds today is because of years of sustained research and grower innovation," Dr. Llewellyn said.

"This is a quiet success story, but it's a battle where you can't pause—the weed challenge keeps evolving and demanding new solutions."

New weed threats continue to emerge at a local level but nationally the most costly weeds remain familiar: ryegrass, brome grass, sow thistle, wild radish and wild oats, while the costliest fallow weeds in grain production at a national level are melons, heliotrope and fleabane.

Management of weeds remains a high research priority with GRDC re-investing in five-year, nationally coordinated, $47 million Weed Management Initiative.

Under the initiative, GRDC will invest $25 million to create regional nodes with strategic partnerships with $22 million in co-contributions from the University of Western Australia, the University of Adelaide, Charles Sturt University and the University of Queensland.

Weed management in Australia is grounded in decades of research, development and extension and reflects GRDC's commitment to grower accountability, innovation and long-term return on investment.

The WMI will support more than 20 weed research scientists, working under experienced node leads, as well as 12 new Ph.D. student scholarships to build critical capacity in this field.

Results by region

Cropping regions vary across Australia and are grouped into similar zones—see below for specific impact and costs per cropping zone.