Australian Researchers Warn of Unprecedented Disease Threat to South Australia’s Grain Industry
Adelaide, May 21, 2025 – Barley growers in South Australia’s Yorke Peninsula are being urged to reassess their disease management strategies after researchers confirmed the presence of fungal resistance to three key fungicide groups in local paddocks. This development presents a serious risk to barley yields and grain quality in one of the country’s most important cereal-producing regions.
Fungal Disease Escalation: Resistance Across Groups 3, 7 and 11
Laboratory analysis of samples collected from farms in Corny Point, Warooka, and Paskeville has revealed genetic mutations in the net form net blotch (NFNB) pathogen. These mutations are associated with reduced sensitivity or outright resistance to three main fungicide modes of action—Demethylation Inhibitors (Group 3), Succinate Dehydrogenase Inhibitors (Group 7), and Quinone outside Inhibitors (Group 11).
These findings were made under a research initiative supported by the Grains Research and Development Corporation (GRDC), with testing led by the Australian Fungicide Resistance Extension Network (AFREN) based at Curtin University.
Implications for Fungicide Efficacy
In affected South Australian fields, fungicide applications failed to control the NFNB disease effectively, indicating a widespread resistance across all registered fungicide options currently available to local growers. While a sample from Streatham in Victoria showed no such resistance, experts caution that continued fungicide use in those areas could foster similar resistance development.
Expert Advice: Rethink Crop Protection Plans
Ruth Peek, GRDC Crop Protection Manager – South, emphasized the need for immediate action:
“Growers should eliminate green bridge volunteers, use resistant barley varieties, and consult local agronomists to tailor fungicide strategies that reduce resistance pressure.”
Associate Professor Fran Lopez-Ruiz, AFREN Project Lead, added:
“Managing crop rotations, minimizing fungicide use, and selecting disease-resistant barley cultivars are the most effective long-term approaches to slowing resistance.”
Researchers are particularly concerned about the rapid spread of resistant spores, which can disperse via wind and rain splash within and between fields, possibly introducing the resistant strain into adjacent areas.
Fungicide Resistance Five: Best Practices for Growers
To combat fungicide resistance, AFREN recommends a multi-pronged approach:
- Choose less susceptible crop varieties
- Rotate crops to break disease cycles
- Apply non-chemical control measures like stubble grazing
- Spray judiciously and only when truly needed
- Use diverse fungicide modes of action and mixtures
A Wake-Up Call for the Barley Industry
Barley plays a critical role in Australia’s agricultural output, particularly in food production, brewing, and livestock feed. The discovery of triple resistance in NFNB pathogens serves as a serious warning for growers to act decisively, especially in areas where disease pressure is already high.
Authorities stress that proactive disease prevention and reduced reliance on fungicides are essential to preserving the effectiveness of existing tools and ensuring long-term crop protection.
