Barley powdery mildew is caused by the fungal pathogen Blumeria graminis f. sp. hordei and is an important disease of barley, especially in Australia’s
western and northern growing regions. It also has the potential to be very damaging in the southern region during conducive seasons.

Key points

• The barley powdery mildew pathogen has a very high fungicide resistance risk.
• Resistance to Group 3 DMIs and Group 11 QoIs has been reported in several countries.
• Field resistance to some Group 3 DMIs has been detected in barley crops in Western Australia.
• Samples from New South Wales, Queensland, Victoria and Tasmania have shown resistance to some Group 3 DMI fungicides in laboratory tests.
• Careful use and rotation of available fungicides will lessen the spread of resistance in the barley powdery mildew pathogen.
• Agronomic practices that minimise disease pressure reduce the need to apply fungicides.
• Good management will help protect the long-term efficacy of current fungicides.