To assess the impact of region and powdery mildew pathotype on field response of varieties with a range of resistance rankings to powdery mildew within the Western Australian barley producing zones.

• Powdery mildew severity at the WMG field site, maximum of only 7% leaf area affected on Baudin, did not allow differences between varieties to be seen, other than VS and S types (Baudin, Stirling, Vlamingh, Gairdner)
• Laboratory seedling tests indicate that some of the genes postulated to provide resistance to powdery mildew in some commercial barley varieties may be compromised by some powdery mildew isolates.
• Field screening of these varieties has shown that local differences in variety responses can occur but no widespread regional variation, or ‘breakdown’ in the field resistance of varieties to powdery mildew was observed in 2013.
• The field response of commonly grown varieties at the WMG site and across the seven trials generally reflected the resistance rankings published in variety guides.
• The differences identified in 2013 were of minor impact, or occurred in non-commercially relevant varieties, however they indicate that regional differences in variety response are possible due to variability within the pathogen population and continued monitoring is important to facilitate appropriate disease risk assessment and in-crop management.
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