Virulence structure of the Blumeria graminis DC.f. sp. avenae populations occurring in Poland across 2010–2013

The aim of the present study was to determine the virulence structure of powdery mildew of oats ( Blumeria graminis DC.f. sp. avena ) in Poland in the years 2010–2013. For this purpose, powdery mildew isolates were collected from three experimental stations in Poland. To assess the virulence of the isolates, eight oat varieties with different responses to the pathogen were used. The results showed that a significant proportion of powdery mildew isolates found in Poland overcame the resistance genes of varieties Bruno ( Pm6 ), Jumbo ( Pm1 ) and Mostyn ( Pm3 ). In contrast, lines Av1860 ( Pm4 ), Am27 ( Pm5 ) and Cc3678 ( Pm2 ) were completely resistant to all pathogen isolates involved in the experiment. Changes constantly occurring in the powdery mildew population perfectly reflect diversity indexes, which were the smallest in the first year of observation, where in the following years these parameters were significantly higher. It is worth noting that the presence of powdery mildew is seasonal and local, which is reflected in the prevalence of the disease in a defined area of the country.