Virulence complexity and its increasing in the Czech population of Blumeria graminis f.sp. hordei
A. Dreiseitlhttps://doi.org/10.17221/10546-PPSCitation:Dreiseitl A. (2002): Virulence complexity and its increasing in the Czech population of Blumeria graminis f.sp. hordei . Plant Protect. Sci., 38: 531-532.
The virulence frequency to 12 resistance genes present in the studied cultivars in the time before their first using in grown cultivars were estimated mainly based on the data of cultivar resistance in the field. The estimated virulence frequency is compared with results obtained from investigations of the air pathogen population in 2001. The comparison shows that virulence complexity increased from about 0.90 in 1971 to 8.73 in 2001. The increase in virulence complexity was caused by necessity of the pathogen to survive on cultivars possessing respective resistance genes, it means by direct selection [(Va1, Va6, Va7, Va9, Va13, Vat, Vk1, VLa, Vg and V(Kr)], indirect selection (Va12) and immigration (Va3).Keywords:
barley; Blumeria graminis f.sp. hordei; Erysiphe graminis f.sp. hordei; powdery mildew; resistance genes; virulence complexity; virulence frequency