University of Hertfordshire

From the same journal

By the same authors


  • A. P. Van de Wouw
  • J. F. Stonard
  • B. J. Howlett
  • Jon S. West
  • Bruce D.L. Fitt
  • S. D. Atkins
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Original languageEnglish
Pages (from-to)809-818
Number of pages10
JournalPlant Pathology
Early online date17 May 2010
Publication statusPublished - Oct 2010


Phoma stem canker (blackleg disease) of Brassica napus (oilseed rape, canola) is caused by the fungus Leptosphaeria maculans. Frequencies of avirulent alleles for loci where virulence can be associated with gene deletion (AvrLm1 and AvrLm6) were determined in samples of L. maculans airborne ascospore inoculum using quantitative PCR. The accuracy, reproducibility and limitations of detection were determined. Changes in the frequency of avirulent alleles were determined for the 2006/2007, 2007/2008 and 2008/2009 growing seasons for winter oilseed rape in the UK. The frequency of AvrLm1 remained small (between 9% and 16%), whilst the frequency of AvrLm6 fluctuated between 35% and 66%. Estimation of frequencies of avirulent alleles in airborne pathogen inoculum gives an efficient and unbiased method to assess the potential of crop cultivars with corresponding resistance genes being at risk of disease.

ID: 398964