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Faba Bean – Viral Diseases

Bean Yellow Mosaic Virus (BYMV)


  • Caused by Bean Yellow Mosaic Virus (BYMV) which is a common mosaic disease of faba bean caused by potyvirus group.
  • Two variants of the virus have been identified: mild (leaf mosaic with no necrosis) and severe (leaf mosaic with necrosis).
  • Virus is spread from overwintering hosts such as clovers and vetch to faba bean by aphids
  • While infections seldom cause plant death, the impact of yield will depend upon the time of infection, with earlier infections having greater impact.


  • Symptoms start to show 7 – 10 days after the plant has been infected.
  • The youngest leaves have milder green mosaic mottling and veins appear to be branded or yellow; rolling and narrowing of leaves occurs and plants suffer from stunting.


  • Use certified seed.
  • Fungicides are ineffective in managing viral diseases.


  • This virus is not currently producing economic losses in Alberta.



Special thanks to Saskatchewan Pulse Growers and Manitoba Pulse & Soybean Growers.