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Faba Bean – Seed and Soil-Borne Diseases

Root Rot Diseases – Seed Rot, Root Rot, Seedling Blights; Rhizoctonia Root Rot, Fusarium Root Rot, and Damping off. 


  • These are soil-borne diseases caused by species of Pythium, Rhizoctonia and Fusarium.
  • Pathogens (various fungal and fungus-like organisms) associated with root rot often appears as a complex, where more than one pathogen is present, making identification of the primary causal agent difficult. 
  • Fusarium is the most widespread disease of faba bean around the world, though it is not currently found in Alberta.
  • These pathogens can infect and kill individual seedlings and affect the plant at any stage between germination and maturity, and any part of the root system up to a short distance above the soil surface.
  • These fungi are common in the soil, and infection is more likely if the soil around the seed is excessively wet.
  • Other factors, including abiotic conditions such as flooding and soil oxygen depletion can result in root cell death. 
  • The pathogens overwinter on crop residue and in the soil.


  • Infected areas are greyish-brown to black – infection often begins on the feeder roots and progresses gradually towards the main root (in some cases, all roots are destroyed).
  • Symptoms on foliage are also progressive, ranging from a few yellow leaves to pronounced yellowing of the top growth and severe stunting.
  • If infection occurs early, it can cause seed rot and pre- and post-emergence damping-off – seedlings will sometimes show a constriction of the stem at or near the soil line.
  • Infected seedlings usually die, resulting in poor stands.
  • Typically occur in patches and may expand if conditions are favourable for the pathogens over several growing seasons. Symptoms are often associated with areas of flooding or waterlogging.


  • Follow a crop rotation that does not include faba bean or other legumes (pea, lentil, bean, alfalfa, clovers) more than once in four years will reduce the build-up of soil-borne pathogens, however, many of these pathogens can survive as saprophytes in the absence of a susceptible host. Therefore, crop rotation may have a limited effect in managing seedling blight and root rot.
  • Ensure good soil fertility to produce a vigorous crop stand
  • No fungicides are presently registered for control of this disease in faba bean.
  • Seedling stress or damage due to environmental or herbicide injury can lead to an increase in the incidence of seedling blight.
  • A seed test can determine if faba bean seed is infected with a seed-borne disease, such as Anthracnose, Ascochyta, Botrytis, Sclerotinia, or Fusarium. Consider using a seed treatment: (1) if disease is detected (2) if there is a history of soil-borne diseases or, (3) if seeding under cool moist soil conditions. If a seed treatment fungicide is used, ensure compatibility with rhizobia inoculants.
  • As prevention measure, seed treatments offer protection to the developing seedling, especially under cool, wet conditions when emergence may be delayed.
  • Taking note of disease presence in previous years’ crops can help tailor seed treatment selections.
  • Use seed with high vigour, practice good soil fertility, liming of acid soils and ripping to reduce soil compaction.
  • Choose fields that have good tilth and no compaction problems, so plants can form hardy roots, and moisture can move freely through the soil.
  • Understanding the disease, identifying the risks for root rot infection, and thorough planning for prevention are the only current options.


  • Root Rot diseases in faba beans have less economic importance than foliar diseases.


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