Potato Review Group

Contents

Background

Risk of Pectobacterium

Reducing the risk of Pectobacterium

Further information:

Blackleg and soft rot notes

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Background

  1. The Erwinia bacteria causing soft rot and blackleg have been re-named as Pectobacterium. More …
  2. There are two forms of concern in the UK:
    • Pectobacterium chrysanthemi atrosepticum (PCA) (formerly Erwinia carotovora sub sp atroseptica, ECA)
      • this survives on plant material but does not survive for long in the environment
      • this is the main cause of Pectobacterium soft rot in the UK
    • Pectobacterium chrysanthemi carotovorum (PCC) (formerly Erwinia carotovora subsp carotovora, ECC).
      • this can be found in the environment (e.g. in irrigation water) in addition to plant material but its presence in the environment is rarely a problem.
    • More …
  3. The major source of Pectobacterium is infected seed tubers. More …
  4. Other species of soft rot have been found in seed imported to the UK from the Netherlands:
    • Dickeya dianthicola
      • this species is becoming established in Europe and disease may develop under warmer, drier conditions than that associated with the Pectobacterium types. More …
    • Dickeya solani
      • this is a particularly aggressive species and has rapidly become the dominant cause of soft rot in the Netherlands. There is a risk of the disease if using seed from the Netherlands. More …

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Risk of Pectobacterium

  1. Many seed tubers will carry sufficient bacteria for infection to occur in suitable conditions. More …
  2. The highest risk of Pectobacterium infection occurs when the environment is cool and moist at planting and then warm and moist after emergence. More …
  3. Anaerobic conditions increase the risk of infection; this can include bruised areas on tubers. More …
  4. Infected seed tubers have the potential to produce blackleg infected plants. More …
  5. Bacteria may be spread to progeny tubers from rotting seed tubers by movement of water in soil or washed from infected haulm on the soil surface. Bacteria may also move through stolons from infected plants to progeny tubers. More …
  6. At harvest bacteria may be spread by contact with rotting tubers or infected soil. More …
  7. Any wounds on progeny tubers, but particularly bruises, increase the risk of soft rot development. More …
  8. The risk of soft rot development in store increases with increasing humidity or temperature and may also be increased by condensation on tubers. More …

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Reducing the risk of Pectobacterium

  1. Handle seed carefully to avoid bruising and damage (tubers are more susceptible to damage after storage than at harvest). See: Bruising and damage.
  2. Avoid planting seed in cold, wet conditions. More …
  3. Harvest in good conditions and avoid bruising and damage. See: Disease development during storage.
  4. Ensure good hygiene of all handling and storage equipment. See: Disease development during storage.

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Further information

Blackleg and soft rot notes

Pectobacterium 2018 (Incidence of infection in seed crops; infection can increase with successive generations of pre-basic seed)

Transmission of seed borne diseases 2018 (Includes soft rot bacteria: Pectobacterium may spread to progeny tubers directly via infection of the plant or indirectly via release into soil and entry via burst lenticels or damage at harvest)

Blackleg and soft rot 2012 (Seed is the main source of inoculum but seed may not show symptoms)

Soft rot updates 2011 (Main source of inoculum is the seed tuber; the higher the contamination of seed, the greater the risk of blackleg and of soft rot on progeny tubers)

Dickeya solani 2010 (A very aggressive form of soft rot)

Recent research on diseases 2008 (Includes soft rots: change of name from Erwinia to Pectobacterium; introduction to Dickeya soft rots)

Tuber rotting diseases 2001 (Includes sources of soft rot bacteria)

Erwinia soft rots 1999 (Erwinia = previous name for Pectobacterium; seed borne bacteria; aerial stem rot; importance of the environment in disease development)

Erwinia soft rots 1998 (Erwinia = previous name for Pectobacterium; different types of Erwinia bacteria; yield loss; bacteria detected on plants with and without symptoms; anaerobic conditions, including bruises on tubers, encourage disease development)

 

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