- Common scab is caused by Streptomyces scabies; the genus Streptomyces is in the Actinomycetes class of bacteria.
- Infection of progeny tubers with common scab is likely to result from soil borne inoculum but high levels of seed borne inoculum can also result in infection of progeny tubers. More …
- Common scab has a wide host range and may persist in fields for a long period in the absence of potatoes.
- Infection occurs through lenticels before they are suberised (usually before tubers reach 20 mm). More …
- Other Streptomyces species may also cause scab symptoms. These species may have different environmental requirements to S. scabies e.g.:
- S. acidiscabies may cause infections at lower pH
- S. turgidiscabies may cause infections in moister soil
- More …
- Some scab-like blemishes can caused by environmental conditions, e.g. healing of burst lenticels. For further details see: Skin appearance.
Reducing the risk of common scab
- Development of common scab may be reduced by antagonistic soil bacteria.
- The bacteria are favoured by low soil pH and high moisture content: these conditions reduce the risk of common scab.
- Application of sulphur to reduce soil pH does not provide consistent suppression of common scab. More …
- The risk of common scab may be reduced most effectively by maintaining moist soil during tuber formation and early growth.
- Avoid growing susceptible cultivars at sites with a risk of common scab, check the British Potato Variety Database.
- Seed certification standards allow relatively high levels of infection but there is some evidence of an influence of seed infection on progeny tuber infection. More …
Common scab notes
Transmission of seed borne diseases 2018 (Infection occurs by Streptomyces filaments entering lenticels; disease on progeny tubers may be related to level of infection on seed)
Common scab and irrigation 2013 (Influence of irrigation regime on soil micro-flora, common scab infection and crop performance)
Tuber blemishing diseases 2012 (Streptomyces species in the UK; role of antagonistic micro-organisms)
Blemishing disease updates 2011 (Includes reports of treatments to potentially suppress common scab)
Tuber blemishing diseases 2006 (Includes affects on common scab of antagonistic bacteria and of seed borne inoculum)
Common scab 2003 (Streptomyces species; influences of sulphur and pH, aluminium, soil moisture and inoculum density)
Common scab 2001 (Summary from previous Notes of influences on infection)
Tuber blemishing diseases 1999 (Includes common scab: infection occurs through lenticels; antagonistic bacteria can suppress infection)
Tuber blemishing diseases 1998 (Includes influence of seed borne common scab)
Common scab 1996 (Influence of water pH and nutrients)
Common scab 1994 (Chapter begins down the page: common scab is one of the most prevalent blemishing diseases; importance of early water)