- Inoculum may be seed borne, soil borne or both; severity may be greatest where both sources occur.
- Infection of growing plants may occur by a variety of methods.
- Severity of infection generally increases with a longer season of growth or later date of harvest.
- Severity of infection may increase during storage.
Blemishing diseases and yield
- Blemishing diseases reduce marketable yield due poor visual quality of tubers.
- Blemishing diseases can also reduce yield potential if infection also occurs on stems, stolons or roots.
Blemishes not caused by diseases
- Blemishes on the tuber surface are not always caused by diseases.
- Blemishes may be initiated by stress or physical damage.
- The tuber surface supports a wide range of micro-flora which may be:
- antagonistic to pathogens
- exploiting areas of damage
- For further information on blemishes not caused by diseases see: Skin appearance.
Blemishing diseases general notes
Transmission of seed borne diseases 2018 (Inoculum on the seed surface may cause infection of growing plants by methods which vary between diseases)
Tuber blemishing diseases 2012 (Bacteria and fungi in soil and on the tuber surface may be antagonistic to pathogenic micro-organisms)
Tuber blemishes 2011 (Skin blemishes not caused by diseases)
Notes for 1993 (Chapter 12: conditions through the season which can influence infection by blemishing diseases. Chapter 13: influence of some blemishing diseases on crop performance)