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Potato tuber blemishes: understanding & diagnosis


Potato tuber blemishes

Potato tubers can exhibit a wide range of tuber blemishes which may affect their marketability as seed, table or processing potatoes.  Some blemishes are the result of infection by pathogens or attack by pests, whilst others can be caused by abiotic factors.  In addition, a number of commonly occurring blemishes are of undetermined provenance. They are cited in literature under variable denominations, and are sometimes loosely attributed to known pathogens following individual field experience rather than by scientific demonstration through Koch’ postulates, for example.  Another issue is that the same blemish may have a range of names, which adds confusion when seeking out the cause.

Identification of a potato tuber blemish and establishing the cause is important if recurrence of the blemish is to be prevented and where risks associated with the blemish are to be understood.

Across the world, research and diagnostic laboratories and commercial companies hold a great deal of knowledge and experience of potato tuber blemishes but there is no easy and accessible means for experience to be shared.

These problems, linked to the complexity of diagnosing tuber blemishes, led French and Scottish scientists to jointly organize a workshops during the 18th and 19th EAPR Triennial Conference in Oulu, Finland, in 2011. Over 80 participants from 20 countries attended the workshop and agreed that it would be valuable to set up a collaborative tool to share knowledge on all potato tuber blemishes whether their cause is established or not. The web site was lauched during the workshop at the 19th EAPR Triennial Conference in Brussels,2014.

This website is the outcome of efforts to produce a collaborative tool. Its initial objectives are:

  • to classify blemishes on the basis of their appearance, identify known or potential causes, and list other blemishes with which it may be confused
  • to describe the causes of blemishes, and to relate them to the different types of symptoms they may cause,
  • to establish a mechanism whereby users of the website can add information, comments or photos to enhance knowledge transfer in this specific area

This web-site is therefore organized according to each of these objectives. It enables information to be accessed in a straightforward way:

either            i) by the observation and categorization of symptoms

or                 ii) by a known specific pathogen, pest orabiotic factors.

We are fully aware that a wealth of descriptive literature on symptom diagnosis is already available but we feel the advantages of this website are its very specific area (only tuber blemishes) and the comparative approach to symptom diagnosis which is not a feature in most literature. It is hoped that this website is complementary to other websites such as the PotatoNet mailing list (developed by the Oregon State University Potato Program and Potato Association of America) where world-wide potato professionals have been exchanging view points for many years.

We would welcome comments, references, photos etc. for inclusion on any of the potato tuber blemishes already included and others not yet included ; it can easily be posted in the Your comments