Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie


Shelf life

CAS and PHP session cookies

Login credentials, session security



Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie


Shelf life


Trace the visitor's route in order to establish visit statistics.

13 months


Store the anonymous ID of the visitor who starts the first time he visits the site

13 months


Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at or by post at :


24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021

Menu logoprincipal INRA logo gnis Potato dynamics LTD ARVALIS FN3PT GERMICOPA

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