Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free:

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site:, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Google Analytics

Targeted advertising cookies


The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at or by post at:

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

Dernière mise à jour : Mai 2018

Menu logoprincipal INRA logo gnis Potato dynamics LTD ARVALIS FN3PT GERMICOPA

Potato tuber blemishes: understanding & diagnosis

Due to abiotic factors

Visual diagnosis

  • Tubers split while still growing
  • Cracks associated with uneven growth  of the tuber frequently start at the bud or apical end of the tuber and can extend lengthwise. If cracking occurs in different directions their may be other causes
  • When tubers are mature, the surface, within the crack, has a corky appearence

The type of deformation depends on when abiotic factors occur :

  • At the beginning of tuberisation, interrupted growth causes a constriction at the basal end of the tuber giving a pear-shape
  • During tuberisation, the tuber may split into two parts, dumbbell-shaped tubers
  • At the end of tuberisation, outgrowth develops at the tip of the rose end (sucker), or at several lateral eyes, tuber with multiple knobs

Potential causes

Tuber deformation and cracks are the results of physiological reactions of the tuber during its growing period
  • One of the main causes of tuber cracks and deformations is an irregular water uptake during the growing period : dry periods alternating with rainfalls
  • Another cause of growth cracking (usually unexpected) is the treatment of the folliage with an unappropriate pesticide causing phytotoxicity (herbicides)
  •  Other abiotic factors such as over or poor nitrogen fertilisation, high temperatures... may also result in tuber cracking
  • Some potato cultivars are more subject to such overall tuber deformation than others.
Specific reference:

Hiller etal (1985). Physiological disorders of potato tubers. In: Potato physiology. Ed.HL Paul. Academic Press, Orlando, Florida, USA. Pp. 389-455

more symptoms

Possible confusing symptoms :