ISF recommends that companies worldwide use these codes in catalogues and other communication with customers.

One of the goals of the seed industry is the consistent use of terminology. To support this ISF proposes pathogen codes for pests affecting vegetable crops.
See latest update (November 2020): pathogen codes for vegetable crops

The pathogen codes of cereal crops are no longer updated it is only informative.

The codes are reviewed at regular intervals to verify the correctness of the information provided and an updated version is posted online every year. As an aid to seed companies in major non-English speaking countries common names of diseases affecting vegetable crops in Dutch, French, Japanese and Spanish have also been listed.
See: compiled pathogen codes table

Guidelines for Coding Pests of Vegetable and Cereal Crops

General Rules

Every effort has been made to remain consistent with the terminology used by internationally recognized institutions such as the American Phytopathological Society (for fungi), the International Committee for the Taxonomy of Plant Pathogenic Bacteria (of the International Society of Plant Pathology (ISPP)) (for bacteria) and CAB International Bioscience (formerly the International Mycological Institute, IMI) (for fungi and bacteria), and the International Committee for Taxonomy of Viruses (ICTV) (for viruses). In case of any deviation an explanatory note is provided.

Taxonomic changes to the Latin binomial may necessitate a change in the code. The following procedure has been established:

  1. List the old name and quote the new name between brackets, i.e. ‘old name’ (now ‘new name’)
  2. List the new name and quote the old name between brackets i.e. ‘new name’ (ex ‘old name’)
  3. Quote the new name only

The transition from one step to the next is three years to allow companies and their customers worldwide to become accustomed to the change. It also takes into consideration the fact that organisations such as ICTV meet only once in three years to evaluate proposed taxonomic changes. Companies may choose to use the new name and accompanying code in catalogues and other communication earlier if they wish.

A pest affecting more than one crop receives one code.


  • Codes adopted by ICTV will be used. They are in capital letters, except in cases where a letter in lower case is added to differentiate between two viruses with the same initials, e.g. TMV and ToMV.
  • In case there is a deviation from the code used by ICTV, an explanatory note will be added to the text.

Fungi, Bacteria, Nematodes and Insects

  • In general two letters corresponding to the first letter of the genus and species of the Latin name will be used, e.g. Fusarium oxysporum = Fo.
  • The use of a single code for different pests affecting a crop species will be avoided. In such cases the second or any other relevant letter of the species name will be added to the code, e.g. Corynespora cassiicola and Cladosporium cucumerinum are two different diseases in gherkin and the assigned codes are Cca and Ccu, respectively.
  • For different subspecies of a pest in the same crop species causing different diseases, the subspecies will be defined by a letter in lower case, e.g. Fol and For respectively for Fusarium oxysporum f. sp. lycopersici and Fusarium oxysporum f. sp. radicis-lycopersici in tomato.


The following separators will be used:

  • / (slash) - to separate pest codes
  • : (colon) - to separate the species code from the strain/race/pathotype code. The colon is followed by a space
  • , (comma) - to separate strain/race codes. The comma is followed by a space
  • - (hyphen) - to indicate an uninterrupted series of strain/race numbers
  • . (dot) - to separate numbers defining a compound strain/race name
  • order of pathogen codes: viruses, bacteria, fungi, insects, nematodes

Using the above convention, resistance in a variety to Ua and Cl strains 1 and 2 would be denoted as Ua/Cl: 1, 2.

A series of race numbers following a logical and uninterrupted order will be abbreviated in a 'from-to' mode. For instance Fol: 1, 2, 3 would be noted as Fol: 1-3. Strains 1 to 25 of Bremia in lettuce will be noted as Bl: 1-25. An interrupted series will be presented in the following manner - Bl: 1-16, 21, 22-25.

An example of a virus strain with a compound name is PMMoV: 1.2.3.

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