Below you will find the definitions of the terms describing the reaction of plants to pests or pathogens and to abiotic stresses for the vegetable seed industry (based upon an ISF approved version, May 2017).
The relationship between a plant and a pest or pathogen is very complex. The terms that describe the reaction of a plant variety to a pest or pathogen are determined by tests with known and characterized biotypes, pathotypes, races or strains of the pest or pathogen in question.
In practice however, the ability of a pest or pathogen to cause disease in or damage to a plant depends on environmental conditions, the properties of the organism itself and the capacity of the plant to defend itself. Plant varieties within a species can differ in their ability to defend themselves. Under different conditions, such as age of the plant, pest or pathogen pressure and degree of virulence or adverse environmental conditions, the interaction between the same plant variety and pest or pathogen may have different outcomes.
Pests and pathogens are known to develop and form new biotypes, pathotypes, races or strains that can cause disease in or damage to plants that remain unaffected by the original form of the pest or pathogen.
Resistances in varieties of our crops will be coded (please, see our coding list for explanation), unless indicated otherwise.
To separate pest organisms, species codes and strain codes, the following separators will be used:
Varieties claiming the same level of resistance against a specific pest or pathogen may exhibit a different resistance response due to a different genetic makeup of a variety.
It is to be noted that if a resistance is claimed in a plant variety it is limited to the specified biotypes, pathotypes, races or strains of the pest or pathogen.
If no biotypes, pathotypes, races or strains are specified in the resistance claim for the variety, it is because no generally accepted classification of the cited pest by biotype, pathotype, race or strain exists. In this case resistance is only claimed against certain not further specified isolates of that pathogen. New biotypes, pathotypes, races or strains that may emerge are not covered by the original resistance claim.