Disease Resistance Abbreviation Guide

Susceptibility is the inability of a plant variety to restrict the growth and/or development of a specified pest.

Resistance is the ability of a plant variety to restrict the growth and/or development of a specified pest and/or the damage it causes when compared to susceptible plant varieties under similar environmental conditions and pest pressure.

Resistant varieties may exhibit some disease symptoms or damage under heavy pest pressure. Two levels of resistance are defined.

• High Resistance (HR): plant varieties that highly restrict the growth and/or development of the specified pest and/or the damage it causes under normal pest pressure when compared to susceptible varieties. These plant varieties may, however, exhibit some symptoms or damage under heavy pest pressure.
• Intermediate Resistance (IR): plant varieties that restrict the growth and/or development of the specified pest and/or the damage it causes but may exhibit a greater range of symptoms or damage compared to high resistant varieties. Plants with Intermediate Resistance will still show less severe symptoms or damage than susceptible plant varieties when grown under similar environmental conditions and/or pest pressure.

Resistance Coding is based on Pathogen Codes of the International Seed Federation.

The order of the resistance claim coding is according to alphabetical order within the pathogen groups, which have the following order; Virus/Bacteria/Fungus/Nematodes/Insect.

Bayer follows commonly used strain denomination and ISF guidelines. As there is still some difference of strain nomenclature, the commonly used strain nomenclature of the region is used.

For example:

• Fusarium:   Fol:0,1,2 (EU)  =  Fol:1,2,3 (US)   is same as Fol:0-2 (EU) = Fol:1-3 (US)
• Verticillium:   Va:0/Vd:0 (EU)  =  Va:1/Vd:1 (US)

For more information on resistance definitions, visit the International Seed Federation.