Codes for pest organisms

The interaction between plants and pests is influenced by multiple factors, including environmental conditions, pest pressure, and the plant’s natural defense capacity. As plant varieties may respond differently — and new pest strains may emerge — consistent terminology is essential for clear communication.

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Harmoniz follows the definitions established by the International Seed Federation (ISF), Vegetable and Ornamental Crops Section (2022) in “Definition of the Terms Describing the Reaction of Plants to Pests” , adopting the internationally recognized terms Susceptibility, High Resistance (HR), Intermediate Resistance (IR), and Immunity to ensure transparency and accuracy in varietal claims.

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1. Terminology and definitions

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Susceptibility (S): the inability of a plant variety to restrict growth and/or development of a pest, causing symptoms and/or damage.

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‍Intermediate Resistance (IR): the ability of a plant variety to restrict the growth and/or development of the specified pest, and/or the symptoms and/or damage it causes, to a moderate degree. IR varieties may exhibit a greater range of symptoms or damage compared to HR varieties (see below High Resistance) under similar environmental conditions and pest pressure. However, IR plant varieties will still show less severe symptoms or damage than susceptible plant varieties when grown under similar environmental conditions and/or pest pressure.

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High Resistance (HR): the ability of a plant variety to restrict the growth and/or development of the specified pest, and/or the symptoms and/or damage it causes, to a high degree. HR varieties may still exhibit minor symptoms or damage under heavy pest pressure and should not be confused with immune plants that are defined as unable to support any pest growth and development.