Vegetable farming disease definitions
Disease resistance is an important element of Starke Ayres’ vegetable seed research, development and production. Here is a glossary of terms used in the area of vegetable seed disease.
Definition of the terms describing the reaction of plants to pests or pathogens
Differing degrees of specificity exist in the relations between plants and pests or pathogens. Identification of such specificity generally requires the use of highly elaborate analytical methods. Recognising whether a plant is subject to a pest or pathogen may depend on the analytical method employed. The specificity of pests or pathogens may vary over time and space, depending on environmental factors, and new pest biotypes or new pathogen races capable of overcoming resistance may emerge.
Immunity: Not subject to attack or infection by a specified pest or pathogen.
Resistance is the ability of a plant variety to restrict the growth and development of a specified pest or pathogen and/or the damage they cause when compared to susceptible plant varieties under similar environmental conditions and pest or pathogen pressure. Resistant varieties may exhibit some disease symptoms or damage under heavy pest or pathogen pressure.
Two levels of resistance are defined:
- High/standard resistance (HR): describes plant varieties that highly restrict the growth and development of the specified pest or pathogen under normal pest or pathogen pressure when compared to susceptible varieties. These plant varieties may, however, exhibit some symptoms or damage under heavy pest or pathogen pressure.
- Moderate/intermediate resistance (IR): describes plant varieties that restrict the growth and development of the specified pest or pathogen, but may exhibit a greater range of symptoms or damage compared to resistant varieties. Moderately/intermediately resistant plant varieties will still show less severe symptoms or damage than susceptible plant varieties when grown under similar environmental conditions and/or pest or pathogen pressure.
Tolerance is the ability of a plant variety to endure abiotic stress without serious consequences for growth, appearance and yield.
Susceptibility: is the inability of a plant variety to restrict the growth and development of a specified pest or pathogen.
Where specific races or strains are not indicated, the variety is resistant to some and not all races or strains of the particular pathogen.
The information presented is based on field and laboratory observations. The reaction of a variety to a pest or pathogen can be affected by environmental conditions and local practices; Starke Ayres does not warrant or guarantee the crop yield, quality and level of claimed pest and pathogen resistances in any manner whatsoever.
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