Since their discovery, viruses have fascinated researchers by their extreme characteristics. Virology, the science of viruses, helps to understand the diseases they cause to human beings. Plant viruses or phytoviruses represent a serious problem in the agricultural sector where they cause important damage.
Virus diseases of plants have an important economical effect. They cause a reduction of the plant’s strength and very often modify the aspect of certain plant organs. In all cases, a decrease of more or less importance in yield is observed.
Viruses are pathogenic organisms of very small dimension, invisible to optical microscopes. They can’t multiply themselves out of a living cell, they are obligatory parasites.
Viroids have been discovered in 1971 by the specialist of plant diseases T. O. Diener. These particles, smaller than viruses, are made of a single stranded RNA and do not have protein coat (capsid).
Virology is a recent subject. One could expect a structured nomenclature and a well codified use. This is not the case, but the subject benefits from mitigating circumstances.
Generally, viral particles are rapidly denatured out of the living cells of a host plant
In plant viruses, contaminations usually occur through an animal vector such as an insect which will transport the virus from an infected plant and inoculate it to a sound plant.
The general rules of control against phytopathogenic agents can be applied to viruses. They include the production of sound planting material, the elimination of infectious sources and vectors as well as the resort to resistant or tolerant varieties.
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