• Identifying the phytopathogenic agents : methods of diagnosis

Diagnosis is a series of methods available to confirm the origin of an infection and identify the responsible pathogen. These diagnostic methods are varied and are characteristic of either direct or indirect diagnosis.

• Direct diagnosis is the only diagnosis of certainty since it enables to identify the bacteria itself. It makes its isolation possible for a subsequent identification and, also, for precisions as regards its sensitivity to antibiotics (antibiogram).
• The indirect diagnosis shows the reaction of the organism to infections through te presence of specific antibodies, more often seric or more seldom through a hypersensitivity reaction, known as allergenic.

To confirm a diagnosis and prove that the isolated pathogenic agent is really responsible for the symptoms observed, artificial inoculations of the bacteria are done on a host plant in conditions favourable to the infection

These methods are frequently used in bacteriological diagnosis. Most of the diagnosis methods finalized are based on genetic amplification.

These tests activate a specific interaction between the antibodies and the antigens and enable to:
¤ Detect a bacterium in the plant tissues
¤ Identify a bacterium species isolated in an agar medium

These tests can lead to the determination of the genus, species, subspecies and guide the diagnosis.