Biology Reference
In-Depth Information
serological methods used in virology are difficult
to apply because phytoplasmas (except for
spiroplasma) have not been cultured. Thus the
true nature of phytoplasmas and RLOs, and
their taxonomic position among microorganisms
is uncertain. In practice, the diseases caused by
mollicutes have been taxonomically been treated
individually. The elucidation of true relatedness
among these organisms awaits further research.
The general nature of the symptoms and the
name of the host plant will, in many cases, leave
little doubt as to the identity of a bacterial dis-
ease. In the case of the soft rot due to
Erwinia
carotovora
the nose alone is a reliable guide. In
other cases identification must be left to the
technically trained bacteriologist. It involves
special staining technique, for examination of
form and motility under the microscope, and to
see whether it is Gram-negative or Gram-posi-
tive, and special culture technique to determine
shape, color, and texture of colonies on agar and
gelatin, production of gases, fermentation of
sugar, coagulation of milk, etc. If you are in
doubt about a plant disease, and the absence of
fungus fruiting bodies leads you to believe that
bacteria may be at work, send a specimen to
your State Experiment Station for expert
diagnosis.
