Phytoplasma

Phytoplasmas are a type of parasitic bacteria. They are pathogens of economically important plants, including coconut, sugarcane, and sandalwood.
They are obligate parasites of plant phloem tissue. Their vectors are insects which inject then into the plant cells. They were discovered by scientists in 1967 and were named mycoplasma-like organisms or MLOs. They cannot be grown "in vitro" (in laboratory conditions), and that limits the information about them. They are described by the special term "Candidatus", reserved for such difficult organisms.