Phytoplasmoses can cause significant economic damage. They are epidemic and have a long incubation period. Symptoms on infected trees become evident only one or two years after contamination, when the disease has already spread to other trees or orchards.

Phytoplasmas (formerly called mycoplasma-like organisms) are considered to be quarantaine organisms in the European Union.

These smallest known microorganisms that - on the contrary to viruses - are able to replicate autonomously, have been termed so in 1994 to distinguish from the animal parasites mycoplasmas. They differ from bacteria by lack of a solid wall and have not been isolated, purified nor cultured on an axenic medium so far. However they are pleomorphic and can strech and cross the sieve plates to migrate towards the roots in autumn and towards the vegetation in spring.

According to EPPO certification schemes planting material of fruit trees in the European Union must be free of phytoplasmas.