Recently, Russian olive trees showing witches'-broom and little leaf symptoms have been widely observed in northwestern and central Iran. Polymerase chain reaction (PCR) and nested PCR assays using phytoplasma universal primer pairs confirmed phytoplasma symptomatic infection of trees. Sequence analyses showed that 'Candidatus Phytoplasma asteris' was the causal agent of the disease in these regions. However, RFLP results using restriction enzymes HpaII, EcoRI, HinfI and AluI indicated that the collected isolates in these regions are genetically different. In addition, leafhopper Macropsis infuscata was recognized as a possible insect vector of the disease for the first time.

Phytoplasmas are non-cultivable, wall-less bacteria belonging to the class Mollicutes. They are classified as ʻCandidatus Phytoplasmaʼ species, all of which are plant pathogens. 'Ca. Phytoplasma phoenicium' is one of the most important phytoplasmas that infects various herbaceous and trees throughout the Middle East and Mediterranean countries. 'Ca. P. phoenicium' belongs to the 16SrIX phytoplasma group (The IRPCM Phytoplasma/Spiroplasma working team-Phytolasma taxonomy group, 2004) and shares several genetic

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