Phytoplasmas are specialised plant pathogenic bacteria, colonizing the plant phloem tissue. They lack a cell wall, are non-culturable and are transmitted by insect vectors and by vegetatively propagated plant material. These plant pathogens are increasingly spreading and causing economical losses especially on fruit tree production. Molecular detection methods are already available; however sampling, extraction and detection require harmonisation and validation throughout European laboratories. This process would improve the reliability of results enabling the development of improved management strategies to prevent the spread of these diseases. The project's main objective was to carry out inter-laboratory ring-testing to validate test methods, on 16S and 23S ribosomal gene, for the detection of phytoplasmas (’Candidatus Phytoplasma mali’,’Ca. P. pyri’, ’Ca. P. prunorum’) in symptomatic and asymptomatic plants from infected orchards, including nested-PCR and real time PCR.